BIOLOGY XII
CHAPTER: ORGANISMS AND POPULATIONS
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PART A
1. Niche is
a) All the biological factors in the organism environment
b) The physical space where an organism live
c) The range of temperature that the organism needs to live
d) The functional role played by the organism where it lives

2. Presence of plants arranged into well-defined vertical layers depending on their height can be seen best in:
a) Tropical Rain Forest

 b) Grassland
c) Temperate Forest

 d) Tropical Savannah

3. An association of individuals of different species living in the same habitat and having functional interactions is
a) Ecological niche

 b) Biotic community
c) Ecosystem

 d) Population

4. Ecology is basically concerned with four levels of biological organization, which one of the following is correct representation?
a) Population→ Ecosystem → Biome→ Landscape.
b) Communities → Population→ Ecosystem→ Biome.
c) Organisms→ Population → Communities → Biome.
d) Species→ Ecosystem →Communities→ Biome

5. A biologist studied the population of rats in a barn. He found that the average natality was 250, average mortality 240, immigration 20 and emigration 30. The net increase in population is
a) 10 

 b) 15 

 c) 05

 d) zero

6. Physiological ecology
a) Works at the organismic level
b) Tries to understand the adaptation with respect to survival only
c) Tries to understand the adaptation with respect to reproduction only
d) None of these

7. Identify the correct sequence of stages in Verhulst – Pearl Logistic growth
a) Lag phase → acceleration →crash down
b) Lag phase→ acceleration → deceleration → asymptote
c) Acceleration →asymptote → deceleration → lag phase
d) Lag phase →acceleration →asymptote → deceleration

8. Geometric representation of age structure is a characteristic of:
a) Biotic community

 b) Population

 c) Landscape

 d) Ecosystem

9. The salt concentration of water bodies is measured in
a) Parts per Thousands

 b) Parts per Million
c) Parts per Billion

 d) Parts per Hundreds

10. Under unfavorable conditions, many zooplankton species in lakes and ponds are known to enter a stage of suspended development called as:
a) Dormancy

 b) Hibernation

 c) Aestivation

 d) Diapause

11. Choose the incorrect match
a) Ascaris in human intestine – Parasitism
b) Clown fish and sea anemone – Amensalism
c) Barnacles on the back of whale – Commensalism
d) Fig tree and wasp – Mutualism

12. Bacteria, fungi, lower plants survive in adverse conditions by
a) Diapause

 b) suspended growth
c) Migration

 d) formation of thick walled spores

13. Connell’s field experiments were in support of
a) Competitive exclusion 

 b) interference competition
c) Competitive release 

 d) co-existence

14. Assertion (A): Competition always eliminates inferior species.
Reason (R): Competition always occurs for limited resources for closely related species
a) If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion
b) If both Assertion & Reason are true but Reason is not a correct explanation of the Assertion
c) If Assertion is True but the Reason is False.
d) If both Assertion & Reason are False.

15. While heat gain or heat loss is the function of ______, heat production is the function of ________ of the body of an animal.
a) Volume; Surface area

 b) Surface area; Volume
c) Volume; Volume

 d) Surface area; Surface area

16. Annual migration does not occur in the case of:
a) Salmons

 b) Siberian crane

 c) Salamander

 d) Artic tern

17. Select the incorrect statement
a) Organisms living in oceans, lakes and rivers do not face any water related problems
b) Productivity and distribution of plants is dependent on water
c) The levels of thermal tolerance of different species determine to a large extent their geographical distribution
d) Foraging, reproductive and migratory activities of some animals are dependent on seasonal variations in light

18. The ‘intrinsic rate of natural increase’ for the flour beetle is
a) 0.015 

 b) 0.12

 c) 0.0205

 d) 0.25

19. Choose the correct option for the given adaptations:
(i) Biochemical adaptations are seen in organisms living in greater depths of the ocean to face crushing pressure
(ii) Allen’s rule explains mammals living in colder climates
(iii) Altitude sickness is caused because of body not getting enough oxygen due to low atmospheric pressure at high altitudes
(iv) Desert lizards lack behavioral means to manage their body temperature
a) (i), (ii) and (iii)

 b) (i), (ii) and (iv)
c) (ii), (iii) and (iv)

 d) (i), (iii) and (iv)

20. The given age pyramid represents a:

a) Fast expanding population

 b) Slowly expanding population
c) Stable population

 d) Declining population

21. Population size in any given habitat is also known as
a) Population cluster

 b) Population explosion
c) Population abundance 

 d) Population density

22. Natality refers to
a) Death rate
b) Birth rate
c) Number of individuals leaving the habitat
d) Number of individuals entering the habitat

23. A biologist studied the population of rats in a barn. He found that the average natality was 250, average mortality 240, immigration 20 and emigration 30. The net increase in population is :
a) 15

 b) 05

 c) zero

 d) 10

24. In a growing population of a country
a) Pre-reproductive individuals are more than the reproductive individuals
b) Reproductive individuals are less than the post-reproductive individuals
c) Reproductive and pre-reproductive individuals are equal in number
d) Pre-reproductive individuals are less than the reproductive individuals

25. The impact of immigration on population density is
a) Negative

 b) Both positive and negative
c) Neutralized by natality

 d) Positive

26. Which of the following is not an attribute of a population?
a) Mortality

 b) Species interaction
c) Sex ratio

 d) Natality

27. The density of a population in a given habitat during a given period fluctuates due to changes in four basic processes. On this basis fill up A and B boxes in the given diagram with correct options:

a) A = Natality + Immigration, B = Mortality + Emigration
b) A = Natality + Mortality, B = Immigration + Emigration
c) A = Birth rate + Death rate, B = Migration + Emigration
d) A = Natality + Emigration, B = Mortality + Immigration

28. In the logistic growth equation given below, the carrying capacity is represented by:
dN/dT = rN(K-N)/K
a) N

 b) r

 c) K

 d) K-N/K

29. A population growing in a habitat with limited resources shows phase of growth in the following sequence:
a) Acceleration → Deceleration → Lag phase → Asymptote
b) Lag phase → Acceleration → Log phase → Deceleration
c) Lag phase → Acceleration → Deceleration → Asymptote
d) Acceleration → Log phase → Crash phase

30. The logistic growth curve of animal population growth is more realistic than J shaped curve because:
a) Asexual mode of reproduction is rare in higher animals
b) Resources are finite and become limiting sooner or later.
c) Most animals are conformers rather than regulators
d) Abiotic factors affect animals more than plants

31. When the population density reaches the carrying capacity, the logistic growth curve is said to be in:
a) Lag phase

 b) A phase of acceleration
c) A phase of deceleration

 d) Asymptote

32. Darwinian fitness is represented by:
a) Low r value

 b) High r value

c) High K value

d) Low K value

33. Which of the following will breed more than once in their life cycle?
a) Pacific salmon fish

 b) Bamboo
c) Cuckoo

 d) both a and c

34. A population interaction where one species is harmed whereas the other is unaffected is called as:
a) Mutualism

 b) Competition

c) Predation

 d) Amensalism

35. A species whose distribution is restricted to a small geographical area because of the presence of a competitively superior species is found to expand its distributional range dramatically when the competing species is experimentally removed. This is called:
a) Competitive Exclusion

 b) Competitive Release
c) Competitive Supremacy

 d) Competitive Inclusion

PART B

36. Which of the following is not a function of predators?
a) They act as conduits for energy transfer across trophic levels
b) They keep prey populations under control
c) They help in the stabilization of the ecosystems
d) They decrease the species diversity in a community

37. A high density of elephant population in an area can result in :
a) Mutualism

 b) Intraspecific competition
c) Interspecific completion

 d) Predation on one another

38. Between which among the following, the relationship is not an example of commensalism?
a) Orchid and the tree on which it grows

 b) Cattle Egret and grazing cattle
c) Sea Anemone and Clown fish

 d) Female wasp and fig species

39. In Brood Parasitism which of the two birds are involved?
a) Cuckoo and Parrot

 b) Parrot and Crow
c) Crow and Cuckoo

 d) Cuckoo and Eagle

40. MacArthur’s Warblers living on the same tree showed which type of interaction?
a) Interspecific Competition

 b) Co-existence
c) Competitive release

 d) Intraspecific Competition

41. In Galapagos Islands, Abingdon tortoises became extinct within a decade after goats were introduced on the island, because
a) Resources are limited

 b) Intraspecific competition
c) Greater browsing efficiency of goats

 d) Resources are limited

42. Mycorrhizae are associations between
a) Fungi and roots of higher plants

 b) Fungi and algae
c) Fungi and cyanobacteria

 d) Both B and C

43. In Connell’s elegant field experiments, on the Rocky sea coasts of Scotland which of the following observation was recorded?
a) Barnacle Balanus dominates and exclude the smaller barnacle Chthamalus from that zone
b) Barnacle Chthamalus dominates Barnacle Balanus and exclude them from that zone.
c) Barnacle Balanus dominates and excludes smaller warblers from that zone.
d) Warblers dominate and exclude smaller Balanus from that area

44. Calotropis doesn’t allow any cows and goats to browse around by releasing
a) Cardiac glucosamine

 b) Cardiac sterol
c) Cardiac glycoside

 d) Cardiac nitroxide

45. Which of the following term implies the maintenance of relatively constant physical and chemical conditions with organisms?
a) Homeostasis 

 b) Adaptation

 c) Isometry 

 d) Acclimation

46. What type of human population is represented by the following age pyramid?

a) Stable population

 b) Declining population
c) Expanding population

 d) Vanishing population

47. Which is correctly labeled with respect to the given diagram?

a) B: Logistic curve

 b) C: Carrying capacity
c) C: Exponential curve

 d) A: Carrying capacity

48. Gause principle is related to
a) competition between closely related species for limited natural resources
b) resource partitioning by different species
c) interference competition under unlimited resources
d) intraspecific competition for food, space and mating

49. Match column I with column II and select the correct option from the codes given below.
Column I Column II
A. Commensalism (i) One inhibited other unaffected
B. Parasitism (ii) One benefited other unaffected
C. Mutualism (iii) Both are benefitted
D. Amensalism (iv) One benefitted other harmed
a) A-(iv), B-(ii), C-(iii), D-(i)

 b) A-(iii), B-(iv), C-(ii), D-(i)
c) A-(ii), B-(iv), C-(iii), D-(i)

 d) A-(ii), B-(iv), C-(i), D-(iii)

50. Which of the following statement is false with respect to adaptations?
a) Many xerophytic plants have thick cuticle on leaf epidermis, sunken stomata
b) Some xerophytic plants have special photosynthetic pathway (CAM) that enables their stomata close during day
c) Opuntia has spines (modified leaves), photosynthetic phylloclade (stem)
d) All adaptations are genetically fixed in all organisms

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ANSWER KEY- ORGANISMS AND POPULATIONS
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