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Transforming Principle 

• In 1928, Frederick Griffith, in a series of experiments with Streptococcus pneumoniae (bacterium responsible for pneumonia), witnessed a miraculous transformation, in the bacteria. During the course of his . experiment, a living organism (bacteria) had changed in physical form.

• When Streptococcus pneumoniae (pneumococcus) bacteria are grown on a culture plate, some produce smooth shiny colonies

(S) while others produce rough colonies (R).

• This is because the S strain bacteria have a mucous (polysaccharide) coat, while R strain does not. Mice infected with the S strain (virulent) die from pneumonia infection but mice infected with the R strain do not develop pneumonia.

S strain -»Inject into mice -» Mice die R strain —»Inject into mice —> Mice live

• Griffith was able to kill bacteria by heating them. He observed that heat- killed S strain bacteria injected into mice did not kill them.

S strain (heat killed) —> Inject into mice —> Mice live

• When he injected a mixture of heat-killed S and live R bacteria, the mice died. Moreover, he recovered living S bacteria from the dead mice.

S strain (heat killed ) + —> Inject into mice —> Mice die R strain (live)

• He concluded that the R strain bacteria had somehow been transformed by the heat-killed S strain bacteria. Some ‘transforming principle’, transferred from the heat-killed S strain, had enabled the R strain to synthesise a smooth polysaccharide coat and become virulent. This must be due to the transfer of the genetic material. However, the biochemical nature of genetic material was not defined from his experiments.

1. India is a large country with varied physiography.

2. In the north there are huge Himalayan mountain ranges, many of which are snow-clad.

3. The southern part of India is a peninsula.

4. India has a very long coastline. This coastal belt is used for fishing, tourism, waterway, etc.

5. There are dense forests in several parts of India.

6. Northern fertile plains are called ‘Storehouse of Grains’ whereas southern plateau is rich in mineral resources.

7. Rajasthan and parts of Gujarat form the desert of India.

8. Owing to a variety of relief features found in India, it can be said that the physiography of India is quite diversified.

Correct answer is (d) live S-strain bacteria

(a) Transforming Principle 

▪ Frederick Griffith (1928) conducted experiments with Streptococcus pneumoniae (bacterium causing pneumonia). 

▪ He observed two strains of this bacterium—one forming smooth shiny colonies (S-type) with capsule, while other forming rough colonies (R-type) without capsule. 

▪ When live S-type cells were injected into mice, they died due to pneumonia. 

▪ When live R-type cells were injected into mice, they survived. 

▪ When heat-killed S-type cells were injected into mice, they survived and there were no symptoms of pnuemonia. 

▪ When heat-killed S-type cells were mixed with live R-type cells and injected into mice, they died due to unexpected symptoms of pneumonia and live S-type cells were obtained from mice. 

▪ He concluded that heat-killed S-type bacteria caused a transformation of the R type bacteria into S-type bacteria but he was not able to understand the cause of this bacterial transformation. 

(b) Biochemical Characterisation of Transforming Principle 

▪ Oswald Avery, Colin MacLeod and Maclyn McCarty repeated Griffith’s experiment in an in vitro system in order to determine biochemical nature of transforming principle. 

▪ They reported that DNA from the heat-killed S-type bacteria caused the transformation of nonvirulent R-type bacteria into virulent S-type bacteria. 

▪ They also discovered that proteases and RNases did not affect transformation while DNases inhibited the process. 

▪ They concluded that DNA is the hereditary material.

(a) 1. S strain -> inject into mice -> mice die

2. R strain inject into mice -> mice live 

(b) When Griffith was injected heat-killed S strain into mice, bacteria did not kill them.

But he injected a mixture of heat-killed S and live R bacteria, the mice died .

(c) \(\frac{-ΔQ}{ΔP}\times \frac{P}{Q}\)

The theme of the poem is a comparison between the world of Human beings that abounds in material pleasures and the world of Nature that is contrary to it. The Mother represents the material world. She recounts some of the features of this human’s material world like jewellery, marriage bridal songs, cradle songs sandal-scented leisure. It implies marriage, births of children and honeymoon. The Daughter represents the world of Nature. The blossoming of champa, the islands in the river resounding with cuckoo’s cooing, gurgling of streams attract her. She knows that laughter and all the songs will end in sorrows.

(b) quantity demanded to a change in price

(d) Demand is inelastic and price rises

The two main factors affecting E_d are the following:

(i) Availability of Substitutions : The closer the substitute, the elasticity of demand for one commodity is higher. For example, coffee and tea can be considered alternatives to each other. If price of one of these goods increases, then the other commodity becomes relatively cheaper. Therefore, consumers buy more of the relatively cheaper goods and less-of the costlier one. The demand elasticity for both items will be high. Besides, the wider the range of the substitutes, the greater the elasticity.

(ii) Time Factor : Price-elasticity of demand also depends on the time that consumers take to adjust to a new price, when the long-term elasticity is high. For this, consumers are able to adjust their expenditure patterns for price changes over a period of time. For instance, if price of TV sets is decreased, demand will not immediately increase unless people possess excess purchasing power. But over time, people may be able to adjust their expenditure pattern so that they can buy a TV set at the (new) lower price.

An increase in income may lead to an increase in the quantities demanded. For most goods, the income elasticity of demand is expressed as Y < 0.

Correct answer is (b) 0.25

This refers to that situation where a given increase in the consumers money-income is followed by an actual fall in the quantity demanded of the commodity. This happens in the case of economically inferior goods.

This refers to the situation where a given increase in consumer’s money-income does not result in any increase of the quantity demanded of the commodity. Zero income elasticity of demand is expressed as Y = 0.

The factors affecting elasticity of demand are the following :

(i) Availability of Substitutes : The most significant determinant of price elasticity of demand for a commodity is the availability of its alternatives. The elasticity of demand for a commodity increases as much as it is close to the alternative. For example, coffee and tea can be considered as a close alternative to each, other, if the price of one of these goods rises, then the second commodity becomes relatively cheaper. Therefore, consumers buy cheaper and less expensive goods.

(ii) Nature of Commodity : The price elasticity of demand depends on the nature of a commodity. Commodities can be broadly divided on the basis of their nature as luxury, comforts and requirements. Luxury goods’ demand is more elastic than the demand for other types of goods because consumption of luxury goods can be postponed when their price rises. On the other hand, consumption of essential goods cannot be postponed and hence their demand is inelastic. Demand for durable goods is more elastic than that for non-durable goods, because when the price of the former increases, people either get the old one repaired instead of replacing it or buy a ‘second hand’ product.

(iii) Proportion of Income spent: Another factor affecting the elasticity of demand is the proportion of income which consumers spend on a particular commodity. If proportion of income spent on a commodity is very small, then its demand will be inelastic, and vice-versa. The classic examples of such commodities are salt, matches, books, toothpastes, etc., which claim a very small proportion of consumers’ income. Demand for these goods is generally inelastic because increase in the price of such goods does not substantially affect the consumer’s budget, and hence its demand.

(iv) Time Factor : The price elasticity of demand also depends on how much time consumers take to adjust to a new price. The more time it takes, the more elastic the demand will be. is. For, consumers are able to adjust their expenditure pattern to price changes over a period of time. For example, if price of TV sets is decreased, demand will not immediately increase unless people possess excess purchasing power. But over time, people may be able to adjust their expenditure pattern so that they can buy a TV set at the new lower price.

(v) Range of Alternative Uses of a Commodity : The wider the range of alternative uses of a product, the higher the elasticity of its demand. Decreases in the price of a multi-use commodity encourages the extension of their use. Therefore, the demand : for such a commodity generally increases more than the proportionate decrease in its price. For instance, milk can be taken as it is, it can be converted into curd, cheese, ghee and butter milk. The demand for milk, will therefore be highly elastic. Similarly, electricity can be used for lighting, cooking, heating and for industrial purposes, therefore, demand for electricity is elastic, especially, for decrease in price.

(vi) The Proportion of Market Supplied : The elasticity of market demand depends also on the proportion of the market supplied at the ruling price. If less than half of the market is supplied, elasticity of demand will be higher and if more than half of the market is supplied, elasticity will be lower. That is, towards the upper end, demand curve is more elastic than towards the lower end.

(vii) Direction of Change in Price : The direction of change in price also determines the elasticity. Between any two finite points on the demand curve, elasticity is higher for the fall in price and vice-versa.

Correct answer is (a) elastic

(a) equal to unitary E_d

(c) positive and greater than 1

The arc elasticity coefficient should be used with caution because the measure of arc elasticity between any two points on a demand curve produces two different elasticity coefficients for the same fall and rise in price. The arc elasticity coefficient varies between the same two finite points on a demand curve when the direction of change in price is reversed. Therefore, it is the cause of misinterpretation.

(a) Highly E_d

Pacemaker is the region that has power of generation of wave of contraction. In heart, sinoatrial node is called pacemaker.

1. Papillary muscles are large and welldeveloped muscular ridges present along the inner surface of the ventricles. 

2. Bicuspid and tricuspid valves are attached to papillary muscles of ventricles by chordae tendinae. 

3. Chordae tendinae are inelastic fibres present in the lumen of ventricles. 

4. The chordae tendinae prevent the valves from turning back into the atria during the contraction of ventricles and regulate the opening and closing of bicuspid and tricuspid valves.

It is the measure of responsiveness of demand for a commodity to the change in any of its determinants, viz. price of the commodity, price of the substitutes and complements, consumers’ income and consumer expectation regarding prices.

(b) a different point elasticity

Pacemaker can generate wave of contraction or cardiac impulse for rhythmic contraction of heart.

At the middle of demand curve, elasticity will be equal to one, or it is called Unitary Elasticity of Demand.

The two main points which show the importance of elasticity of demand are:

(i) For Finance Minister : The finance minister imposes taxes on those whose demand is price-insecure so that tax revenues increase. Similarly, on indirect taxes, the finance minister imposes a tax on the items which have a continuous demand among the rich section and thus the burden of taxes is levied on the rich class.

(ii) For Taking Over Public Utility Services : State takeing over of public utility services can also be explained with the help of elasticity of demand. Demand for public utilities such as electricity and water supply, posts and telegraphs, public transportation, etc., is generally inelastic in nature. If operation of such public utilities is entrusted to private individuals, they are likely to exploit the consumer. Therefore, in the interest of social welfare, the government owns and runs such services.

(b) many uses

If demand curve is paralled to X axis, then elasticity of demand is equal to infinity and this type of demand is called Perfectly Elastic Demand.

‘T’ wave represents ventricular diastole.

(a) increase in the number of sex chromosomes

Inelastic demand.

(a) perfectly inelastic

The importance of the study of elasticity of demand is given below:
(i) For the Businessman : A knowledge of the nature of the elasticity of demand for his products will help a businessman to decide whether he can cut prices in a particular case or not. In general, for items where the demand is elastic, it will pay him to charge relatively low prices, while those whose demand is inelastic are better with higher prices.

(ii) For Monopolist : The price elasticity concept is very important, particularly to a monopolist who decides his own prices for goods. If the demand for their goods is inelastic, it would be beneficial to charge it at a higher price and sell a slightly smaller volume. If demand is elastic, it will be beneficial to charge a lower price and increase the sales volume.

(iii) For Finance Minister : Whenever the finance minister considers raising the rates of tax on existing tax items in view of the introduction of fresh levy on some items or for getting more revenue for the state, he conducts a thorough study of the elasticity of demand for commodity. The finance minister often taxes those items less whose demand is price-elastic. This leads to an increase in the taxation revenue from indirect taxes. In contrast, the finance minister taxes those items highly which are constantly demanded by the rich class and the burden of taxation is laid more on the rich class.

(iv) For Determination of Prices of Joint Products : The concept of elasticity of demand is used in the value of combined products, such as cotton and cotton seeds, wool and mutton, wheat and straw etc. It is not possible to find individual marginal costs of combined products here. During price fixing, producers are mostly directed by elasticity of demand. But its total receipts must cover the total cost. Transport authorities have decided to fix their rates according to the principle that ‘what will be the traffic’.

(v) For Explaining the Paradox of Poverty in the Midst of Plenty: The concept of elasticity of demand suitably explains the parodox of poverty in the midst of plenty. For example, if there is a bumper crop of wheat, then it can give farmers a signal of calamity rather than prosperity, if the demand for wheat is incompatible. Due to the increase in supply, the decline in the price of wheat will reduce the income of the farmers.

(vi) For Determining Reward of Factors of Production : The elasticity of demand is equally important in determining the awards of various factors of production in the country. For example, if demand for workers is elastic, trade unions’ efforts to meet the wages of workers will be met with failure. On the contrary, if demand for labour in a particular area is real, then trade unions can get more wages from the employer. This is also true about other factors of production. The factors of production that have more elastic demand, they accept small prizes; and the factors having an inelastic demand can be provided a big reward.

(vii) For Taking Over Public Utility Services : The state’s decision can also be explained with the help of the elasticity of demand for acquisition of public utility services. Demand for public utilities such as electricity and water supply, posts and telegraphs, public transport, etc. is generally inelastic in nature. If such public utility is assigned to private iiidividuals, then they are likely to exploit the consumer. Therefore, in the interest of social welfare, the government is the owner of such services and runs these services. For example, in Bombay City, the bus service was operating privately in the suburban areas. It was later acquired by the Greater Bombay Municipal Corporation.

(viii) For Pricing Policy for Public Utilities : Price elasticity is also influential in determining the price policy of public utility undertakings, like electric supply undertakings, railways, etc. Such undertakings determine their rates for different uses on the basis of the elasticity of demand and try to cover the losses from one group of users out of the gains reaped from the other group.

(ix) Terms of Trade Between Two Countries : In international trade, the price elasticity of demand is helpful in ascertaining the ‘terms of trade’. If exports have inelastic demand, a higher price can be charged from abroad. Similarly, if imported goods have elastic demand in the domestic market, a lower price is to be fixed. Both these enable a country to have favourable ‘terms of trade’ in respect of international trade.

(x) Determination of Rates of Foreign Exchange : In order to determine the foreign exchange rates for domestic currency, the government must keep in mind the elasticity of demand for its exports and imports. This will help the government to know the potential effects of devaluation or re-evaluation of its currency with respect to foreign currencies. If the government devalues the currency without carefully studying the elasticity of demand and demand for the country’s exports, then it cannot be successful in achieving its goal.

(xi) For Price Control Policy : In undeveloped countries like India, the price control policy can be adopted only after assessing the value of strategic goods demand. In terms of low-level items with elasticity or redundant demand, price control is usually used.

(xii) For Tariff Policy : Imposition of tariff raises the prices of domestic goods. The extent to which the internal price rises, depends on the elasticity of demand of the protected goods. If the demand for the protected goods is elastic, their sales will be reduced with the rise in prices. On the contrary, if the demand is less elastic, people will have to bear the burden of higher prices as a result of the tariff policy.

(xiii) Incidence of Taxation : Incidence of tax lies on the person who ultimately pays the tax. The incidence is on the buyer. If demand is perfectly inelastic, he will go on buying, as much as before, despite the price rise. The government has to keep in mind the ultimate burden of the tax, which depends on the elasticity of demand of the commodity taxed. If necessities, which have less elastic demand, are taxed, the burden will fall more on the poor section of society.

Elasticity of demand (at P)= PN (Lower Part from P)/PM(Upper part from p).

Sutton and Bovery

(d) fruit flies

Correct answer is (d) 1.50

Functions of blood:

1. Transport of oxygen and carbon dioxide 

2. Transport of food 

3. Transport of waste product 

4. Transport of hormones 

5. Maintenance of pH 

6. Water balance 

7. Transport of heat 

8. Defence against infection 

9. Temperature regulation 

10. Blood clotting/coagulation 

11. Helps in healing

ECG helps to diagnose the abnormality in conducting pathway, enlargement of heart chambers, damage to cardiac muscles, reduced blood supply to cardiac muscles and causes of chest pain.

1. Sutton and Bovery

2. Thomas Hunt Morgan

3. Drosophila was very suitable for his studies because

• They could be grown on simple synthetic medium. 
• Complete life cycle in 2 weeks.
• A single mating could produce a large progeny.
• Male and female are easily distinguishable
• Many hereditary variations can be seen with low power microscope

Correct answer is (c) 1.25

Circulatory system consists of Heart, Blood vessels and Blood

Correct answer is (b) Cockroach

Semilunar valves prevent the backward flow of blood from pulmonary aorta and the aorta into the respective ventricles.

Valves in the heart prevent the backflow of the blood at the time of systole and help in maintaining a unidirectional flow of blood.

Semilunar valves located at the base of pulmonary artery and systemic aorta prevent the backward flow of blood at the time of ventricular systole.