# NEET Organisms and Populations MCQs May ’17

1. The growth rate of a population can often be described with the logistic growth equation:
dN/dt = rN(K-N)/K
In this equation, N is the number of individuals, r is the intrinsic rate of natural increase and K is the carrying capacity. According to this equation, the equilibrium number of individuals in the population is determined by
(a) r only (b) K only
(c) r and K (d) N and K

2. If we wish to produce a huge deer population, we should manage the population so that
(a) the number of deer is far below the carrying capacity to support high birth and growth rates.
(b) the number of deer is at the carrying capacity to provide the largest sustainable deer population.
(c) the deer are rare and have little contact with each other.
(d) the number of deer greatly exceeds the carrying capacity to provide a large number of excess individuals.

3. The relationship between ants and Acacia plants in the tropics is a co-evolved mutualism because
(a) the ants are well-suited to live in the swollen red thorns of the Acacia.
(b) the ants are immune to the chemical secondary defenses of the Acacia.
(c) the plants rapidly lose their leaves when ants are removed.
(d) both the plants and the ants benefit from the interaction

4. Which of the following is true regarding mimicry?
(a) A mimic has greater fitness when the model is present than when the model is absent.
(b) The predator responds similarly to both the model and the mimic.
(c) Both species benefit from having the particular traits in common.

5. One of the predictions of the Lotka-Voltera equation is that populations of two species can co-exist. This occurs when
(a) inter-specific competition is greater than intraspecific competition.
(b) intra-specific competition is greater than interspecific competition.
(c) species 1 is competitively superior to species 2.
(d) species 2 is competitively superior to species 1

6. The growth curve of a population is shown in the graph

The environmental resistance will be maximum at
(a) m (b) n (c) o (d) p

7. Deep black soil is productive due to high proportion of
(a) sand and zinc (b) gravel and calcium
(c) clay and humus (d) silt and earthworm

8. What is a keystone species?
(a) A species which makes up only a small proportion of the total biomass of a community, yet has a huge impact on the community’s organization and survival.
(b) A common species that has plenty of biomass, yet has a fairly low impact on the community’s organization.
(c) A rare species that has minimal impact on the biomass and on other species in the community.
(d) A dominant species that constitutes a large proportion of the biomass and which affects many other species

9. A community comprises of three species (K, L and M). The pyramids below show the distribution of pre-reproductive, reproductive and post-reproductive individuals. Which of the following statements are correct regarding given age pyramids?
10. Two opposite forces operate in the growth and development of every population. One of them is related to the ability to reproduce at a given rate. The force opposite to it is called
(a) fecundity (b) environmental resistance
(c) biotic control (d) mortality

11. Which of the following does not have stomata?
(a) Mesophytes (b) Xerophytes
(c) Sub-merged hydrophytes
(d) Floating hydrophytes

12. Littoral zone in the ocean ecosystem comprises of the
(a) dark abyssal zone
(b) benthic and pelagic zone
(c) coast to shallow water
(d) continental shelf to the ocean basin

13. Spongy tissue and less developed root system is present in
(a) xerophytes (b) halophytes
(c) hydrophytes (d) mesophytes

14. Phytoplanktons are dominant in which of the following zones?
(a) Limnetic zone (b) Profound zone (c) Littoral zone (d) Benthic zone

15. Which one of the following is a xerophytic plant in which the stem is modified into the flat green and succulent structure?
(a) Opuntia (b) Casuarina
(c) Hydrilla (d) Acacia

16. Plants that grow in sandy soil are known as
(a) heliophytes (b) psammophytes
(c) sciophytes (d) mesophytes

17. Which of the following shows Verhulst Pearl logistic growth?

18. Barnacles growing on the back of whale is an example of
(a) mutualism (b) commensalism
(c) parasitism (d) amensalism

19. The figure given below is a diagrammatic representation of response of organisms to abiotic factors. What do (i), (ii) and (iii) represent respectively?

20. Bell-shaped polygonal pyramid indicates
(a) high percentage of young individuals
(b) moderate percentage of young individuals
(c) low percentage of young individuals
(d) low percentage of old individuals

21. The feature of the xerophytic plant leaves are
(i) Leathery surface
(ii) Large surface area
(iii) Waxy cuticle
(iv) Sunken stomata on upper epidermis
(a) i, ii and iv (b) ii and iii
(c) i, iii and iv (d) i and iv

22. Select the incorrect statement from the following.
(a) An overwhelming majority of animals and nearly all plants maintain a constant internal temperature.
(b) An orchid growing as an epiphyte on a mango branch is an example of commensalism.
(c) In brood parasitism, the parasitic bird lays its eggs in the nest of its host and lets the host to incubate them.
(d) In amensalism, one species is harmed whereas the other is unaffected

23. Match list I with list II and choose the correct option

24. The vertical distribution of different species occupying different levels is called as

(a) stratification (b) fragmentation
(c) mobilization (d) mineralization

25. Thestageofsuspendeddevelopmentshownbyzooplanktons is called
(a) desiccation (b) diapause
(c) hibernation (d) aestivation

26. Which of the following statements is incorrect regarding predators?
(a) Predators keep prey populations under control.
(b) Predators help in maintaining species diversity in a community.
(c) If a predator is not efficient, then the prey population would rapidly become extinct.
(d) Herbivores (predators) have a greater advantage since the plants cannot run away to avoid predation.

27. Which is correctly labelled with respect to the given diagram?

(a) B : Logistic curve (b) C : Carrying capacity
(c) C: Exponential curve (d) A: Carrying capacity

28. Shade loving plants are called
(a) xerophytes (b) sciophytes
(c) halophytes (d) hydrophytes

29. The term niche of a species refers to
(a) specific place where an organism lives
(b) competitive power of an organism
(c) specific function of an organism
(d) specific and habitual function.
30. Soil formation is a slow and continuous process. Following graph indicates soil composition over time. In this graph P, Q and R must be

31. Territoriality occurs as a result of
(a) co-operation (b) parasitism
(c) competition (d) predation

32. The inherent maximum capacity of an organism to reproduce or increase in number is termed as
(a) carrying capacity
(b) biotic potential
(c) reproductive health
(d) intrinsic rate of increase

33. Which of the following is a correct statement?
(a) Commensalism – when none of the interacting populations affect each other.
(b) Symbiosis – when the interaction is useful to both the populations.
(c) Symbiosis – when neither populations affects each other.
(d) Commensalism – when the interaction is useful to both the populations

34. The population of an insect species shows an explosive increase in number during rainy season followed by its disappearance at the end of the season. What does this show?
(a) The food plants mature and die at the end of the rainy season.
(b) Its population growth curve is of J-type.
(c) The population of its predators increases enormously.
(d) S-shaped or sigmoid growth of this insect.

35. Some bird species follow army ants which walk on the forest floor. As the army ant colony travels on the forest floor, they stir up various flying insect species. As the insects flee the birds following the ants catch the fleeing insects. The type of interaction between the army ants and birds; and between birds and insects respectively is
(a) commensalism and amensalism
(b) commensalism and predation
(c) mutualism and predation
(d) predation and commensalism

36. A two month study on a population of 500 rats showed that the emigration of individuals from the population was 1.5 times the rate of immigration. At the same time the birth rate was found to be two times the rate of death. If the number of emigrants during the period of study was 75 and the birth rate was 10 %, what would be the number of rat individuals in the population at the end of the study?
(a) 500 (b) 475
(c) 450 (d) 525

37. Competitive exclusion among species is regulated by various ecological factors. Which of the following is incorrect regarding it?
(a) It is intense among species with similar ecological niches.
(b) It is occasionally interrupted by environmental disturbances.
(c) It is promoted by species succession.
(d) It is alleviated by habitat segregation among species

38. Temperature has a direct effect on which of the following?
i. Body size
ii. Size of the extremities of the body
iii. Mutation
iv. Life span
v. Metabolism in poikilotherm
(a) i,iii and iv (b) ii, iii and iv
(c) ii.iii and v (d) i,ii and v
39. Of the following sequences, which one shows trend from mutually beneficial to mutually deleterious interactions?
(a) Protocooperation -> Obligatory symbiosis -» Competition Parasitism
(b) Commensalism —> Amensalism —> Facultative symbiosis —»Predation
(c) Obligatory symbiosis -» Commensalism -4 Amensalism -»Competition
(d) Facultative symbiosis -> Amensalism -> Parasitism -»Predation

40. Leaves of eucalyptus hang vertically on weak branches that themselves hang down. The advantages of it are:
i. Availability of light is assured to all leaves
ii. Leaf lamina is not presented directly to mid-day sun
iii. Heating as well as water loss is kept under control
iv. Trunk and major branches get shielded from intense light
(a) Only ii and iii (b) i, iii and iv
(c) i, ii and iii (d) Only i and iii

41. Two insect species were used in a laboratory experiment. For one treatment, both species were grown by themselves (in separate chambers) on a suitable food source. For the second treatment, the two species were grown together (in the same chamber) on the same type and amount of food as in the first treatment. The given figure shows the results (the number of individuals of each species in the two treatments) at the end of the experiment. Based on these results the two species should be classified as

(a) competitors
(b) mutualists
(c) predators or pathogens
(d) commensalists.
42. A wasp population (.) lays eggs on the larvae of another insect weevil (—). After hatching, the wasp eats the weevil. Which of the following is the correct representation of these two populations in an ecosystem?

43. Young plant seedlings were subjected to two different growth conditions. Results at the end of 10 days are given in the table.

The relationship observed between fungus and plant is
(a) commensalism (b) mutualism
(c) parasitism (d) neutral interaction

44. A species of earthworm ‘P’ can grow successfully if the soil water content is 5-8%. Another species ‘Q’ is able to do so if soil water content is 7-10%. If the population of these species is grown together under limited resources and gradient distribution of moisture, then:
(i) the reproductive success of ‘P’ will be maximum in 5-6% soil moisture.
(ii) the reproductive success of ‘Q’ will be maximum in 9- 10% soil moisture.
(iii) the reproductive success of both the species will be greatest in the overlapping zone /.&, 7 – 8% of soil moisture.
(iv) the reproductive success of ‘Q’ will be minimum in soil moisture of 5 – 8%.
(v) the realized niche of species ‘P’ is soil with 7 – 8% moisture.
Which of the above statements are correct?
(a) (i), (ii) and (iv) (b) (iii) only
(c) (iii) and (v) (d) (iv) and (v)

45. The following curves show the growth of two different species of bacteria G and H. They were cultured in Petri plates of two different sizes (7 cm diameter and 10 cm diameter) with 20 ml of a similar nutrient media. (The lighter colour indicates the population in the smaller Petri plate.)

Which of the following would be true for the above experiment?
I. Species G has reached its carrying capacity.
II. Species H has reached its carrying capacity.
III. Species G is limited in its population by space
IV. Species H is limited in its population by space
(a) I, II and III (b) I and II
(c) III and IV (d) I, II, III and IV
46. To determine the effect of intra-specific competition on the growth of saplings of Eucalyptus dives, an experiment was designed in which two sets of pots were used. In the first set only 1 sapling was planted per pot and in the other set 16 saplings were planted per pot. To check for the effect of intra-specific competition on allocation of resources, a decreasing amount of water was added to each set. The results have been graphically indicated below. Which of the following conclusions drawn from the study is correct?

(a) More resources are allocated to the root during low water conditions.
(b) Competition for water among individuals of a population causes more root growth as compared to individuals who are growing alone.
(c) Lesser leaves are formed under low water conditions.
(d) Root growth is higher in individuals grown singly as compared to individuals in populations.
47. The relationship between population density (Nt) and population growth rate (R = Nttl / Nt) in a certain animal species is shown below.
Choose from the following graphs the appropriate population growth patterns that would be obtained if the population is at the densities (I, II, III) shown in the graph above.
[Note that the y-axis in A to D is relative density that cannot be compared to the absolute density in the figure.]

48. Given below is the net primary productivity and biomass without soil organic matter in five ecosystems.

49. The figure below depicts life-history strategies for three plant species (p, q and r) along 3 axes: strength of competition with other organisms, level of disturbance in the habitat, and level of environmental stress in the habitat. Species p grows in habitats where competition among species is high but disturbance and stress are low. Species q grows in habitats with high environmental stress but with low interspecies competition. Species r grows in highly disturbed habitats with low environmental stress.

Which of the statements below is/are correct?
I. Characteristics of “a-type” plants are slow growth rate and short-lived leaves.
II. Desert annual plants are “b-type” species. They have rapid growth and produce large amount of seeds in a short time after rains.
III. Most plants belonging to “c-type” species would be herbaceous while “a-type” and “b-types” species are likely to be trees or shrubs.
(a) Only II (b) I and II
(c) I and III (d) II and III
50. Island biogeography theory states that the number of species on an island is determined by immigration rates of new species to the island and extinction rates of species on the island. Immigration rates to an island decline as its distance from the mainland increases, and extinction rates decrease with increasing island size. When the immigration and extinction rates on an island are equal, the number of species on the island reaches equilibrium

Which of the following gives the correct combination of distance (near and far) and area (small and large) of islands where species (S,-S4) occur?
(a) Si – small island, near island
(b) S2 – large island, near island
(c) S3 – small island, far island
(d) S4 – large island, near island