Organisms and Populations Class 12 Biology MCQs

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Organisms and Populations Questions

Question 1. The keystone species in an ecosystem are those which:

  1. Are present in a large number
  2. Arc most frequent
  3. Attain a large biomass
  4. Contribute to ecosystem properties.

Answer: 4. Contribute to ecosystem properties.

Question 2. The sphere of living matter together with water, air, and soil on the earth is called:

  1. Atmosphere
  2. Hydrosphere
  3. Lithosphere
  4. Biosphere

Answer: 4. Biosphere

Question 3. Plants with irreversible and genetically fixed adaptations are known as :

  1. Ecotypes
  2. Ecotones
  3. Ecophenes
  4. Ecological Equivalents.

Answer: 1. Ecotypes

Read and Learn More 12th Class Biology MCQs

Question 4. Species which has a restricted distribution is called :

  1. Endemic
  2. Sympatric
  3. Allopatric
  4. Ecospecies

Answer: 1. Endemic

Organisms and Populations Class 12 Biology MCQs

Question 5. The study of communities, especially their environmental relationship, and structure, is known as

  1. Autoecology
  2. Synecology
  3. Genecology
  4. Phytosociology

Answer: 2. Synecology

Organisms and Populations Class 12 Biology MCQs

Question 6. When the organisms live together in such a manner that one organism is benefited while the other remains unaffected. This type of association is called:

  1. Commensalism
  2. Symbiosis
  3. Mutualism
  4. Parasitism.

Answer: 1. Commensalism

Question 7. Plants and animals living in a given area form a:

  1. Biome
  2. Ecotone
  3. Biotic community
  4. Bioindicator.

Answer: 3. Biotic community

Question 8. The part of the earth and atmosphere supporting life is:

  1. Biota
  2. Biome
  3. Ecotone
  4. Biosphere

Answer: 4. Biosphere

Question 9. Which of the following is synecology?

  1. Study of the same species
  2. Study of different species
  3. Both of these
  4. None of these.

Answer: 2. Study of different species

Question 10. The term ‘biocoenosis’ was coined by:

  1. Karl Mobius
  2. Charles Darwin
  3. E.P. Odum
  4. E.Haeckel.

Answer: 4. E.Haeckel.

Question 11. A number of immigrants is more than emigration and deaths is lower than natality. The growth curve of the population will show:

  1. Exponential phase
  2. Lag phase
  3. Declining phase
  4. Steady phase.

Answer: 1. Exponential phase

Class 12 Biology Chapter Organisms and Populations MCQs

Question 12. Which one of the following has raised check bone, oblique eyes, and yellowish skin color

  1. Negroids
  2. Mongoloids
  3. Polynesians
  4. Caucasoids

Answer: 2. Mongoloids

Question 13. Scent-producing glands arc:

  1. Anal glands
  2. Adrenal glands
  3. Bertholin’s gland
  4. Prostate gland.

Answer: 1. Anal glands

Question 14. Pheromone is:

  1. Product of endocrine gland
  2. A protein
  3. mRNA
  4. Used for animal communication

Answer: 4. mRNA

Question 15. The percentage ratio of natality over mortality is:

  1. Population dynamics
  2. Vital index
  3. Population density
  4. Total count.

Answer: 2. Vital index

Question 16. The human population shows:

  1. J-shaped growth curve
  2. Z-shaped growth curve
  3. S-shaped growth curve
  4. All the above.

Answer: 3. S-shaped growth curve

Question 17. The process of mating of individuals which are more closely related than the average of the population to which they belong is called :

  1. Inbreeding
  2. Hybridization
  3. Heterosis
  4. Self-Breeding.

Answer: 1. Inbreeding

Question 18. Adaptation of a species is its :

  1. Ecdysis
  2. Metamorphosis
  3. Acquired Character
  4. Hereditary Character.

Answer: 4. Hereditary Character

Class 12 Biology Chapter Organisms and Populations MCQs

Question 19. The abundance of a species in a population, within its habitat, is called:

  1. Atniche density
  2. Absolute density
  3. Relative density
  4. Regional density.

Answer: 1. Atniche density

Question 20. Asymptote is a stage when a population is:

  1. Stabilized
  2. Changing
  3. Increasing
  4. Decreasing.

Answer: 1. Stabilised

Question 21. Two species cannot occupy the same niche. This law is known as:

  1. Wien Law
  2. Gause Law
  3. Allen Law
  4. Competition Exclusion Principle.

Answer: 2. Gause Law

Question 22. In which one of the following habitats, does the diurnal temperature of the soil surface vary most?

  1. Forest
  2. Desert
  3. Grassland
  4. Shrub land

Answer: 2. Desert

Question 23. Broad-leaved forest oaks are found in

  1. North coniferous forests
  2. Mediterranean evergreen forest
  3. Temperate deciduous forests
  4. Tropical deciduous forest.

Answer: 2. Mediterranean evergreen forest

Question 24. Prolonged liberal irrigation of agricultural fields is likely to create the problem of

  1. Aridity
  2. Acidity
  3. Metal toxicity
  4. Salinity.

Answer: 4. Salinity.

Question 25. At which latitude, does heat gain through insolation approximately equals heat loss through terrestrial radiation?

  1. 66%° North and South
  2. 22½° North and South
  3. 421½° North and South
  4. 40° North and South.

Answer: 3. 42½° North and South

Question 26. Animals have the innate ability to escape from predation. Examples for the same are given below. Select the incorrect example:

  1. Colomuchange in chameleon
  2. Melanism in moths
  3. Poison fangs in snakes
  4. Enlargement of body size by swallowing air in puffer fish.

Answer: 3. Poison fangs in snakes

Question 27. There exists a close association between the alga and the fungus within lichen. The fungus:

  1. Fixes the atmospheric nitrogen for the alga
  2. Provides protection, anchorage, and absorption for the alga
  3. Releases oxygen for the alga
  4. Provides food for the alga.

Answer: 2. Provides protection, anchorage, and absorption for the alga

State Board Class 12 Biology Organisms and Populations MCQs

Question 28. Identify the correctly matched pair:

  1. Montreal Protocol – Global warming
  2. Kyoto Protocol – Climatic change
  3. Ramsar Convention – Groundwater pollution
  4. Basal Convention – Biodiversity Conservation

Answer: 2. Kyoto Protocol – Climatic change

Question 29. The ability of the Venus fly trap to capture insects is, due to:

  1. Specialized ’muscle-like’ cells
  2. Chemical stimulation by the prey
  3. A passive process requiring no special ability on the part of the plant
  4. Rapid turgor pressure changes.

Answer: 4. Rapid turgor pressure changes.

Question 30. Sunderban contains mainly:

  1. Mangrove plants
  2. Alpine trees
  3. Thick forest
  4. Grass.

Answer: 1. Mangroove plants

Question 31. Pneumatophores are present/common in

  1. Xerophytes
  2. Hygrophytes
  3. Mesophytes
  4. Helopytes

Answer: 4. Helopytes

Question 32. Which one of the following correctly represents an organism and its ecological niche?

  1. Vallisncria and pond
  2. Desert locust (Scistoccrca)
  3. Plant lice (aphids) and leaf
  4. Vultures and dense forest.

Answer: 3. Plant lice (aphids) and leaf

Question 33. Humidity in the atmosphere decreases the rate of:

  1. Transpiration
  2. Photosynthesis
  3. Glycolysis
  4. Growth.

Answer: 1. Transpiration

Question 34. Niche overlap indicates:

  1. Sharing of one or more resources between the two species
  2. Mutualism between two species
  3. Active cooperation between two species
  4. Two different parasites on the same host.

Answer: 1. Sharing of one or more resources between the two species

State Board Class 12 Biology Organisms and Populations MCQs

Question 35. Annual migration does not occur in the case of:

  1. Salamander
  2. Salmon
  3. Arctic tern
  4. Siberian crane.

Answer: 1. Salamander

Question 36. Choose the correct combination of labeling of the zones in water in a lake.

  1. a-Limnetic zone, b-Profoundal zone, c-Littoral zone, d-Benthic zone
  2. a-Littoral zone, b-Benthic zone, c-Profundal zone, d-Limnetic zone
  3. a-Littoral zone, b-Limnetic zone, c-Profundal zone, d-Benthic zone
  4. a-Limnetic zone, b-Littoral zone, c-Benthic zone, d-profundal zone
  5. a-Littoral zone, b-Profundal zone, c-Benthic zone, d-Limnetic zone.

Answer: 3. a-Littoral zone, b-Limnetic zone, c-Profundal zone, d-Benthic zone

Question 37. Geometric representation of age structure is a characteristic of

  1. Population
  2. Landscape
  3. Ecosystem
  4. Biotic community.

Answer: 1. Population

Question 38. 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?

  1. The food plants mat arc and die at the end of the rainy season.
  2. Its population growth curve is of J-type.
  3. The population of its predators increases enormously
  4. S-shaped or sigmoid growth of this insect.

Answer: 2. Its population growth curve is of J-type.

Question 39. Which one of the following is categorized as a parasite in the true sense?

  1. The female Anopheles bites and sucks blood from humans
  2. A human fetus developing inside the uterus draws nourishment from the mother
  3. Head louse living on the human scalp as well as laying eggs on human hair
  4. The cuckoo (koel) lays its eggs in a crow’s nest.

Answer: 3. Head louse living on the human scalp as well as laying eggs on human hair

Question 40. Consider the following four conditions (1 – 4) and select die correct pair of them as adaptation to the environment in desert lizards. The conditions:

  1. Burrowing in soil to escape high-temperature
  2. Losing heat rapidly from the body during high-temperature
  3. Bask in the sun when the temperature is low
  4. The insulating body is due, to the thick fatty dermis.

Options:

  1. (3), (4)
  2. (1), (3)
  3. (2), (4)
  4. (1), (2)

Answer: 2. (1), (3)

State Board Class 12 Biology Organisms and Populations MCQs

Question 41. What type of human population is represented by the following age pyramid?

  1. Vanishing population
  2. Stable population
  3. Declining population
  4. Expanding population

Answer: 3. Declining population

Question 42. People, who migrated from the planes to an area adjoining Rohtang Pass about six months back:

  1. Are not physically fit to play games like football.
  2. Suffer from altitude sickness with symptoms like nausea, fatigue, etc.
  3. Have the usual RBC count but their haemoglobin has a very high binding affinity to O2
  4. Have more RBCs and their haemoglobin has a lower binding affinity to O2

Answer: 4. Have more RBCs and their hemoglobin has a lower binding affinity to O2

Question 43. The fungal association of roots of higher plants in mycorrhiza is known as :

  1. Parasitism
  2. Hyperparasitism
  3. Mutualism
  4. Commensalism.

Answer: 3. Mutualism

Question 44. Hyperparasite is a kind of parasite which:

  1. Kills its host
  2. Completes life cycle in one host
  3. Uses host machinery for reproduction
  4. None of the above.

Answer: 4. None of the above.

Question 45. Plants obtaining nourishment from other plants by haustoria are:

  1. Mcsophytes
  2. Parasites
  3. Xerophytes
  4. Halophytes.

Answer: 2. Parasites

Question 46. A successful parasite is the one which

  1. Grows rapidly
  2. Reproduces last
  3. Sdcks to host for a long
  4. Makes minimum demands from its host.

Answer: 4. Makes minimum demands from its host.

Question 47. Which of the following statements is correct regarding the two organisms in commensalism?

  1. No one is harmed
  2. Both partners are harmed
  3. One partner benefits whether another suffers partner benefits and the other remains unharmed.
  4. Answer: 4. One partner benefited while another suffering partner benefited and the other remains unharmed.

Organisms and Populations MCQs with Answers Class 12

Question 48. Which is not characteristic of intestinal symbionts?

  1. Feeding on extra food of the host
  2. Providing vitamins to host
  3. Anaerobic respiration
  4. Aerobic respiration.

Answer: 4. Aerobic respiration

Question 49. Ecological succession on sand is:

  1. Timomere
  2. Xerosere
  3. Halosere
  4. Hydrosere

Answer: 1. Timomere

Question 50. The cause of mimicry is

  1. Concealment
  2. Offense
  3. Defense
  4. Both (2) And (3).

Answer: 1. Concealment

Question 51. Which of the following insects mimics thin dry branches of the plant on which it lives?

  1. KaIlima parallactic
  2. Mantis religiosa
  3. Phyllium frondosum
  4. Caraitstusmorosus.

Answer: 2. Mantis religiosa

Question 52. The individual that shows mimicry is called:

  1. Mimic
  2. Predator
  3. Prey
  4. Parasite

Answer: 1. Mimic

Question 53. Heterodon flattens its head and produces frequent hissing and strikes to advertise as if it is dangerous. This is an example of:

  1. Alluring mimicry
  2. Warning mimicry
  3. Concealing mimicry
  4. Batesian mimicry.

Answer: 2. Warning mimicry

Question 54. In conscious mimicry:

  1. The organisms behave as if they are dead bodies
  2. The organisms become more conscious
  3. The organism catches its prey with great ease
  4. None of the above.

Answer: 1. The organisms behave as if they are dead bodies

Question 55. Which of the following resembles a dry leaf?

  1. Phyllium
  2. Paralectci
  3. Cryptolithodes
  4. Pap ilia machaon.

Answer: 2. Paralectci

Question 56. July 11 is observed as:

  1. No tobacco day
  2. World health day
  3. World population day
  4. World environment day

Answer: 4. World Environment Day

Organisms and Populations MCQs with Answers Class 12

Question 57. Which among the following is the primary function of mimicry prevalent in some animals?

  1. Warning
  2. Concealment
  3. Allurement
  4. Aggression.

Answer: 2. Concealment

Question 58. Succession in an ecosystem is the result of:

  1. Occurrence of diseases
  2. Changes in grazing habits of animals
  3. Competition among animals
  4. Adaptive ability to environmental changes.

Answer: 4. Adaptive ability to environmental changes

Question 59. Mycorrhiza is an example of:

  1. Decomposers
  2. Endoparasitism
  3. Symbiotic relationship
  4. Ectoparasitism.

Answer: 3. Symbiotic relationship

Question 60. Two opposite forces operate in the growth and development of every population. One of them relates to the ability to reproduce at a given rate. The force opposing it is called :

  1. Morbidity
  2. Biotic potential
  3. Fecundity
  4. Environmental resistance

Answer: 4. Environmental resistance

Question 61. Maximum growth rate occurs in:

  1. Senescent Phase
  2. Lag Phase
  3. Exponential Phase
  4. Stationary Phase.

Answer: 3. Exponential Phase

Question 62. Lichens are a well-known combination of an alga and a fungus where the fungus has:

  1. An epiphytic relationship with the alga
  2. A parasitic relationship with the alga
  3. Symbiotic relationship with the alga
  4. A saprophytic relationship with alga.

Answer: 3. Symbiotic relationship with the alga

Organisms and Populations MCQs with Answers Class 12

Question 63. An ecosystem that can be easily damaged but can recover after some time if the damaging effect stops will have the following:

  1. High stability and low resistance
  2. Low stability and low resistance
  3. High stability and high resistance
  4. Low stability and high resistance.

Answer: 1. High stability and low resistance

Question 64. A terrestrial animal must be able to:

  1. Actively pump salts out through the skin
  2. Excrete large amounts of salts in urine
  3. Excrete a large amount of water in urine
  4. Conserve water.

Answer: 4. Conserve water.

Question 65. What is a keystone species?

  1. A common species that has plenty of biomass yet has a fairly low impact on the community’s organization
  2. A rare species that has minimal impact on the biomass and no other species in the community
  3. A dominant species that constitutes a large proportion of the biomass and which affects many other species
  4. A species that makes only a small proportion of the total biomass of a community yet has a huge impact on the community’s organization and survival.

Answer: 4. A species that makes only a small proportion of the total biomass of a community, yet has a huge impact on a community’s organization and survival.

Question 66. The most thoroughly studied of the known bacteria-plant interaction is the:

  1. Nodulation of Sesbania stems by N2 fixing bacteria
  2. Plant growth stimulation by phosphate-solubilizing bacteria
  3. Cyanobacterial symbiosis with some aquatic ferns
  4. Gall formation on certain angiosperms by Agrobacterium.

Answer: 4. Gall formation on certain angiosperms by Agrobacterium.

Question 67. A term used to describe non-dominant species that dictate community structure is:

  1. Pioneer species
  2. Exogenous species
  3. Keystone species
  4. Transitional species.

Answer: 3. Keystone species

Question 68. In succession, complexities in structure:

  1. Drastically increase
  2. Slowly increase
  3. Does not increase
  4. Constant.

Answer: 2. Slowly increase

Question 69. The presence of diversity at the junction of territories of two different habitats is known as

  1. Bottleneck effect
  2. Edge effect
  3. Junction effect
  4. Pasteur effect.

Answer: 2. Edge effect

Question 70. Small fish get stuck near the bottom of a shark and derive its nutrition from it. This kind of association is called as:

  1. Symbiosis
  2. Commensalism
  3. Predation
  4. Parasitism.

Answer: 2. Commensalism

Question 71. A praying mantis is a good example of:

  1. Social insects
  2. Camouflage
  3. Mullerian mimicry
  4. Warning coloration.

Answer: 2. Camouflage

Question 72. The formula for exponential population growth is:

  1. rN/dN = dt
  2. dN/dt = rN
  3. dt/dN = rN
  4. dN/rN = dt.

Answer: 2. dN/dt = rN

Question 73. Match the following with the correct combination:

  1. 1-A, 2-B, 3-C, 4-D
  2. 1-D, 2-C, 3-B, 4-A
  3. 1-A, 2-B, 3-B, 4-D
  4. 1-B, 2-C, 3-A, 4-D
  5. 1-D, 2-B, 3-C, 4-A.

Answer: 2. 1-D, 2-C, 3-B, 4-A

Question 74. Find out the correct order of succession levels in xerarch.

  1. Lichen moss stage, annual herb stage, perennial herb stage, scrub stage, forest
  2. Annual herb stage, perennial herb stage, lichen moss stage, scrub stage, forest
  3. Perennial herb stage, annual herb stage, lichen moss stage, scrub stage, forest
  4. Scrub stage, forest, annual herb stage, perennial herb stage, lichen moss stage
  5. Forest, scrub stage, annual stage, perennial herb stage, lichen moss stage.

Answer: 1. Lichen moss stage, annual herb stage, perennial herb stage, scrub stage, forest

Organisms and Populations MCQs with Answers Class 12

Question 75. The concept of chemical evolution is based on:

  1. Interaction of water, air, and clay under intense heat
  2. Effect of solar radiation on chemicals
  3. Possible origin of life by combination of chemicals under suitable environmental conditions
  4. Crystallization of chemicals.

Answer: 3. Possible origin of life by a combination of chemicals under suitable environmental conditions

Question 76. If the mean and the median pertaining to a certain character of a population are of the same value, the following is most likely to occur:

  1. A bimodal distribution
  2. A T-shaped curve
  3. A skewed curve
  4. A normal distribution.

Answer: 4. A normal distribution.

Question 77 The equation \(\frac{\Delta N_n}{\Delta N}\) represents which of the following?

  1. Natality
  2. Growth rate
  3. Mortality
  4. All of these.

Answer: 2. Growth rate

Question 78. The change in population size at a given time interval t, is given by the expression Nt = N0 + I – D – E, I, B, and D stand respectively for

  1. Rate of immigration, mortality rate, natality rate
  2. Rate of emigration, natality rate, mortality rate
  3. Mortality rate, natality rate, rate of immigration
  4. Mortality rate, rate of immigration, natality rate
  5. Rate of immigration, natality rate, mortality rate.

Answer: 5. Rate of immigration, natality rate, mortality rate.

Question 79. Which one of the following is considered as pioneer community in xerarch?

  1. Annual herb
  2. Perennial herb
  3. Scrub stage
  4. Forest stage
  5. Lichen

Answer: 5. Lichen

Question 80. Which one of the following statements is correct for secondary succession?

  1. It begins on a bare rock
  2. It occurs on a deforested site
  3. It follows a primary succession
  4. It is similar to primary succession except that it has a relatively fast pace.

Answer: 2. It occurs on a deforested site

Question 81. A sedentary sea anemone gets attached to the shell lining of a hermit crab. The association is:

  1. Symbiosis
  2. Commensalism
  3. Amensalism
  4. Ectoparasitism

Answer: 2. Commensalism

Question 82. A biologist studied the population of rats in a bam. He found that the average natality was 250, average mortality was 240, immigration was 20, and emigration 30. The net increase in population is:

  1. 15
  2. 05
  3. Zero
  4. 10

Answer: 3. Zero

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