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Students can Download Chapter 10 Applications of Computers in Accounting Notes, Plus One Accountancy Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Accountancy Notes Chapter 10 Applications of Computers in Accounting

Summary:
Meaning of a Computer:
The computer is an electronic device capable of performing a variety of operations as desired by a set of instructions.

Elements of a Computer System:

1. Hardware
2. People
3. Data Connectivity
4. Software
5. Procedure

Capabilities of a Computer:

1. Speed
2. Reliability
3. Storage
4. Accuracy
5. Versatility

Need for Computers in Accounting:
The advent of globalisation has resulted in a rise in business operations. Consequently, every medium and large-sized organisations require well-established information system in order to generate information required for decision making and achieving the organisational objectives. This made Information technology to play a vital role in supporting business operations.

MIS and Accounting Information System:
A management information system provides information necessary to take decisions and manage an organisation effectively. Accounting information system on the other hand identifies, collects, processes and communicates economic information about an entity to a wide variety of users.

Accounting Reports:
Information supplied to meet a particular need is called a report. An accounting report must fulfil the following conditions:

• Relevance
• Timeliness
• Accuracy
• Completeness
• Summarisation

Computerised Accounting System:
A computerised accounting system is an accounting information system that processes the financial transactions and events to produce reports as per user requirements. It is based on the concept of database and has two basic requirements:

1. Accounting framework and
2. Operating Procedure.

Advantages of Computerised Accounting System:

1. Speed
2. Reliability
3. Scalability
4. Efficiency
5. MIS Reports
6. Storage and Retrieval
7. Accuracy
8. Up-to-date
9. Legibility
10. Quality Report
11. Real-time user interface
12. Motivation and Employees interest
13. Automated document production

Limitations of Computerised Accounting System:

• Cost of training
• Disruption
• Breach of security
• Inability to check unanticipated errors
• Staff Opposition
• System failure
• III-effects on health

Categories of Accounting Packages:

• Ready-to-Use
• Tailored
• Customised

Students can Download Chapter 9 Accounts from Incomplete Records Notes, Plus One Accountancy Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Accountancy Notes Chapter 9 Accounts from Incomplete Records

Summary:
Incomplete Records:
Incomplete records refer to a lack of accounting records according to the double-entry system. It is an incomplete, unscientific and unsystematic method of keeping the books of accounts of a trader.

Computation of profit and loss from incomplete records:
The statement of affairs is used to compute capital when a firm has a set of incomplete records. It shows assets on one side and the liabilities on the other as in the case of a balance sheet. The difference between the totals of the two sides is the capital.

Format of Statement of Affairs:
Statement of Affairs as on …………………

The statement of profit or loss is prepared to ascertain the exact amount of profit or loss made during the year.

Format of Statement of Affairs:
Statement of Profit or Loss for the year ended ………….

Preparation of Profit and Loss Account and Balance Sheet. (Conversion method):
In order to prepare final accounts from incomplete records, we have to find out the missing figures by making further computations and adjustments to the available information. The following are the steps to prepare the final accounts from incomplete records.

(i) Preparation of statement of Affairs.
(ii) Preparation of cash book
(iii) Ascertaining credit purchases and credit sales:-
Credit purchase can be ascertained by preparing a statement or by preparing Total creditors Account.

Format of Total Creditors Account:

Format of Total Creditors Account:

(a) Bills Receivable and Bills payable Accounts are prepared for finding out their opening or closing balances or for finding out the amount of bills accepted or bills received during the year.

(b) The proforma of total bills receivable account and total bills payable account. The proforma of total bills receivable account and total bills payable account is shown.

Total Bills Receivable Account:

Total Bills Payable Account:

(iv) Calculate:

• Total purchase by adding cash purchases and credit purchases.
• Total sales by adding cash sales and credit sales.

(v) Prepare Trial balance with the given information and missing information ascertained:
The components of the trial balance and their sources of information are summarised below

(vi) Prepare final accounts in the usual manner.

Students can Download Chapter 8 Financial Statements – I & II Notes, Plus One Accountancy Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Accountancy Notes Chapter 8 Financial Statements – I & II

Summary:
Financial Statements:
Meaning and types Financial statements are the statements which present periodic reports on the process of business enterprises and the results achieved during a given period. Financial statement includes trading, profit & loss account, balance sheet and other statements.

Trading and Profit & Loss Account:
Trading and Profit & Loss account is prepared to ascertain the net result of business operations during a given period.

Format of Trading and Profit & Loss Account (In horizontal form):
Trading and Profit & Loss Account for the year ended ………………

Need for Adjustment:
For the preparation of financial statements, it is necessary that all adjustments arising out of the accural basis of accounting are made at the end of the accounting period. Entries which are given outside the trial balance are called adjustment entries.

Treatment of various types of adjustments:

Balance Sheet:
The balance sheet is a statement of assets and liabilities of a business enterprises and shows the financial position at a given date. It is not an account. It is only a statement.
Assets and liabilities shown in the balance sheet are marshalled in order to liquidity or in order to permanence.

Format of Balance Sheet (In horizontal form)
Balance sheet as on …………….

The Performa of income statement and balance sheet in vertical form.

Income Statement for the period ended ……..

Balance sheet as on………..

Students can Download Chapter 10 Neural Control and Coordination Notes, Plus One Zoology Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Zoology Notes Chapter 10 Neural Control and Coordination

What is coordination?
Coordination is the process through which two or more organs interact and complement the functions of one another.

Neural System
The neural system of all animals is composed neurons that receive and transmit different kinds of stimuli.

Neural system in lower forms

• The neural organisation is very simple in lower invertebrates.
• For example, in Hydra it is composed of a network of neurons.
• The neural system is better organised in insects, where a brain is present.

The vertebrates have a more developed neural system.

Human Neural System
The human neural system is divided into two parts:

• The CNS includes the brain and the spinal cord and is the site of information processing and control.
• The PNS comprises of all the nerves of the body associated with the CNS.

The nerve fibres of the PNS are of two types:

Function of afferent efferent of nerve fibres:
The afferent nerve fibres transmit impulses from tissues/organs to the CNS. The efferent fibres transmit regulatory impulses from the CNS to the peripheral tissues/organs.
The PNS is divided into two divisions

1. Somatic neural system
2. Autonomic neural system.

Function:
The somatic neural system relays impulses from the CNS to skeletal muscles. The autonomic neural system transmits impulses from the CNS to the involuntary organs and smooth muscles of the body.
The autonomic neural system is classified into

1. sympathetic neural system
2. parasympathetic neural system.

Neuron As Structural And Functional Unit Of Neural System
A neuron is composed of three major parts,

1. The cell body contains cytoplasm with cell organelles and certain granular bodies called Nissl’s granules.

2. Repeated branches project out of the cell body are called dendrites.

3. The axon is a long fibre, the distal end of which is branched. Each branch terminates as a bulb-like structure called synaptic knob which possess synaptic vesicles containing chemicals called neurotransmitters. Based on the number of axon and dendrites, the neurons are divided into three types,

• multipolar (with one axon and two or more dendrites; found in the cerebral cortex)
• bipolar (with one axon and one dendrite, found in the retina of eye)
• unipolar (cell body with one axon only found usually in the embryonic stage).

4. The myelinated nerve fibres are enveloped with Schwann cells, which form a myelin sheath around the axon.

5. The gaps between two adjacent myelin sheaths are called nodes of Ranvier.

6. Myelinated nerve fibres are found in spinal and cranial nerves.

8. Non-myelinated nerve fibre is enclosed by a Schwann cell that does not form a myelin sheath around the axon, and is commonly found in autonomous and the somatic neural systems.

Generation and Conduction of Nerve Impulse
Neurons are excitable cells because their membranes are in a polarized state.
In resting state of neuron:
The axonal membrane is more permeable to potassium ions (K⁺) and impermeable to sodium ions (Na⁺) and negatively charged proteins present in the axoplasm. The fluid outside the axon contains a low concentration of K⁺, a high concentration of Na⁺ and thus form a concentration gradient.

These ionic gradients are maintained by the active transport of ions by the sodium-potassium pump which transports 3 Na⁺ outwards for 2 K⁺ into the cell.

As a result, the outer surface of the axonal membrane possesses a positive charge while its inner surface becomes negatively charged and therefore is polarised. The electrical potential difference across the resting plasma membrane is called as the resting potential.

When a stimulus is applied at a site on the polarised membrane:
The membrane freely permeable to Na and influx of Na⁺ followed by the reversal of the polarity at that site, i.e., the outer surface of the membrane becomes negatively charged and the inner side becomes positively charged.

This is called depolarized state. The electrical potential difference across the plasma membrane is called the action potential At sites immediately ahead, the axon membrane has a positive charge on the outer surface and a negative charge on its inner surface. As a result, a current flows on the inner surface from site A to site B.

On the outer surface current flows from site B to site A to complete the circuit of current flow. Hence, the polarity at the site is reversed, and an action potential is generated at site B. Thus, the impulse (action potential) generated at site A arrives at site B. The sequence is repeated along the length of the axon and consequently the impulse is conducted.

Transmission of Impulses
A nerve impulse is transmitted from one neuron to another through junctions called synapses. The junction between pre-synaptic neuron and a post-synaptic neuron is called synaptic cleft. There are two types of synapses, namely

At electrical synapses, erlectrical current flowdirectly from one neuron into the other across these synapses. It is very similar to impulse conduction along a single axon, impulse transmission across an electrical synapse is always faster than that across a chemical synapse.

At a chemical synapse, the membranes ofthepre-and post-synaptic neurons are separated by a fluid-filled space called synaptic cleft Chemicals called neurotransmitters are involved in the transmission of impulses at these synapses.

The released neurotransmitters bind to the specific receptors, present on the post-synaptic membrane. This binding opens ion channels allowing the entry of ions which can generate a new potential in the post- synaptic neuron.

Central Neural System
It controls the voluntary movements such as balance of the body, functioning of vital involuntary organs (e.g., lungs, heart, kidneys, etc.), thermoregulation, hunger and thirst, circadian (24-hour) rhythms of our body, activities of several endocrine glands and human behaviour.

It is also the site for processing of vision, hearing, speech, memory, intelligence, emotions and thoughts. The human brain is well protected by the skull. Inside the skull, the brain is covered by cranial meninges consisting of an outer layer called dura mater, a very thin middle layer called arachnoid and an inner layer called pia mater.

The brain is divided into three major parts:

• forebrain
• midbrain
• hindbrain

Forebrain
The forebrain consists of cerebrum, thalamus and hypothalamus. Cerebrum forms the major part of the human brain. Cerebrum divided longitudinally into two halves the left and right cerebral hemispheres. The hemispheres are connected by nerve fibres called corpus callosum.

The layer of cells which covers the cerebral hemisphere is called cerebral cortex. The cerebral cortex is referred to as the grey matter .The cerebral cortex contains motor areas, sensory areas and large regions These regions called as the association areas.They are responsible functions like memory and communication.

The inner part of cerebral hemisphere gives white appearance to the layer and called as the white matter. Hypothalamus lies at the base of the thalamus contains a number of centres which control body temperature, urge for eating and drinking. Hypothalamus secrete hormones called hypothalamic hormones.

he inner parts of cerebral hemispheres and a group of associated deep structures like amygdala, hippocampus, etc., form a complex structure called the limbic lobe or limbic system. Along with the hypothalamus,

Midbrain
The midbrain is located between the thalamus/hypothalamus of the forebrain and pons of the hindbrain. A canal called the cerebral aqueduct passess through the midbrain.

The dorsal portion of the midbrain consists mainly of four round swellings (lobes) called corpora quadrigemina. Midbrain and hindbrain form the brain stem..

Hindbrain
The hindbrain comprises pons, cerebellum and medulla (also called the medulla oblongata). Pons consists of fibre tracts that interconnect different regions of the brain. Cerebellum provide the additional space for many more neurons.

The medulla of the brain is connected to the spinal cord. The medulla contains centres which control respiration, cardiovascular reflexes and gastric secretions.

Reflex Action And Reflex Arc
It involves the sudden withdrawal of a body part which comes in contact with objects that are extremely hot, cold pointed or animals that are poisonous. The reflex pathway consists of one afferent neuron (receptor) and one efferent (effector or excitor) neuron arranged in a series.

The afferent neuron receives signal from a sensory organ and transmits the impulse via a dorsal nerve root into the CNS (at the level of spinal cord). The efferent nueuron carries signals from CNS to the effector. The stimulus and response thus forms a reflex arc in the knee jerk reflex.

Sensory Reception And Processing
The sensory organs detect all types of changes in the environment and sent to different parts/centres of the brain. The sense organs are the eye (sensory organ for vision) and the ear (sensory organ for hearing).

Eye
Our paired eyes are located in sockets of the skull called orbits.

Parts of an eye
The wall of the eye ball is composed of three layers. External layer is composed of a dense connective tissue and is called the sclera. Anterior portion of this layer is called the cornea. Middle layer, choroid, contains many blood vessels and looks bluish in colour.

The choroid layer is thin over the posterior part of eye ball, but it becomes thick in the anterior part to form the ciliary body. The ciliary continues forward to form a pigmented and opaque structure called the iris which is the visible coloured portion ofthe eye.

1. The eye ball contains lens which is held in place by ligaments attached to the ciliary body. In front of the lens, the aperture surrounded by the iris is called the pupil.
2. The inner layer is the retina contains three layers of cells – from inside to outside.
3. Ganglion cells, bipolar cells and photoreceptor cells.
4. There are two typ es of photoreceptor cells, namely, rods and cones
5. The daylight (photopic) vision and colour vision are functions of cones
6. The twilight (scotopic) vision is the function of the rods.
7. The rods contain a purplish-red protein called the rhodopsin which contains a derivative of Vitamin A. In the human eye, there are three types of cones that respond to red, green and blue lights.

What is blind spot?
The optic nerves and the retinal blood vessels enter above the posterior pole of the eye ball. Photoreceptor cells are not present in that region and hence it is called the blind spot.

What is macula lutea?
At the posterior pole of the eye lateral to the blind spot, there is a yellowish pigmented spot called macula lutea with a central pit called the fovea where only the cones are densely packed. It is the point where the visual acuity (resolution) is the greatest.

The space between the cornea and the lens is called the aqueous chamber and contains fluid called aqueous humor. The space between the lens and the retina is called the vitreous chamber and contains fluid called vitreous humor.

Mechanism of Vision
The light rays falls on the retina through cornea and lens generate impulses in rods and cones. The photosensitive compounds (photopigments) in the human eyes is composed of opsin (a protein) and retinal (an aldehyde of vitamin A). Light induces the changes in the structure of the opsin.

This causes membrane permeability changes. As a result, potential differences are generated in the photoreceptor cells. This produces a signal that generates action potentials in the ganglion cells through the bipolar cells.

These action potentials are transmitted by the optic nerves to the visual cortex area of the brain, where the neural impulses are analysed and the image formed on the retina is recognised based on earlier memory and experience.

The Ear
The ear is divided into three major sections called the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and external auditory meatus (canal).The pinna collects the vibrations of sound. The external auditory meatus leads inwards and extends up to the tympanic membrane (the ear drum).

There are wax-secreting sebaceous glands in the skin of the pinna and the meatus. The middle ear contains three ossicles called malleus, incus and stapes which are attached to one another in a chain-like fashion.

The malleus is attached to the tympanic membrane and the stapes is attached to the oval window. of the cochlea. The ear ossicles increase the efficiency of transmission of sound waves to the inner ear.

An Eustachian tube connects the middle ear cavity with the pharynx. The Eustachian tube helps in equalising the pressures on either sides of the eardrum. The fluid-filled inner ear called labyrinth consists of two parts, the bony and the membranous labyrinths.

The bony labyrinth is connected with membranous labyrinth, which is surrounded by a fluid called perilymph. The membranous labyrinth is filled with a fluid called endolymph. The coiled portion of the labyrinth is called cochlea.

The membranes constituting cochlea, the reissner’s and basilar, divide the surounding perilymph filled bony labyrinth into an upper scala vestibuli and a lower scala tympani. The space within cochlea called scala media is filled with endolymph.

At the base of the cochlea, the scala vestibuli ends at the oval window The organ of corti is a structure located on the basilar membrane which contains hair cells that act as auditory receptors. The hair cells are present in rows on the internal side of the organ of corti.

The basal end of the hair cell is in close contact with the afferent nerve fibres. A large number of processes called stereo cilia are projected from the apical part of each hair cell. Above the rows of the hair cells is a thin elastic membrane called tectorial membrane. The inner ear also contains vestibular apparatus, located above the cochlea.

The vestibular apparatus is composed of three semi-circular canals and the otolith organ consisting of the saccule and utricle. The membranous canals are suspended in the perilymph of the bony canals. The base of canals is swollen and is called ampulla, which contains a projecting ridge called crista ampullaris which has hair cells.

The saccule and utricle contain a projecting ridge called macula. The crista and macula are the specific receptors of the vestibular apparatus responsible for maintenance of balance of the body and posture.

Mechanism of Hearing
How does ear convert sound waves into neural impulses, which are sensed and processed by the brain enabling us to recognise a sound?
The external ear receives sound waves and directs them to the ear drum.The ear drum vibrates in response to the sound waves and these vibrations are transmitted through the ear ossicles (malleus, incus and stapes) to the oval window.

The vibrations are passed through the oval window on to the fluid of the cochlea, where they generate waves in the lymphs. The waves in the lymphs induce a ripple in the basilar membrane. These movements of the basilar membrane bend the hair ceils, pressing them against the tectorial membrane.

As a result, nerve impulses are generated in the associated afferent neurons. These impulses are transmitted by the afferent fibres via auditory nerves to the auditory cortex of the brain, where the impulses are analysed and the sound is recognized.

The vibrations are passed through the oval window on to the fluid of the cochlea, where they generate waves in the lymphs. The waves in the lymphs induce a ripple in the basilar membrane. These movements of the basilar membrane bend the hair cells, pressing them against the tectorial membrane.

As a result, nerve impulses are generated in the associated afferent neurons. These impulses are transmitted by the afferent fibres via auditory nerves to the auditory cortex of the brain, where the impulses are analysed and the sound is recognized.

NCERT SUPPLEMENTARY SYLLABUS
Sense organs:
The environmental changes (both internal and external) called stimuli detected by the special sensory cells, are conveyed to the brain in the form of nerve impulses. The response for each stimulus from brain is sent to the various body parts for its well being. There are five senses: touch, vision, hearing, smell and taste.

While touch is a complex general sense, the other four are special senses. The general sensory receptors are simple receptors that are present in the skin, mucous membranes, connective tissues and muscles.

These sense the information such as tactile sensation (a mix of touch, pressure, stretch and vibration), heat, cold, pain and muscle sense.

Special sensory receptors are present in the head especially sensory organs like eyes and ears and tissues of the taste buds and olfactory epithelium. These sensory organs and tissues of eye and ear are photoreceptors and the auditory receptors respectively.

The chemical senses: the taste and smell:
The receptors fortaste and smell are called as chemoreceptors found as film of liquid coating in the membranes of the receptor cells. The taste receptors are specialized cells that detect chemicals present in the mouth while smell receptors are modified sensory neurons in the nasal passage which detect the volatile chemicals.

These two types of receptors complement each other and often respond to the same stimulus. The smell receptors are 3,400 times more sensitive than the taste receptors.

Sense of smell (olfaction):
Nose contains the receptors of smell, in the mucous coated thin, yellowish patch (about 5 cm2) of modified pseudo stratified epithelium called olfactory epithelium. It is located at the roof of the nasal cavity on either sides of the nasal septum.

The olfactory epithelium contains three types of cells:

• millions of olfactory receptor cells
• columnar supportive cells
• short basal cells.

Olfactory receptors bear a cluster of about 20 modified cilia which function as receptor sites. These cilia extend from the olfactory epithelium into the thin coat of nasal mucous secreted by the supportive cells and olfactory glands. This mucous dissolves the airborne odour molecules.

Once dissolved, the chemicals bind to the specific receptors on the cilia stimulating the receptor cells. This causes depolarization then action potential in the receptor cell.

The axons of the olfactory receptors unite to form the olfactory nerve which transmits the information directly to olfactory bulb, a relay station in the brain. The nasal cavity contains pain receptors that respond to irritants such as ammonia, vinegar or hot chilly pepper.

Impulses from these pain receptors reach the brain. The brain combines these sensations with those of smell to identify the odours Humans can detect about 10,000 different odours but the olfactory capability of fish and mammals such as a dog is high.

Sense of taste (gustation):
The receptor cells fortaste are located in taste buds. Humans have about 10,000 taste buds are located in pockets around the papillae on the surface and sides of the tongue, but some on the surface of the pharynx and the larynx.

Each taste bud contains about 40 specialized receptor cells or gustatory cells, that helps to replace the worn out cells of the taste buds. The receptor cells for taste are not neurons, but they are microvilli .The microvilli protrude into the surrounding fluids through a narrow opening called the taste pore.

Dissolved chemicals contacting the microvilli bind to specific receptor proteins on the microvilli, thereby depolarizing the cell,it releases neurotransmitter which leads to the generation of an action potential in the associated sensory neuron.

Each dendrite receives signals from several receptor cells within the taste bud pass to the brain stem. From here the nerve impulse is relayed to the taste centre in the cerebral cortex of the brain that perceives the taste sensation.
In humans there are four basic taste senses:

Sense of touch:
Skin is the largest sense organ. These sensations of touch come from millions of microscopic simple sensory receptors located all over the skin and associated with the general sensations of contact or pressure, heat, cold, and pain. Some parts of the body have a large number of these such as the fingertips.

Structurally, these touch receptors are either free dendritic endings or encapsulated dendritic endings present in the skin (and other parts of the body). Free or bare dendritic nerve endings are present throughout the epidermis in “zigzag” form .These respond chiefly to pain and temperature but some respond to pressure as well.

Whenever one or more of these sensory receptors are stimulated (by heat, cold, vibrations, pressure or pain) an impulse or action potential is generated. This impulse is then taken to the spinal cord and from there to the brain which analyses the stimulus and then generates appropriate response.

Students can Download Chapter 7 Bill of Exchange Notes, Plus One Accountancy Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Accountancy Notes Chapter 7 Bill of Exchange

Summary:
Bill of Exchange:
A bill of exchange is an acknowledgement of debt given by one person to another, incorporating all the terms and conditions of payment.

Features and advantages of a bill:
A bill is a written unconditional order, it is signed by the creditor and accepted by the debtor, the amount of the bill is payable either on demand or at a fixed period.

Parties to a bill of Exchange:
There are three parties, ie., drawer, drawee and payee.

Promissory Note:
A promissory note is an undertaking in writting given by the debtor to the creditor to pay the latter a certain sum of money in accordance with the conditions stated therein. There are two parties to a promissory note, the promissor and the promisee.

Maturity of Bill:
The term maturity refers to the date on which a bill or promissory note becomes due for payment. In arriving at the maturity date three days known as “days of grace” must be added to the date on which the period of credit expires instrument is payable.

Endorsement:
An endorsement is a written order on the back of the instrument by the payee or the holder for transferring his right to another person.

Accounting treatment:
A bill can be treated in the following four ways by its receiver.

Dishonour of a bill:
A bill is said to have been dishonoured when the drawee fails to make the payment on the date of maturity. In this situation, liability of the acceptor is restored. Therefore, the entries made on the receipt of the bill should be reserved. The entries of dishonour of bill as follows
(i) When the bill was kept by drawer till maturity.

Noting Charges:
When a bill is dishonoured due to non-payment, it is usual to get it ‘noted’, to establish the matter of dishonour. The noting is done by “Notary Public.” Noting authenticates the fact of dishonour. For providing this service, a fees is charged by the Notary Public which is called Noting Charges. The following facts are generally noted by the Notary;

• Date, fact and reasons of dishonour;
• If the bill is not expressly dishonoured, the reasons why he treats it as dishonoured and;
• The amount of noting charges.

The entries recorded for noting charges in the drawers book are as follows:
When Drawer himself pays:

Where endorsee pays:

When the bank pays on discounted bill:

When the bank pays in the event of sending the bill for collection to the bank:

The entry recorded for noting charges in the book of drawee as follows:
For recording noting charges the drawee opens “Noting ChargesAccount”.

Renewal of the bill:
Sometimes the acceptor of the bill foresees that it may be difficult to meet the obligation of the bill on maturity and may, therefore approach the drawer with the request for extension of time for payment.

If it is so, the old bill is cancelled and . the fresh bill with new terms of payment is drawn and duly accepted and delivered. This is called renewal of the bill. The drawee may have to pay interest to the drawer for the extended period of credit.
Following journal entries are recorded in the case of renewal of the bill.

Retiring of the Bill:
Making payment of the bill of exchange before the due date is called retiring of the bill. To encourage the retirement of the bill, the holder allows some discount called “Rebate on bill” for the period between date of retirement and maturity. The rebate is calculated at a certain rate of interest.

The following journal entries are recorded:
(i) In the book of drawer:
On retiring the acceptance, rebate allowed.

(ii) In the book of drawee:

Students can Download Chapter 9 Locomotion and Movement Notes, Plus One Zoology Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Zoology Notes Chapter 9 Locomotion and Movement

What is locomotion?
The movements result in a change of place or location. Such voluntary movements are called locomotion. Walking, running, climbing, flying, swimming are all some forms of locomotory movements.

Locomotory Movements In Lower Organisms

1. Paramoecium, cilia helps in the movement of food through cytopharynx and locomotion.
2. Hydra use its tentacles for capturing its prey and also use them for locomotion.

All locomotions are movements but all movements are not locomotions.

Types Of Movement
The three main types of movements of cells of the human body are

• Amoeboid
• Ciliary
• Muscular.

Muscle
About 40-50 perent of the body weight of a human adult is contributed by muscles. Muscles are classified based on their location, three types of muscles are identified.

1. Skeletal
2. Visceral
3. Cardiac.

1. Skeletal muscles:
They have a striped appearance and called as striated muscles. They are voluntary muscles because their activities are under the voluntary control of the nervous system. They are involved in locomotory actions and changes of body postures.

2. Visceral muscles:

• They are located in the innerwalls alimentary canal, reproductive tract, etc. They are called smooth muscles (non striated muscle).
• Their activities are not underthe voluntary controlcalled as involuntary muscles.
• They helps in transportation of food through the digestive tract and gametes through the genital tract.

3. Cardiac muscles:

• They are found in the muscles of heart. Based on appearance, cardiac muscles are striated and involuntary.
• Skeletal muscle is made of a number of muscle bundles or fascicles held together by a common collagenous connective tissue layer called fascia
• Each muscle bundle contains a number of muscle fibres. Each muscle fibre is lined by the plasma membrane called sarcolemma enclosing the sarcoplasm.
• Muscle fibre is a syncitium because it contains many nuclei.
• The endoplasmic reticulum, i.e., sarcoplasmic reticulum of the muscle fibres is the store house of calcium ions.

Structure of Contractile Proteins
Each actin filament is made of two ‘F’ (filamentous) actins helically wound to each other. Each ‘F’ actin is a polymer of monomeric ‘G’ (Globular) actins. Two filaments of another protein, tropomyosin also run close to the ‘F’ actins throughout its length.

Acomplex protein Troponin is distributed at regular intervals on the tropomyosin. In the resting state a subunit of troponin masks the active binding sites for myosin on the actin filaments.

Monomeric proteins called Meromyosins forms one thick filament. Each meromyosin has two important parts, a globular head with a short arm and a tail, the former being called the heavy meromyosin (HMM) and the latter, the light meromyosin (LMM). The globular head is an active ATPase enzyme and has binding sites for ATP and active sites for actin.

Mechanism of Muscle Contraction
The sliding filament theory which states that contraction of a muscle fibre takes place by the sliding of the thin filaments over the thick filaments.
Muscle contraction is initiated by a signal sent by the central nervous system (CNS) via a motor neuron. The junction between a motor neuron and the sarcolemma of the muscle fibre is called the neuromuscular junction or motor-end plate.

1. In the junction, the neurotransmitter (Acetyl choline) is released which generates an action potential in the sarcolemma. This spreads and release of calcium ions into the sarcoplasm.
2. Increase in Ca⁺⁺ level leads to the binding of calcium with a subunit of troponin on actin filaments and thereby remove the masking of active sites for myosin.
3. The energy from ATP hydrolysis is used to bind the myosin head with exposed active sites on actin to form a cross bridge.
4. This pulls the attached actin filaments towards the centre of ‘A’ band. The Z’ line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere, i.e. contraction.
5. During shortening of the muscle the T bands get reduced, whereas the ‘A’ bands retain the length The myosin, releasing the ADP and P1 goes back to its relaxed state.
6. The ATP is again hydrolysed by the myosin head and the cycle of cross bridge formation and breakage is repeated causing further sliding.
7. The process continues till the Ca⁺⁺ ions are pumped back to the sarcoplasmic cisternae resulting in the masking of actin filaments.

This causes the return of ‘Z’ lines back to their original position, i.e., relaxation.

What is muscle fatigue?
Repeated activation of the muscles can lead to the accumulation of lactic acid due to anaerobic breakdown of glycogen causing fatigue. Muscle contains a red coloured oxygen storing pigment called myoglobin. These muscles contain plenty of mitochondria which helps in ATP production.

Hence they are called aerobic muscles. Some of the muscles possess very less quantity of myoglobin and gives whitish appearance . These are the White fibres. Number of mitochondria are also few in them. They depend on anaerobic process for energy.

Seletal System
1. Skeletal system consists of a framework of bones and a few cartilages.

2. Bone and cartilage are specialised connective tissues.

3. The former has a very hard matrix due to calcium salts in it and the latter has slightly pliable matrix due to chondroitin salts. In human beings, this system is made up of 206 bones and a few cartilages. It is grouped into two divisions.

Axial skeleton:

1. It comprises 80 bones distributed along the main axis of the body.
2. The skull, vertebral column, sternum and ribs constitute axial skeleton.

The skull is composed of two sets of bones – Cranial bones are 8 in number. The facial region is made up of 14 skeletal elements which form the front part of the skull.

Diagrammatic view of human skull:
A single U-shaped bone called hyoid is present at the base of the buccal cavity and it is also included in the skull.

What is ear ossicles ?
Each middle ear contains three tiny bones – Malleus, Incus and Stapes, collectively called Ear Ossicles.

Vertebral column:
It is formed by 26 serially arranged units called vertebrae and is dorsally placed. Each vertebra has a central hollow portion (neural canal) through which the spinal cord passes. First vertebra is the atlas and it articulates with the occipital condyles. The vertebral column is differentiated into cervical (7), thoracic (12), lumbar (5), sacral (1-fused)and coccygeal (1-fused) regions starting from the skull.

Vertebral column (right lateral view) Ribs and rib cage. The vertebral column protects the spinal cord, supports the head and serves as the point of attachment for the ribs and musculature of the back.

Sternum:
It is a flat bone on the ventral midline of thorax.
There are 12 pairs of ribs.
1. First seven pairs of ribs are called true ribs. Dorsaily, they are attached to the thoracic vertebrae and ventrally connected to the sternum with the help of hyaline cartilage.

2. The 8^th, 9^th and 10^th pairs of ribs do not articulate directly with the sternum but join the seventh rib with the help of hyaline cartilage. These are called vertebrochondral (false) ribs.

3. Last 2 pairs (11^th and 12^th) of ribs are not connected ventrally and are called floating ribs. Thoracic vertebrae, ribs and sternum together form the rib cage.

Appendicular skeleton:
It includes bones of the limbs alongwith their girdles Each limb is made of 30 bones. The bones of the hand (fore limb) are humerus, radius and ulna, carpals (wrist bones-8 in number), metacarpals (palm bones – 5 in number) and phalanges (digits – 14 in number) Femur (thigh bone – the longest bone), tibia and fibula, tarsals (ankle bones – 7 in number), metatarsals (5 in number) and phalanges (digits -14 in number) are the bones of the legs (hind limb).

A cup shaped bone called patella cover the knee ventrally (knee cap). Pectoral and Pelvic girdle bones help in the articulation of the upper and the lower limbs respectively with the axial skeleton.

Each half of pectoral girdle consists of a clavicle and a scapula. Scapula is a large triangular flat bone situated in the dorsal part of the thorax between the second and the seventh ribs. The dorsal, flat, triangular body of scapula has a slightly elevated ridge called the spine which projects as a flat, expanded process called the acromion.

Below the acromion is a depression called the glenoid cavity which articulates with the head of the humerus to form the shoulder joint. Each clavicle is a long slender bone with two curvatures. This bone is commonly called the collar bone. Pelvic girdle consists of two coxal bones Each coxal bone is formed by the fusion of three bones

1. ilium
2. ischium
3. pubis.

Joints
Joints are points of contact between bones, or between bones and cartilages. The movability of joints vary depending on different factors.
Joints are classified into three,

Disorders Of Muscular And Skeletal System
Myasthenia gravis:
Auto immune disorder affecting neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscle.

Muscular dystrophy:
Progressive degeneration of skeletal muscle mostly due to genetic disorder.

Tetany:
Rapid spasms (wild contractions) in muscle due to low Ca⁺⁺ in body fluid.

Arthritis:
Inflammation of joints.

Osteoporosis:
Age-related disorder characterised by decreased bone mass and increased chances of fractures. Decreased levels of estrogen is a common cause.

Gout:
Inflammation of joints due to accumulation of uric acid crystals.

NCERT SUPPLEMENTARY SYLLABUS
Types of movements: Flagellar movement
The three main types of movements shown by the cells of the human body are amoeboid, ciliary and muscular. Human sperms shows type of movement called the flagellar movement. The flagellum is the propulsion equipment (due to whip like movement of the tail and the middle piece of the sperm) forthe movement of sperm towards the ovum.

Students can Download Chapter 6 Depreciation, Provisions and Reserves Notes, Plus One Accountancy Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Accountancy Notes Chapter 6 Depreciation, Provisions and Reserves

Summary:
Meaning of depreciation:
Depreciation is decline in the value of a tangible fixed asset. In accounting depreciation is the process of allocating depreciable cost over useful life of a fixed asset.

Depreciation and similar terms:
Depreciation term is used in the context of tangible fixed assets. Depletion (in the context of extractive industries), and amortisation (in the context of intangible assets) are other related terms.

Factors Affecting Depreciation:

• Wear and Tear due to use and/or passage of time
• Expiration of Legal Rights
• Obsolescence

Importance of depreciation:

• Depreciation must be charged to ascertain true and fair profit or loss.
• Depreciation is a non-cash operating expense.

Methods of charging depreciation:
Depreciation amount can be calculated using:

• Straight line method, or
• Written down value method

Methods of recording depreciation:
In the books of account there are two types of arrangements for recording depreciation on fixed assets.

• Charging depreciation to asset account or
• Creating provision for depreciation/ accumulated depreciation account.

Charging depreciation to asset account:
According to this arrangement depreciation is deducted from the depreciable cost of the asset (credited to the asset account) and charged (or debited) to profit and loss account. Journal entries under this recording method are as follows:

2. Following two entries are recorded at the end of every year.
(a) For deducting depreciation amount from the cost of the asset.

(b) For charging depreciation to profit and loss account

3. Balance Sheet Treatment
When this method is used, the fixed asset appears at its net book value (ie. cost less depreciation charged till date) on the asset side of the balance sheet and not at its original cost (also known as historical cost).

Creating Provision for depreciation account/ Accumulated depreciation Account:
This method is designed to accumulate the depreciation provided on an asset in a separate account generally called “Provision for Depreciation” or “Accumulated Depreciation” account.

The following journal entries are recorded under this method:

2. The following two journal entries are recorded at the end of each year
(a) For crediting depreciation amount to provision for depreciation account.

(b) For charging depreciation to profit and loss account

3. Balance Sheet treatment
In the balance sheet the fixed asset continues to appear at its original cost on the asset side. The depreciation charged till that date appears in the provision for depreciation account, which is shown either on the “liabilities side” of the balance sheet or by way of deduction from the original cost of the asset concerned on the asset side of the balance sheet.

Disposal of Asset:
Disposal of asset can take place either

• At the end of its useful life or
• During the useful life (due to absolescence or any other abnormal factors). In this case the following journal entries are recorded.

1. For the sale of asset as scrap

2. For transfer of balance in asset account

In case, however “the provision for depreciation account” has been in use for recording the depreciation, then before passing the above entries transfer the balance of the provision for depreciation account to the asset account by recording the following journal entry.

Factors affecting the amount of depreciation:

• Depreciation amount is determined by Original cost
• Salvage value, and
• Useful life of the asset

Provisions and Reserves:
A provision is a charge against profit. It is created for a known current liability the amount of which is uncertain. Reserve on the other hand, is an appropriation of profit. It is created to strengthen the financial position of the business.

Types of Reserves:
Reserves may be:

• General reserve and specific reserve;
• Revenue reserve and capital reserve.

Secret Reserve:
When the total depreciation charged is higher than the total depreciable cost, the Secret reserve is created. The secret reserve is not explicitly shown in the balance sheet.

Students can Download Chapter 5 Trial Balance and Rectification of Errors Notes, Plus One Accountancy Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Accountancy Notes Chapter 5 Trial Balance and Rectification of Errors

Summary:
Meaning of trial balance:
A statement showing the abstract of the balance (debit/credit) of various accounts in the ledger.

Objectives of trial balance:
The main objectives of preparing the trial balance are:

• To ascertain the arithmetical accuracy of the ledger accounts;
• To help in locating errors; and
• To help in the preparation of the final accounts.

Preparation of trial balance by the balance method:
In this method, the trial balance has three columns. The first column is for the head of the account, the second column for writing the debit balance and the third for the credit balance of each account in the ledger.

Format of a Trial balance
Trial Balance of ………………… as on March 31.2005

It is normally prepared at the end of an accounting year. However, an organisation may prepare a trial balance at the end of any chosen period, which may be monthly, quarterly, half yearly or annually depending upon its requirements.
In order to prepare a trial balance following steps are taken:

• Ascertain the balances of each account in the ledger.
• List each account and place its balance in the debit or credit column as the case may be. (If an account has a zero balance, it may be included in the trial balance with zero in the column for its normal balance).
• Compute the total of debit balances column.
• Compute the total of the credit balances column.
• Verify that the sum of the debit balances equal the sum of credit balances. If they do not tally, it indicates that there are some errors. So one must check the correctness of the balances of all accounts.

It may be noted that all assets expenses and receivables account shall have debit balances whereas all liabilities, revenues and payables accounts shall have credit balances.

Illustrative Trial Balance

Various types of errors:
1. Errors of commission:
Errors caused due to wrong recording of a transaction, wrong totalling, wrong casting, wrong balancing, etc.

2. Errors of omission:
Errors caused due to omission of recording a transaction entirely or partly in the books of account.

3. Errors of principle:
Errors arising due to wrong classification of receipts and payments between revenue and capital receipts and revenue and capital expenditure.

4. Compensating errors:
Two or more errors committed in such a way that they nullify the effect of each other on the debits and credits.

Rectification of errors:
Errors affecting only one account can be rectified by giving an explanatory note or by passing a journal entry. Errors which affect two or more accounts are rectified by passing a journal entry.

Meaning and utility of suspense account:
An account in which the difference in the trial balance is put till such time that errors are located and rectified. It facilitates the preparation of financial statements even when the trial balance does not tally.

Disposal of suspense account:
When all the errors are located and rectified the suspense account stands disposed off.

Students can Download Chapter 4 Bank Reconciliation Statement Notes, Plus One Accountancy Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Accountancy Notes Chapter 4 Bank Reconciliation Statement

Summary
Bank Reconciliation Satement
A statement prepared to reconcile the bank balance as per cash book with the balance as per passbook or bank statement, by showing the items of difference between the two accounts.

Causes of difference
Timing of recording the transaction Errors made by business or by the bank.

Need for Reconciliation
It is generally experienced that when a comparison is made between the bank balance as shown in the firm’s cash book, the two balances do not tally. Hence, we have to first ascertain the causes of difference thereof and then reflect them in a statement called Bank Reconciliation Statement to reconcile (tally) the two balances.

In order to prepare a bank reconciliation statement we need to have a bank balance as per the cash book and a bank statement as on a particular day along with details of both the books.

If the two balances differ, the entries in both the books are compared and the items on account of which the difference has arisen are ascertained with the respective amounts involved so that the bank reconciliation statement may be prepared.

Proforma of bank reconciliation statement

It can also be prepared with two amount columns one showing additions (+ column) and another showing deduction (- column).

Proforma of bank reconciliation statement (table form)

Correct cash balance
It may happens that some of the receipts or payments are missing from either of the books and errors, if any, need to be rectified. This arises the need to look at the entries/errors recorded in both statements and other information available and compute the correct cash balance before reconciling the statements.

Students can Download Chapter 2 Theory Base of Accounting Notes, Plus One Accountancy Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Accountancy Notes Chapter 2 Theory Base of Accounting

Summary:
Generally accepted Accounting Principles (GAAP):
GAAP refers to the rules or guidelines adopted for recording and reporting to business transactions in order to bring uniformity in the preparation and presentation of financial statements. These principles are also referred to as concepts and conventions.

From the practicality viewpoint, the various terms such as principles, conventions, modifying principles, assumptions, etc., have been used interchangeably and are referred to as basic accounting concepts.

Systems of Accounting:
There are two systems of recording business transactions, i.e., double entry system and single entry system.

Basis of Accounting:
There are two broad approach of accounting are cash basis and accural basis. Under cash basis transactions are recorded only when cash are received or paid, where as under accural basis, revenue or costs are recognises when they Occur rather than when they are paid.

Accounting Standards:
Accounting standards are written statement of uniform accounting rules and guidelines in practice for preparing the uniform and consistent financial statements.

Students can Download Chapter 1 Introduction to Accounting Notes, Plus One Accountancy Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Accountancy Notes Chapter 1 Introduction to Accounting

Summary
Meaning of Accounting:
Accounting is a process of identifying, measuring, recording the business transactions and communicating thereof the required information to the interested users.

Accounting as a source of information:
Accounting as a source of information system is the process of identifying, measuring, recording and communicating the economic events of an organization to interested users of the information.

Users of accounting information:
Accounting plays a significant role in society by providing information to management at all levels and to those having a direct financial interest in the enterprise, such as present and potential investors and creditors.

Accounting information is also important to those having an indirect financial interests, such as regulatory agencies, tax authorities, customers, labour unions, trade associations, stock exchanges, and others.

Qualitative characteristics of Accounting:
To make accounting information decision-useful, it should possess the following qualitative characteristics.

• Reliability
• Understandability
• Relevance
• Comparability

The objective of accounting:
The primary objectives of accounting are to:

• Maintain records of business;
• Calculate profit or loss;
• Depict the financial position: and
• Make information available to various groups and users.

Role of accounting:
Accounting is not an end in itself. It is a means to an end. It plays the role of a:

• Language of a business
• Historical record
• Current economic reality
• Information system
• Service to users

Students can Download Chapter 8 Excretory Products and their Elimination Notes, Plus One Zoology Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Zoology Notes Chapter 8 Excretory Products and their Elimination

What is excretion?
Excretion is the elimination common nitrogenous wastes. Ammonia, urea and uric acid are the major forms of nitrogenous wastes excreted by the animals.

Ammonotelic.ureotelic and urecotelic animals and their excretion:
1. The process of excreting ammonia is Ammonotelism. eg: Many bony fishes, aquatic amphibians and aquatic insects are ammonotelic.

2. Mammals, many terrestrial amphibians and marine fishes mainly excrete urea and are called ureotelic animals.

3. Reptiles, birds, land snails and insects excrete nitrogenous wastes as uric acid in the form of pellet or paste with a minimum loss of water and are called uricotelic animals.

Where is urea produced?
Ammonia produced by metabolism is converted into urea in the liver and released into the blood which is filtered and excreted out by the kidneys.

Excretion in lower organisms:

Human Excretory System
In humans, the excretory system consists of

1. A pair of kidneys
2. One pair of ureters
3. A urinary bladder
4. A urethra.

Each kidney of an adult human measures 10 – 12 cm in length, 5 – 7 cm in width, 2 – 3 cm in thickness with an average weight of 120 – 170 g.

1. Centre of the inner concave surface of the kidney is a notch called hilum through which ureter, blood vessels and nerves enter.

2. Innerto the hilum is a broad funnel shaped space called the renal pelvis with projections called calyces.

3. Inside the kidney, there are two zones, an outer cortex and an inner medulla.

4. The medulla is divided medullary pyramids projecting into the calyces.

5. The cortex extends in between the medullary pyramids as renal columns called Columns of Bertini.

6. Each kidney has nearly one million complex tubular structures called nephrons, which are the functional units. A diagrammatic representation of a nephron showing blood vessels, duct and tubule Each nephron has two parts -1 The glomerulus & 2 Renal tubule.

7. Glomerulus is a tuft of capillaries formed by the afferent arteriole – a fine branch of renal artery.

8. Blood from the glomerulus is carried away by an efferent arteriole.

9. The renal tubule begins with a double walled cup-like structure calle Bowman’s capsule, which encloses the glomerulus.

10. Glomerulus alongwith Bowman’s capsule, is called the malpighian body or renal corpuscle

11. The tubule continues further to form a highly coiled network proximal convoluted tubule (PCT).

12. A hairpin shaped Henle’s loop is the next part of the tubule which has a descending and an ascending limb.

13. The ascending limb continues as another highly coiled tubular region called distal convoluted tubule (DCT).

14. The DCTs open into a straight tube called collecting duct, many of which open into the renal pelvis through medullary pyramids in the calyces.

15. The Malpighian corpuscle, PCT and DCT of the nephron are situated in the cortical region of the kidney whereas the loop of Henle dips into the medulla.

Types of Nephrons:
1. In majority of nephrons, the loop of Henle is too short and extends only very little into the medulla. Such nephrons are called cortical nephrons.

2. In some of the nephrons, the loop of Henle is very long and runs deep into the medulla.These nephrons are called juxta medullary nephrons. A minute vessel of capillary network runs parallel to the Henle’s loop forming a ‘LT shaped vasa recta. Vasa recta is absent or highly reduced in cortical nephrons.

Urine Formation
1. It involves three main processes namely, glomerular filtration, reabsorption and secretion

2. The first step in urine formation is the filtration of blood, which is carried out by the glomerulus and is called glomerular filtration.

3. 1100 – 1200 ml of blood is filtered by the kidneys per minute. The glomerular capillary blood pressure causes filtration of blood through 3 layers,

4. The epithelial cells of Bowman’s capsule called podocytes which possess minute spaces called filtration slits.

5. Blood is filtered through these membranes, that almost all the constituents of the plasma except the proteins pass onto the lumen of the Bowman’s capsule. It is the process of ultra filtration.

6. The kidneys have efficient mechanism for the regulation of glomerular filtration rate. It is carried out by juxta glomerular apparatus (JGA).JGA is found in the distal convoluted tubule .

7. A fall in GFR can activate the JG cells to release renin which can stimulate the glomerular blood flow and thereby the GFR back to normal.

8. Nearly 99 percent of the filtrate is reabsorbed by the renal tubules. This process is called reabsorption.

9. For example, substances like glucose, amino acids, Na⁺, etc., in the filtrate are reabsorbed actively whereas the nitrogenous wastes and water are absorbed by passive transport.

10. During urine formation, the tubular cells secrete substances like H⁺, K⁺ and ammonia into the filtrate.

11. Tubular secretion is helpful in the maintenance of ionic and acid-base balance of body fluids.

Function Of The Tubules
Proximal Convoluted Ttubule (PCT):
1. PCT consists of simple cuboidal brush border epithelium which increases the surface area for reabsorption.

2. All essential nutrients, and 70 – 80 per cent of electrolytes and water are reabsorbed by this segment.

3. PCT also helps to maintain the pH and ionic balance of the body fluids. It occurs through selective secretion of hydrogen ions, ammonia and potassium ions into the filtrate and by absorption of HCO₃^– from it.

Henle’s Loop
Function:
It helps to maintain high osmolarity of medullary interstitial fluid. The descending limb of loop of Henle is permeable to water but impermeable to electrolytes. This concentrates the filtrate as it moves down.

The ascending limb is impermeable to water but allows transport of electrolytes actively or passively. Therefore, as the concentrated filtrate pass upward, it gets diluted due to the passage of electrolytes to the medullary fluid.

Distal Convoluted Tubule (DCT):
The reabsorption of Na⁺, HCO₃^– and water takes place in this segment. In this segment selective secretion of hydrogen and potassium ions and NH₃ to maintain the pH and sodium-potassium balance in blood.

Collecting Duct:
It extends from the cortex of the kidney to the inner parts of the medulla. Large amounts of water is reabsorbed from this region to produce a concentrated urine. This part maintains pH and ionic balance of blood by the selective secretion of H⁺ and K⁺ ions.

Mechanism Of Concentration Of The Filtrate
The flow of filtrate in the two limbs of Henle’s loop is in opposite directions and thus forms a counter current. The flow of blood through the two limbs of vasa recta is also in a counter current pattern.

The proximity between the Henle’s loop and vasa recta, as well as the counter current in them help in maintaining an increasing osmolarity towards the inner medullary interstitium, i.e. from 300 mOsmolL^-1 in the cortex to about 1200 mOsmolL^-1 in the inner medulla. This gradient is mainly caused by NaCl and urea.

NaCl is transported by the ascending limb of Henle’s loop which is exchanged with the descending limb of vasa recta. NaCl is returned to the interstitium by the ascending portion of vasa recta. Similarly, small amounts of urea enterthe thin segment of the ascending limb of Henle’s loop which is transported back to the interstitium by the collecting tubule.

This transport is facilitated by the counter current mechanism This mechanism helps to maintain a concentration gradient in the medullary interstitium. Presence of such interstitial gradient helps in an easy passage of water from the collecting tubule thereby concentrating the filtrate (urine).

Regulation Of Kidney Function
The functioning of the kidneys is influenced by hypothalamus, JGA and to a certain extent, the heart in the body are activated by changes in blood volume.

How can diuresis is prevented in body?
The decrease of fluid from the body can activate these Osmoreceptors which stimulate the hypothalamus to release antidiuretic hormone (ADH) or vasopressin from the neurohypophysis. ADH facilitates water reabsorption Hence it prevents diuresis.

An increase in body fluid volume switch off the osmoreceptors and suppress the ADH release. ADH can also affect the kidney function by its constrictory effects on blood vessels. This causes an increase in blood pressure. An increase in blood pressure increase the glomerular blood flow and the GFR.

Micturition
It is the voluntary signal from the central nervous system (CNS). This signal is initiated by the stretching of the urinary bladder in response to the stretch receptors on the walls of the bladder.

The urine is slightly acidic (pH – 6.0) and has a characterestic odour. 25 – 30 gm of urea is excreted out per day. Analysis of urine helps to know malfunctioning of the kidney.

Role Of Other Organs In Excretion
Lungs remove large amounts of CO₂ (18 litres/day) and water every day. Liver secretes bile-containing substances like bilirubin, biliverdin, cholesterol, degraded steroid hormones, vitamins and drugs.

The sweat and sebaceous glands in the skin eliminates watery fluid containing NaCl, small amounts of urea, lactic acid, etc. Sebaceous glands eliminates sterols, hydrocarbons and waxes through sebum. This secretion provides a protective oily covering for the skin.

Disorders Of The Excretory System
Uemia:
It leads to the accumulation of urea in blood. It lead to kidney failure. In such patients, urea can be removed by a process called hemodialysis.

Procedure of Dialysis:
Blood drained from a artery is pumped into a dialysing unit after adding an anticoagulant like heparin.The unit contains a coiled cellophane tube surrounded by a fluid (dialysing fluid).

The porous cellophane membrance allows the passage of molecules based on concentration gradient.
As nitrogenous wastes are absent in the dialysing fluid, the cleared blood is pumped back to the body through a vein after adding anti-heparin to it.

Remedy for kidney damage:
Kidney transplantation is the ultimate method in the correction of acute renal failures (kidney failure). A functioning kidney is used in transplantation from a donor to minimise its chances of rejection by the immune system of the host.

Renal calculi:
Stone or insoluble mass of crystallised salts (oxalates, etc.) formed within the kidney.

Glomerulonephritis:
Inflammation of glomeruli of kidney

NCERT SUPPLEMENTARY SYLLABUS
Diabetes Insipidus:
Antidiuretic hormone (ADH) is released from the posterior pituitary, prevents dehydration. It helps in the reabsorption of water by the distal parts of the kidney tubules and prevents diuresis. Deficiency of ADH leads to diabetes insipedus, that means huge amounts of dilute urine is formed followed by intense thirst.

The name itself (diabetes = overflow; insipidus = tasteless) distinguishes it from diabetes .mellitus (mel = honey), in which insulin deficiency causes large amounts of blood sugar to be lost in the urine

Artificial kidney:
Hemodialysis machine is known as the artificial kidney. Hemodialysis is an artificial process of removing toxic substances from the blood in patients of kidney failure.

Students can Download Chapter 14 Oscillations Notes, Plus One Physics Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Physics Notes Chapter 14 Oscillations

Introduction
In this chapter, we study oscillatory motion. The description of an oscillatory motion requires some fundamental concept like period, frequency, displacement, amplitude and phase.

Periodic And Oscillatory Motions
Periodic Motion:
A motion that repeats itself at regular intervals of time is called periodic motion.
Example:

• The orbital motion of planets in the solar system.
• The piston in a steam engine going back and forth

Oscillations or Vibrations:
A body executes to and fro motion at regular intervals of time is called oscillatory (or) vibratory motion.

Note:
(1) When the frequency is small, we call it oscillation. When the frequency is high, we call it vibration.
Period and frequency:
Period (T):
Time taken to complete one oscillation is called period

Frequency (n):
The number of oscillations per second is called frequency.
frequency v = \(\frac{1}{T}\)Hz

Displacement:
Displacement of oscillation means the change of any physical property with time under consideration.

Explanation:
For example, consider the oscillation of block attached to a spring. In this case the displacement of block with time is referred to as displacement.

In the case if oscillation of simple pendulum, the angle from the vertical as a function of time may be regarded as a displacement variable. The voltage across a capacitor, changing with time in an a.c. circuit is also a displacement variable

Note:
The displacement variable may take both positive and negative values.

Mathematical expression for displacement:
The displacement of a periodic function can be written as

Simple Harmonic Motion (S.H.M.)
Simple harmonic motion is the simplest form of oscillatory motion.

The oscillatory motion is said to be simple harmonic motion if the displacement ‘x’ of the particle from the origin varies with time as

Where
x(t) = displacement x as a function of time t
A = amplitude
ω = angular frequency
(ω t+ Φ) = phase (time-dependent)
Φ = phase constant or initial phase

Graphical Variation of S.H.M.

The above graph shows the graphical representation of x(t) = A coswt with time.
(Initial phase Φ = 0)

Amplitude of S.H.M.
The maximum displacement of S.H.M. from mean position is called the amplitude of S.H.M.
Note:
1.

Two simple harmonic motions having, same w and Φ but different amplitudes A and B as shown in the above figure.

2.

Two simple harmonic motions having the same A and w but different phase angle Φ as shown in the above figure.

Simple Harmonic Motion And Uniform Circular Motion

Question 1.
Show that the projection of uniform circular motion on any diameter of the circle is S.H.M.

Answer:
Consider a particle moving along the circumference of a circle of radius ‘a’ and centre O, with uniform angular velocity w. AB and CD are two mutually perpendicular diameters along X and Y axis. At time t = 0. let the particle be at P₀ so that ∠P₀OB = Φ.

After time Y second, let the particle reach P so that ∠POP₀ = ωt. N is the foot of the perpendicular drawn from P on the diameter CD.

Similarly M is the foot of the perpendicular drawn from P to the diameter AB. When the particle moves along the circumference of the circle, the foot of the perpendicular executes to and fro motion along the diameter CD or AB with O as the mean position. From the right angle triangle O MP, we get
cos (ωt + Φ) = \(\frac{\mathrm{OM}}{\mathrm{OP}}\)
∴ OM = OP cos (ωt + Φ)
X = a cos (ωt + Φ) ………………. (1)
Similarly, we get
sin (ωt + Φ) = \(\frac{y}{a}\) (or)
Y = a sin (ωt + Φ) ……………… (2)
Equation (1) and (2) are similar to equations of S.H.M. The equation(1) and (2) shows that the projection of uniform circular motion on any diameter is S.H.M.
At t = 0, if the particle is at B, then Φ = 0. Then equations (1) and (2) reduce to
x = a cos ωt ………………….. (3)
y = a sin ωt …………………….(4)

Velocity And Acceleration In Simple Harmonic Motion B
Velocity Of S.H.M.
The y displacement of S.H.M. is given by
y = a sin ω t
∴ velocity in y direction

Case – 1
At the mean position y=0, therefore velocity is maximum. The maximum velocity is given by

Case – 2
At the extreme position, y = a
∴ V_minimum = \(\sqrt{a^{2}-a^{2}}\) = 0
So the velocity of a S.H.M. varies between o and wa

Acceleration of S.H.M
We know y = a sin ω t
Velocity v = \(\frac{d y}{d t}\) = a ω cos ω t
Acceleration a = \(\frac{d^{2} y}{d t^{2}}\) = -aω² sin ωt
a = -aω² sin ωt

This equation shows that acceleration of a SHM is directly proportional to the displacement and opposite to the displacement.

Variation of displacement Y with time t:

Variation of velocity (v) with time:

Variation of acceleration with time:

Force Law For Simple Harmonic Motion
According to Newton’s second law of motion F = ma
But a = -ω²y(t)
ie. force acting on the S.H.M. in Y direction
F = -mω²y(t)
(or) F = -ky(t)
Where k= mω²
From the above equation (1), we can take an alternative definition of simple harmonic motion.

Statement:
Simple harmonic motion is the motion executed by a particle subject to a force, which is proportional to the displacement of the particle and is directed towards the mean position.

Energy In Simple Harmonic Motion
A simple harmonically moving particle possesses both potential energy and kinetic energy. Potential energy is due to its displacement against restoring force. Kinetic energy is due to its motion.

Total energy of the S.H.M. is the sum of the kinetic energy and potential energy. Total energy remains a constant throughout its motion.

Expression for Kinetic energy:
Let m be the mass of the particle executing SHM. Let V be the velocity at any instant,

Expression for potential energy:
Potential energy is work required to take the particle against the restoring force.

Work done to displace the particle through a small distance dy, dw = force × displacement
= mω²y × dy [force = ω²y ]. Therefore total work done to take the particle from o to y.


This work done is stored in the particle as its potential energy.

At extreme position y = a

At equilibrium position y = 0
∴ PE = 0
Total energy of a S.H.M.
Total energy = PE + kE

∴ Total energy = maximum KE = maximum PE

Graphical variation of PE, KE and TE of S.H.M.

Some Systems Executing Simple Harmonic Motion
Oscillations due to a spring Hooks Law:
The force acting simple harmonic motion is proportional to the displacement and is always directed towards the centre of motion.
F α – x (or) F= kx
where k is called spring constant

Period of oscillation of a spring:

Consider a body of mass m attached to a massless spring of spring constant K. The other end of spring is connected to a rigid support as shown in figure. The body is placed on a frictionless horizontal surface.

If the body be displaced towards right through a small distance ‘x’, a restoring force will be developed.

The Simple Pendulum:

Consider a mass m suspended from one end of a string of length L fixed at the other end as shown in figure. Suppose P is the instantaneous position of the pendulum. At this instant its string makes an angle θ with the vertical.

The forces acting on the bob are (1) weight of bob F_g (mg) acting vertically downward. (2) Tension T in the string.

The gravitational force F_g can be divided into a radial component F_gCos θ and tangential component F_gSin θ. The radial component is cancelled by the – tension T. But the tangential component F_gSin θ produces a restoring torque.

Restoring torque τ = – F_g sin θ . L.
τ = -mg sin θ.L …………….. (1)
-ve sign shown that the torque and angular displacement θ are oppositely directed. For rotational motion of bob,.
τ = Iα …………. (2).
Where I is a moment of inertia about the point of suspension and α is angular acceleration. From eq (1) and eq (2).
Iα = -mg sin θ.L
If we assume that the displacement θ is small, sin θ ≈ θ.
∴ Iα = -mg θ.L
Iα + mg θ.L = 0

Damped Simple Harmonic Motion
Periodic oscillations of decreasing amplitude due to the presence of resistive forces of the medium are called damped oscillations.

Question 2.
Derive a differential equation for a damped simple harmonic oscillation.

Answer:
Consider a block of mass ‘m’ connected to one end of a massless spring of spring constant K. The other end of spring is connected to rigid support. The block is connected to a vane through a rod (The vane and rod are massless). The vane is submerged in a liquid.

Let the equilibrium position of block be ‘O’. If this block is moved along downward direction through a distance x, a damping force will be developed on vane due to liquid. This damping force is proportional to velocity of vane ie; damping force F_d α – v (or) F_d = -bv

where b is called damping constant. The value of b depends on the characteristics of the liquid and the vane.

The restoring force on the block due to spring. F_s = -kx. where x is the displacement of the mass from its equilibrium position.
∴ Total force on the block, F = -bv + -kx
ma = -bv + -kx
ma + bv + kx = 0
\(m \frac{d^{2} x}{d t^{2}}+b \frac{d x}{d t}+k x=0\)
This is the differential equation of S.H.M.

The motion of damped harmonic oscillator:
The solution of the above differential equation of damped harmonic oscillator is

Case – 1
b = 0 (There is no damping force). In this case, we get

The above result shows that, if there is no damping force (b = 0). The oscillator behaves like a undamped oscillator.

Case – 2
If b is small, the amplitude of the oscillator decreases continuously with time. The motion is approximately a periodic. The Variation of displacement x (t) with time T is shown below.

Case – 3
If damping constant b is large, the amplitude of the oscillator decreases to zero very quickly. The motion is not a periodic motion. The variation of displacement x (t) with time T is shown below.

The Energy variation of damped oscillator:
The energy of an undamped oscillator, E = \(\frac{1}{2}\)kA².
where A is the amplitude of an undamped oscillator. But for the damped oscillator, amplitude = Ae^-bt/2m.

The above equation shows that the energy of a damped oscillator decreases exponentially with time, which is shown below

Note:
Small damping means that the dimensionless ratio
\((b / \sqrt{k m})\) is much less than 1.

Forced oscillations and resonance
Free oscillation:
When a body oscillates in the absence of external forces (eg. friction etc.) the oscillations are said to be free oscillations.

Forced oscillation:
When an external periodic force is applied to a damped harmonic oscillator, the oscillator will vibrate with a constant amplitude and frequency of vibration will be that of the applied periodic force. This type of oscillation is called forced oscillation.

The differential equation of forced oscillator:
Let F(t) = F₀ cosω_dt is an external force applied to a damped oscillator.

The total force acting on the damped oscillator,
F = – bv – kx + F₀ cosω_dt
where -bv is the damping force and -kx is the linear restoring force.
F + bv + kx = F₀ cosω_dt
\(m \frac{d^{2} x}{d t^{2}}+b \frac{d x}{d t}+k x=F_{0} \cos \omega_{d} t\)
This is the differential equation of an oscillator of mass m on which a periodic force of (angular) frequency ω_d is applied. The oscillator initially oscillates with its natural frequency w. When we apply the external periodic force, the oscillation with the natural frequency die out, and the body oscillates with the (angular) frequency of the external periodic force.

The motion of forced oscillator:
The solution (displacement) of the above differential equation of forced oscillator can be written as
x(t) = Acos(ω_dt + Φ)

where m is the mass of the particle v₀ and x₀ are the velocity and the displacement of the particle at time t = 0, (which is the moment when we apply the periodic force)

Case -1
When b = 0 (damping force = 0) and ω = ω_d,
we get A = \(\frac{F_{0}}{0}\)
A = ∞
This is an ideal case. This case never arises in a real situation as the damping is never perfectly zero.

Case – 2
(Small damping, driving frequency far from natural frequency).
In this ω_db << m(ω² – ω_d²). Hence we can neglect ω_db. Hence amplitude of oscillation can be written as.

Case – 3
(Small damping, driving frequency close to natural frequency).
In this case m(ω² – ω_a²) << ω_db. Hence we can neglect m (ω² – ω_a²). Hence amplitude of oscillation can be written as

This equation shows that the maximum amplitude fora given driving frequency is governed by the driving frequency and damping constant.

Resonant Oscillation
When the frequency of the external periodic force is varied, it is found that the amplitude of the forced vibration increases and reaches a maximum value and then decreases.

The amplitude will be maximum when the frequency of the applied periodic force is equal to the natural frequency of the vibration. Such oscillations are called resonant oscillations and the phenomenon is called resonance.

Graphical variation amplitude with driving frequency:

Examples of resonance:
All mechanical structures have one or more natural frequencies, and if a structure is subjected to a strong external periodic driving force that matches one of these frequencies, the resulting oscillations of the structure may rupture it.

The Tacoma Narrows Bridge at Puget Sound, Washington, USA was opened on July 1, 1940. Four months later winds produced a pulsating resultant force in resonance with the natural frequency of the structure.

This caused a steady increase in the amplitude of oscillations until the bridge collapsed. It is for the same reason the marching soldiers break steps while crossing a bridge. Aircraft designers make sure that none of the natural frequencies at which a wing can oscillate match the frequency of the engines in flight! Earthquakes cause vast devastation.

In an earthquake, short and tall structures remain unaffected while the medium height structures fall down. This happens because the natural frequencies of the short structures happen to be higher and those of taller structures lower than the frequency of the seismic waves.

Students can Download Chapter 7 Body Fluids and Circulation Notes, Plus One Zoology Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Zoology Notes Chapter 7 Body Fluids and Circulation

Blood
Blood is a special connective tissue contains

• Fluid matrix
• Plasma
• Formed elements.

Plasma:
It constitute nearly 55 per cent of the blood. 90 – 92 percent of plasma is water and proteins (Fibrinogen, globulins and albumins) contribute 6 – 8 percent of it. Fibrinogens are needed for clotting or coagulation of blood.

Defence mechanism and osmotic balance:
Globulins primarly are involved in defense mechanisms of the body and the albumins help in osmotic balance. Plasma also contains small amounts of minerals like Na⁺, Ca⁺⁺, Mg⁺⁺, HCO₃^–, CI^–, etc. Factors for coagulation or clotting of blood are also present in the plasma in an inactive form.

What is serum?
Plasma without the clotting factors is called serum.

Formed Elements

1. Erythrocytes
2. Leucocytes
3. Platelets

They constitute nearly 45 per cent of the blood.
1. Erythrocytes or red blood cells (RBC):
They are the most abundant and on an average, 5 millions to 5.5 millions of RBCs mm-3 of blood. RBCs are formed in the red bone marrow in the adults. RBCs are devoid of nucleus in most of the mammals and are biconcave in shape. They have a red coloured, iron containing complex protein called haemoglobin.

A healthy individual has 12 – 16 gms of haemoglobin in every 100 ml of blood. These molecules play a significant role in transport of respiratory gases. RBCs have an average life span of 120 days after which they are destroyed in the spleen (graveyard of RBCs).

2. Leucocytes:
They are also known as white blood cells, colourless, nucleated and are relatively lesser in number which averages 6000 – 8000 mm-3 of blood. Leucocytes are generally short lived. The two main categories of WBCs granulocytes and agranulocytes.

• Neutrophils are the most abundant cells (60 – 65 percent) of the total WBCs and basophils are the least (0.5 – 1 percent) among them.
• Neutrophils and monocytes (6 – 8 per cent) are phagocytic cells which destroy foreign organisms entering the body.
• Basophils secrete histamine, serotonin, heparin, etc., and are involved in inflammatory reactions.
• Eosinophils (2 – 3 per cent) resist infections and are also associated with allergic reactions.

Lymphocytes (20-25 percent) are of two major types – ‘B’ and ‘T’ forms. Both B and T lymphocytes are responsible for immune responses of the body.

3. Platelets:
They are also called thrombocytes, are cell fragments produced from megakaryocytes (special cells in the bone marrow). Blood normally contains 1,500,00 – 3,500,00 platelets mm-3. Platelets are involved in the coagulation or clotting of blood. A reduction in their number can lead to clotting disorders which will lead to excessive loss of blood from the body.

Blood Groups
The ABO and Rh- are widely used all over the world.

ABO grouping
It is based on the presence or absence of two surface antigens on the RBCs namely A and B. The plasma of different individuals contain two natural antibodies (proteins produced in response to antigens). There are four groups of blood, A, B, AB and O.

Who are called as universal donor and receipient?
The group ‘O’ blood can be donated to persons with any other blood groupand hence ‘O’group individuals are called ‘universal donors’. Persons with ‘AB’ group can accept blood from persons with AB as well as the other grbups of blood, such persons are called ‘universal recipients’.

Rh grouping
Rh antigen is observed on the surface of RBCs of majority (nearly 80 percent) of humans. Such individuals are called Rh positive (Rh+ve) and without antigen are called Rh negative (Rh-ve). Rh group should also be matched before transfusions.

What is Rh incompatibility?
It is the mismatching of blood between the Rh-ve blood of a pregnant mother with Rh+ve blood of the foetus. Rh antigens of the foetus do not get exposed to the Rh-ve blood of the mother in the first pregnancy as the two bloods are well separated by the placenta.

But during the delivery of the first child, there is a possibility of mixing of the maternal blood to small amounts of the Rh+ve blood from the foetus. In such cases, the mother starts preparing antibodies against Rh in her blood. In subsequent pregnancies, the

Solving of Rh incompatibility:
This can be avoided by administering anti-Rh antibodies to the mother immediately after the delivery of the first child.

Coagulation of Blood
Blood coagulates or clots in response to an injury or trauma to prevent excessive loss of blood from the body. The network of threads called fibrins in which dead and damaged formed elements of blood are trapped.

Fibrins are formed by the conversion of inactive fibrinogens in the plasma by the enzyme thrombin. Thrombins are formed from another inactive substance present in the plasma called prothrombin.

An enzyme complex, thrombokinase, is required forthe above reaction. An injury stimulates the platelets in the blood to release certain factors which activate the mechanism of coagulation .Calcium ions play a very important role in clotting.

Lymph (tissue fluid)
As the blood passes through the capillaries in tissues, fluid released out is called the interstitial fluid or tissue fluid. It has the same mineral distribution as that in plasma. An elaborate network of vessels called the lymphatic system collects this fluid and drains it back to the major veins.

The fluid present in the lymphatic system is called the lymph. Lymph is a colourless fluid which are responsible forthe immune responses of the body. Lymph is also an important carrier for nutrients, hormones, etc. Fats are absorbed through lymph in the lacteals present in the intestinal villi.

Circulatory Pathways
The circulatory patterns are of two types – open or closed.

Open circulatory system:
It is present in arthropods and molluscs in which blood pumped by the heart passes through large vessels into open spaces or body cavities called sinuses.

Closed circulatory system:
It is present in Annelids and chordates in which the blood is pumped by the heart circulated through a closed network of blood vessels.
All vertebrates possess a muscular chambered heart.
1. Fishes have a 2-chambered heart with an atrium and a ventricle.

2. Amphibians and the reptiles (except crocodiles) have a 3-chambered heart with two atria and a single ventricle.

3. Crocodiles, birds and mammals possess a 4-chambered heart with two atria and two ventricles. In fishes the heart pumps out deoxygenated blood which is oxygenated by the gills and supplied to the body parts from where deoxygenated blood is returned to the heart (single circulation).

In amphibians and reptiles, the left atrium receives oxygenated blood from the gills/lungs/skin and the right atrium gets the deoxygenated blood from other body parts. However, they get mixed up in the single ventricle which pumps out mixed blood (incomplete double circulation).

In birds and mammals, oxygenated and deoxygenated blood received by the left and right atria respectively passes on to the ventricles of the same sides. The two separate circulatory pathways are present in these organisms, hence the animals have double circulation.

Human Circulatory System
Heart:
It is situated in the thoracic cavity, in between the two lungs. It is protected by a double walled membranous bag,pericardium, enclosing the pericardial fluid. It has four chambers, two small upper chambers called atria and two larger lower chambers called ventricles.

A thin, muscular wall called the inter atrial septum separates the right and the left atria, whereas a thick- walled, the inter-ventricular septum, separates the left and the right ventricles. The atrium and the ventricle of the same side are separated by a thick fibrous tissue called the atrioventricular septum.

Tricuspid and bicuspid valve:
The opening between the right atrium and the right ventricle is guarded by a valve formed of three muscularflaps or cusps, the tricuspid valve. Bicuspid or mitral valve guards the opening between the left atrium and the left ventricle.

Semilunar valve:
The openings of the right and the left ventricles into the pulmonary artery and the aorta respectively are provided with the semilunar valves.

Function of semilunar valve:
It allows the flow of blood only in one direction, i.e., from the atria to the ventricles and from the ventricles to the pulmonary artery or aorta. These valves prevent any backward flow.

SAN & AVN:
A specialised cardiac musculature called the nodal tissue is also distributed in the right upper corner of the right atrium called the sino-atrial node (SAN). Another mass of this tissue is seen in the lower left comer of the right atrium close to the atrio-ventricular septum called the atrio-ventricular node (AVN).

A bundle of nodal fibres, atrioventricular bundle (AV bundle) continues from the AVN which passes through the atrio-ventricular septa to emerge on the top of the interventrical sepyum and divides into a right and left bundle. These branches give rise to minute fibres throughout the ventricular musculature, they are called purkinje fibres.

These fibres alongwith right and left bundles are known as bundle of HIS. The nodal musculature has the ability to generate action potentials without any external stimuli.

What is the pacemaker of heart?
The SAN can generate the maximum number of action potentials, i.e., 70 – 75 min^-1, and is responsible for initiating and maintaining the rhythmic contractile activity of the heart. Hence it is called the pacemaker. Our heart normally beats 70 – 75 times in a minute (average 72 beats min^-1).

Cardiac Cycle
As the tricuspid and bicuspid valves are open, blood from the pulmonary veins and vena cava flows into the left and the right ventricle respectively. The semilunar valves are closed at this stage. The action potential is conducted to the ventricular side by the AVN and AV bundle from where the bundle of HIS transmits it through the entire ventricular musculature.

This causes the ventricular muscles to contract, (ventricular systole), the atria undergoes relaxation (diastole). As the ventricular pressure increases the semilunar valves open, allowing the blood in the ventricles to flow through these vessels into the circulatory pathways.

The ventricles relax (ventricular diastole) and the ventricular pressure falls causing the closure of semilunar valves which prevents the backflow of blood into the ventricles.

This sequential event in the heart which is cyclically repeated is called the cardiac cycle and it consists of systole and diastole of both the atria and ventricles. The heart beats 72 times per minute,i.e., that many cardiac cycles are performed per minute.

Cardiac output is the volume of blood pumped out by each ventricle per minute and averages 5000 mL or 5 litres in a healthy individual.

Sound produced in heart:
For example, the cardiac output of an athlete will be much higherthanthat of an ordinary man. During each cardiac cycle sounds are produced, the first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves whereas the second heart sound (dub) is associated with the closure of the semilunar valves. These sounds are of clinical diagnostic significance.

Electrocardiograph (ECG)
ECG is a graphical representation of the electrical activity of the heart during a cardiac cycle. Each peak in the ECG is identified with a letter from P to T that corresponds to a specific electrical activity of the heart.
1. The P-wave represents the electrical excitation Diagrammatic presentation of a standard ECG (or depolarisation) of the atria, which leads to the
contraction of both the atria.

2. The QRS complex represents the depolarisation of the ventricles, which initiates the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole.

3. The T-wave represents the return of the ventricles from excited to normal state (repolarisation). The end of the T-wave marks the end of systole.

Since the ECGs obtained from different individuals have the same shape any deviation from this shape indicates abnormality or disease.

Doube Circulation
It involves two types of circulation,
1. Pulmonary circulation:
The deoxygenated blood pumped into the pulmonary artery is passed on to the lungs from where the oxygenated blood is carried by the pulmonary veins into the left atrium. This pathway constitutes the pulmonary circulation.

2. Systemic circulation:
The oxygenated blood entering the aorta is carried by a network of arteries, arterioles and capillaries to the tissues from where the deoxygenated blood is collected by a system of venules, veins and vena cava and emptied into the right atrium. This is the systemic circulation.

The systemic circulation provides nutrients, O₂ and other essential substances to the tissues and takes CO₂ and other harmful substances away for elimination. A vascular connection between the digestive tract and liver called hepatic portal system.

The hepatic portal vein carries blood from intestine to the liver before it is delivered to the systemic circulation. In Coronary system of blood vessels is present in our body exclusively for the circulation of blood to and from the cardiac musculature.

Regulation Of Cardiac Activity
Normal activities of the heart are auto regulated by specialised muscles (nodal tissue), hence the heart is called myogenic. Medulla oblangata control the cardiac function through autonomic nervous system (ANS).

Neural signals through the sympathetic nerves (part of ANS) increase the rate of heart beat. On the other hand, parasympathetic neural signals decrease the rate of heart beat. Adrenal medullary hormones can also increase the cardiac output.

Disorders Of Circulatory System
High Blood Pressure (Hypertension):
Hypertension is the term for blood pressure that is higherthan normal (120/80). In this measurement 120 mm Hg (millimetres of mercury pressure) is the systolic, or pumping, pressure and 80 mm Hg is the diastolic, or resting, pressure. High blood pressure leads to heart diseases and also affects vital organs like brain and kidney.

Coronary Artery Disease (CAD):
Coronary Artery Disease, often referred to as atherosclerosis, affects the vessels that supply blood to the heart muscle. It is caused by deposits of calcium, fat, cholesterol and fibrous tissues, which makes the lumen of arteries narrower.

Angina:
It is also called ‘angina pectoris’. A symptom of acute chest pain appears when no enough oxygen is reaching the heart muscle. It occurs due to conditions that affect the blood flow.

Heart Failure:
It is the state of heart when it is not pumping blood effectively enough to meet the needs of the body. Heart failure is not the same as cardiac arrest (when the heart stops beating) or a heart attack (when the heart muscle is suddenly damaged by an inadequate blood supply).

Students can Download Chapter 15 Waves Notes, Plus One Physics Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Physics Notes Chapter 15 Waves

Summary
The wave is the propagation of disturbance that carries energy from one point to another point, without translatory motion of particles in the medium. There are three types of wave.
1. Mechanical Wave: Requires medium for propagation.
Eg: Sound wave, Matter wave, Seismic wave, etc.

2. Electromagnetic Wave: No medium for propagation.
Eg: Light, X-rays, UV ray, etc.

3. Matter Wave: Wave associated with moving particles (microscopic particle).
Eg: Wave of moving electron, proton, etc.

Generation of longitudinal waves by tuning for k
When prongs of tuning fork moves outward, it compresses the surrounding air and a region of increased pressure is formed. This region is called condensation. When the prongs move inward a region of low pressure called rarefraction is formed. Thus condensations and rarefractions are alternately produced.

Expression for progressive wave (Displacement relation)
A plane progressive wave propagating along positive direction of ‘x’ is given by

The wave propagating along negative ‘x’ direction is given by y (x, t) = a sin (kx + ωt + Φ).
y(x, t) gives the transverse displacement of element at position x at time t.

Crust and Trough:
Crust is the point of maximum positive displacement of wave. Trough is the point of maximum negative displacement of wave.

Transverse and Longitudinal Wave
Based on the direction of propogation and vibration wave can be of two types.

Parameters of wave
Amplitude:
The magnitude of maximum displacement of element of the wave from initial position is called amplitude (a).
Phase and initial phase:
The value (kx + ωt + Φ) is called phase and f is the initial phase. The phase gives the state of motion of wave at position ‘x’ and at time V. Initial phase gives initial state of wave.
Wave length (λ):
The linear distance travelled by the wave in one complete oscillation(or vibration). Or it can be defined as distance between two conT secutive crusts or troughs. It is the distance travelled during time period T.
Wave number/Angular wave number/propagation constant:
Wave number ‘k’ is defined as

Its unit is radian/m
Time period (T):
Time for one complete oscillation/vibration is called time period.
Frequency (ν):
The number of oscillations/vibrations in one second is called frequency. Its unit is S^-1 or Hz (Hetz).
ν = \(\frac{1}{T}\)
Angular velocity or angular frequency (ω):
Angular displacement per unit time is called angular velocity or angular frequency.

The speed of travelling wave [Relation connecting V, ν and λ]

The wave propagating along x direction is represented by y = A sin (kx – ωt + Φ). As wave moves, each point on the wave from (like A) retains its displacement. This is possible only if (kx – ωt) is constant. As the wave moves both x and t are changing to keep (kx – ωt) as constant (x increase with t).

The velocity depends on wavelength and frequency. The wavelength and frequency of wave depends on the properties of medium, i.e. velocity of wave in a medium is determined by

• linear mass density
• Elastic properties.

Speed of wave in stretched string (Transverse wave)
The velocity of wave in stretched string depends on

• linear mass density (µ)
• The tension (T)

Speed of sound wave (Longitudinal wave)
The speed of sound in medium depends on

• density of medium (ρ)
• Modulus of elasticity

Case: 1( In solid )
If solid has Young’s modulus ‘Y’

Case: 2( In liquid )
If liquid has Bulk modulus ‘B’

Case: 3 In gas
The speed of sound waves in gas was determined by Newton. According to Newton, condensations and rare fractions are isothermal processes. Hence modulus of elasticity is equal to pressure.

This is called Newton’s formula.
Correction in Newton’s formula.

Question 1.
Find velocity of sound in air using Newton’s formula (P = 1.013 × 10⁵ ρ =1.239 kg m^-3)
Answer:

Note: The velocity of sound at STP is found to be 332 ms^-1
Laplace’s Formula:
Laplace corrected Newton’s formula taking condensation and rare fraction as adiabatic process. The
modulus of elasticity is now ‘γP‘ where γ = \(\frac{C_{p}}{C_{v}}\). C_p is specific heat capacity at constant pressure and C_v is specific heat capacity at constant volume.

The principle of superposition of waves
It states that when two or more waves pass through a media the net displacement of particle at any time is the algebraic sum of displacements due to each wave.

(or)

The overlapping waves algebraically add to produce a resultant wave.

Reflection of waves
Reflection from rigid boundary:
When a travelling wave is reflected by a rigid boundary, phase reversal (phase difference of π or 180°) will take place.

Reflection from open boundary:
When a travelling wave is reflected by an open boundary, no phase change will happen. The incident and reflected wave superimpose to give maximum displacement at boundary.

Standing waves

When two waves of same amplitude and frequency travelling in opposite direction superimpose the resulting wave pattern does not move to either sides. This pattern is called standing wave.
The wave travelling in positive direction of x axis y₁(x, t) = a sin(kx – ωt)
The wave travelling in negative direction of x axis y₂(x, t) = a sin(kx + ωt)
According to superposition Principle, the combined wave is
y(x, t) = y₁(x, t) + y₂(x, t)
y(x, t) = a sin(kx – ωt) + a sin(kx + ωt)
But sin A + sin B = 2 sin \(\frac{(A+B)}{2} \cos \frac{(A-B)}{2}\)
Hence we get,combined wave as

This wave has an amplitude of ‘2asinkx’, and it is not a moving wave.
Nodes & Antinodes:
The position of maximum amplitude in a standing wave is termed as anti node and position of minimum amplitude (zero) is termed as node.
Node: The amplitude of standing wave is ‘2 a sin kx’. It is zero when kx = 0, π, 2π…. etc.
ie kx = nπ.

Antinode:
The amplitude has maximum value 2a when (2a sin kx = 2a)
sinkx = 1;
ie; kx = π/2, 3π/2, 5π/2 …… etc

But k = \(\frac{2 \pi}{\lambda}\)
Hence we get

n = 0, 1, 2, 3 etc.

1. Standing Waves In Stretched String & Modes Of Vibration Of String:
A string of length L is fixed at two ends. The position of one end is chosen as x = 0, then the position of other end will be x = L. At x = 0, there will be node. To occur node at x = L, it must satisfy

The frequency of vibrations of stretched string of length L is

n = 1,2, 3…etc.
This set of frequencies at which the string can vibrate are called natural frequencies or modes of vibration or harmonics. The above equation shows that the modes of vibration (natural frequencies) of string are integral multiple of lowest frequency
n = \(\frac{V}{2 L}\) (for n = 1)
Fundamental mode(or) First harmonics:
For n = 1
ν₁ = \(\frac{V}{2 L}\)
This is the lowest frequency with which string vibrates. This is called fundamental mode or first harmonic of vibration.
Relation between I and L for first harmonics:

The string vibrate in a single segment as shown in figure.

Second harmonic:

For n = 2

Relation between I and L for second harmonics

Third harmonic:

For n = 3, there is 3^rd harmonic. Thus collection of all possible mode is called harmonic series and n is called harmonic number.

2. Vibrational modes of an air column:
(a) In closed tube:
In closed tube one end is closed and other end is open. Air column in a glass tube partially filled with water is an example of closed system. The air column in tube can be set into vibrations with the help of air excited by tuning fork.

The longitudinal waves thus generated is reflected at the closed end and a node is formed there [reflected and incident wave are out of phase and at the closed end, they superimpose to give minimum displacement]. At the open end, the displacement is maximum and antinode is formed. If L is the length of air column, anti node occurs at x = L.
We know the condition for antinode x = (n + 1/2) λ/2
Therefore L = (n + 1/2) λ/2
for n = 0, 1, 2, …….etc.
The wavelength, λ = \(\frac{2 \mathrm{L}}{(\mathrm{n}+1 / 2)}\) _____(1)
for n = 0, 1, 2, …. etc.
The frequency ν = (n + 1/2) \(\frac{V}{2 L}\) ____(2)
for n = 0, 1, 2, …….etc.
From this equation, it is clear that the air column can vibrate with different modes of frequencies (normal modes or harmonics)
Fundamental Mode(or) First harmonic:
We get fundamental mode when n=0 Substitute this in eq(2), we get
ν₁ = \(\frac{V}{4 L}\)
This is the fundamental frequency. The higher frequencies are odd harmonics of fundamental frequency ie;

(b) Open tube:
In open tube, both ends are open. At both ends, antinodes are formed.
The condition to get antinode x = n λ/2

The frequency (fundamental frequency):
We will get fundamental frequency in open tube,when n = 1. Substitute this in eq(4)
ν₁ = \(\frac{V}{2 L}\)
In open pipe all harmonies are generated whereas in closed pipe only odd harmonies are generated.
For n = 2, ν₂ = 2\(\frac{V}{2 L}\). This is second harmonic.
For n = 3, ν₃ = 3\(\frac{V}{2 L}\). This is 3rd harmonic.
ν₂ = 2 ν₁ & ν₃ = 3 .ν₁. Thus both odd and even harmonics are generated.

Beats:
When two sound waves of nearly same frequency and amplitude travelling in same direction super imposed and periodic variation of sound intensity (wavering of sound or waxing and waning of sound) is produced. This is called beats.
Explanation:
If two tuning forks of slightly different frequencies are sounded together, a regular rise and fall of sound can be heard. The sound travels in the form of condensation and rarefactions.

When two condensations due to two notes reach our ear at the same time, they superimpose to get maximum intensity (waxing of sound). If two rarefactions are reached simultaneously, they superimpose to get minimum intensity (waning of sound).

Analytical treatment of beats
Beats frequency
Suppose two sound waves of u₁ and u₂ propagating in the same direction through a medium. For simplicity let the listener be situated at x = 0 and the amplitudes of waves to be equal ie. a₁ = a₂ = a.
The displacements y₁ and y₂ due to each wave are given by
y₁ = a sin2pu₁t and y₁ = a sin2pu₂t
According to super position principle, the resultant displacement at the same time t is
y = y₁ + y₂
= a sin2pu₁t + a sin2pu₂t
y = a [sin2pu₁t + sin2pu₂t]

It is clear that, the amplitude of resultant wave (A) changes with time. It shows maxim and minima.
The resultant amplitude will be maximum, if,

Hence the amplitude of the resultant wave will be maximum at times

Time interval between successive maxima = \(\frac{1}{v_{1}-v_{2}}\)
resultant amplitude will be minimum if

Time internval between two consecutive minima = \(\frac{1}{v_{1}-v_{2}}\)
Frequency of minima = ν₁ – ν₂
Graphical representation of beats

Doppler Effect
The apparent change in the frequency of sound wave due to the relative motion of source or listener or both is called Doppler effect. It was proposed by John Christian Doppler and it was experimentally tested by Buys Ballot.

Considers source is producing sound of frequency n. Let V be the velocity of sound in the medium and I the wavelength of sound when the source and the listener are at rest. The frequency of sound heard by the listener is
ν = \(\frac{v}{\lambda}\)
Let the source and listener be moving with velocities v_s and v_l in the direction of propogation of sound from source to listener. (The direction S to L is taken as positive)
The relative velocity of sound wave with respect to the source = V – V_s.
Apparent wavelength of sound,
λ¹ = \(\frac{V-V_{s}}{v}\) ____(1)
Since the listener is moving with velocity v f, the rela¬tive velocity of sound with respect to the listener,
V¹ = V – V_l _____(2)

Question 2.
A string fixed one end is suddenly brought in to up and down motion.

1. What is the nature of the wane produced in the string and name the wave?
2. A brass wire 1 m long has a mass 6 × 10^-3 kg. If it is kept at a tension 60N, What is the speed of the wave on the wire?

Answer:
1. Transverse wave

2.