AIIMS AIPMT Organisms and Populations Practice questions

1. List any two physiological responses that may help you to gradually get acclimatised to higher altitudes.
2. Define biogeochemical cycling.
3. In a pond there were 40 lotus plants. If 10 lotus plants died in a week, reducing the current population to 10, then calculate death rate of lotus population for the said period.
4. What are the two major causes of loss of biodiversity?
5. What do you mean by ‘standing crop’?
6. Name any two organisms which can occupy more than one trophic level in an ecosystem.
7. List any two adaptive features evolved in parasites enabling them to live successfully with their hosts.
8. Which are the three hot spots of India?
9. Differentiate between genetic diversity and species diversity.
10. How do herbs and shrubs survive under the shadow of big canopied trees in forests?
11. Certain species of wasps are seen frequently visiting the flowering fig trees. What type of interaction is seen between them and why?
12. (i) Study the given pie diagrams representing the proportionate number of species of major taxa of plants and invertebrates. Identify the taxa (a), (b) and (c).


(ii) What percentage of total number of species recorded is constituted by plants and animals?
13. Name the type of interaction in each of the following.
(a) Clown fish living among the tentacles of sea anemone.
(b) Nepenthes capturing an insect.
(c) Mycorrhizae living on the roots of higher plants.
(d) Lice living on skin of humans.
(e) Superior barnacle (Balanus) dominating the rocky sea coasts of Scotland and excluding the smaller barnacle Chathamalus.
14. Name the pioneer species on a bare rock. How do they help in establishing the next type of vegetation? Mention the type of climax community that ultimately gets established.
15. Differentiate between in situ and ex situ approaches of conserving biodiversity.
16. Write any three measures which will control vehicular air pollution in Indian cities.
17. Name any two sources of electronic wastes. Mention any one way for their disposal in developing and developed countries.
What is the broadly utilitarian argument for conserving biodiversity?
18. How does an electrostatic precipitator work to remove particulate matter from industrial exhaust?
19. Given figures show the different types of age pyramids for human population.

1(i) What does the parts ‘X’, Y and “11 represent?
(ii) What type of population is represented in pyramids A, B
(iii) Name the type of age pyramid in which the number of pre-reproductive and reproductive individuals are almost the same.
20. Giving two reasons explain why there is more species biodiversity in tropical latitudes than in temperate ones.
21. (i) Plot a logistic growth curve.
(ii) Briefly describe nature’s carrying capacity for a species in a particular habitat.
22. Who proposed ‘rivet popper hypothesis’? Explain.
(i) Mention the information that the health workers can derive by measuring BOD of a water body.
(ii) What is photochemical smog?
23. Construct a pyramid of energy when 10,000 joules of energy is available at the producer level.
24. ‘Sometimes introduction of an exotic species upsets native species of the ecosystem’. Substantiate this statement with an example.
25. A crane had DDT level as 5 ppm in its body. What would happen to the population of such birds? Explain giving reasons.
26. Define
(i) Allen’s rule
(ii) Diapause
27. State the difference between the first trophic levels of detritus food chain and grazing food chain.
(i) Draw and explain species area relationship curve.
(ii) Discuss catalytic converters.
29. Janette attended a seminar conducted in her school on ‘Biodiversity and Conservation.’ In the evening, she insists her father who is very much fond of hunting wild animals, not to go for hunting again, to which her father objects.
(a) In such a case, what wins your support — Janette ‘s concern for the safety/conservation of biodiversity or her father’s objection. Justify your answer giving reasons.
(b) Suggest any two steps to be taken to conserve biodiversity.
30. (i) Explain giving reasons the cause of appearance of peaks ‘a’ and ‘b’ in the graph shown below.

sewage-processing(ii) Study the table given below with regard to population interactions and answer the questions that follow:

1(a) Identify the interactions (P), (Q), (R), (S) and (T).
(b) Explain any one of them.
(i) What is meant by ozone shield? Name two gases that can cause damage to this shield. Give one harmful effect of this damage, each on plants and animals.
(ii) Explain the differences between primary succession and secondary succession.


1. (i) Increase in RBCs production to compensate low oxygen availability
(ii) Increase in breathing rate
2. The term biogeochemical cycling is used for exchange/circulation of biogenetic nutrients between living and non-living components of biosphere.
3. Lotus plants in the pond = 40 Plant died in a week = 10 Death rate of lotus population

14.(i) Habitat destruction
(ii) Alien species invasion
5.Standing crop is the amount of living biomass or number of living organisms present in unit area of an ecosystem.(
6. Man and sparrow
7(i) Presence of suckers for attachment to the host
(ii) Very well developed reproductive organs and enormous reproductive capacity
8.Western Ghats and Sri Lanka, Indo-Burma (North-East India) and Himalayas.
9.Genetic diversity is the diversity in the number and types of genes as well as chromosomes present in different species and the variations in the genes and their alleles in the same species.
10.Species diversity is the variety in the number and richness of the species of a region.
11.Herbs and shrubs survive under the shadow of big canopied trees in forests as they are perfect shade tolerant plants showing better growth in lower level of light intensity and are arranged in different strata according to their shade tolerance.
12.Mutualism is found between fig tree and wasp species as both are beneficial for each other. Fig flower is pollinated by wasp, in return wasp gets suitable egg-laying site and developing seeds as food for the larvae.
12. (i) (a) = Fungi
(b) = Angiosperms
(c) = Insects
(ii)Animals constitute more than 70% of the total number of species recorded whereas plants constitute approximately 22% of the total number of species.
13. (a) Commensalism
(b) Predation
(c) Mutualism
(d) Parasitism
(e) Competition.
14. Lichens are the pioneer species on a bare rock. They are resistant to desiccation and temperature extremes. They produce organic acids which corrode the rock surface. This produces depressions and releases minerals which facilitate their further growth. The dead lichens add organic matter to the forming soil and thus provide a suitable surface for the establishment of next type of vegetation. The climax community will be trees.
15 .In situ conservation is the conservation of genetic resources through their maintenance within their natural habitats. This approach includes biosphere reserves, national parks, wildlife sanctuaries, sacred groves, etc. Ex situ conservation is the conservation of genetic resources outside their habitats. It includes botanical gardens, zoological gardens, seed banks, pollen banks, etc.
16. (i) Use of CNG as fuel in the vehicles because it burns more efficiently and is also cheaper
(ii) Use of unleaded petrol
(iii) Use of catalytic converter in the vehicles as it reduces emission of poisonous gases
17. Irreparable computers and other electronic goods are the sources of electronic wastes (e-wastes). Developed countries have specifically built facilities for recycling electronic wastes. In developing countries, recycling of electronic wastes involves manual participation of workers, which exposes them to toxic substances present in e-wastes.
The broadly utilitarian argument says that biodiversity plays a major role in many ecosystem services that nature provides. Some of these services are:
(i) Production of oxygen through photosynthesis
(ii) Pollination of flowers by providing natural pollinators
(iii) Aesthetic pleasures etc.
18. Electrostatic precipitator has electrode wires that are maintained at several thousand volts, which produce a corona that releases electrons. These electrons attach to dust particles giving them a net negative charge. The collecting plates are grounded and attract the charged dust particles.
19. (i) X – Post-reproductive stage
Y – Reproductive stage Z – Pre-reproductive stage
(ii) A – Expanding population B – Stable population
C – Declining population
(iii) Bell shaped age pyramid (Pyramid ‘B’ in the given figure)
20. (i) Temperate region was subjected to frequent glaciations in the past, while tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification.
(ii) Tropical environments, unlike temperate ones, are less seasonal, relatively more constant and predictable. Such constant environments promote niche specialisation and lead to a greater species diversity.
21. (i)

1(ii) In nature, a given habitat has resources to support a certain number of individuals of a population, beyond which no further growth is possible. This limit is called nature’s carrying capacity (K) for that species in that habitat. Nature’s limited resources limit the carrying capacity for a species in a particular habitat.
22. Rivet popper hypothesis was proposed by Paul Ehrlich which explains the effect of reduction in biodiversity. The theory compares aeroplane to an ecosystem and rivets to the number of species. If passengers start popping rivets and taking them home, it may not affect flight safety in the beginning but soon the aeroplane will become dangerous to fly. Similarly, the loss of species leads to ecosystem imbalance affecting the latter adversely.
(i) BOD (Biochemical Oxygen Demand) refers to the amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria during a particular time period. BOD test measures the rate of uptake of oxygen by micro-organisms in a sample of water, and thus indirectly BOD is a measure of the organic matter present in the water.
(ii) Photochemical smog is composed of secondary air pollutants. It is formed by interaction of hydrocarbons with nitrogen oxides. The products are ozone, peroxyacyl nitrate (PAN), aldehydes and phenols.



24. Exotic species often become invasive and drive away the local species. Eichhornia (Water hyacinth) was introduced in Indian waters due to its aesthetic value. However, it has clogged water bodies resulting in death of several aquatic plants and animals.
25. The population of birds with high DDT level will decrease. High concentration of DDT disturbs calcium metabolism in birds which causes thinning of egg shell and their premature breaking. Thus, it will eventually lead to decline in bird population.
26. (i) Mammals from colder climates generally have shorter ears and limbs to minimise heat loss. This is called as the Allen’s rule.
(ii) Diapause is a stage of suspended development, which is exhibited by many zooplankton species in lakes and ponds, under unfavourable conditions.
27. In a grazing food chain, producers constitute the first trophic level. Producers are autotrophic living green plants which can manufacture their own food through photosynthesis utilizing inorganic raw materials and sunlight. In a detritus food chain, decomposers constitute the first trophic level. Decomposers are the saprophytes, chiefly bacteria and fungi that break down the complex compounds of dead organisms into simple substances.
28. (i) Pyramid of biomass shows the total amount of living matter (fresh weight or dry weight) present in each trophic level. In a terrestrial ecosystem, there is a gradual decrease in biomass of organisms at successive trophic levels from the producers to the top carnivores. Thus the pyramid of biomass is upright. But in an aquatic ecosystem, it is inverted because the biomass gradually increases from the producers to carnivores.


Primary productivity Secondary productivity
1 It is rate of synthesis of organic matter by producers. It is rate of synthesis of organic matter by consumers.
2 It is comparatively quite high. It is small and decreases with rise of trophic level
3 It is due to synthesis of fresh organic matter from inorganic raw material. It is due to synthesis of organic matter from preexisting organic matter.

29. (a) I will support Janette ‘s concern for the conservation of biodiversity. It has taken millions of years of evolution to accumulate the rich diversity of plants and animals in nature, but we could lose all that wealth if the present rates of species losses continue. Biodiversity provides countless direct economic benefits to human beings (such as food, drugs, various industrial products, etc.). Also, biodiversity plays a major role in many ecosystem services prevailing in nature.
(b) (i) The wild life should be protected in natural habitats as well as in artificial habitats under human control, such as zoological parks and botanical gardens.
(ii) The threatened species should be given preference over others in the conservation programme. Among these, the
endangered species should get priority over the vulnerable species, and the latter over the rare species. The species which are the sole representative of their genus or family should be paid special attention.
30. (i) Due to the discharge of sewage into the river, the micro-organisms present in the river get involved in biodegradation of organic matter due to which a lot of oxygen is consumed. The peak ‘a’ shows a sharp decline in dissolved oxygen downstream from the point of sewage discharge. Gradually as sewage is decomposed, there is a rise in dissolved oxygen downstream. The peak ‘b’ shows a gradual increase in the dissolved oxygen.
(ii) (a) (P) = Amensalism
(Q) = Parasitism, Predation
(R) = Competition
(S) = Mutualism
(T) = Commensalism
(b) Parasitism is is a type of population interaction in which one organism is benef itted and the other one is harmed.The parasite lives on or in the body of another organism (host), from which it obtains its nutrients. e.g., lice living on human skin.
(i) Ozone shield is the region of stratosphere, where ozone is present in high concentration. It is called ozone shield because it protects the living beings from harmful effects of ultraviolet radiations.
The two gases that can cause damage to ozone shield are chlorofluorocarbons (CFCs) and methane (CH4).
Damage to ozone shield results in impairment of photosynthetic machinery in plants and skin cancer in humans.
(ii) Differences between primary succession and secondary succession are as follows:

Primary succession Secondary succession
1 It occurs in an area which has been bare from the beginning. It occurs in an area which has been denuded recently.
2 Soil is absent at the time of beginning of primary succession. Soil is present in the area where secondary succession begins.
3 Reproductive structures of any previous community are absent. Reproductive structures of the previous occupants are present in the area.
4 Pioneer community comes from outside. Pioneer community develops partly from previous occupants and partly from migrants.

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