Class 10

SSLC Biology Chapter 1 Sensations and Responses Textbook Questions and Answers

SCERT Class 10th Standard Biology Chapter 1 Sensations and Responses Solutions

Biology Class 10 Kerala Syllabus Question 1.

List the variety of experiences experienced by the children and other organisms in the picture.
Answer:

• A child tasting a mango.
• A snail withdrawing its body into the shell when it ¡s touched.
• Butterfly sipping nectar from flowers.
• The chirping of birds.
• The gentle pat of the breeze.
• The birds fly away on hearing sound.
• Enjoying colourful scenes
• The intoxicating fragrance of flowers.
• Washing the face using cold water.

Question 2.
What are the factors to which children and organisms respond in the picture?
Answer:

• Touch
• Sound
• Taste
• Light
• Smell

Question 3.
What are stimuli?
Answer:
The senses that evoke responses in organisms are called stimuli.

Question 4.
What are the differences between internal and external stimuli?
Answer:
The senses from our immediate surroundings that evoke responses in organisms are called external stimuli. The stimuli that are formed inside the body are called internal stimuli. Hunger and thirst are examples for internal stimuli.

Question 5.
What are receptors.? Write its function also.
Answer:
There are specialized cells in the sense organs and other parts of the body to receive stimuli. These cells are known as receptors. They receive stimuli and generate suitable impulses.

Question 6.
What are the functions of nervous system?
Answer:
Normally, responses occur when the impulses generated by the receptors on receiving the stimuli reach the brain. The nervous system controls and co-ordinates these actions.

Question 7.
What are the major parts of nervous system?
Answer:
Brain, spinal cord and nerves are the major parts of nervous system.

Question 8.
Explain neuron.
Answer:
Neuron or nerve cell is the basic structural unit of the nervous system. Like all other cells, the neuron has a cell membrane, cytoplasm and nucleus.

Question 9.
Write the important parts, peculiarities and functions of neuron.
Answer:

Main parts	Peculiarities	Functions
Cell body (cyton)	It is the main part of neuron. It contains a nucleus and cytoplasm.	It carries impulses from the dendron to axon.
Dendron	Short filament from the cell body.	It carries impulses from dendrites to the cell body.
Dendrite	Branches of dendron.	Receives impulses from the adjacent neuron.
Axon	Longest filament from the cell body.	Carries impulses from the cell body to outside.
Axonite	Terminal branches of axon.	Carries impulses to the synaptic knob.
Synaptic knob	Tip of axonite.	Secretes neurotransmitter

Question 10.
What is myelin sheath?
Answer:
Axons of most of the neurons are repeatedly encircled by myelin, a membrane containing lipid. This is called myelin sheath.

Question 11.
Explain the formation of myelin sheath.
Answer:
Nerve is a group of axons. Myelin sheath in the nerves is formed of Schwann cells. Myelin sheath in the brain and the spinal cord is. formed of specialized cells called oligodendrocytes.

Kerala Syllabus 10th Standard Biology Question 12.
What is the difference between grey matter and white matter?
Answer:
The myelin sheath has a shiny white colour. The part of the brain and the spinal cord where myelinated nerve cells are present in abundance is called white matter and the part where nonmyelinated nerve cells are present is called grey matter.

Question 13.
What are the functions of myelin sheath?
Answer:
The major functions of the myelin sheath are to provide nutrients and oxygen to the axon, accelerate impulses, act as an electric insulator and protect the axon from external shocks.

Question 14.
Explain how impulses are transmitted through neurons.
Answer:
The outer surface of the plasma membrane of the neuron is positively charged and the inner surface is negatively charged. This is due to the difference in the distribution of certain ions. Impulses are messages conducted through nerves. These impulses transmit in the form of electric charges. Impulses are generated when stimuli evoke changes in polarity in the plasma membrane of receptors, the modified neurons.

The difference in the distribution of ions helps to maintain positive charge on the outer surface and negative charge inside the plasma membrane of the neuron. When stimulated, the ionic equilibrium in the particular part changes. As a result, polarity changes and the outer surface becomes negatively charged while the inner surface becomes positively charged. This change does not persist for long. It regains its original state. But the momentary charge difference in the axon membrane stimulates its adjacent parts and similar changes occur there too.

As this process proceeds, impulses get transmitted through axon. When stimulated, the distribution of ions in that particular part changes and hence the inner surface becomes positively charged and the outer surface becomes negatively charged . This momentary charge difference stimulates its adjacent parts and similar changes occur there too. As this process proceeds, impulses get transmitted as electric charges. Nerve impulses are messages transmitted through the neurons.

Question 15.
What is meant by synapse?
Answer:
Synapse is the junction between two neurons or a neuron and a muscle cell or a neuron and a glandular cell. Synapse helps to regulate the speed and direction of impulses.

Question 16.
How do impulses pass through synapse?
Answer:
When electric impulsesfrom the axon reach the synaptic knob, certain chemical substances are secreted from there to the synaptic cleft. These chemical substances are called neurotransmitters. They stimulate the adjacent dendrite or cell and new electric impulses are generated.

Question 17.
What are the different types of synapse?.
Answer:
Synapse is the junction between two neurons or a neuron and a muscle cell or a neuron and a glandular cell.

Question 18.
Prepare a flow chart of impulses passing through a neuron.
Answer:
Stimulus → Dendrite → Dendron → Cell body → Axon → Axonite → Synaptic knob → Synapse → Dendrite of adjacent neuron.

Question 19.
What are the different types of neuron?
Answer:
On the, basis of the direction of impulse, neurons can be classified into sensory neurons and motor neurons. Sensory neurons carry impulses to the brain and spinal cord. Motor neurons carry impulses from the brain and spinal cord to various parts of the body.

Biology Class 10 Chapter 1 Kerala Syllabus Question 20.
What are nerves? Which are they? Write their peculiarities and functions.
Answer:
Nerves are groups of axons or nerve fibres covered by connective tissue. On the basis of their functions, nerves are further classified into three.

a. Sensory nerve: Formed of sensory nerve fibres. It carries impulses from various parts of the body to the brain and the spinal cord.
eg: Optic nerve

b. Motor nerve: Formed of motor nerve fibres. It carries impulses from brain and spinal cord to various parts of the body.
eg: Hypoglossal nerve

c. Mixed nerve: Formed of sensory nerve fibres and motor nerve fibres. It carries impulses to and from the brain and spinal cord.
eg: Vagus nerve

Question 21.
How is nervous system classified? Write the peculiarities of each part.
Answer:
The nervous system consists of two parts, namely the central nervous system and the peripheral nervous system. The central nervous system consists of brain and the spinal cord. The peripheral nervous system consists of 12 pairs,of cranial nerves and 31 pairs of spinal nerves.

Question 22.
Prepare a short note about the protection of brain.
Answer:
The brain is protected inside the skull. It is covered by the meninges, a three-layered membrane. The cerebrospinal fluid is filled within the inner membranes of meninges and the ventricles of the brain.

Question 23.
What are the functions of cerebrospinal fluid?
Answer:
The cerebrospinal fluid is filled within the inner membranes of meninges and the ventricles of the brain. The cerebrospinal fluid is formed from the blood and is reabsorbed into the blood. The functions of the cerebrospinal fluid are to provide nutrients and oxygen to the tissues of the brain, regulate the pressure inside the brain and to protect the brain from injuries.

Question 24.
Explain the main parts and functions of brain.
Answer:

Cerebrum:
Cerebrum is the largest part of the brain and it has numerous fissures and folds. In cerebrum grey matter is seen in the external cortex and white matter is seen in the internal medulla. Cerebrum is the centre of thought, intelligence, memory and imagination. Cerebrum also evokes sensations and controls voluntary movements.

Cerebellum:
Cerebellum is the second largest part of the brain. It is seen behind the cerebrum as two flaps and has fissures, and grooves. Cerebellum coordinates muscular activities and maintains the equilibrium of the body.

Medulla oblongata :
The rod shaped medulla oblongata is seen below the cerebrum, located near to cerebellum. Medulla oblongata controls involuntary actions like heart beat, breathing, etc.

Thalamus :
Thalamus is situated below the cerebrum. It acts as relay station of impulses to and from the cerebrum. Thalamus analyses impulses from the various parts of the body and sends the important ones to the cerebrum.

Hypothalamus:
Hypothalamus is situatedjust below the thalamus and plays a major role in the maintenance of homeostasis.

Question 25.
What is the necessity of wearing helmets while riding two wheelers?
Answer:
Wearing helmets while riding two wheelers reduces the impact of accident. About 70% to 80 % of death in two wheeler accident is due to the injury of brain

Question 26.
How is the spinal cord protected?
Answer:
The spinal cord is protected inside the vertebral column. Like the brain, the spinal cord is also covered by meninges.

Question 27.
How does the dorsal root differ from ventral root?
Answer:
A dorsal root and a ventral root join to form a spinal nerve. Sensory impulses reach the spinal cord through the dorsal root. Motor impulses go out of the spinal cord through the ventral root.

Question 28.
Write about the major functions of the spinal cord.
Answer:
Impulses from different parts of the body are transmitted to and from the brain through the spinal cord. It also coordinates the repeated movements during walking, running, etc.

10th Standard Biology Textbook Kerala Syllabus Question 29.
What are reflex actions? Write examples also.
Answer:
The accidental and involuntary responses towards stimuli are called reflex actions.
eg:

• Sudden withdrawal of leg while touching a thorn.
• We blink our eyes when objects come towards our eyes.

Question 30.
Explain reflex arc.
Answer:
Reflex arc is the pathway of impulses in the reflex action.

Question 31.
Prepare a flow chart related to reflex arc.
Answer:

Question 32.
What is the difference between spinal reflex and cerebral reflex?
Answer:
Mainly spinal cord acts as the centre of reflex action and such reflexes are called spinal reflexes, eg: Sudden withdrawal of leg while touching a thorn.
But all reflexes are not under the control of the spinal cord. Reflexes under the control of the cerebrum are called cerebral reflexes.
eg: We blink our eyes when light suddenly falls on our eyes.

Question 33.
Is it advisable to lift up people quickly by holding their arms or legs in an accident?
Answer:
It is not advisable to lift up people quickly by holding their arms or legs in an accident, because these actions may lead to injuries in spinalcord.

Question 34.
What are the changes that take place in the body during emergency situations?
Answer:
Heart beat increases, breathing rate increases, body shivers and the production of saliva decreases.

Question 35.
Explain autonomous nervous system.
Answer:
Activities that take place beyond the conscious level are controlled by the autonomous nervous system, a part of the peripheral nervous system. The autonomous nervous system contains the sympathetic system and the parasympathetic system.

Question 36.
Write the action of sympathetic and parasympathetic systems during emergency situations.
Answer:

Organ	Sympathetic system	Parasympathetic system
Eye	The pupil in the eye dilates	The pupil constricts
Salivary gland	Production of saliva decreases	Production of saliva increases
Lung	Trachea dilates	Trachea constricts
Heart	Heartbeat increases	Heartbeat becomes normal
Stomach	Gastric activities slow down	Gastric activities become normal
Liver	Glycogen is converted to glucose	Glucose is converted to glycogen
Intestine	Peristalsis slows down	Peristalsis becomes normal
Urinary bladder	Urinary bladder retains to normal state	Urinary bladder contracts

Question 37.
Prepare a note on the diseases affecting the nervous system.
Answer:
Alzheimer’s:
Caused by the accumulation of an insoluble protein in the neural tissues of the brain and neurons get destroyed. The major symptoms are loss of memory, inability to recognize friends and relatives and inability to do routine works.

Parkinson’s:
Caused by the destruction of specialized ganglions in the brain due to reduced production ofdopamine, a neurotransmitter. The major symptoms are loss of body balance, irregular movement of musc les, shivering of the body and
profuse salivation.

Epilepsy:
Caused by continuous and irregular flow of electric charges in the brain. The
symptoms of epilepsy are due to continuous muscular contraction, frothy discharge from the mouth, clenching of the teeth following which the
patient falls unconscious.

Let Us Assess

Question 1.
The part of the brain which helps to maintain body balance.
a. Cerebrum
b. Cerebellum
c. Medulla oblongata
d. Thalamus
Answer:
b. Cerebellum

Biology Class 10 Kerala Syllabus Chapter 1 Question 2.
Identify the relation and fill in the blank.
Irregular flow of charge in the brain : Epilepsy Decreased production of dopamine : ………………….
Answer:
Parkinson’s

Question 3.
Analyze the following instances and answer the questions.

• A thorn accidental ly pierces the foot
• The leg is withdrawn
• The thorn is taken out slowly

a. Write the stimuli and responses.
b. Which is the conscious response?
c. Was the leg withdrawn after sensing the pain? Which action took place there? Prepare an illustration showing the parts through which the impulses were transmitted.
Answer:
a. Stimuli -touch
Response – withdrawal of leg
b. The thorn is taken out slowly
c. No. Reflex action
Stimulus → receptor → sensoryneuron → intemeuron → motor neuron → related muscle → withdraws the leg.

Kerala Syllabus 10th Standard Biology Guide

SSLC Biology Chapter 8 The Paths Traversed by Life Textbook Questions and Answers

SCERT Class 10th Standard Biology Chapter 8 The Paths Traversed by Life Solutions

Question 1.
What are the theories related to the origin of life on earth and are discussed even today?
Answer:
The Panspermia Theory and the Theory of Chemical Evolution are the theories related to the origin of life on earth and are discussed even today.

Question 2.
Explain the Panspermia Theory and the Theory of Chemical Evolution.
Answer:
The Panspermia argues that life originated in some other planet in the universe and accidentally reached the earth. The organic substances obtained from the meteors that fell on earth support this.

The hypothesis that evolved into the theory of chemical evolution is that life originated as a result of the changes that occurred in the chemical substances in seawater, under specific conditions in primitive earth. This theory is generally accepted by the scientific world due to its experimental evidences. The Russian scientist A.I. Oparin (1924) and the British scientist
J.B.S.Haldane (1929) are the proponents of this theory.

Question 3.
Explain the Theory of Chemical Evolution.
Answer:
The Russian scientist A.I. Oparin and the British scientist J.B.S. Haldane are the proponents of the theory of chemical evolution. Atmosphere of primitive earth contained gases like hydrogen, nitrogen, carbondioxide, hydrogen sulphide, Methane, ammonia and water vapour. No free oxygen was not present on primitive earth. Sources of energy of primitve earth was thunder and lightning, ultraviolet radiations and volcanic eruptions.

The earth cooled and the water vapour condensed. Incessant rains led to the formation of oceans and other water bodies. Molecules like monosaccharides, amino acids and fatty acids, nitrogen bases were formed in the oceans as a result of chemical reactions. Complex molecules like polysaccharides, proteins, fats, nucleotides, etc., were formed from simple molecules. Followed by Nucleicacids are formed covered by a lipid layer. This leads to the formation of primitive cell.

Question 4.
Prepare a table containing the comparison between chemical evolution and Urey – Miller experiment.
Answer:

Situations	Primitive earth	Urey – Miller experiment
1.Atmosphere	Contained gases like hydrogen, nitrogen, carbon dioxide, hydrogen sulphide, methane, ammonia, water vapour.	Contain methane, ammonia and water vapour
2. Source of energy	Lightning, Ultra Violet rays, Volcanic eruptions.	High voltage electricity
3. Products	Monosaccharides, amino acids, fatty acids, nitrogenbases, polysaccharides, proteins fats, nucleotides.	Amino acids

Question 5.
Prepare a brief description about Urey- Miller experiment.
Answer:
Urey and Miller conducted their experiment by artificially recreating the atmosphere of primitive earth that contained methane, ammonia, hydrogen and water vapour. In the place of natural energy sources like thunder and lightning in the atmosphere of primitive earth, high voltage electicity is passed through the gaseous mixture in the glass flask. Then, this gaseous mixture*was cooled with the help of a condensor.

The sediment substances were seperated and when observed, organic molecules such amino acids, were found. Later many scientists designed similar experiments and more organic compounds were synthesized. This finally gave more acceptance to the OParin – Haldane hypothesis.

Question 6.
How primitive cell were formed?
Answer:
From the organic molecules formed as a result of chemical evolution, primitive cell were formed 3800 millions of years ago.

Question 7.
Explain the origin of prokaryotes.
Answer:
From the organic molecules formed as a result of chemical evolution, primitive cell were formed 3800 millions of years ago. From the primitive cell prokaryotes were formed 3500 millions of years ago.

Question 8.
Explain the origin of eukaryotes.
Answer:
From the organic molecules formed as a result of chemical evolution, primitive cell were formed 3 800 millions of years ago. From the primitive cell prokaryotes were formed 3500 millions of years ago. Eukaryotes were formed 1500 millions of years ago. The origin of eukaryotic cells having membrane bound cell organelles originated from prokaryotic cells.

Question 9.
Explain about the origin of multicellular organisms.
Answer:
The origin of eukaryotic cells having membrane-bound cell organelles from prokaryotic cells is a milestone in the history of evolution. Multicellular organisms were formed 1000 millions of years ago. Gradually colonies of eukaryotic cells were formed. This led to the emergence of multicellular organisms.

Question 10.
Prepare a geological time scale related to the major eras of origin of life on earth. .
Answer:
Origin of life on earth 3800 million years ago. Origin of prokaryotes 3500 million years ago. Origin of eukaryotes 1500 million years ago. Origin of multicellular organisms 1000 million years ago.

Question 11.
Prepare a flowchart related to origin of multicellular organisms.
Answer:

Question 12.
What are acquired characters?
Answer:
The Characters developed during the lifetime of organisms are called acquired characters.

Question 13.
Explain Lamarckism?
Answer:
Many scientists have attempted to explain the history of evolution from primitive cells to the biodiversity that exists today. The first attempt among them was by Jean Baptist Lamarck, a French biologist.

According to Lamarck giraffes had short necks in the beginning. When they faced food scarcity, they stretched their necks to reach out tall trees. The characters developed during the lifetime of organisms are called acquired characters. Lamarck explained that these characters accumulate through generations and lead to the formation of new species. Thus giraffes with long necks emerged through generations. But this argument was not accepted by the scientific world as these acquired characters are not inheritable.

Question 14.
Which peculiarity of the finches attracted Darwin?
Answer:
Finches were one among the organisms observed and closely studied by Darwin in the Galapagos island. Though the finches look similar to one another, the differences in their beaks attracted Darwin.

Question 15.
How do the differences in their beaks help finches in their survival?
Answer:
Insectivore finches have small beaks and those that feed on cactus plants have long and sharp beaks. There were also woodpecker finches that feed on worms from the holes in tree trunks using small twigs taken with its sharp beak. The ground finches that feed on seeds with large beaks were also present. The differences in their beaks help finches in their survival. It is clear that the finches Darwin observed had beaks adapted to their feeding habits.

The Theory of Natural Selection

Question 16.
Explain the Theory of Natural Selection.
Answer:
The ‘Theory of Natural Selection’ was put forward by Daiwin. Every species produce more number of offsprings than that can survive on earth. They compete among one another for food, space and mates. The competition becomes hard when the number of organisms is greater and the availability of resources is less. Many variations are visible in organisms. You are also aware of how these variations occur.

These variations may be favourable or unfavourable. Those with favourable variations survive in the struggle for existence. Others are eliminated. Variations that are inherited through generations and repeated differently help to form species different from their ancestors. This type of selection, done by nature, leads to the diversity of species that we see around us. This is the explanation of Darwin’s Theory which is known as the theory of natural selection.

Question 17.
What are the limitations of Darwinism?
Answer:
During Darwin’s period, there was no idea regarding genes, chromosomes, etc. Though Darwin identified that continuous variations occurred in organisms, he could not explain the reasons for these variations.

Question 18.
What is Neo Darwinism?
Answer:
Though Darwin identified that continuous variations occurred in organisms, he could not explain the reasons for these variations. Later it was explained that mutations that caused variations led to the evolution of organisms. Darwinism was revised in the light of new information from the branches of genetics, cytology, geology and paleontology. This modified version of Darwinism is known as Neo Darwinism.

Mutation Theory

Question 19.
Explain Mutation Theory.
Answer:
This theory was formulated by a Dutch scientist, Hugo de Vries. Changes in genes is one of the reasons for variations in organisms. Sudden changes that occur in genes are called mutations. Mutation theory explains that new species are formed by the inheritance of such changes. Later it was explained that mutations that cause variations lead to the evolution of species.

Evidences of Evolution

Question 20.
What are the evidences to support evolution?
Answer:
There are many evidences to support the evolution of new species. Paleontology, comparative morphology, physiology and modem molecular biology provide evidences to validate evolution.

Question 21.
What are fossils? What is the importance of fossil study?
Answer:
Fossils are the remnants of primitive organisms. Fossils may either be the body, its parts or imprints of organisms. The age of fossils can be calculated scientifically. They are categorised on the basis of geological time scale and their peculiarities are studied. The inferences arrived at from such studies are

• Primitive fossils have simple structure.
• Recently formed fossils have complex structure.
• Certain fossils are connecting links between different species.

Question 22.
How morphological studies become an evidence for evolution?
Answer:
The forelimbs of organisms differ in their external appearance. Differences in their external appearances are their adaptations to live in their own habitats. But these forelimbs are made up of blood vessels, nerves, muscles and bones. Organs that are similar in structure and perform different functions are called homologous organs. Anatomical resemblances justify the inferences that all organisms evolved from a common ancestor.

Question 23.
What are the inferences that we get from the study of biochemistry and physiology?
Answer:
Microbes, plants and animals are different in their appearance. But there are close resemblances in their cell structure and physiology.

• Enzymes control chemical reactions
• Energy is stored in ATP molecules.
• Genes determine hereditary traits.
• Carbohydrates, proteins and fats are the basic substances.

From these facts, it is clear that different species that exist today have a common ancestor.

Question 24.
How many amino acids differ in the chain of haemoglobin in man and chimpanzee?
Answer:
No amino acids differ in the chain of haemoglobin in man and chimpanzee.
Man and chimpanzee have no difference in the amino acids of chain of haemoglobin.

Question 25.
What is the difference in the number of amino acids in the chain of haemoglobin in man and gorilla?
Answer:
Man and gorilla have no difference in the number of amino acids of chain of haemoglobin: But there is a change in one amino acid.

Question 26.
Which organism is close to man from the evolutionary point of view? What is the reason for this?
Answer:
Chimpanzee: Man and chimpanzee have no difference in the amino acids of chain of haemoglobin.

Question 27.
What is the importance of Molecular biology?
Answer:
Through a comparative study of protein molecules in different species, the evolutionary relationship among organisms can be identified. This is an effective method to draw the evolution showing the branching of organisms from a common ancestor. Molecular studies help to find out the evolutionary relationship of different species of organisms.

Question 28.
Which organism is the closest to humans in specific characters?
Answer:
Chimpanzee

Question 29.
How Anthropoidea, Cercopithecoidea and Hominoidea are related to each other?
Answer:
Humans, chimpanzee, gorilla, orangutan, gibbon and monkeys are included in the category Anthropoidea. This is further classified into Cercopithecoidea and Hominoidea.

Question 30.
Has a species directly evolved from another species? Why?
Answer:
No. Organisms which have evolved from a common ancestor show many resemblances.

Question 31.
What are the characteristics of the organisms which belong to the group hominoidea?
Answer:
Gibbon, Orangutan, Gorilla, Chimpanzee and Man belongs to hominoidea. They have developed brain and freely movable hands.

Question 32.
“Man evolved from monkeys ”. How would you respond to this statement?
Answer:
The given statement is an incorrect one. Man belongs to Hominoidea and Monkeys belong to Cercopithecoidea.

Question 33.
Prepare a table which contains the features of organisms that can be included in the evolutionary history of modern man.
Answer:

Organism	Fossil found from	Features
Ardipithecus ramidus	Africa	Most primitive member of the human race
Australopithecus afarensis	Africa	Slender body
Homo habilis	Africa	Made weapons from stones and bone pieces
Homo erectus	Africa and Asia	Thick chin and large teeth, have the ability to stand erect
Homo neanderthalensis	Europe and Asia	Contemporary to modern man
Homo sapiens	France	Modern man

Question 34.
Does the interference of human beings have a negative impact on the existence of organisms and nature itself?
Answer:
Biodiversity at global level has increased much recently than ever before. But this biodiversity is on a dangerous decline due to the interference of human beings. Statistics indicate that if these conditions persist, 1/4 th species of organisms will vanish from the earth within the next 50 years. If it happens* it will be the largest and the sixth mass extinction of species on earth.

Question 35.
Will the unwise interference of intelligent human beings destroy the continuity of life on earth?
Answer:
Today we are aware of the challenges raised by climatic changes brought in by human interventions and the extinction of organisms. Individuals and organizations are actively participating in programmes for the conservation of nature. This solidifies the reality that human life is possible on earth only with the existence of many other diverse ecosystems. Human beings are capable of foreseeing far-reaching consequences and taking necessary precautions in this regard. This leaves us with hopes of a future life on earth.

Let Us Assess

Question 1.
Which concept is put forward by The Theory of Natural Selection?
a. Origin of life
b. Origin of species
c. Origin of eukaryotes
d. Chemical evolution of life
Answer:
b. Origin of species

Question 2.
List the main concepts that indicate how the biodiversity seen today has been developed from prokaryotes.
Answer:
The origin of eukaryotic cells having membrane bound cell organelles originated from prokaryotic cells. Gradually colonies of eukaryotic cells were formed. This led to the emergence of multicellular organisms.

Question 3.
How does the interference of human beings in nature influence the process of evolution? How do these affect the existence of other organisms?
Answer:
Due to the interference of human beings in nature, many organisms lose their natural habitat. This leads to extinction. This also affects the other organisms which depend on them.

Question 4.
What are the evidences that substantiate the theories of evolution? Identify and explain them.
Answer:
Evidences from fossil study.

• Primitive fossils have simple structure.
• Recently formed fossils have complex structure.
• Certain fossils are connecting links between different species.
• Can be infered as organisms with complex structure are formed from organisms with simple structure.

Evidences from morphological studies’.
The forelimbs of organisms differ in their external appearance. Differences in their external appearances are their adaptations to live in their own habitats. But these forelimbs are made up of blood vessels, nerves, muscles and bones. Organs that are similar in structure and perform different functions are called homologous organs. Anatomical resemblances justify the inferences that all organisms evolved from a common ancestor.

Evidences from the study of biochemistry and physiology.
Microbes, plants and animals are different in their appearance. But there are close resemblances in their cell structure and physiology.

• Enzymes control chemical reactions.
• Energy is stored in ATP molecules.
• Genes determine hereditary traits.
• Carbohydrates, proteins and fats are the basic substances.

From these facts, it is clear that different species that exist today have a common ancestor.

Evidences from the study of Molecular biology.
Through a comparative study of protein molecules in different species, the evolutionary relationship among organisms can be identified. This is an effective method to draw the evolution showing the branching of organisms from a common ancestor. Molecular studies help to find out the evolutionary relationship of different species of organisms.

Kerala Syllabus 10th Standard Biology Guide

Students can Download Biology Chapter 7 Genetics for the Future Questions and Answers, Notes Pdf, Activity in Malayalam Medium, Kerala Syllabus 10th Standard Biology Solutions helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

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SSLC Biology Chapter 5 Soldiers of Defense Textbook Questions and Answers

SCERT Class 10th Standard Biology Chapter 5 Soldiers of Defense Solutions

Class 10 Biology Chapter 5 Pdf Question 1.
What are the uses of wearing masks in situations where epidemics spread out?
Answer:

• Prevent the entry of germs.
• Prevent the entry of pathogens from one person to another.

Question 2.
What do you mean by the term defence?
Answer:
Defence is the ability of the body to prevent the entry of pathogens and to destroy those that have already entered the body.

Question 3.
What are the defense mechanisms of the body?
Answer:
Body coverings like skin, mucous membrane and body secretions like mucous, saliva and tear are the defence mechanisms of the body. Body fluids like blood and lymph also play an important role in defence mechanism.

Question 4.
What is the role of skin in defense?
Answer:

A protein called keratin present in the epidermis prevents the entry of germs. Sebum produced by the sebaceous gland makes the skin oily and waterproof. The disinfectants present in the sweat produced by sweat gland destroy the germs.

Question 5.
What is mucous membrane?
Answer:
The mucous membrane is protective covering of body parts.

Question 6.
What is the function of mucous membrane?
Answer:
Pathogens trapped in the mucus produced by mucous membrane, get destroyed. The destroyed germs are expelled out by the cilia cells of the mucous membrane.

Biology Class 10 Soldiers of Defense Question 7.
What is the role of useful bacteria seen in skin and mucous membrane?
Answer:
Coverings of the body act as a habitat for many useful bacteria. The germs that enter the body need to compete with such useful bacteria for shelter and nutrients. A great number of germs get destroyed in this competition.

Question 8.
How the body secretions help to defend pathogens?
Answer:

• The disinfectants present in the sweat produced by this gland destroy the germs.
• Pathogens trapped in the mucus produced by this membrane, get destroyed. The destroyed germs are expelled out by the cilia cells of the mucous membrane.
• The wax in the ear prevents pathogens.
• The enzyme lysozyme present in tear and saliva fights against germs.
• The hydrochloric acid present in the stomach has the ability to destroy germs. It kills the germs that reach the stomach along with food.
• Lysozyme present in the urine kills the germs.

Question 9.
What are the defense strategies of body fluids?
Answer:
Body fluids like blood and lymph play an important role in defense mechanism. These body fluids follow different defense strategies like controlling the entry of germs into the body, neutralising germs and the toxic substances they produce, preventing their multiplication, etc.

Question 10.
What are the defense action of white blood cells?
Answer:

• Neutrophil – Engulfs bacteria, synthesizes chemicals that destroys bacteria.
• Basophil – Stimulates other white blood cells. Dilates the blood vessels.
• Eosinophil – Synthesizes chemicals that destroy foreign bodies. Synthesizes chemicals required for
  the inflammatory responses.
• Monocyte – Engulfs and destroys germs.
• Lymphocyte-Identifies and destroys germs specifically.

Hsslive Class 10 Biology Chapter 5  Question 11.
Explain inflammatory response.
Answer:
The cells that get damaged by a wound or an infection produce certain chemical substances. These substances dilate the blood vessels thereby increasing the blood flow. Blood plasma and white blood cells reach the wound site. This is the reason for the swelling of the wound site. This defense mechanism is known as inflammatory response.

Question 12.
What is the advantage of the dilation of blood vessels at the wound site?
Answer:
The cells that get damaged by a wound or an infection produce certain chemical substances. These substances dilate the blood vessels thereby increasing the blood flow. Blood plasma and white blood cells reach the wound site. The white blood cells destroy germs.

Question 13.
What is the role of white blood cells in the inflammatory response?
Answer:
White blood cells reach the wound site through the walls of the capillaries. Neutrophils and monocytes engulf and destroy germs.

Question 14.
Is inflammatory response a defense activity? Why?
Answer:
Yes. Inflammatory response is a defense activity. It is the mechanism that destroys the germs that have entered the body. This is a second-level defense mechanism.

Question 15.
Prepare a flowchart showing the stages of inflammatory response.
Answer:
Germs enter through wounds → Produces chemical messages → Blood vessels dilate → White blood cells reach the wound site through the walls of the capillaries → Neutrophils and monocytes engulf and destroy germs.

Question 16.
What is phagocytosis?
Answer:
Phagocytosis is the process of engulfing and destroying germs. The cells engaged in this process are called phagocytes. Monocytes and neutrophils are phagocytes.

Question 17.
Prepare a flowchart show the stages in phagocýiosis.
Answer:

Phagocytes reach near the pathogen → Engulfs pathogen in the membrane sac → Lysosome combines with membrane sac → The pathogens are degenerated and destroyed by the enzymes in lysosome.

Class 10 Biology Chapter 5 Pdf Kerala Syllabus  Question 18.
Prepare a note on blood clotting.
Answer:
Blood clotting is a defense mechanism to prevent the loss of blood through wounds. Wounds cause loss of blood. Tissues degenerate to form the enzyme called thromboplastin. Thromboplastin converts prothrombin in the plasma to thrombin in the presence of calcium ions and vitamin K. Thrombin converts the fibrinogen in the plasma to fibrin. Blood clot is formed by the entangling of platelets and red blood cells in the fibrin network.

Question 19.
Explain the situation in which wound scar remains.
Answer:
Healing of the wound is a stage after inflammatory response and blood clotting. When wound occurs, new tissues are formed in the place of the tissues damaged by the wound.

In such situations, the wound scar does not remain. In cases when new tissues cannot be formed, the connective tissue heals the wound. In such situations, the wound scar Remains.

Question 20.
Fever is a defense mechanism. Why?
Answer:
Pathogens enter the body. Then the presence of toxins produced by the pathogens stimulates the white blood cells. The chemical substances produced by the white blood cells raise the body temperature. The rise in body temperature reduces the rate of multiplication of pathogens and increases the effect of phagocytosis. So fever is a defense mechanism.

Question 21.
If the rise in body temperature persists for a long time, it is necessary to seek medical assistance immediately. Why?
Answer:
When infection becomes uncontrollable, the body temperature may rise very high. We take medicines to reduce the body temperature. But it is advisable to treat after diagnosing the exact reason. If the rise in body temperature persists for a long time, it may badly affect the internal organs including the brain. Hence it is necessary to seek medical assistance immediately.

Question 22.
Define non – specific defense.
Answer:
Non-specific defense mechanism is a mechanism that protects us from all pathogens without considering their characteristic features.

Kerala Syllabus 10th Standard Biology  Question 23.
Define specific defense.
Answer:
Foreign bodies or pathogens that enter the body and stimulate the defense mechanism are called antigens. The defense mechanism that identifies the structure of each antigen and destroys it specifically is called specific defense.

Question 24.
Prepare a short note on lymphocytes.
Answer:
In certain situations, pathogens enter the body and multiply by overcoming the immune system. Specific defense is the system which identifies and destroys such pathogens. White blood cells known as lymphocytes are capable of destroying the pathogens in this way. Lymphocytes are of two types, namely B lymphocytes and T lymphocytes. B lymphocytes mature in the bone marrow. T lymphocytes mature in the thymus.

Question 25.
How do B lymphocytes act?
Answer:
Foreign bodies or pathogens that enter the body and stimulate the defense mechanism are called antigens. B- Lymphocytes produce certain proteins that act against antigens. These are called antibodies.
Antibodies destroy the pathogens in three different ways.

1. Destroy the bacteria by disintegrating their cell membrane.
2. Neutralise the toxin of the antigens.
3. Destroy the pathogens by stimulating other white blood cells.

Question 26.
How do T lymphocytes act?
Answer:
T lymphocytes stimulate other defense cells of the body. Moreover, these cells are capable of destroying cancer cells and cells affected by virus.

Question 27.
Why is the defense mechanism of lymphocytes known as specific defense mechanism?
Answer:
Lymphocytes become activated in the presence of j certain particular types of antigens. Lymphocytes can defend only such antigens. Hence, this; defense mechanism is known as specific defense mechanism.

Question 28.
What are the defense mechanisms of blood?
Answer:
Raising body temperature, production of antibodies, healing of wound, blood clotting, inflammatory response, phagocytosis.

Question 29.
How does lymph help in defense mechanisms? j
Answer:
The lymph, formed from the blood and reabsorbed into blood has a prominent role in defense j mechanisms, like the blood itself. Lymph contains plenty of lymphocytes. They destroy the disease causing bacteria in lymph nodes and spleen.

Question 30.
What is immunization?
Answer:
Defense mechanisms become slow when germs enter the body. This causes the spread and multiplication of germs. Immunization is the artificial method to make the defense cells alert against the attack of pathogens.

Question 31.
What are vaccines? What are the component of vaccines?
Answer:
Vaccines are the substances used for artificial immunization. Any one of the components from alive or dead neutralised germs, neutralised toxins or cellular parts of the pathogens will be the component of each vaccine.

Question 32.
What is the role of Edward Jermer in immunization?
Answer:
Edward Jenner, an English doctor started immunization. He observed that people affected by cowpox escaped from the attack of smallpox. He injected the pus taken from a cowpox patient into the body of an 8-year-old boy. The boy was affected by cowpox and recovered.

After two months the pus taken from a smallpox patient was injected into the boy. He was not affected by smallpox. The immunization programmes got the name vaccination from the Latin word ‘vacca’ meaning cOw, in memory of the cowpox experiments of Jenner.

Question 33.
How vaccines help in immunization?
Answer:
Vaccines are the substances used for artificial immunization. These act as antigens that stimulate the defense mechanism of the body. Antibodies are formed in the body against them. These antibodies are retained in the body which in future protect the body from the pathogen responsible for the same disease.

Question 34.
Prepare a table related to vaccines and diseases.
Answer:

Vaccine	Disease
B.C.G.	Tuberculosis
O.P.V.	Polio
Pentavalent	Diphtheria, tetanus, pertussis (whooping cough), hepatitis B and Haemophilus influenza type b
M.M.R.	Measles, mumps, and rubella (German measles)
T.T	Tetanus

Question 35.
Prepare a note on the various systems of medicine.
Answer:
Medical treatment becomes necessary when we are affected by diseases, crossing all obstacles of our immune system. We depend on the various systems of medicine to recover from diseases.

In various parts of the world, methods of treatment have evolved in accordance with the lifestyle of the people, their culture and available natural resources. These methods are the result of long periods of experience and observation.

Ayurveda: It is a system of treatment which prevailed in India from the ancient times. Beyond being an urgent treatment measure against some diseases, Ayurveda gains acceptance as a lifestyle to maintain the body fit. The speciality of Ayurveda is the medicine, taken from nature.

Homoeopathy: The main principle behind homoeopathy is that the causative factor of the disease can itself effect the cure. This is a system of treatment introduced by Samuel Haniman, a German doctor. Homoeopathy gives great importance to the symptoms in each individual since it aims at treating not the disease but the patient. Another significant principle of this system of treatment is that the more the medicine is diluted the more is its potency.
Unani: The treatment in Unani is based on some principles put forward by Hippocrates. The diagnosis of a disease is done by checking pulse.

Allopathy: This is a cosmopolitan medical practice widely used all over the world. This branch of medicine, introduced by the ancient Greek physician Hippocrates, gives much importance to diagnosis, treatment, medicines, etc.

Sslc Biology Chapter 5 Question 36.
Prepare a table containing the equipment for diagnosis and their use.
Answer:

Equipment for diagnosis	Uses
Stethoscope	Measuring heartbeat
Sphygmomanometer	Measuring blood pressure
Electroencephalogram (EEG)	To record electric waves in the brain
Electrocardiogram (ECG)	To record electric waves in the heart muscle
Ultrasound Scanner	To understand the structure of internal organs using ultrasonic sound waves.
C.T. Scanner(Computed Tomography Scanner)	To get three-dimensional visuals of internal organs with the help of computer, using X-rays
MRI Scanner (Magnetic Resonance Imaging Scanner)	To get three-dimensional visuals of internal organs.

Biology Chapter 5 Class 10 Kerala Syllabus Question 37.
What are the different factors in blood?
Answer:

Blood factor	Normal Value
Haemoglobin	12-17 gm/100 ml of blood
Number of White Blood Cells	5000- 10000/ml of blood
Number of Red Blood Cells	45 lakhs to 60 lakhs/ml of blood
Number of platelets	2.5 lakhs to 3.5 lakhs/ml of blood

Question 38.
Prepare a lubie containing the specializations in medicine ami the related areas.
Answer:

Specialization	Related Area
Cardiology	Treatment of heart
Ophthalmology	Treatment of eye
Neurology	Treatment of disorders of the nervous system.
Chemotherapy	Cancer treatment
E.N.T	Treatment of ear, nose, and throat disorders.

Question 39.
What are antibiotics?
Answer:
Medicines that are extracted from microorganisms like bacteria, fungi. etc. and used to destroy bacteria are called antibiotics. They can be used externally and internally.

Question 40.
Explain the role of Alexander Fleming in the discovery of antibiotics.
Answer:
It was Alexander Fleming who first discovered antibiotics in 1928. He accidentally discovered that the fungus Penicillium notatum has the ability to destroy bacteria. But it took several years to extract medicine from it.

Question 41.
What are the side effects caused by the regular use of antibiotics?
Answer:
Antibiotics are used to resist bacterial diseases. Though antibiotics are effective medicines, their regular use brings many side effects.
Some important side effects of regular use are it develops immunity in pathogens against antibiotics, destroys useful bacteria in the body,
reduces the quantity of sorne vitamins in the body.

Question 42.
Observe figures A, B and C and identify the instances in which the following type of first aid is given.
Answer:

A – Giving artificial respiration – Artificial respiration, breathing induced by some manipulative technique when natural respiration has ceased or is faltering. Such techniques, if applied quickly and properly. can prevent some deaths from drowning, choking, strangulation, suffocation, carbon monoxide poisoning, and electric shock.

B – Arm supported by sling – During bone fracture
C – Removing objects stuck in trachea – Block in trachea

Question 43.
What is blood transfusion?
Answer:
The transfer of blood from one person to another is called blood transfusion.

Soldiers of Defence Questions And Answers Question 44.
What all things should be taken care of while transfusing blood?
Answer:

• People in the age group 18-60 can donate blood.
• Blood donation can be done once in three months.
• Blood donation causes no problem to the donor’s health.
• Pregnant women and breastfeeding mothers should not donate blood.
• Persons with communicable diseases
  (transmitted through blood) should not donate blood.

Question 45.
What are the different types öf blood groups?
Answer:
A, B, AB, O

Question 46.
What is the basis of blood grouping?
Answer:
The basis of blood grouping is the presence of antigen A and antigen Binredbloodcells. The blood group of a person is named according to the antigen present in that person’s blood.

Question 47.
Write the importance of antibody in blood groups.
Answer:
In blood transfusion, antibodies present in the blood plasma are of special importance. In blood group A, antibody b and in group B, antibody a are present.

Question 48.
What is antigen D?
Answer:
In addition to antigens A and B, another antigen called D or Rh factor is present in the cell membrane of red blood cells of certain persons.
The blood groups in hich Rh factor is present are known as positive blood groups and those without Rh factor are called negative blood groups.

Question 49.
What is the importance of blood group in blood transfusion?
Answer:
When a foreign antigen reaches one’s blood, it stimulates the defense mechanism. On receiving unmatching blood, the antigen present in the donor’s blood and the antibody present in the recipientes blood will react with each other and form a blood clot. Hence, everyone cannot receive blood from all blood groups.

For example, in blood group A, antigen A and in group B, antigen B are present. If a person with blood group A receives blood from a person with B group blood, the recipient’s blood does not contain B antigen. So it stimulates defense activity of the body. As a result, antigen B in blood group B forms a clot with antibody of A group blood.

Question 50.
What are the structural methods in the defense of plants?
Answer:
The characteristics in their body structure and the specific molecules produced by plant tissues protect the plants from diseases. Wax covering, cuticle, bark of plant and cell wall are the structural methods in the defense of plants. Waxy covering and cuticle prevent the entry of germs through leaves. The bark of plants protects inner cells from the direct contact of pathogens. Cell wall is a well equipped resistant coat.

Question 51.
What are the biochemical methods in the defense of plants?
Answer:
Chemical substances such as lignin, cutin, suberin, etc., provide rigidity to the cell wall. A polysaccharide called callose prevents the entry
of germs which have crossed the cell wall, through the cell membrane.

Let Us Assess

Question 1.
Which among the following is not included in non-specific body defense?
a. production of sebum.
b.action of hydrochloric acid in the stomach.
c. action of B lymphocytes.
d. action of lysozyme in saliva.
Answer:
c. action of B lymphocytes.

Question 2.
Write the functions of blood cells in the defense mechanism of the body.
Answer:
Neutrophil – Engulfs bacteria, synthesizes chemicals that destroys bacteria.
Basophil – Stimulates other white blood cells. Dilates the blood vessels.
Eosinophil – Synthesizes chemicals that destroy foreign bodies. Synthesizes chemicals required for the inflammatory responses.
Monocyte – Engulfs and destroys germs.
Lymphocyte – Identifies and destroys germs specifically.

10th Standard Biology Textbook Kerala Syllabus  Question 3.
What is the basis of grouping blood into different types? Everybody cannot receive blood of all blood groups. Why?
Answer:
The basis of blood grouping is the presence of antigen A and antigen B in red blood cells. The blood group of a person is named according to the antigen present in that person’s blood. In blood transfusion, antibodies present in the blood plasma are of special importance. In blood group A, antibody ‘b’ and in group B, antibody ‘a’ are present.

When a foreign antigen reaches one’s blood, it stimulates the defense mechanism. On receiving unmatching blood, the antigen present in the donor’s blood and the antibody present in the recipient’s blood will react with each other and form a blood clot.

Hence, everyone cannot receive blood from all blood groups. For example, in blood group A, antigen A and in group B, antigen B are present. If a person with blood group A receives blood from a person with B group blood, the recipient’s blood does not contain B antigen. So it stimulates defense activity of the body. As a result, antigen B in blood group B forms a clot with antibody ‘a’ of A group blood.

Kerala Syllabus 10th Standard Biology Guide

SSLC Biology Chapter 4 Keeping Diseases Away Textbook Questions and Answers

SCERT Class 10th Standard Biology Chapter 4 Keeping Diseases Away Solutions

Biology Class 10 Kerala Syllabus Chapter 4 Question 1.
What threatended the state again, soon after the great floods?
Answer:
The spread of contagious diseases threatended the state soon after the flood. Increase in number of rats may lead to spreading of rat fever. There is a shortage of drinking water in the flood affected areas of the state. The mental health of children in flood affected areas also is in threat.

Question 2.
What are the reasons for the proliferation of diseases?
Answer:
Lack of hygiene, Dirty surroundings, Environmental pollution, Stagnant water, Organic wastes, Poor sanitation, etc. lead to the proliferation of diseases.

Question 3.
What are the pathogenic microorganisms.?
Answer:
Bacteria, Fungus, Virus, Protozoa

Question 4.
How are pathogens transmitted from one person to another?
Answer:
Pathogens are transmitted from one person to another by contact, through contaminated food and water, cough, sneezing, unsterilized equipments, vectors and cloth.

Question 5.
What can we do to avoid the proliferation of diseases?
Answer:

Situations	Practical suggestions
Lack of hygiene	Awareness about hygiene
Dirty surroundings	Continuous cleaning activities
Environmental pollution	Continuous cleaning activities
Stagnant water	Provide situations for flowing of water
Organic wastes	Organic waste disposal
Poor sanitation	Common urinal and toilets

Question 6.
Prepare a short note on bacteria.
Answer:
Bacteria is a prokaryote. They enter the body and multiply through binary fission. The toxins produced by them destroy cells and cause disease.

Question 7.
Prepare a short note on rat fever.
Answer:
Leptospira is the bacteria that causes rat fever. The bacteria that comes out through the urine of rat, dog and certain other animals remain alive in stagnant water and moisture. When bacteria reach blood through wounds, they affect body cells and produce certain toxins.

They cause damage to blood capillaries which in turn leads to internal bleeding. Severe fever, headache, muscle pain, redness in eyes, etc. are the major symptoms. Rat fever can be completely cured through early diagnosis and treatment. The realization that immunization is better than treatment is very important to stop the spread of disease.

Question 8.
What are the precautions taken after flood?
Answer:
The Department of Health has given numerous instructions to avoid health issues that may arise after overcoming the emergency situations. Drinking boiled water and water purified using enough quantity of chlorine prevents water borne diseases. As there is a chance for the multiplication of mosquitoes in stagnant water, proper measures to check increase in mosquitoes should be adopted.

For controlling diseases like rat fever, eliminate the vectors and take preventive medicines as per the directions of experts. Disease affected persons must undergo diagnostic tests to confirm their illness and should take proper medicines. People living in unsafe places must shift to safe places as per instructions. Ensure personal hygiene and environmental hygiene at the rehabilitation centres and create an atmosphere to protect health.

Question 9.
Name the pathogen of Diphtheria.
Answer:
Diphtheria spreads through cough, sneezing or directly from the infected person to another person. Diphtheria affects the mucus membrane of the nose and the throat. Corynebacterium diphtheriae is the pathogen.

Class 10 Biology Chapter 4 Kerala Syllabus Question 10.
What are the symptoms of Diphtheria?
Answer:
Diphtheria affects the mucus membrane of the nose and the throat. Toxins produced by the Corynebacterium diphtheriae cause fever, throat pain and inflammation in the lymph glands of the throat. Cells in the mucus membrane which are destroyed by the toxins produce an ash coloured thick coating in the throat within two or three days. Gradually brain, heart and kidneys are affected.

Question 11.
Explain the treatment of Diphtheria.
Answer:
Antitoxins which act against the toxins are used to protect the uninfected cells. But, if the disease becomes severe the patient cannot be recovered through medication. So vaccination is the best preventive method.

Question 12.
Which is the causative agent of tuberculosis?
Answer:
Tuberculosis is an air borne disease that affects the lungs. Tuberculosis is caused by the bacterium Mycobacterium tuberculosis.

Question 13.
Which are the symptoms of tuberculosis?
Answer:
This disease can affect us at any age. Loss of body weight, fatigue and persistent cough are the major symptoms.

Question 14.
How does tuberculosis spread?
Answer:
When the patient speaks, coughs or sneezes, the pathogens spread to air providing a chance to reach other people.

Question 15.
Which parts of the body can be affected by tuberculosis?
Answer:
Tuberculosis mainly affects the lungs-. Kidneys, bones, joints, brain, etc., are also affected by this disease.

Question 16.
Name the vaccine against tuberculosis.
Answer:
BCG is used as preventive vaccine against tuberculosis

Question 17.
Prepare a short note on virus.
Answer:
Virus has the simple structure with a DNA or RNA molecule within a protein coat. Virus has no cell organelles as seen in normal cells. Hence virus multiplies by taking control over the genetic mechanism of the host cells. Viruses infect not only human beings but also plants, other animals and even bacteria.

Question 18.
Which is the natural vector of Nipah virus?
Answer:
Fruit eating bats act as the Nipah virus vectors.

Question 19.
What are the situations that enable the Nipah virus to enter humans?
Answer:
Fruit eating bats act as the Nipah virus vectors. ’ From the saliva and urine of fruit eating bats that are seen in the remains of fruits eaten by bats, Nipah virus enters humans and pigs. From pigs also Nipah virus enters humans.

Question 20.
Explain AIDS.
Answer:
AIDS (Acquired Immuno Deficiency Syndrome) is a dreadful disease that has gripped the world by fear. Lymphocytes play a major role in providing immunity to the body. HIV (Human Immunodeficiency Virus) enters the body and multiplies using the genetic mechanism of lymphocytes. Hence the number of lymphocytes decreases considerably and reduces the immunity of the body. Various other pathogens which enter the body in such a situation make the condition of AIDS even more fatal.

Class 10 Biology Keeping Diseases Away Question 21.
What are the ways by which HIV spreads?
Answer:

Question 22.
How AIDS does not spread?
Answer:

• By touch, shaking hands, coughing, sneezing, etc.
• Through insects like mosquitoes, houseflies, etc.
• By staying together and sharing food
• By using same toilets
• By taking bath in the same pond.

Question 23.
What is the reason for hepatitis?
Answer:
Hepatitis is a liver disease. Hepatitis is also caused by virus.

Question 24.
What are the symptoms of hepatitis?
Answer:
Inflammation of the liver is its major symptom. When the flow of bile secreted by the liver is blocked, an increase in the level of bile pigment called bilirubin in blood is noticed. This imparts dark yellow colour to the mucus membrane, white portion of the eyes and the nails. This is the external symptom of the disease.

Question 25.
How hepatitis get transmitted?
Answer:
Disease gets transmitted through contaminated food and water, blood components and excreta of the patient. Certain hepatitis do get transmitted in the same way as the transmission of HTV.

Question 26.
What are the preventive measures taken against the transmission of dengue fever and chikungunya?
Answer:
Dengue fever and Chikungunya that are common in Kerala are also viral diseases. These diseases are transmitted through mosquitoes. Contaminated surroundings promote the multiplication of pathogens. The increase in the number of vectors like mosquitoes leads to the spread of communicable diseases much beyond control. Observing dry day, prevent the stagnation of water, etc. can be taken to prevent the multiplication of mosquitoes. It is our duty to keep our surroundings clean.

Question 27.
Explain about fungus.
Answer:
Fungi are of various types. Some fungi are pathogenic. The toxins produced by the fungi cause diseases.

Question 28.
Prepare a table containing diseases caused by fungus, symptoms and mode of transmission.
Answer:

Diseases caused by fungus	Mode of transmission	Symptoms
Ringworm	Spreads through contact.	Manifests as round, red blisters on the skin
Athletes’ foot	Pathogens enter through the toes when they come in contact with contaminated water, and soil.	Manifests on the sole of the foot and between the toes. Appearance of reddish scaly rashes that cause itching

Question 29.
Write about malaria.
Answer:
Malaria is caused by the protozoan, plasmodium. High fever with shivering and profuse sweating are the major symptoms of malaria. Other symptoms include headache, vomiting, diarrhoea, anaemia. The vector is female Anopheles mosquito.

Question 30.
Write about diseases in which worms as pathogens.
Answer:
Filariasis is caused by filarial worms that are spread by culex mosquitoes. The worms stay in the lymph ducts and obstruct the flow of lymph by blocking the ducts. This causes swelling in the lymph ducts in the legs.

Question 31.
What are the preventive measures to be taken against communicable diseases?
Answer:
Contaminated surroundings promote the multiplication of pathogen’s. The increase in the number of vectors like mosquitoes leads to the spread of communicable diseases much beyond control. In order to control the spread of communicable diseases, it is necessary to avoid situations that lead to the multiplication of pathogens and vectors. It is our duty to keep our surroundings clean.

Question 32.
What are non-pathogenic diseases?
Answer:

• Deficiency of nutrients – Marasmus, Kwashiorkor, Rickets
• Lifestyle diseases – Diabetes, Heart attack, Hypertension
• Occupational diseases – Silicosis, Asbestosis
• Genetic diseases – Haemophilia, Sickle cell anaemia.

Question 33.
Why do haemophilia patients lose blood excessively, even through minor wounds?
Answer:
Blood clots with the help of some proteins present in blood plasma. The synthesis of proteins fails when the genes that control protein synthesis become defective. Hence excess blood is lost even through minor wounds.

Question 34.
What is the treatment of haemophilia?
Answer:
As haemophilia is a genetic disease, a complete cure is not possible at present. Temporary relief is brought in by injecting the deficient protein identified through clinical diagnosis.

Question 35.
Explain the reason for sickle cell anaemia.
Answer:
The defects of genes may also cause deformities in the sequencing of amino acids which are the building blocks of haemoglobin. As a result of this, the structure of haemoglobin changes and this in turn decreases its oxygen carrying capacity.

Question 36.
How does the deformity of red blood cells in sickle cell anaemia patients affect their body?
Answer:
The defects of genes may also cause deformities in the sequencing of amino acids which are the
building blocks of haemoglobin. As a result of this, the structure of haemoglobin changes and this in turn
decreases its oxygen carrying capacity. The oxygen carrying capacity of red blood cells decreases. The
sickle shaped RBCs get collected in the blood vessels and block the flow of blood in them

Question 37.
Explain cancer.
Answer:
Cancer is caused by the uncontrolled division of cells spreading to other tissues. The normal cells get transformed into cancerous cells when the control system of cell division fails.

Question 38.
How cancer becomes complicated?
Answer:
Various reasons such as environmental factors, smoking, radiations, virus, hereditary factors, and alterations in genetic material lead to the transformation of normal cells into cancer cells. The disease may become complicated with the spread of cancer cells to other parts of the body through blood and lymph.

Question 39.
How is cancer treated?
Answer:
Currently surgery, chemotherapy, radiation therapy, etc., are used in the treatment of cancer. It is difficult for the patients to recover if the disease becomes severe. Hence, early diagnosis of the disease is crucial in the treatment of cancer.

Biology Class 10 Kerala Syllabus Chapter 4 Question 40.
What are lifestyle diseases? Write the reasons also.
Answer:

Lifestyle diseases are caused by unhealthy living style. The changes in food habits, lack of physical exercise, stress, bad habits like consumption of alcohol, drug abuse, smoking, etc., lead to various lifestyle diseases.

• Diabetes – deficiency of insulin or its malfunctioning
• Fatty Liver – deposition of excess fat in the liver
• Stroke- rupture’ of blood vessels in brain, block of blood flow
• Hypertension – decrease in diameter of arteries due to deposition of fat
• Heart attack – block of blood flow due to deposition of fat in coronary arteries, which carry blood to heart

Question 41.
How does smoking affect heart, lungs, and brain?
Answer:
Brain – Stroke, addiction to nicotine.
Lungs – Lung cancer, emphysema, bronchitis Heart – Hypertension, loss of elasticity of arteries, decrease in functional efficiency

Question 42.
Prepare a poster to make people aware of drug abuse.
Answer:

Question 43.
Find out diseases which are affected by domestic animals and complete the table.
Answer:

Diseases	Causative organisms	Symptoms
Anthrax	Bacteria	Oozing of blood from nose and mouth Foam and froth from mouth Sudden occurrence of fever
Foot and mouth diseases	Virus	Severe fever Boils in the mouth and between claws, which burst open . Loss of appetite
Swelling of udder	Bacteria	Swelling of udder Low yield of milk Infection in the udder Inflammation of nipple
Pullorum Poultry disease	Bacteria	Loose and white coloured excreta Drowsiness Block in breathing

Question 44.
Prepare an illustration related to plant diseases.
• Brown spots on leaves
• Leaves dry up
• Leaves shrink and become chaff
• Reduced yield
Answer:

Let Us Assess

Question 1.
Which among the following is not a bacterial disease? ,
a. Tuberculosis
b. Nipah
c. Diphtheria
d. Anthrax
Answer:
b. Nipah

Question 2.
“Food safety will be adversely affected with the spread of plant diseases. ”
a. Do you agree with this statement? Why?
b. Give two examples of plant diseases.
Answer:
a. I agree with this statement. Food safety can be ensured by the availability of food materials. Spread of plant diseases adversely affect the production of food materials.
b. Bunchy top of banana, Blight disease of paddy.

Question 3.
Prepare a pamphlet including the major measures to be taken to prevent rat fever.
Answer:
Leptospira is the bacteria that causes rat fever. The bacteria that comes out through the urine of rat, dog and certain other animals remain alive in stagnant water and moisture. Prevention of stagnation of water, avoid food which contains the urine of rat, keep the surroundings clean, engage in destroying rats, etc. help to prevent rat fever.

Question 4.
What is the importance of vaccination in preventing diphtheria?
Answer:
Antitoxins which act against the toxins are used to protect the uninfected cells. But, if the disease becomes severe, the patient cannot be recovered through medication. So vaccination is the best preventive method.

Question 5.
What health habits should be adopted to prevent lifestyle diseases?
Answer:
Lifestyle diseases are caused by unhealthy living styles. The changes in food habits, lack of physical exercise, mental stress, bad habits like consumption of alcohol, drug abuse, smoking, etc. lead to various lifestyle diseases. Avoiding junk foods and fast food, regular exercise, avoid the consumption of alcohol and drugs, avoid smoking, decreasing stress, etc. should be adopted to prevent lifestyle diseases

Kerala Syllabus 10th Standard Biology Guide

Students can Download Biology Chapter 5 Soldiers of Defense Questions and Answers, Notes Pdf, Activity in Malayalam Medium, Kerala Syllabus 10th Standard Biology Solutions helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

SSLC Biology Chapter 5 Soldiers of Defense Questions and Answers Malayalam Medium

SCERT 10th Standard Biology Textbook Chapter 5 Solutions Malayalam Medium

SSLC Biology Chapter 3 Chemical Messages for Homeostasis Textbook Questions and Answers

SCERT Class 10th Standard Biology Chapter 3 Chemical Messages for Homeostasis Solutions

Sslc Biology Textbook Solutions Question 1.
What is the speciality of endocrine system?
Answer:
The endocrine system is an organ system that works along with the nervous system to control and co-ordinate all activities in the body.

Question 2.
Endocrine glands are known as ductless glands. Write reasons.
Answer:
Hormones are chemical messengers that regulate cellular activities. Endocrine glands do not have particular ducts to carry hormones to various tissues. Hence they are known as ductless glands. Hormones are transported through blood.

Question 3.
Explain target cells.
Answer:
Hormones reach every cell in the body as they are transported by blood. But each hormone acts only upon those cells which have specific receptors. The cells which are acted upon by hormones are their target cells.

Question 4.
How do hormones affect cells?

Answer:
Only those cells having specific receptors can receive a specific hormone. Each hormone molecule binds with the receptor to form a hormone-receptor complex. Following this, enzymes are activated within the cell and certain changes occur in cellular activities.

Question 5.
Where is insulin and glucagon produced?
Answer:
The beta cells in the islets of Langerhans, a special group of cells in pancreas secrete insulin and the alpha cells secrete glucagon.

Question 6.
Explain the action of insulin to prevent the rise in the level of glucose in blood.
Answer:
When the level of glucose in blood is high, the production of insulin increases. Insulin enhances cellular uptake of glucose molecules and converts glucose into glycogen in the liver and muscles. As a result, the glucose in blood becomes normal.

Question 7.
Explain the action of glucagon when the level of glucose in blood decreases.
Answer:
When the level of glucose in blood is low, the production of glucagon increases. Glucagon converts the glycogen stored in the liver to glucose and synthesizes glucose from amino acids. As a result, the glucose in blood becomes normal.

Question 8.
What is the normal level of glucose in blood?
Answer:
The normal level of glucose in blood is 70-110 mg / 100 mg.

Question 9.
How is the level of glucose in blood maintained while fasting?
Answer:
During fasting, the glucose in blood becomes low. In such situations, the alpha cells of islets of Langerhans in pancreas secrete glucagon. The glucagon converts the glycogen stored in the liver to glucose and synthesizes glucose from amino acids. Such actions help to maintain the blood glucose level tononnal.

Question 10.
What is the reason for increase in the level of glucose in blood.?
Answer:
Decreased production of insulin due to the destruction of beta cells or the inability of cells to utilize the insulin produced, raises the level of glucose in blood. Excess glucose in the blood is expelled through urine.

Question 11.
What is diabetes mellitus?
Answer:
Diabetes is clinically referred to as a condition when the level of glucose before breakfast is above 126mg/ 100ml of blood.

Kerala Syllabus 10th Standard Biology Textbook Solutions Question 12.
Write about the symptoms and reasons for diabetes.
Answer:
Increased appetite and thirst and frequent urination are the major symptoms of diabetes. Decreased production of insulin is the reason for diabetes.

Question 13.
Write the test to detect the presence of glucose in urine.
Answer:
Take 2ml of the urine in a test tube. Add 2ml Benedict solution into it. Heat for 2 minutes. Observe the change in colour. Formulate your inference by comparing the glucose indicator on the reagent bottle.

Question 14.
What is metabolism?
Answer:
The anabolic and catabolic processes taking place in the body are commonly referred as metabolism. Metabolic activities are also under the control of hormones.

Question 15.
Name the hormones secreted by thyroid gland.
Answer:
The thyroid gland secrets two hormones- thyroxine and calcitonin.

Biology Class 10 Kerala Syllabus Question 16.
What are the functions of thyroxine?
Answer:
Thyroxine plays an important role in controlling life activities. Thyroxine increases energy production and raises the rate of metabolism. It also accelerates the growth and development of the brain in the foetal stage and infancy and regulates growth in children.

Question 17.
What are the problems due to thyroxine deficiency?
Answer:
Hypothyroidism is a condition in which the production of thyroxine decreases. The decrease in production of thyroxine during the foetal stage or infancy, hinders proper physical and mental development. This condition is Cretinism. Prolonged deficiency of thyroxine in adults leads to a condition called Myxoedema. Low metabolic rate, sluggishness, increase in body weight, hypertension and inflammation in body tissues are the major symptoms of this disorder.

Question 18.
What are the problems caused by excessive production of thyroxine?
Answer:
All the life activities controlled by thyroxine are accelerated due to the excessive production of thyroxine. This condition is known as hyper-thyroidism. The major symptoms are high metabolic rate, rise in body temperature, excessive sweating, increased heart beat, sleeplessness, weight loss, emotional imbalance, etc. Persistent hyperthyroidism may lead to Graves disease, characterised by bulging of the eyeballs.

Question 19.
How is iodine related to thyroid gland?
Answer:
Iodine is essential for the production of thyroxine. The production of thyroxine is obstructed in the absence of iodine. In an attempt to produce more thyroxine, the thyroid gland enlarges. This condition is called goitre.

10th Biology 3rd Chapter Question 20.
What is the normal level of calcium in blood?
Answer:
The normal level of calcium in blood is 9-11 mg / 100 ml.

Question 21.
What is the role of calcitonin in regulating the level of calcium in blood?
Answer:
When the level of calcium in blood increases, thyroid gland secretes a hormone named calcitonin. It lowers the level of calcium in blood. This hor-mone helps in maintaining the level of calcium in blood by depositing excess calcium in bones and by preventing the mixing of calcium with blood from the bones.

Question 22.
What is the role of parathormone in regulating the level of calcium in blood?
Answer:
Parathyroid gland secretes a hormone called parathormone. The function of this hormone is to raise the level of calcium in blood. When the level of calcium in the blood decreases, parathormone helps in the reabsorption of calcium to the blood from the kidneys and also prevents the deposition of calcium in bones.

Question 23.
Complete the illustration showing the maintenance of the level of calcium in blood by the action of hormones.

Answer:

A. Thyroid
B. Parathormone
C. Decrease
D. Depositing excess calcium in bones and by preventing the mixing of calcium with blood from the bones.
E. Helps the reabsorption of calcium to the blood from kidneys and also prevents the deposition of calcium in bones.

Kerala Syllabus 10th Standard Biology Question 24.
Write the importance of thymus gland.
Answer:
Thymus gland is very active during infancy but constricts as we reach puberty. The major function of this gland is to control the activities and maturation of lymphocytes which help to impart immunity. This gland secretes a hormone called thymosin.

Question 25.
Name the hormones secreted by the adrenal cortex.
Answer:
The outer part of the adrenal gland is known as the cortex which produces hormones namely cortisol, aldosterone and sex hormones.

Question 26.
Write the function of cortisol.
Answer:
The synthesis of glucose from protein and fat, controls inflammation and allergy, slows down the action of defence cells, are the functions of cortisol.

Question 27.
How does the maintenance of salt-water balance take place in the body?
Answer:
Aldosterone is produced from the cortex of adrenal gland. Aldosterone maintains the salt-water level by acting in kidneys.

Question 28.
Explain the functions of epinephrine and norepinephrine during emergencies.
Answer:
Epinephrine and norepinephrine are produced from the medulla, the inner part of Adrenal gland. Epinephrine acts along with the sympathetic nervous system during emergencies. We can resist or withdraw ourselves from such situations. In these situations, norepinephrine acts along with epinephrine. The action of epinephrine and norepinephrine prolongs the body activities for more time, when the sympathetic system gets stimulated.

Question 29.
How does melatonin help in maintaining the rhythm of our daily activities?
Answer:
Pineal gland secretes the hormone, melatonin which helps in maintaining the rhythm of our daily activities. The production of melatonin is high at night and low during the day. When the level of melatonin increases, we feel sleepy and when it decreases we wake up. Thus, this hormone regulates the rhythm of life. This hormone also controls reproductive activities of organisms with definite reproductive periods.

Sslc Biology Chapter 3 Questions And Answers Question 30.
Describe the structure of pituitary gland.
Answer:

Pituitary gland is a two lobed gland seen below the hypothalamus.

Question 31.
Prepare a table containing the hormones secreted by the anterior lobe of the pituitary gland and its function.
Answer:

Hormones secreted by the anterior lobe of the pituitary gland	Function
Thyroid Stimulating Hormone (TSH)	Stimulates the activity of the thyroid gland
Adreno Cortico Tropic Hormone (ACTH)	Stimulates the activity of adrenal cortex
Gonado Tropic Hormone (GTH)	Stimulates the activity of testes in males and ovary’ in females
Growth Hormone (GH) Somato Tropic Hormone (STH)	Promotes the growth of the body
Prolactin	Production of milk

Kerala Syllabus 10th Standard Biology Solutions Question 32.
Write the function of somatotropin.
Answer:
Somatotropin is secreted by the anterior lobe of pituitary gland. It promotes growth of the body during its growth phase.

Question 33.
Explain dwarfism, gigantism and acromegaly.
Answer:

• If the production of somatotropin decreases during the growth phase, it causes dwarfism.
• If the production of somatotropin increases during the growth phase, it leads to the excessive growth of the body. This condition is called gigantism.
• Acromegaly is the condition caused by the excessive production of somatotropin after the growth phase. It is characterised by the growth of the bones on face, jaws and fingers.

Question 34.
The posterior lobe of pituitary gland is a storage centre. Write your opinion about this statement.
Answer:
This is a correct statement. The hormones oxytocin and vasopressin which are secreted from the posterior lobe of the pituitary are actually produced in the neuro-secretory cells of the hypothalamus. The posterior lobe of pituitary stores these two hormones and releases them into blood.

Question 35.
What is the function of oxytocin?
Answer:
Oxytocin facilitates child birth by stimulating the contraction of smooth muscles in the uterine wall. Oxytocin also facilitates lactation.

Question 36.
Explain the function of vasopressin in kidneys.
Answer:
Vasopressin helps in the reabsorption of water in kidneys. Thus vasopressin regulates the loss of water through urine.

Sslc Biology Chapter 3 Pdf Question 37.
Write the reason for excessive production of urine during the rainy season.
Answer:
The production of vasopressin is less during winter and rainy seasons. This decreases the reabsorption of water in the kidneys and thus the quantity of urine increases.

Question 38.
What is the role of vasopressin in preventing loss of water from the body?
Answer:
When the normal water level in blood decreases, the production of vasopressin increases. This increases the reabsorption of water in kidneys and thus the quantity of urine lowers.

Question 39.
What is diabetes insipidus?
Answer:
When the production of vasopressin decreases, the reabsorption of water in the kidney is decreased and excess amount of urine is eliminated. This condition is known as diabetes insipidus. Frequent urination, increased thirst, etc. are the symptoms

Question 40.
Explain the action of male sex hormones.
Answer:
The male sex hormone testosterone controls sperm production and secondary sexual characters in males such as change in voice, growth of hair, etc.

Question 41.
Write the action of female sex hormones.
Answer:
Ovary produces the female sex hormones namely estrogen and progesterone. Estrogen controls secondary sexual characters, ovulation, menstrual cycle, etc. Progesterone controls ovulation, menstrual cycle and implantation of embryo in the uterus.

Question 42.
Explain the influence of gonadotropic hormones in sex organs.
Answer:
Testes and ovary, the male and female sex organs respectively, secrete different types of hormones. Gonadotropic hormones from the pituitary regulate the development and functions of the sex organs.

Question 43.
Hypothalamus plays an important role in maintaining homeostasis. How?
Answer:
Vasopressin, oxytocin, releasing hormones and inhibitory hormones are secreted by hypothalamus. Vasopressin regulates the water level. Oxytocin facilitates child birth by stimulating the contraction of smooth muscles in the uterine wall and facilitates lactation. Releasing hormone stimulates the anterior lobe of the pituitary and secretes tropic hormones.

The tropic hormones are TSH which stimulates the activity of the thyroid gland, ACTH which stimulates the activity of adrenal cortex and GTH which stimulates the sex organs. The inhibitory hormone inhibits the production of tropic hormones in the anterior lobe of the pituitary gland, thus controls the activity of endocrine glands.

Biology Class 10 Chapter 3 Kerala Syllabus Question 44.
Write about pheromones and their function.
Answer:
Chemical substances that are secreted by certain animals to the surroundings to facilitate communication are called pheromones.
Pheromones help in attracting mates, informing the availability of food, determining the path of travel, signalling dangers, etc. The chemical messages of pheromones also help honey bees and termites to live in colonies. The muscone in the musk deer, the civeton in the civet cat, bombykol in the female silk worm moth, etc., are examples for pheromones.

Question 45.
What are plant growth regulators?
Answer:
There are certain chemical substances in plant cells to control and co-ordinate life activities as in animals. These are the plant hormones. These are also called plant growth regulators.

Question 46.
Prepare a table containing plant hormones and their functions.
Answer:

Plant hormone	Function
Gibberellin	Stimulates break down of stored food to facilitate germination, sprouting of leaves
Auxin	Cell growth, cell elongation, promoting the growth of terminal buds, fruit formation.
Cytokinin	Cell growth, cell division, cell differentiation.
Abscisic acid	Dormancy of embryo, dropping of ripened leaves and fruits.
Ethylene	Ripening of leaves and fruits, excess amount of ethylene causes dropping of leaves and fruits.

Biology Class 10 Kerala Syllabus Chapter 3 Notes Question 47.
Prepare a short note on artificial plant hormones.
Answer:
Plant hormones are synthesized artificially by identifying the chemical structure of hormones. Use of such hormones has contributed a lot to the progress of the agricultural sector.

• Auxins –
  It is used in the agricultural field to prevent the dropping of premature fruits, for the sprouting of roots and as a weedicide.
• Gibberellins –
  It is used for increasing fruit size in grapes and apple and also for preventing ripening of fruits to assist marketing.
• Ethylene –
  Ethylene is used for the flowering of pineapple plants at a time and for the ripening of tomato, lemon, orange, etc. Ethyphon, a chemical which is available in liquid form, gets transformed into ethylene, when used in rubber trees and it increases the production of latex.
• Abscisic acid –
  It is used for harvesting fruits at the same time.

Let Us Assess

Question 1.
Identify the word-pair relationship to fill in the blank.
Thyroxine : Thyroid gland
Epinephrine : …………………
Answer:
Adrenal gland

10th Std Biology Guide Question 2.
Analyse the information given in the box and answer the questions.
X -The production of this hormone is more in night and less in day time.
Y -Hormones from the adrenal gland work along with the sympathetic system.

a. Identify and name the hormone ’X’ and its gland.
b. Identify the hormones indicated as ‘Y’.
Answer:
a. Melatonin, Pineal gland
b. Epinephrine (Adrenaline), Norepinephrine (Noradrenaline)

Question 3.
Analyse the illustration and complete the table appropriately.


Answer:

Gland	Location	Hormones
Hypothalamus	Below the thalamus	Oxytocin, Vasopressin, Releasing hormone, Inhibitory hormone
Pituitary	Below the hypothalamus	Tropic hormones (TSH, ACTH, GTH), Growth hormone, Prolactin
Thyroid	In the throat just below the larynx.	Calcitonin, Thyroxine
Parathyroid	Behind the thyroid gland	Parathormone
Thymus	Just below the sternum	Thymosin
Pancreas	Below the stomach, near the duodenum	Insulin, Glucagon
Ovary (female)	On either side of uterus	Estrogen, Progesterone
Testis (male)	In the scrotum, outside the abdominal cavity	Testosterone
Adrenal	Above the kidneys	Cortisol, Aldosterone, Sex hormones, Epinephrine, Norepinephrine
Pineal	Centre of brain	Melatonin

Question 4.
The hormone that helps in the reabsorption of water in the kidneys.
a. TSH
b. ACTH
c. ADH
d. GDH
Answer:
c. ADH

Kerala Syllabus 10th Standard Biology Guide

SSLC Biology Chapter 6 Unravelling Genetic Mysteries Textbook Questions and Answers

SCERT Class 10th Standard Biology Chapter 6 Unravelling Genetic Mysteries Solutions

Sslc Biology Chapter 6 Question 1.
Observe the picture.

What are the features that the children show different from their parents?
Answer:

• The hair of deer and cat differ from their parents.
• The daughters have a different hair pattern from the mother.
• The forehead and ear of the son are different from his mother.

Question 2.
Explain the terms heredity, variations and genetics.
Answer:
The transmission of features of parents to offsprings is termed as heredity. The features seen in offsprings that are different from their parents are called variations. The branch of science that deals with heredity and variations is called Genetics.

Question 3.
Why is Mendel considered as the Father of Genetics?
Answer:
Certain laws of inheritance, formulated by Gregor Johann Mendel, on the basis of hybridization experiments in pea plants, have led to the foundation of genetics. This is why Mendel is considered as the Father of Genetics.

Question 4.
What are the traits that were experimented by Mendel?
Answer:
Gregor Johann Mendel studied the inheritance of 7 pairs of contrasting traits in pea plants, scientifically known as Pisum sativum. He formulated the laws of inheritance by analysing the inheritance of characters like height of plants, position of flower, shape of seed, colour of seed coat, colour of cotyledon, colour of fruit and shape of fruit.

Question 5.
What are the contributions of Gregor Johann Mendel?
Answer:
Through Gregor Johann Mendel’s studies on inheritance, he explained that each character is controlled by a pair of factors, which he illustrated using symbols.

The illustration of the hybridization experiment conducted on the basis of two contrasting traits of the character height in pea plant. Here the factors are illustrated using symbols.

Question 6.
Which character of pea plants is considered in this experiment?
Answer:
Height of plants

Question 7.
What are the contrasting traits of the character height?
Answer:
Tall and dwarf.

Class 10 Biology Kerala Syllabus Question 8.
What are the traits those were apparent and not apparent in the first generation?
Answer:
Expressed trait – tall Hidden trait – Dwarf

Question 9.
Difference in the factors of tall parent plant and the first generation plant.
Answer:
Tallness in parent plant is controlled by the factor T. But in the first generation tallness is controlled by the factors T, t.
When plants that differ in a pair of contrasting traits are hybridized, only one trait is expressed while the other remains hidden in the offsprings of the first generation. The expressed trait is called dominant trait and the hidden trait is called recessive trait.

Question 10.
What are alleles?
Answer:
The gene present in the chromosome of the nucleus determines the character. A gene that controls a .trait has different forms. The different forms of a gene are called alleles. Generally, a gene has two alleles.

Question 11.
Which are the alleles of a tall plant?
Answer:
The alleles of a tall plant are ‘TT’.

Question 12.
Which are the alleles of a dwarf planet?
Answer:
The alleles of a dwarf plant are ‘tt’.

Biology Class 10 Kerala Syllabus Question 13.
How are alleles represented?

Answer:
The different forms of a gene are called alleles. Generally a gene has two alleles. The different alleles of the gene that control the trait, height in the illustration of hybridization, given above are T and t. The allele T determines the trait tallness and the allele t determines the trait dwarfness. When we illustrate hybridization experiment, the allele that controls the dominant character that is expressed in the first generation is generally indicated by a capital letter and the allelle that controls recessive character is indicated by a small letter.

Question 14.
Explain dominant trait and recessive trait.
Answer:
When plants that differ in a pair of contrasting traits are hybridized, only one trait is expressed while the other remains hidden in the offsprings of the first generation. The expressed trait is called dominant trait and the hidden trait is called recessive trait.

Question 15.
What are the characters of plants in the second generation and their factors?
Answer:
In second generation three plants were tall and one plant was dwarf.

Question 16.
Explain the characters of plants and their alleles in the second generation.
Ans:
Tall – 1 (TT), Tall – 2 (Tt), Dwarf – 1 (tt).

Question 17.
Recessive trait in the first generation and the second generation?
Answer:
The recessive trait in the first generation is expressed in the second generation.

Question 18.
Why does the recessive trait in the first generation appear in the second generation?
Answer:
Mendel came up with the assumption that during gamete formation, the factors that determine a particular character segregate without getting mixed; ie., half of the gametes formed from first generation plant Tt, contains T and the other half contains t.

Class 10 Biology Chapter 6 Kerala Syllabus Question 19.
What are the inferences formulated by Mendel from hybridization experiments?


Answer:
A character is controlled by the combination of two factors.
One trait is expressed (dominant trait) and the other trait remains hidden (recessive trait) in the offsprings of the first generation.
The traits that remain hidden in the first generation appear in the second generation.
The ratio of the dominant and the recessive traits in the second generation is 3 : 1.
Hybridization experiment conducted on two characters

Question 20.
What are the factors present in the gametes produced by first-generation?
Answer:
The factors present in the gametes produced by first-generation are, TR, Tr, tR, tr.

Question 21.
What are the characters in the plants of second-generation?
Answer:
Tall plant with round seed, Tall plant with wrinkled seed, Dwarf plant with round seed, Dwarf plant with wrinkled seed.

Question 22.
What are the characters different front parents that appeared in the second generation?
Answer:
The characters different from parents that appeared in the second generation are tall plant with wrinkled seed and dwarf plant with round seed.

Question 23.
What is the reason for the appearance of new combination of characters in offsprings that were not expressed in parents?
Answer:
Mendel explained that the appearance of variations in offsprings (characters not present in previous generation) is due to the independent assortment of each character.

Question 24.
Explain the double-helical model of DNA.
Answer:
Two scientists, James Watson and Francis Crick presented the double-helical model of DNA in 1953. This model got wide acceptance in the scientific world. As per the double-helical model, DNA contains two strands. A model of two long strands with sugar and phosphate and steps with nitrogen bases were suggested.

Question 25.
What are nitrogen bases? Which are the nitrogen bases seen in DNA?
Answer:
Nitrogen bases are molecules that contain nitrogen and are alkaline in nature. DNA contains four kinds of nitrogen bases. They are adenine, thymine, guanine and cytosine.

Question 26.
What is the speciality seen in the pairing of nitrogen bases?
Answer:
Nitrogen bases which are the basic units of DNA are molecules with special features. In DNA, the base adenine pairs with thymine and guanine pairs with cytosine.

Question 27.
What are the components of nucleotides?
Answer:
DNA molecule is the repetitive unit of a deoxyribose sugar molecule, a phosphate molecule and a nitrogen base. This unit is called nucleotide. Since DNA has four kinds of nitrogen bases, DNA has four kinds of nucleotides too.

Question 28.
Illustrate the arrangement of nucleotides in a DNA molecule.
Answer:

Question 29.
Write the differences between DNA and RNA.
Answer:

	DNA	RNA
1.Number of strands	Double	Single
2. Type of sugar	Deoxyribose sugar	Ribose sugar
3. Nitrogen bases	Adenine, Adenine, Thymine, Uracil,	Guanine, Guanine, Cytosine Cytosine

Kerala Syllabus 10th Standard Biology Notes Pdf Question 30.
Prepare a short note on genes.
Answer:
The activity of particular proteins (enzymes) controls metabolic activities and is responsible for specific characteristics. Genes contain information for protein synthesis. Genes are particular segments of DNA.

Question 31.
How do genes act? Explain.
Answer:
Genes which are the specific units of DNA control metabolic activities and they are responsible for specific characters. DNA does not participate directly in protein synthesis. RNA (Ribo Nucleic Acid) is the molecule that carries information from DNA to ribosomes and controls protein synthesis. Since this RNA is the messenger of DNA, it is called messenger RNA or mRNA. mRNA reaches ribosomes outside the nucleus. Different kinds of amino acids reach ribosomes.

Question 32.
Write the difference between mRNA, tRNA, rRNA.
Answer:

• mRNA – Since this RNA is the messenger of DNA, it is called messenger RNA or mRNA.
• tRNA – tRNA (Transfer RNA) carries amino acids to the ribosome.
• rRNA – rRNA (Ribosomal RNA) are seen associated with ribosomes.

Protein molecule is synthesized by adding amino acids as a result of all these activities.

10th Standard Biology Notes Question 33.
Write note on human chromosomes.
Answer:
46 chromosomes are seen in humans. Among these, 44 chromosomes are autosomes (somatic chromosomes) and two chromosomes are sex chromosomes. An autosomal pair constitutes two identical chromosomes. Hence 22 pairs of autosomes are found in humans.

Question 34.
What are the sex chromosomes in humans?
Answer:
Sex chromosomes are of two types. They are called X chromosome and Y chromosome. Two X chromosomes are seen in female but an X chromosome and a Y chromosome are seen in male. That is, the genetic constitution of female is 44 + XX and that of male is 44 + XY.

Question 35.
What is crossing over of chromosomes?
Answer:
During the initial phase of meiosis, chromosomes pair and exchange their parts. This process is called crossing over of chromosomes.

Question 36.
How does crossing over cause variation?
Answer:
As a result of crossing over, part of a DNA crosses over to become the part of another DNA. This causes a difference in the distribution of genes. When these chromosomes are transferred to the next generation, it causes the expression of new characters in offsprings.

Question 37.
How the combination of allele during fertilization causes variations in the next generation?
Answer:
The chromosomes of parents reach the offsprings through gametes. When gametes undergo fusion, the combination of allele changes. This causes the expression of characteristics in offsprings that are different from parents. Thus, fertilization causes variations in the next generation.

Kerala Syllabus 10th Standard Biology Question 38.
What is mutation?
Answer:
A sudden heritable change in the genetic constitution of art organism is called mutation.

Question 39.
What are the reasons for mutation?
Answer:
Mutation may occur due to the defects in the duplication of DNA, certain chemicals, radiations, etc.

Question 40.
What is the importance of mutation?
Answer:
Certain mutations are harmful and some are helpful for survival. Mutations lead to variations in characters. The effects of certain mutations are visible immediately while some are expressed after many generations. Mutation has great relevance in evolution.

Question 41.
Is there any difference in the number of chromosomes in male and female?
Answer:
46 chromosomes are seen in humans. Among these, 44 chromosomes are autosomes (somatic chromosomes) and two chromosomes are sex chromosomes. An autosomal pair constitutes two identical chromosomes. Hence 22 pairs of autosomes are found in humans. Sex chromosomes are of two types.

They are called X chromosome and Y chromosome. Two X chromosomes are seen in female but a X chromosome and a Y chromosome are seen in male. That is, the genetic constitution of female is 44 + XX and that of male is 44 + XY.

Question 42.
What is the possibility for the birth of a male or a female child?
Answer:

The XY chromosomes of the father determine whether the child is male or female. Child with XX sex chromosomes is female and one with XY sex chromosomes is male.

Question 43.
What may be the reason for the difference in the colour of skin in people living in various parts of the world?
Answer:
Melanin, a pigment protein imparts colour to the skin. It can be assumed that the difference in gene function is the reason for the colour difference of skin.

Let Us Assess

Question 1.
The nitrogen base absent in RNA
a. Adenine
b. Thymine
c. Uracil
d. Cytosine
Answer:
b. Thymine

Question 2.
Arrange the stages of protein synthesis in the form of a flow chart.

• combines amino acids
• mRNA reaches ribosomes
• mRNA is formed
• amino acids are carried to the ribosomes

Answer:
mRNA is formed → mRNA reaches ribosomes → amino acids are carried to the ribosomes → combines amino acids.

Question 3.
Observe the hybridisation experiment given below.

a. Prepare an illustration of this hybridization experiment using symbols.
b. Prepare an illustration for the second generation.
Answer:
a.

b. Self-pollination in first-generation

Biology Class 10 Kerala Syllabus Notes Question 4.
Three processes that cause variations in new generations are given. Prepare a short note on each of the processes.

• Crossing over of chromosome
• Fertilization
• Mutation

Answer:
Crossing over of chromosome – During the initial phase of meiosis, chromosomes pair and exchange their parts. This process is called crossing over of chromosomes. As a result of this, part of a DNA crosses over to become the part of another DNA. This causes a difference in the distribution of genes. When these chromosomes are transferred to the next generation, it causes the expression of new characters in offsprings.

Fertilization – The chromosomes of parents reach the offsprings through gametes. When gametes undergo fusion, the combination of allele changes. This causes the expression of characteristics in offsprings that are different from parents. Thus, fertilization causes variations in the next generation

Mutation – A sudden heritable change in the genetic constitution of an organism is called mutation. This may occur due to defects in the duplication of DNA, certain chemicals, radiations, etc. Mutations bring about changes in genes which can be transmitted over generations and thus leading to variations in characters. Mutations have great relevance in evolution.

Kerala Syllabus 10th Standard Biology Guide

SSLC Biology Chapter 2  Windows of Knowledge Textbook Questions and Answers

SCERT Class 10th Standard Biology Chapter 2  Windows of Knowledge Solutions

Biology Class 10 Kerala Syllabus Chapter 2 Question 1.
Why are dogs more capable than human beings in tracking the injured. in such circumstances?
Answer:
The number of receptors influence the efficiency of sense organs. The number of receptors in the sense organs is different in different organisms. The surface of a postage stamp is enough to arrange all the olfactory cells in the nose of a human being. But a large scarf is required to arrange the olfactory cells of a dog.

Question 2.
List various sense organs and the stimuli they receive.
Answer:

Sense organ	Receptors	Stimuli
Eye	Photoreceptors	Light
Ear	Auditory receptors	Sound
Tongue	Taste receptors	Taste
Nose	Olfactory receptors	Smell
Skin	Various receptors	Touch, pain temperature, cold, pressure

Question 3.
Make a table to explain how eyes are protected.
Answer:

Eye socket (orbit)	Protection of eyeball.
External eye musc1e	Fix the eyeball in the orbit.
Eyebrow	Protects the eyes from dust, sweat.
Eyelashes	Protect the eyes from dust.
Eyelids	Protect the eyes from dust and external shocks.
Conjunctiva	Secretes mucus which protects the anterior portion of the eyeball from being dry.
Tears	Clean and lubricate the anterior part of the eyeball.

Question 4.
Make a table containing important paris of eye, its peculiarities and functions.

Answer:

Parts	Peculiarity	Functions
Sclera	Outermost layer, made up of connective tissues.	Gives rigidity to the eyeball.
Choroid	Middle layer which contains a large number of blood vessels.	Gives nutrients and oxygen to the tissues of eye.
Retina	The inner most layer of eye.	Photoreceptors are seen. Images are formed.
Conjunctiva	A thin membrane covers the front part of the eyeball except cornea.	Protects the front part of eyeball.
Cornea	Slightly projected transparent anterior part of the sclera.	Refracts light rays to focus on retina.
Iris	Part of the choroid seen behind the cornea.	Presence of melanin prevents harmful light rays.
Pupil	The aperture seen at the centre of the iris.	Contracts and relaxes according to the intensity of light.
Lens	Elastic transparent convex lens.	Helps to focus light on retina.
Ciliary muscles	Circular muscles seen around the lens.	The contraction and relaxation of these muscles alter the curvature of lens.
Aqueous chamber	The chamber between the lens and the cornea filled with watery fluid – aqueous humour.	Gives nutrients to the lens and cornea.
Vitreous chamber	The chamber between the retina and the lens; filled with jelly like fluid – vitreous humour.	Gives shape to the eyeball.
Yellow spot	The part of retina where plenty of photoreceptors are present.	It is the point of maximum visual clarity.
Blind spot	Photoreceptors are absent.	The part of retina from where the optic nerve begins.
Optic nerve	Nerve fibre connecting eyeball and brain.	Transmits impulses from photo receptors to the visual centre in the brain.

Biology Class 10 Kerala Syllabus Chapter 2 Question 5.
Explain the changes which occur in the pupil based on the intensity of light.
Answer:
Light which passes through the cornea reaches the lens through an aperture called the pupil. The size of the pupil is regulated with the help of muscles in the iris. The pupil dilates in dim light and constricts in bright light. Thus the amount of light falling on the lens is regulated according to the intensity of light.

Question 6.
What is the role of circular muscles and radial muscles in regulating the size of pupil?
Answer:
The size of the pupil is regulated by the action of circular muscles and radial muscles. When the radial muscles contract in dim light, the size of the pupil increases. When the circular muscles contract in intense light, the size of the pupil decreases. Thus the amount of light falling on the lens is regulated according to the intensity of light.

Question 7.
What are the peculiarities of image formed?
Answer:
Real, small, inverted.

Question 8.
Write down the features of the eye that help to view near and distant objects.
Answer:

While viewing near objects, the curvature of lens increases. As a result, the focal length decreases. The contraction of ciliary muscles and relaxation of ligaments help to increase the curvature of lens.

While viewing distant objects, the curvature of lens decreases. As a result, focal length increases. The relaxation of ciliary muscles and stretching of ligaments help to decrease the curvature of lens.

Question 9.
What is the power of accommodation of the eye?
Answer:
The capacity of the eye to change the curvature of lens depending on the distance between the eye and the object by adjusting the focal length is called the power of accommodation of the eye.

Question 10.
Name the photoreceptors in the eye. How do they differ from one another?
Answer:
The two photoreceptors present in the retina of the eye are rod cells and cone cells. Rod cells are more in number than cone cells. Rod cells have the shape of a rod and cone cells are cone shaped. Rod cells contain visual pigment called rhodopsin and in cone cells the pigment is photopsin (iodopsin). Rod cells are highly photosensitive and since they are activated even in very dim light, we are able to see objects in dim light. The cone cells provide us with colour vision.

Question 11.
Prepare a short note on the diversity of cone cells.
Answer:
Three types of cone cells which help us to detect three primary colour of light-red, green and blue are present in our eyes. This is due to the change in amino acid in the opsin molecule.

Question 12.
Explain the function of cone cells and rod cells.
Answer:
The visual pigment seen in cone cell is photopsin (iodopsin) and rod cell is rhodopsin. Both these pigments are formed from a protein named opsin and retinal which is a derivative of Vitamin A. When light rays fall on pigments present in photoreceptors, the pigments dissociate into retinal and opsin. This chemical change leads to the formation of impulses.

Question 13.
How is vision enabled?
Answer:
The visual pigment seen in cone cell is photopsin (iodopsin) and rod cell is rhodopsin. When light rays fall on pigments present in photoreceptors, the pigments dissociate into retinal and opsin. This chemical change leads to the formation of impulses. These impulses are transmitted to cerebrum through the optic nerves and this enables vision.

Question 14.
Prepare a flow chart showing the process of ‘ vision.
Answer:
Light → Cornea → Aqueous humour → Pupil → Lens→ Vitreous humour → Retina → Impulse → Optic nerve → Cerebrum → Sense of sight

Binocular vision
The activity to feel binocular vision:
Stretch your left hand forward. Close your right eye and focus the forefinger of your left hand. Now close your left eye and without changing the direction of your head, focus the I same finger. You can feel the change in the position of finger.

Question 15.
What is binocular vision?
Answer:
The images from two sides of the same object are formed in the left and right eye. These two images are combined together in the visual area of our brain to form a three dimensional image of the object. This is called binocular vision.

Biology Class 10 Notes Kerala Syllabus Question 16.
What is the difference between night blindness and xerophthalmia?
Answer:

The deficiency of Vitamin A results in the low production of retinal. This in turn creates the deficiency of rhodopsin in rod cells. The resynthesis of rhodopsin also gets blocked. This causes a condition called night blindness. Persons with night blindness cannot see objects clearly in dim light.

Due to the prolonged deficiency of Vitamin A, the conjunctiva and cornea will become dry and opaque. This condition is called xerophthalmia.

Question 17.
Prepare a note on the eye defects and diseases.
Answer:

Night blindness:
The retinal, a part of the visual pigment, is derived from Vitamin A. The deficiency of Vitamin A results in the low production of retinal. This in turn prevents the resynthesis of rhodopsin. In this condition, objects cannot be seen clearly in dim light and this disease is called night blindness.

Xerophthalmia:
If there is a prolonged deficiency of Vitamin A, the conjunctiva and cornea become dry and opaque. This causes xerophthalmia and leads ultimately to blindness.

Colour blindness:
Retina contains cone cells which can detect red, green, and blue colours. Colour blindness is caused due to the defect of cone cells which detect red and green colours. Persons with this defect cannot distinguish green and red colours.

Glaucoma:
If the reabsorption of aqueous humour does not occur, it causes an increase in the pressure inside the eyes which causes a defect called glaucoma. This causes damage to the retina and the photoreceptor cells and ultimately leads to blindness. This defect can be rectified by laser surgery.

Cataract: It is a condition in which the lens of the eyes become opaque resulting in blindness. This can be rectified by replacing the lens with an artificial one, through surgery.

Conjunctivitis:
This is an infection of the conjunctiva. The causative organisms may be bacteria, virus, etc. This disease is transmitted through contact and can be prevented by maintaining personal hygiene.

Question 18.
Food materials rich in Vitamin A and health of the eye
Answer:
The retinal, a part of the visual pigment, is derived from Vitamin A. The deficiency of Vitamin A results in the low production of retinal. This in turn prevents the resynthesis of rhodopsin. So food containing vitamin A is necessary for the health of eye.

Question 19.
Excessive use of mobile, computer, etc and health of the eye.
Answer:
The problems of the eyes caused by the excessive use of cell phones, computer, tablet, etc is called computer vision syndrome. The continuous use of such devices affects the ability of the eye to focus. Headache is its major symptom. Drying of the eye, high pressure in the eye, etc are other symptoms.

Question 20.
Write the functions performed by ear.
Answer:
Ear helps us in hearing and maintaining the balance of the body.

Biology Chapter 2 Class 10 Kerala Syllabus Question 21.
What are the parts and their function of the externa1 ear?

Answer:
Pinna – Carries sound waves to the auditory canal.
Auditory canal –
Carries sound waves to the tympanum. Small hairs and wax present inside the canal help to prevent dust and foreign particles from entering the ear.
Tympanum –
A thin circular membrane that separates the middle ear from . the external ear. It vibrates in resonance with sound waves.

Question 22.
What are the parts of middle ear?

Answer:
Ear ossicles (Malleus, Incus, Stapes), Eustachian tube are the parts of middle ear.

Question 23.
Explain the function of ear ossicles.
Answer:
Malleus, incus and stapes are the bones seen in ear ossicles. The ear ossicles connect the tympanum to the internal ear through the oval window. Ear ossicles amplify and.transmit the vibrations of tympanum to the internal ear.

Question 24.
What is the peculiarity of Eustachian-tube?
Answer:
Eustachian tube connects middle ear and pharynx. It helps in maintaining balance of pressure on either side of the tympanum.

Question 25.
Write the features of labyrinth seen in internal ear.
Answer:
The internal ear is situated inside a bony case in the skull called the bony labyrinth. In this bony case, there are membraneous labyrinths as well.

Question 26.
What are the fluids seen in internal ear?
Answer:
The space inside the membraneous labyrinth is filled with a fluid named endolymph. The space between the membraneous and bony labyrinth is filled with a fluid called perilymph.

Question 27.
Write the main parts and function of internal ear.
Answer:

Semicircular canals, vestibule and cochlea are the main parts of the internal ear. Semicircular canals and vestibule help in balancing the body whereas cochlea helps in hearing.

Question 28.
Explain oval window and round window.
Answer:

• Oval window is a membrane seen attached to the stapes. Spreads the vibration of ear ossicles to the inner ear.
• Round window helps in the movement of fluid inside the cochlea

Question 29.
How is hearing possible?
Answer:
Cochlea is a coiled tube like a snail shell. It consists of three chambers. Specialized sensory hair cells which are present in basilar membrane that separate the middle and lower chambers, function as auditory recepttjrs. The sound waves which pass through the external ear vibrate the tympanum.

This vibration of the tympanum is transmitted to the ear ossicles which causes the vibration of the membrane in the oval window. This vibration causes the movement of fluid inside the cochlea. As a result, the sensory hair cells seen in the basilar membrane of the cochlea are stimulated and impulses are generated. These impulses reach the cerebrum through the auditory nerve and hearing is effected.

Question 30.
Prepare a flow chart related to the process of hearing.
Answer:
Pinna → Auditory canalTympanum → Ear ossicles → Oval window → Cochlea → Hair cells → Impulse → Auditory nerve → Cerebrum → Sense of hearing.

Question 31.
What are the parts of the internal ear which help in body balancing?
Answer:

Vestibule and the three semicircular canals play a major role in body balancing.

Question 32.
Explain the maintenance of body balancing?
Answer:
Body balance is maintained in accordance with the movement of the head. Movements of the head bring about the movement of the endolymph present inside the vestibule and the semicircular canals. This causes movement of the sensoiy hair cells and generates impulses. These impulses are transmitted by the vestibular nerves to the cerebellum, and the equilibrium of tl maintained.

10 Th Std Biology Notes Question 33.
How are the taste buds arranged on the tongue?
Answer:
Chemoreceptors seen inside the mouth and tongue help us to detect taste. These are seen mainly on the surface of the tongue. The projected structures seen on the surface of the tongue are called papillae. The parts seen on the papillae that detect taste are the taste buds. We have taste buds that are stimulated by tastes like sweet, salt, sour, bitter, umami, etc.

Question 34.
How do we experience taste?
Answer:
Substances responsible for taste dissolve in saliva, stimulate the chemoreceptors and generate impulses. These impulses reach the brain through the respective nerves and we experience taste.

Question 35.
How do we detect smell?
Answer:
The smell of various substances diffuse in the air and enter the nostrils along with the inhaled air. These aromatic particles dissolve in the mucus inside the nostrils, stimulate olfactory receptors and generate impulses. These impulses from olfactory receptors reach the cerebrum and smell is detected.

Question 36.
What are the receptors in the skin to receive stimuli?
Answer:
Touch receptor, pressure receptor, cold receptor, temperature receptor and pain receptor.

Question 37.
Are the receptors uniformly distributed all over the skin? Prove.
Answer:
The receptors are not uniformly distributed all over the skin. This can be proved by the following activity. Take two refillers of any ball point pen. Ask your friend to close his/her eyes and stretch his/her hand. Place two pointed tips of the refiller firstly at the fingertip and then at the wrist of your friend. The touch receptors are seen more in finger tip. The touch in finger tip is experienced in two points and the touch in hand is experienced in a single point.

Question 38.
Explain about the receptors seen in planaria, housefly, shark and snake.
Answer:
In planaria, the eye spot helps to detect light. The eyes of a housefly consist of cluster of photoreceptors called ommatidia. In shark, lateral lines are seen. There are receptors in the lateral line on either side of the body which help to detect the change in the balance of body. In shark, highly sensitive olfactory receptors are also present. The aromatic particles that stick on the tongue of snake reach Jacobson’s organ seen on the roof of the mouth cavity. The olfactory receptors seen there get stimulated.

Let Us Assess

Question 1.
While viewing nearby objects
a. Ciliary muscles relax
b. Curvature of lens decreases
c. Ciliary muscles contract
d. Focal length increases
Answer:
c. Ciliary muscles contract

Class 10 Biology Chapter 2 Kerala Syllabus Question 2.
Identify the odd one and write down the common feature of others.
Malleus, Eustachian tube, Stapes, Incus
Answer:
Eustachian tube
Others are bones in ear ossicles.

Question 3.
Redraw the figure. Identify the parts
according to the hints and label them.
Hints:
a. The part where the muscles that regulate the size of the pupil are seen.
b. Jelly like fluid.
c. The layer of eye where photoreceptors are seen.

Answer:

Question 4.
Figure of Ear is given. Redraw it and name and label the parts mentioned.

a. Part that receives the vibrations of the eardrum.
b. The tube that connects the pharynx.
c. Part where the auditory receptors are seen.
Answer:

a. Ear ossicles
b. Eustachian tube
c. Cochlea

Kerala Syllabus 10th Standard Biology Guide

SSLC Biology Chapter 7 Genetics for the Future Textbook Questions and Answers

SCERT Class 10th Standard Biology Chapter 7 Genetics for the Future Solutions

Question 1.
How are insulin-producing bacteria created?
Answer:
Cut the gene responsible for the production of insulin in humans. Cut bacterial DNA (plasmid), then join the gene responsible for the production of insulin in humans in bacterial DNA. Insert this DNA in the bacterial cell. Thus insulin producing bacteria are created.

Question 2.
What is the change that occurred in the genetic constitution of the bacteria that produce insulin?
Answer:
Cut the gene responsible for the production of insulin in humans. Cut bacterial DNA (plasmid). Then join the gene responsible for the production of insulin in humans in bacterial DNA. The genetic constitution of the bacteria get changed.

Question 3.
Will the future generation of this bacteria have the ability to produce insulin? Why?
Answer:
Provide a favourable medium for the multiplication of bacteria that has the change in genetic constitution. Bacteria produce inactive form of insulin. From inactive insulin active insulin is produced. Thus the future generation of bacteria show the ability to produce insulin.

Question 4.
What are traditional methods of biotechnology?
Answer:
From BC 4000 onwards organisms like yeast, a kind of fungus, were used to prepare food items like bread. The ability of fungi and bacteria to convert sugar into alcohol was utilised to make wine, appam and cake. These can be considered as traditional methods of biotechnology.

Question 5.
What is biotechnology?
Answer:
The use of microorganisms and biological processes for industrial purpose is called Biotechnology.

Question 6.
What is genetic engineering?
Answer:
Genetic engineering is the technology of controlling traits of organisms by bringing about desirable changes in the genetic constitution of organisms.

Question 7.
What is the basis of genetic engineering?
Answer:
The basis of genetic engineering is the discovery of the fact that genes can be cut and joined.

Question 8.
Explain molecular scissors and molecular glue.
Answer:
The enzyme which is used for cutting genes are called molecular scissors. Restriction endonuclease is an example. The enzyme which is used for joining genes are called molecular glue. Ligase is an example of ‘ genetic glue ’.

Question 9.
How do new genes become a part of the genetic constitution of target cells?
Answer:
Suitable vectors are used to transfer genes from one cell to another. Bacterial DNA is generally used as vectors. DNA with ligated genes enter the target cell. Thus new genes become a part of the genetic constitution of target cells.

Question 10.
What are the scope of genetic engineering?
Answer:
Gene therapy, Genetically modified animals and
crops, Forensic test are the major scopes of genetic engineering.

Question 11.
Why is gene therapy essential?
Answer:
Genetic engineering has made a great leap in the treatment of genetic diseases. Gene therapy is a method of treatment in which the genes that are responsible for diseases are removed and normal functional genes are inserted in their place. This has triggered great hope in the control of genetic diseases.

Question 12.
What is the relevance of the human genome project?
Answer:
Even though science has progressed a lot, we couldn’t control genetic diseases. The reason for this is that we could not identify the exact gene and its location which is responsible for each trait. In 1990, the Human Genome Project was started as an attempt to solve the issue.

As a result of experiments conducted in various laboratories of the world until 2003, the secrets of human genome were revealed. With this, we can identify the location of a gene in the DNA, responsible for a particular trait.

Question 13.
What is the benefit of gene mapping?
Answer:
The technology known as gene mapping helped to identify the location of a gene in the DNA responsible for a particular trait. Gene mapping leads to gene therapy.

Question 14.
Explain the term genome, junk genes.
Answer:
The sum of genetic material present in an organism is called its genome. In human DNA, majority of genes, except the genes that code for protein are non-functional. They are called junk genes.

Question 15.
What are the major findings of human genome project?
Answer:

• Human genome has about 24000 functional genes.
• Major share of human DNA includes junk genes.
• There is only 0.2 per cent difference in DNA among humans.
• About 200 genes in human genome are identical to those in bacteria.

Question 16.
Prepare a short note on the proteins that can be used for the treatment of diseases in humans are produced through genetic engineering?
Answer:
Interferons is the protein required for treatment of viral diseases, Insulin is used for the treatment of diabetes, Endorphin is a protein required for treatment of the symptom pain, Somatotropin is a protein required for treatment growth disorders.

Question 17.
How genetic modification is possible?
Answer:
Genetic engineering has progressed a lot more from biotechnology. Today, genetic modification in organisms can be implemented more effectively. This is made possible through the insertion of gene that code for desirable characters into the genetic constitution of an organism.

Question 18.
Write a short note on pharm animals.
Answer:
One of the future promises of genetic engineering is pharm animals: Genes responsible for the production of insulin and growth hormones required for humans are inserted into animals like cow, pig etc, transforming them into pharm animals. There are certain limitations in producing insulin using bacteria. The most important hurdle in this field is the culturing of bacteria. Researches in this field show that instead of this, medicines can be extracted from the blood or milk of, genetically modified animals.

Question 19.
Prepare a short note on the genetic modification in plants?
Answer:
Genetic modification is implemented not only in animals but in plants also. Today, insect-resistant plants like Bt brinjal, soybean, cotton, maize etc are common.

Question 20.
What are the things should be ensured while genetic modification carried out?
Answer:
When genetic modification is carried out in organisms, it should be ensured that there are no harmful consequences to humans or nature.

Question 21.
Explain DNA profiling.
Answer:
The technology of testing the arrangement of nucleotides is DNA profiling. Like the difference in the fingerprint of each person, the arrangement of nucleotides in each person also differs. Hence this technology is also called DNA fingerprinting.

Question 22.
What is the basis of DNA testing?
Answer:
The arrangement of nucleotides in the DNA of each person differs. This finding is the basis of DNA testing.

Question 23.
How are relations identified through DNA testing?
Answer:
The arrangement of nucleotides among close relatives have many similarities. So DNA fingerprinting is helpful to find out hereditary characteristics.

Question 24.
What is the scope of DNA testing?
Answer:
Certain experiments conducted by the scientist Alec Jeffrey in 1984 paved the way for DNA testing. DNA fingerprinting is helpful to find out hereditary characteristics, to identify real parents in cases of parental dispute and to identify persons found out after long periods of missing due to natural calamities or wars.

DNA of the skin, hair, nail, blood and other body fluids obtained from the place of murder, robbery, etc., is compared with the DNA of suspected persons. Thus, the real culprit can be identified from among the suspected persons through this method.

Question 25.
Prepare a short note on the misuse and side effects of genetic engineering.
Answer:
Genetic modification – Genetic modification is an intrusion upon the freedom of living beings and it is a violation of rights. It is criticized that genetically modified varieties cause haim to indigenous varieties and may cause health issues to humans.
Bio-weapons – Application of genetically modified pathogens and its multiplication through biotechnology’ upon enemies ‘is called Bioware. This becomes a threat to the existence of human beings.

Let Us Assess

Question 1.
Which of the following is not a part of modern genetic engineering?
a. DNA profiling
b. Gene mapping
c. DNA fingerprinting
d. X-ray diffraction
Answer:
d. X-ray diffraction

Question 2.
Gene therapy 1c an example of the benefits of science for human existence.
a. What is gene therapy?
b. What was the discovery that led to gene therapy?
c. How does gene therapy become useful to human beings?
Answer:
a. The sum of genetic material present in an organism is called its genome. We can cure genetic diseases by removing disease-causing genes from the genome and inserting normal functional genes. This method of treatment is called gene therapy.

b. The technology known as gene mapping helped to identify the location of a gene in the DNA responsible for a particular trait. Gene mapping leads to gene therapy.

c. We can cure genetic diseases by removing disease-causing genes from the genome and inserting normal functional genes.

Question 3.
Since genetic engineering has many harmful effects, it can t be promoted’. Do you agree with this statement? Why?
Answer:
I do not agree with this statement. We must use science and technology as a means to overcome the challenges faced by human beings. Science and technology are the products of human thought. We can justify this only if they are utilized for human benefit.

Kerala Syllabus 10th Standard Biology Guide