NEET Practice Questions (MCQs) with Answers & Solutions

Correction :-
IV. Thermoregulation is energetically expensive for many organisms. This is particularly true for small animals like shrews and humming birds. Heat loss or heat gain is a function of surface area. Since small animals have a larger surface area relative to their volume, they tend to lose body heat very fast when it is cold outside; then they have to expend much energy to generate body heat through metabolism.
V. 99% of animals are conformers.
VI. Archaebacteria can tolerate high temperatures and salinity.

Heat loss or heat gain is a function of surface area. Since small animals have a larger surface area relative to their volume, they tend to lose body heat very fast when it is cold outside; then they have to expend much energy to generate body heat through metabolism. This is the main reason why very small animals are rarely found in polar regions.

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In the absence of an external source of water, the kangaroo rat in North American deserts is capable of meeting all its water requirements through its internal fat oxidation. It also has the ability to concentrate its urine so that minimal volume of water is used to remove excretory products

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Some organisms show behavioural responses to cope with variations in their environment. These include migrating to a less stressful habitat.

(page- 225)

Not all but some adaptations are genetically fixed in organisms.

For example- In the absence of an external source of water, the kangaroo rat in North American deserts is capable of meeting all its water requirements through its internal fat oxidation.

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If the age distribution (per cent individuals of a given age or age group) is plotted for the population, the resulting structure is called an age pyramid.

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Timing of birth, timing of death and the rate of population growth determines the age distribution of a population.

The density of a population in a given habitat during a given period, fluctuates due to changes in four basic processes:-

1. Natality and immigration contribute an increase in population density
2. Mortality and emigration to a decrease in population density

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Exponential growth occurs when there are unlimited food resources and  each species has the ability to realise fully its innate potential to grow in number. When there is no inhibition from crowding, exponential growth occurs.

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In nature, a given habitat has enough resources to support a maximum possible number, beyond which no further growth is possible. This limit is called as nature’s carrying capacity (K) for that species in that habitat.

Logistic growth:  No population of any species in nature has its disposal unlimited resources to permit exponential growth. This leads to competition between individuals for limited resources. Eventually, the ‘fittest’ individual will survive and reproduce.

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