Kerala SSLC Biology Chapter 1 Questions Sensations and Responses

Kerala SSLC Biology Chapter 1 Questions Sensations and Responses English Medium

Select the correct answer.

Question 1.
The tip of axonite
a. Axon
b. Dendron
c. Synaptic knob
d. Dendrite
Answer:
c. Synaptic knob

Question 2.
In spinal cord
a. white matter outside and grey matter inside ”
b. white matter on outside and inside
c. grey matter on outside and inside
d. white matter inside and grey matter outside
Answer:
a. white matter outside and grey matter inside

Question 3.
The part of brain which plays a major role in the maintenance of homeostasis.
a. Thalamus
b. Hypothalamus
c. Cerebrum
d. Medulla oblongata
Answer:
b. Hypothalamus

Question 4.
Read the statements given below.
i. The part where myelinated neurons are present in abundance is called white matter.
ii. Nerves are groups of dendrites covered by connective tissue.
a. i and ii correct
b. i and ii wrong
c. i wrong ii correct
d. i correct ii wrong
Answer:
d. i correct ii wrong

Question 5.
Fill up the blanks by observing the relationship between the first pair.
a. SoundExternal stimulus : : Hunger : …………………
b. Spinal nerves : 31 pairs : : Cranial nerves …………………
c. Sensory impulses reach the spinal cord : Dorsal root: : Motor impulses go out of the spinal cord : ………………..
Answer:
a. Internal stimulus
b. 12 pairs
c. Ventral root

Question 6.
Find out the odd one and note down the com-mon features of others.
a. Alzheimer’s, Tuberculosis, Parkinson’s, Epilepsy
b. Dendron, Axon, Nephron, Dendrite
c. Thought, maintains equilibrium, memory, imagination
Answer:
a. Tuberculosis
Others are diseases affecting nervous system
b. Nephron. Others are parts of neuron
c.

• Maintains equilibrium
• Others are functions of cerebrum

Question 7.
Explain the differences between axons and dendrons.
Answer:
Axons and dendrons are projections from the cyton (cell body). Axons are the longest filament from the cell body and dendrons are the short filament from the cell body. Dendrites are the branches of dendron and branches of axons are axonites. Dendron carries impulses from dendrites to the cell body while axon carries impulses from the cell body to outside. Axon is encircled by myelin sheath.

Question 8.
Complete the table suitably.

Nerve	Function
Sensory nerve	(a)
(b)	Carries impulses from brain and spinal cord to various parts of the body.
(c)	(d)

Answer:
a. Carries impulses from various parts of the body to the brain and the spinal cord.
b. Motor nerve
c. Mixed nerve
d. Carries impulses to and from the brain and spinal cord.

Question 9.
Select the correct pairs.
a. Axonite – secretes neurotransmitter
b. Schwann cell – encircles the axon
c. Axonite – branches of dendron
d. Axon – carries impulses from the cell body to outside
e. Synaptic knob – secretes neurotransmitter
Answer:
b. Schwann cell – encircles the axon
d. Axon – carries impulses from the cell body to outside
e. Synaptic knob – secretes neurotransmitter

Question 10.
Arrange columns B, C in accordance with the data given in column A.

A	B	C
Cerebrum	Situated just below the thalamus	Maintains equilibrium of the body
Cerebellum	The largest part of the brain	Plays a major role in the maintenance of homeostasis
Hypothalamus	Seen behind the cerebrum as two flaps	Centre of thought, imagination and intelligence

Answer:

A	B	C
Cerebrum	The largest part of the brain	Centre of thought, imagination and intelligence
Cerebellum	Seen behind the cerebrum as two flaps	Maintains equilibrium of the body.
Hypothalamus	Situated just below the thalamus	Plays a major role in the maintenance of homeostasis

Question 11.
The cause of a disease affecting the nervous system is given below.
Continuous and irregular flow of electric charges in the brain
a. Identify the disease.
b. Write the symptoms.
Answer:
a. Epilepsy
b. Fits due to continuous muscular contraction, frothy discharge from the mouth, clenching of teeth following which the patient falls unconscious.

Question 12.
Observe the illustration and answer the questions given below.
a. Identify the part indicated as A.
b. How is this part formed?
c. Write the functions of this part.

Answer:
a. A – Myelin sheath.
b. Schwann cells repeatedly encircle the axons to form the myelin sheath.
c. To provide nutrients and oxygen to the axon, accelerate impulses, act as an electric insulator and protect the axon from external shocks.

Question 13.
Rajesh ate his food while watching the hairraising scenes of a film on TV. Will this affect hi’s digestion? Formulate an inference related to sympathetic-parasympathetic actions. List out the facts which led you to the inference.
Answer:
Adversely affects digestion.
Sympathetic system gets stimulated in such situations. So secretion of saliva decreases, peristalsis slows down and functions of the stomach slow down in this situation.

Question 14.
a. What are the parts of the central nervous system?
b. What are the parts included in the peripheral nervous system?
c. How does the brain communicate with organs?
d. How does the spinal cord communicate with organs?
e. Complete the flowchart of nervous system.

Answer:
a. Brain and spinal cord
b. Peripheral nervous system includes 12 pairs of cranial nerves, 31 pairs of spinal nerves and sympathetic and parasympathetic systems of autonomous nervous system.
c. Brain communicates with the organs by 12 pairs of cranial nerves.
d. Spinal cord communicates with the organs by 31 pairs of spinal nerves.

Question 15.
The diagram below shows neuron and the direction of nerve impulse through it. Observe the diagram and answer the questions.

a. If there is a mistake in the direction of nerve impulse, redraw the diagram and correct it.
b. How does the impulse pass through the part X?
Answer:

b. When electric impulses from 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 16.
Observe the figure and answer the questions given below.

a. Identify the figure.
b. Identify the parts A, B and C.
c. Write the functions of part indicated as A and B.
d. Write the peculiarity of part indicated as C.
Answer:
a. Spinal cord
b. A – Dorsal root B – Ventral root C – Central canal
c. Dorsal root – Sensory impulses reach the spinal cord through the dorsal root.
Ventral root – Motor impulses go out of the spinal cord through the ventral root.
d. Filled with cerebrospinal fluid.

Question 17.
Select the answer for the statements from the box given below.
Thalamus, Synaptic knob, Spinal cord, Dendrite, Axonite, Medulla oblongata

a. Secretes neurotransmitter.
b. Carries impulses to the synaptic knob.
c. Branches of dendron.
d. Acts as relay station of impulses.
e. Controls involuntary actions
f. Coordinates the rapid and repeated movements during walking, running.
Answer:
a. Synaptic knob
b. Axonite
c. Dendrite
d. Thalamus
e. Medulla oblongata
f. Spinal cord

Question 18.
Arrange the statements suitably.
a. Trachea dilates
b. Glycogen is converted to glucose.
c. Production of hormone increases.
d. Urinary bladder contracts
e. Production of saliva increases.
f. Peristalsis in the intestine slows down
g. Heartbeat increases.
h. Glucose is converted to glycogen.

Sympathetic system	Parasympathetic system
. .	. .

Answer:

Sympathetic system	Parasympathetic system
Glycogen is converted to glucose.	Trachea dilates
Production of hormone increases.	Urinary bladder contracts
Peristalsis in the intestine slows down.	Production of saliva increases
Heartbeat increases	Glucose is converted to glycogen.

Question 19.
The symptoms of a disease affecting the nervous ’ system are given below.
Loss of body balance, irregular movement of muscles, shivering of the body, profuse salivation
a. Identify the disease.
b. Write the causes of this disease.
Answer:
a. Parkinson’s
b. Destruction of specialised ganglions in the brain, production of dopamine reduces.

Question 20.
Redraw the picture of brain and identify and label the parts based on the statements given below.
a. Centre of thought, intelligence, memory and imagination.
b. The part which controls involuntary actions.
c. The part which coordinates muscular activities and maintains equilibrium of the body.

Answer:

a. Cerebrum
b. Medulla oblongata
c. Cerebellum

Question 21.
Observe the figure and answer the questions given below.

a. Identfy the parts indicated as A, B, C.
b. How are the parts indicated by A and B structurally different?
c. What are the functions of part indicated as C?
Answer:
a. A – Cerebrum B – Cerebellum
C – Medulla oblongata
b

• Cerebrum – the largest part of the brain, numerous fissures and folds are seen.
• Cerebellum – the second largest part of brain, fissures and grooves are present.

c. Medulla oblongata controls involuntary actions like heartbeat, breathing. etc.

Question 22.
Arrange columns B and C in accordance with the data given in A.

A	B	C
Axon	Tip of the axonite	Part which receives impulses from the adjacent neuron
Synaptic knob	Branches of dendron	curries impulses from the cell body lo outside
Dendrite	Longest filament from the cell body	Secretes neurotransmitter

Answer:

B

A	B	C
Axon	Longest filament from the cell body	Carries impulses from the cell body to outside
Synaptic knob	Tip of the axonite	Secretes neurotransmitter
Dendrite	Branches of dendron	Part which receives impulses from the adjacent neuror

Question 23.
Radha is moving away with fear from a snake.
a. State what happens to the functioning of following organs?

• Heart
• Pupil
• Trachea
• Liver

b. Which nervous system is activated during such emergency situations?

Answer:

a.

• Heart – Heart beat increases
• Pupil – The pupil in the eye dilates
• Trachea – Trachea dilates
• Liver – Glycogen is converted to glucose

b. Sympathetic system

Question 24.
Myelin sheath in the brain and the spinal cord is formed of specialized cells called ………………….
Answer:
oligodendrocytes.

Question 25.
The thalamus is the post office of the brain. Evaluate this statement based on the function of thalamus.
Answer:
Thalamus analyses impulses from various parts of the body and sends the important ones to cerebrum. Thalamus also acts as relay station of impulses to and from the cerebrum.

Question 26.
Segregate the following statements suitably.
a. Covered by meninges
b. Connected to different parts of body through 31 pairs of nerves
c. Part of central nervous system
d. Filled with cerebrospinal fluid
e. Filled with aqueous fluid
f. Consists of 12 pairs of nerves
g. Centre of consciousness
h. All are mixed nerves

Answer:
A – f, g
B – b, h
C – a, c, d
D – e

Question 27.
How is the brain protected?
Answer:
The brain is protected inside a hard skull. Brain 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 help to protect the brain from injuries.

Question 28.
How does sympathetic system act on the ‘ following organs?

• Liver
• Heart
• Stomach

Answer:

• Liver – Glycogen is converted to glucose.
• Heart – Heartbeat increases
• Stomach – Gastric activities slow down.

Question 29.
Complete the flow chart.

Answer:
A – Sensory neuron – carries impulses to the spinal cord
B – Motor neuron – carries the information from spinal cord to related muscles.

Question 30.
Observe the figure and answer the questions given below.

a. Identify the part indicated as A.
b. Explain the role of the part in the transmission of impulses from one neuron to another.
Answer:
a. Synapse .
b. The electric impulses generated by stimuli reach the synaptic knob where certain chemical substances are secreted. The chemical substance (neurotransmitter) which is released in the synaptic cleft stimulates the adjacent dendrite and new electric impulses are formed.

Question 31.
Complete the flow chart.

Answer:
a. Dendrite
b.Axon
c. Synaptic knob
d. Synapse

Question 32.
Observe the figure and answer the following questions.

a. What is indicated in the diagram?
b. What are the peculiarities of this, common to that of brain?
Answer:
a. Spinal cord
b. Covered with meninges and filled with cerebrospinal fluid

Question 33.
Analyze the illustration and answer the questions.

a. What is indicated in the illustration?
b. A and B are neurons. Write their difference.
c. Write an example related to this illustration.
Answer:
a. Reflex action
b. A – Sensory neuron
Carries impulses to the spinal cord . B – Motor neuron
Carries the information from the spinal cord to related muscles.
c. Hand is withdrawn while touching fire.

Question 34.
The brain contains a fluid which is formed from and reabsorbed into the blood.
a. Identify the fluid.
b. What are the functions of that fluid?
Answer:
a. Cerebrospinal fluid
b. Provides nutrients and oxygen to brain tissue, protects the brain from injuries

Question 35.
One of the components of the nervous system is illustrated below. Fill in the blanks appropriately.

Answer:
a. Cranial nerves
b. 31 pairs
c. Autonomous nervous system
d. Sympathetic system

Question 36.

The causes of diseases related to the nervous system in two individuals X and Y are given above.
i. Identify the diseases.
ii. The deficiency of which neurotransmitter causes disease in Y?
Answer:
i. X-Alzheimer’s Y – Parkinson’s
ii. Dopamine

Question 37.
Analyse the illustration of impulse transmis¬sion through axon and answer the following questions.

a. What are the changes that take place in illustration B when compeared to A? Give reasons for this change.
b. Explain how this change brings about the transmission of impulses through axon.
Answer:
a. When stimulated, ionic equilibrium in the particular part changes, and the outer surface of the plasma membrane of axon becomes negatively charged while the inner surface becomes positively charged.

b.

• These changes generate impulses.
• The momentary charge difference in the axon stimulates its adjacent parts.
• Similar changes occur there also.
• Impulses get transmitted through axon

Question 38.
Mohan lost his memory and was partially paralysed after he met with an accident.
a. Which part of Mohan’s brain was affected?
b. How is the brain protected?
Answer:
a. Cerebrum
b.

• Skull
• Meninges
• Cerebrospinal fluid

Question 39.
Identify the correct statements from those given below.
i. The central nervous system consists of the brain and the spinal cord.
ii. The peripheral nervous system consists of 31 pairs of cranial nerves and 12 pairs of spinal nerves.
iii. The sympathetic system and the parasym-pathetic system are parts of the central nervous system.
iv. The autonomous nervous system which is a part of the peripheral nervous system helps to overcome the emergency situations.
Answer:
i. The central nervous system consists of the brain and the spinal cord,
iv. The autonomous nervous system which is a part of the peripheral nervous system helps to overcome the emergency situations.

Question 40.
Balu :
In the spinal cord and the cerebrum , white matter is seen outside and grey matter is seen inside.

Ramu :
In the cerebrum, the grey matter is seen outside and the white matter is seen inside, But in the spinal cord, the white matter is seen outside and the grey matter is seen inside.
In the group discussion related to the nervous system, Balu and Ramu said so.
a. Whose opinion do you agree with?
b. Explain white matter and grey matter.
Answer:
a. Ramu’s opinion
b.

• White matter
  The part of the brain and the spinal cord where myelinated nerve cells are present in abundance.
• Grey matter.
  The part where non-myelinated nerves cells are present is called grey matter.

Kerala SSLC Biology Chapter Wise Questions and Answers