Below are the NEET MCQ questions on Class 12 Biology Chapter “Organisms and Populations” based on the NCERT textbook. Solve the below free NEET mock test for a better understanding of the various topics. 100+ important MCQs (multiple choice questions) are given in this NEET question bank.
“Organisms and Populations” is the 13th chapter in the unit “Ecology” of class XII or class 12th Biology NCERT. Do note that NEET (which is conducted by NTA) is based on NCERT textbooks so they are a must-have. You can also download PDFs of NCERT textbooks.
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1. What causes territoriality?
(a) competition
(b) parasitism
(c) predation
(d) co-operation
(a) competition
2. What do obligate parasites live on?
(a) living host only
(b) living host and dead organic matter
(c) dead organic matter only
(d) artificial liquid medium
(a) living host only
3. Mycorrhiza help in the absorption of?
(a) calcium
(b) nutrients
(c) metals
(d) None of these
(b) nutrients
4. The plants which can withstand a narrow range of temperature, tolerance is called?
(a) stenothermal
(b) eurythermal
(c) mesothermal
(d) monothermal
(a) stenothermal
5. What is the abundance of a species in a population within a habitat called?
(a) niche density
(b) absolute density
(c) relative density
(d) geographic density
(a) niche density
6. The ability to maintain internal favourable conditions, by a self-regulated mechanism despite changes in the environment, is called?
(a) entropy
(b) enthalpy
(c) homoeostasis
(d) steady-state
(c) homoeostasis
7. What is observed on July 11?
(a) World Population Day
(b) No Tobacco Day
(c) World Environment Day
(d) World Health Day
(a) World Population Day
8. In which of the following cases are an organism and its kind of association a matching pair?
(a) Shark and suckerfish – Commensalism
(b) Algae and fungi in lichens – Mutualism
(c) Orchids growing on trees – Parasitism
(d) Cuscuta (dodder) growing on other – flowering plants – Epiphytism
(b) Algae and fungi in lichens – Mutualism
9. Which of the following best describes the great barrier reef along the east coast of Australia?
(a) population
(b) community
(c) ecosystem
(d) biome
(c) ecosystem
10. Which of the following represents an organism and its ecological niche correctly?
(a) Vallisneria and pond
(b) Desert locust (Schistocerca) and desert
(c) Plant lice (aphids) and leaf
(d) Vultures and dense forest
(c) Plant lice (aphids) and leaf
11. Keystone species should be protected because these
(a) are capable of surviving in harsh environmental conditions.
(b) indicate the presence of certain minerals in the soil.
(c) have become rare due to overexploitation.
(d) play an important role in supporting other species.
(d) play an important role in supporting other species.
12. There is a lizard-like member of reptila sitting on a tree with its tail coiled around a twig. What kind of animal is this?
(a) Hemidactylus showing sexual dimorphism
(b) Varanus showing mimicry
(c) Garden lizard (Calotes) showing camouflage
(d) Chamaeleon showing protective colouration
(d) Chamaeleon showing protective colouration
13. What is carrying capacity?
(a) the capacity of an individual to produce young ones.
(b) availability of resources in a given habitat to support a certain no of individuals of a population, beyond which no further growth is possible.
(c) gene frequency from one generation to the next.
(d) gene frequency in the same generation.
(b) availability of resources in a given habitat to support a certain no of individuals of a population, beyond which no further growth is possible.
14. Some species within biological communities are important in determining the ability of a large number of other species to persist in the community. What are such species called?
(a) keystone species
(b) allopatric species
(c) sympatric species
(d) threatened species
(a) keystone species
15. The presence of flagellated protozoans in the gut of termites is an example of?
(a) Symbiosis
(b) Parasitism
(c) Antibiosis
(d) Commensalism
(a) Symbiosis
16. What is the formula for exponential population growth?
(a) dN/rN = dt
(b) rN / dN = dt
(c) dN / dt = rN
(d) dt / dN = rN
(c) dN / dt = rN
17. The rate by which a rabbit produces new organic matter in grassland is called?
(a) Net productivity
(b) Secondary productivity
(c) Net primary productivity
(d) Gross primary productivity
(b) Secondary productivity
18. In a laboratory population of 40 fruitflies, if 4 individuals died during a specified time interval (i.e., a week), what is the death rate in the population for that period?
(a) 1
(b) 0.1
(c) 0.01
(d) 0.4
(b) 0.1
19. In one year, a population of 500 witnesses 55 births and 5 deaths. What is the population’s reproductive rate during one year?
(a) 0.01/year
(b) 0.05/year
(c) 0.1/year
(d) 50/year
(c) 0.1/year
20. What is the study of pedology?
(a) Locomotion of animals
(b) Rocks
(c) Soil
(d) Reproduction
(c) Soil
21. What is soil made of?
(a) Mineral + Water + Air
(b) Mineral + Organic matter + Water
(c) Mineral + Organic matter + Air + Water
(d) Organic matter + Water
(c) Mineral + Organic matter + Air + Water
22. Who coined the term ecology to describe the study of plants?
(a) Haeckel
(b) Odum
(c) Warming
(d) Dudgeon
(c) Warming
23. What are biotic factors?
(a) Chemical factors of soil that affect life
(b) Physical factors of soil that affect life
(c) All living organisms which influence other organisms
(d) Atmospheric factors which influence life
(c) All living organisms which influence other organisms
24. What does the age of the pyramid with a broad base indicate?
(a) High percentage of young individuals
(b) Low percentage of young individuals
(c) High percentage of old individuals
(d) Low percentage of old individuals
(a) High percentage of young individuals
25. Permafrost is the most distinctive feature of what part of the world?
(a) Taiga
(b) Temperate grasslands
(c) Tundra
(d) Pacific northwest
(c) Tundra
26. What statement does not explain why grasses predominate savannas?
(a) There are few native herbivores in this biome.
(b) Grasses grow well in fine, sandy soils.
(c) The above-ground portions of grass plants die during dry seasons.
(d) The deep roots of the grasses can survive many months of drought.
(a) There are few native herbivores in this biome.
27. There are __ centimetres of rainfall per year in desert regions
(a) less than 5
(b) less than 15
(c) less than 25
(d) over 50
(c) less than 25
28. For plants living in tropical rain forests, the critical competition is for?
(a) soil nutrients
(b) water
(c) space
(d) light
(d) light
29. The similarity of one organism to another for protection and hiding is called?
(a) Mimicry
(b) Predation
(c) Adaptation
(d) Camouflage
(a) Mimicry
30. What is a biome?
(a) a sum of ecosystems in a geographical area.
(b) a sum of ecosystems of the whole earth.
(c) biotic component of an ecosystem.
(d) the biotic potential of a population.
(a) a sum of ecosystems in a geographical area.
31. Choose all of the following that aren’t adapted to seasonal changes in habitat quality.
(a) Migration
(b) Expansion of the species range
(c) Production of seeds
(d) Hibernation
(b) Expansion of the species range
32. Keystone species are those
(a) present in maximum number.
(b) that are most frequent.
(c) attaining large biomass.
(d) contributing to ecosystem properties.
(d) contributing to ecosystem properties.
33. For a population of animals to succeed, what is the most important factor?
(a) Natality
(b) Unlimited food
(c) Adaptability
(d) Inter-species activity
(c) Adaptability
34. Unrestricted reproductive capacity in a population is called?
(a) Biotic potential
(b) Fertility
(c) Carrying capacity
(d) Birth rate
(a) Biotic potential
35. Which region of the world has a high density of organisms?
(a) Grasslands
(b) Savannahs
(c) Deciduous forests
(d) Tropical rain forests
(d) Tropical rain forests
36. Out of the following pairs, which one is mismatched?
(a) Tundra – Low rainfall
(b) Savanna – Acacia trees
(c) Prairie – Grassland
(d) Coniferous forest – Evergreen trees
(a) Tundra – Low rainfall
37. Which of the following is not part of the atmosphere?
(a) Light
(b) Temperature
(c) Edaphic factor
(d) Precipitation
(c) Edaphic factor
38. The lack of vegetation in deserts is caused by what biological factor?
(a) Grazing by animals and goats
(b) Low rainfall
(c) Poor fertility of the soil
(d) Native mankind
(b) Low rainfall
39. During the 20th century, what was the most important factor determining India’s population increase?
(a) Natality
(b) Mortality
(c) Immigration
(d) Emigration
(a) Natality
40. What are the sun-loving plants referred to?
(a) Halophytes
(b) Heliophytes
(c) Heterotrophs
(d) Sciophytes
(b) Heliophytes
41. A majority of organisms are confined to a narrow range of temperature, and are referred to as?
(a) Stenothermal
(b) Endothermal
(c) Ectothermal
(d) Eurythermal
(a) Stenothermal
42. What are the primary factors that determine the foraging, reproductive, and migratory activities of organisms?
(a) Light
(b) Temperature
(c) Water
(d) Soil
(a) Light
43. Select the correct answer
(a) In the case of a bear, hibernating during winter, is an example of ‘escape in time’
(b) To prevent desiccation some snails and fishes enter into diapause
(c) Under unfavourable conditions many zooplankton species go into aestivation
(d) All of these
(a) In the case of a bear, hibernating during winter, is an example of ‘escape in time’
44. Mammals can thrive in Antarctica as well as in the Sahara desert. This is because they are?
(a) Conformers
(b) Regulators
(c) Partially regulators
(d) Partially conformers
(b) Regulators
45. What does the bell-shaped polygonal pyramid indicate?
(a) High percentage of young individuals
(b) Moderate percentage of young individuals
(c) Low percentage of young individuals
(d) Low percentage of old individuals
(b) Moderate percentage of young individuals
46. Rhododendrons are characteristic of which type of vegetation?
(a) Gangetic plains
(b) Tropical zone
(c) Alpine zone
(d) Mangrove zone
(c) Alpine zone
47. What type of plants can be found in Taiga & Tundra?
(a) Halophytes
(b) Xerophytes
(c) Epiphytes
(d) Psychrophytes
(d) Psychrophytes
48. Forests are called “Nation’s green gold” as
(a) They provide timber and medicine
(b) They provide shelter to animals
(c) They prevent erosion of soil
(d) All of the above
(d) All of the above
49. Where can succulents be found?
(a) Deserts
(b) Tundra
(c) Temperate deciduous forests
(d) Tropical rain forests
(a) Deserts
50. Individuals most often show a _____ pattern of dispersion in wild populations.
(a) random
(b) density-dependent
(c) equilibrial
(d) clumped
(d) clumped
51. There would be an exponential increase in population
(a) if it were limited only by density-dependent factors.
(b) until it reaches carrying capacity.
(c) if there were no limiting factors.
(d) if it were a population with an equilibrial life history.
(c) if there were no limiting factors.
52. Out of the following pairs, which one is mismatched?
(a) Tundra – permafrost
(b) Savanna – Acacia trees
(c) Prairie – epiphytes
(d) Coniferous forest – evergreen trees
(c) Prairie – epiphytes
53. Which of the following environmental factors would probably not change as a population grows?
(a) Disease
(b) Limited food supply
(c) Competition for nesting sites
(d) Weather
(d) Weather
54. A broad-based, pyramid-shaped age-structure diagram is characteristic of a population that is?
(a) growing rapidly.
(b) at carrying capacity.
(c) stable.
(d) limited by density-dependent factors.
(a) growing rapidly.
55. A population increases at first and then levels off at carrying capacity if it is
(a) limited by density-dependent factors.
(b) limited by density-independent factors.
(c) an opportunistic species.
(d) limited by both density-dependent or density-independent factors.
(a) limited by density-dependent factors.
56. What is the percentage of natural growth rate if the birth rate is 100, the death rate is 10, and the number of individuals in a population group is 1000?
(a) 0.09%
(b) 9.0%
(c) 0.9%
(d) 90%
(b) 9.0%
57. What does ‘r’ stand for in the models that describe population growth?
(a) population density.
(b) a time interval.
(c) the total number of individuals in the population.
(d) growth rate.
(d) growth rate.
58. There is a species of tropical fish that has only a few offspring and takes care of them for a long time. Alternatively, the fish population might
(a) be controlled mostly by density-independent factors.
(b) show exponential growth.
(c) live in a harsh environment.
(d) be relatively stable, near carrying capacity
(d) be relatively stable, near carrying capacity
59. Chimpanzees have a relatively low birth rate. They take good care of their young, and most chimps live a long life. What would the chimp survivorship curve look like?
(a) line that slopes gradually upward.
(b) relatively flat line that drops steeply at the end.
(c) line that drops steeply at first then flattens out.
(d) line that slopes gradually downward.
(b) relatively flat line that drops steeply at the end.
60. If a population is growing rapidly, an ecologist would suspect it?
(a) contains many more pre-reproductive than reproductive individuals.
(b) is near its carrying capacity.
(c) is limited only by density-dependent factors.
(d) shows a clumped pattern of dispersion.
(a) contains many more pre-reproductive than reproductive individuals.
61. If the birth rate equals the death rate,
(a) a population grows rapidly.
(b) the size of a population remains constant.
(c) density-dependent limiting factors do not affect the population.
(d) a population is in danger of extinction.
(b) the size of a population remains constant.
62. According to an ecologist’s point of view, population structure does not include the
(a) distribution of genotypes within a population.
(b) population density.
(c) spacing of population members.
(d) biomass of the population.
(d) biomass of the population.
63. Which of the following would probably not be true of a population whose dynamics are mainly influenced by density-independent factors?
(a) The population’s growth pattern is similar to the logistic growth curve.
(b) The birth rate of the population is dependent on the nutritional status of its adult females.
(c) The most important source of mortality in the population is unfavourable weather conditions.
(d) Both (a) and (b)
(d) Both (a) and (b)
64. When the number of deaths in a population equals the number of births, it is?
(a) Plateau phase
(b) Log phase
(c) Lag phase
(d) Exponential phase
(a) Plateau phase
65. At carrying capacity, the population
(a) increases rapidly
(b) decreases slowly
(c) decreases rapidly
(d) fluctuates around a median number
(d) fluctuates around a median number
66. The factor rN causes the population to _____ in the formula G = rN (K – N)/K.
(a) remain stable at the carrying capacity
(b) grow at a slower rate than the (K – N/K) factor
(c) grow increasingly rapidly
(d) decrease in size
(c) grow increasingly rapidly
67. Why has the human population grown so rapidly?
(a) declining death rates due to improved medical care.
(b) the proliferation of fast-food outlets, leading to easier access to nutrients.
(c) increasing birth rates due to better health and fertility.
(d) declining death rates due to the declining incidence of war.
(a) declining death rates due to improved medical care.
68. Human population growth ________.
(a) has an S-shaped curve
(b) is currently in a logistic phase
(c) is currently exponential
(d) has reached carrying capacity
(c) is currently exponential
69. Mexico, which has a high population growth rate, has an age-structure diagram that has the shape of?
(a) a triangle with the point at the bottom
(b) a rectangle tapered at the top
(c) a pyramid
(d) an hourglass
(c) a pyramid
70. What is the number of people per unit area or volume known as?
(a) population density
(b) population growth
(c) community ecology
(d) population distribution
(a) population density
71. The following populations would likely have uniform dispersion patterns except
(a) nesting penguins on a small beach
(b) territories of bears in a forest
(c) perennial shrubs (of a given species) growing in a desert habitat
(d) lions on the savanna
(d) lions on the savanna
72. During one year, there are 55 births and 5 deaths in a population of 500. What is the population’s reproductive rate in one year?
(a) 0.01/year
(b) 0.05/year
(c) 0.1/year
(d) 50/year
(c) 0.1/year
73. A population of 600 experiences 65 births and 5 deaths in a year. How would a plot of the population’s growth look if it maintains its current growth pattern?
(a) exponential growth
(b) fluctuating growth
(c) K-selected growth
(d) logistic growth
(a) exponential growth
74. A population’s maximum rate of expansion under the best conditions is referred to as_____. There are abundant resources that last forever and no limit to growth.
(a) biotic potential
(b) cohort
(c) mortality rate
(d) biome
(a) biotic potential
75. Which of the following ecosystem types has the most annual net primary productivity?
(a) Tropical deciduous forest
(b) Temperate evergreen forest
(c) Temperate deciduous forest
(d) Tropical rain forest.
(d) Tropical rain forest.
76. What is unrestricted reproductive capacity in a population called
(a) biotic potential
(b) fertility
(c) carrying capacity
(d) birth rate
(a) biotic potential
77. The number of people in reproductive age is less than those in pre-reproductive age but higher than those in post-reproductive age. The population is
(a) Growing
(b) Declining
(c) Stable
(d) Can not be predicted
(a) Growing
78. Precipitation includes?
(a) Rain
(b) Hails
(c) Snow
(d) All forms of water that fall to the ground
(d) All forms of water that fall to the ground
79. A population’s natality and mortality ratio is expressed in percentage as?
(a) Vital index
(b) Growth rate
(c) Survival rate
(d) Biotic potential
(a) Vital index
80. What type of green foliage mimic is found in animals?
(a) Carausisius
(b) Rhyllium
(c) Praying mantis
(d) Kalima
(c) Praying mantis
81. In commensalism
(a) Population of commensal and host remains unaffected
(b) Population of commensal may increase while that of the host remains unaffected
(c) Population of both commensal and host increases
(d) Population of commensal increases while the population of host gradually decreases
(b) Population of commensal may increase while that of the host remains unaffected
82. Fruit from a plant species is eaten by a bird. The seeds are not digested, so they germinate in the bird’s excreta at a distance from the parent plant. This is an example of
(a) predation
(b) competition
(c) commensalism
(d) mutualism
(d) mutualism
83. Seawater’s salinity in parts per thousand (ppt) ranges between?
(a) 5-15 %
(b) 30-35%
(c) 50-75%
(d) More than 100 %
(b) 30-35%
84. The principle of competitive exclusion states that two species cannot coexist in the same
(a) biome.
(b) ecological niche.
(c) environmental habitat.
(d) range.
(b) ecological niche.
85. Predation and parasitism involve which of the following types of interactions?
(a) (+, +)
(b) (+, 0)
(c) (+, –)
(d) (–, –)
(c) (+, –)
86. Interactions in which the consumer lives inside the host and affect the host slowly are referred to as?
(a) commensalism.
(b) parasitism.
(c) mutualism.
(d) competition.
(b) parasitism.
87. What is the relationship between a hermit crab and sea anemone?
(a) symbiosis
(b) mutualism
(c) parasitism
(d) commensalism
(d) commensalism
88. What are the main factors affecting the foraging, reproductive, and migratory activities of organisms?
(a) Light
(b) Temperature
(c) Water
(d) Soil
(a) Light
89. A small fish gets stuck near the bottom of a shark and feeds on it. What is this kind of association called?
(a) Symbiosis
(b) Commensalism
(c) Predation
(d) Parasitism
(b) Commensalism
90. An association between two individuals or populations where both benefit and where neither can survive without the other?
(a) Commensalism
(b) Amensalism
(c) Proto-cooperation
(d) Mutualism
(d) Mutualism
91. What do niche overlaps indicate?
(a) two different parasites on the same host
(b) sharing of one or more resources between the two species
(c) mutualism between two species
(d) active cooperation between two species
(b) sharing of one or more resources between the two species
92. What is the formula for exponential population growth?
(a) dN/rN = dt
(b) rN / dN = dt
(c) dN / dt = rN
(d) dt / dN = rN
(c) dN / dt = rN
93. Geometric representation of age structure is one of the characteristics of?
(a) population
(b) landscape
(c) ecosystem
(d) biotic community.
(a) population
94. There is an explosive increase in the population of an insect species during the rainy season, followed by its disappearance at the end of the season. What does this indicate?
(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.
(b) Its population growth curve is of J-type
95. Is it possible to conclude that two plants belong to the same species if they
(a) have more than 90 per cent similar genes
(b) look similar and possess identical secondary metabolites
(c) have the same number of chromosomes
(d) can reproduce freely with each other and form seeds.
(d) can reproduce freely with each other and form seeds.
96. What is the truth about the isolated small tribal populations?
(a) There is a decline in population as boys marry girls only from their own tribe
(b) Hereditary diseases like colour blindness do not spread in the isolated population
(c) Wrestlers who develop strong body muscles in their lifetime pass this character on to their progeny
(d) There is no change in population size as they have a large gene pool
(a) There is a decline in population as boys marry girls only from their own tribe
97. During the industrial revolution in England, the black form of the peppered moth (Biston betularia) became dominant over the light form. This is an example of
(a) the appearance of the darker coloured individuals due to very poor sunlight
(b) protective mimicry
(c) inheritance of darker colour character acquired due to the darker environment
(d) natural selection whereby the darker forms were selected
(d) natural selection whereby the darker forms were selected
98. What is the most common place to find large woody vines?
(a) temperate forest
(b) mangroves
(c) tropical rainforests
(d) alpine forests
(c) tropical rainforests
99. Consider the following four conditions (i) – (iv) and choose the correct pair of them as an adaptation to the environment of the desert lizards. The conditions:
(i) Burrowing in the soil to escape high temperature
(ii) Losing heat rapidly from the body during high temperature
(iii) Bask in the sun when the temperature is low
(iv) Insulating body due to thick fatty dermis
Options :
(a) (iii) and (iv)
(b) (i)
(c) (iii), (ii) and (iv)
(d) (i) and (ii)
(b) (i)
100. The shell lining of a hermit crab gets attached to a sedentary sea anemone. This association is
(a) Symbiosis
(b) Commensalism
(c) Amensalism
(d) Ectoparasitism
(b) Commensalism
101. A biologist studied the rat population in a barn. He found that the average natality was 250, the average mortality was 240, the average immigration was 20 and the average emigration was 30. What is the net increase in population?
(a) 15
(b) 05
(c) zero
(d) 10
(c) zero
102. What affects benthic organisms most?
(a) Water-holding capacity of soil
(b) Light reaching the forest floor
(c) Surface turbulence of water
(d) Sediment characteristics of aquatic ecosystems
(d) Sediment characteristics of aquatic ecosystems
103. What does an age pyramid with a broad base indicate?
(a) High percentage of young individuals
(b) High percentage of old individuals
(c) Low percentage of young individuals
(d) A stable population
(a) High percentage of young individuals
104. Which of the following adaptations is not parasitic?
(a) Loss of unnecessary sense organs
(b) Development of adhesive organs
(c) Loss of digestive organs
(d) Loss of reproductive capacity
(d) Loss of reproductive capacity
105. Which of the following statement(s) is/are true?
(1) Organisms living in oceans, lakes and rivers do not face any water-related problems
(2) Euryhaline can tolerate a wide range of salinities
(3) Stenohaline are restricted to a narrow range of salinities
(4) No freshwater animals cannot live for long in seawater but sea animals can live in freshwater for a long time because of osmotic balance
(a) All are correct
(b) All are false
(c) Only (4)
(d) (1), (3) and (4)
(c) Only (4)
106. Which of the following statement(s) is/are true?
(1) In a population growth rate curve the lag phase represents the period when a population is adjusting to a new environment.
(2) In a population growth rate curve the steepest part of the growth phase represents the period when a population is growing exponentially.
(3) In the stationary phase of a population growth rate curve the population is in dynamic equilibrium.
(4) Humans have changed the carrying capacity of the earth.
(a) All of these
(b) (1), (2) and (3)
(c) (2) and (3)
(d) (1) and (4)
(a) All of these
Goodluck Medicoholics! Until next time.