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CBSE 12th Standard Biology Organisms and Populations Important Questions And Answers Study Material - QB365 Set A

Published on: 28/11/2025

Question Set A

CBSE 12th Standard Biology Organisms and Populations Important Questions And Answers Study Material - QB365

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Std: 12th Standard CBSE - Biology

chapter: Organisms and Populations - Important Questions And Answers

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Questions:

1 Marks

10 x 1 = 10

Give the name of two parasitic plants and two parasitic animals.

What are omnivores?

What is metapopulation?

What is brood parasitism? Explain with the help of an example.

Mention the adaptations the mammals of colder seas have.

What would be the growth curve pattern, when the resources are unlimited?

How does comouflage help an insect?

What is an interaction called, when an orchid grows on a mango plants?

Name the interspecific interaction in which one is detrimental while the other is neutral.

10.

How do snails escape from the stressful time in summer?

Generic 2

5 x 2 = 10

11.

Construct an age pyramid which reflects an expanding growth status of human population

12.

How do mammals living in colder regions and seals living in polar regions able to reduce the loss of their body heat?

13.

What is mutualism? Mention any two examples where the organisms involved are commercially exploited in agriculture.

14.

Give two evidences for the occurence of competition.

15.

How do kangaroo rats live in the absence of water in the North American deserts?

Generic 3

5 x 3 = 15

16.

Why are small animals not found in polar regions. Explain.

17.

Fill in the blanks:
(i) Population dispersion has two main patterns. these are _________ and_________
(ii) The number of individuals of a species present per unit area or volume at a given time is _________
(iii) _________is the natural ability of a population to increase at its maximum rate under ideal conditions.
(iv) Populations have characteristic patterns of growth with time .Two contrasting types of growth forms are_________and._________
(v) The interaction between individuals of same species are termed .... interactions and those between individuals of different species are termed_________interactions.
(vi) Termites and flagellates illustrate _________type of interspecific interaction, Similarly, female mosquitoes and man illustrate_________type of interspecific interaction.
(vii) Succession that starts on a bare rock is called _________and that which begin on sand is called._________

18.

Mutualism often involves co-evolution of the mutualists. Describe taking the example of animal plant (wast-fig) relationship.

19.

Describe any three reproductive strategies that organisms have evolved in relation to a particular set of selective pressures.

20.

List three symptoms of high altitude sickness and state three adaptations to overcome it.

Multiple Choice Question

9 x 1 = 9

21.

Consider the following statements (A-D) each with one or two blanks:
(A) Bears go into(1) during winter to (2) cold weather.
(B) A conical age pyramid with a broad base represents (3) human population.
(C) A wasp pollinating a fig flower is an example of(4).
(D) An area with high levels of species richness is known as (5).
Which one of the following options gives the correct fill ups for the respective blank numbers from (1) to (5) in the statements?

(a)

(3)-stable, (4)-commensalism, (5) marsh

(b)

(1)-aestivation, (2)-escape, (3)-stable, (4)-mutualism

(c)

3-expanding, (4)-commensalism, (5)-diversity park

(d)

(1)-hibernation, (2)-escape, (3)-expanding, (5)-hot spot

22.

Parasite can be explained as an organism which depends on others.

(a)

for food

(b)

for shelter

(c)

for both food and shelter

(d)

for reproduction

23.

Niche is defined as the

(a)

position of species in a community in relation to other species

(b)

place where organism lives

(c)

place where organism lives and performs its duty

(d)

place where population perform their duties

24.

In the sigmoid growth curve, the upper asymptote represents the period od

(a)

establishment

(b)

positive acceleration

(c)

negative acceleratin

(d)

equilibrium

25.

Animals undergo inactive stage during winter is known as

(a)

aestivation

(b)

hibernation

(c)

adaptation

(d)

acclimitisation

26.

Pneumatophores are present/common in

(a)

xerophytes

(b)

hygrophytes

(c)

mesophytes

(d)

halophytes

27.

The term ecology was coined by

(a)

Odum

(b)

E. Munch

(c)

Tansley

(d)

Reiter

28.

In which one of the following habitats does the diurnal temperature of soil surface vary most?

(a)

Forest

(b)

Desert

(c)

Grassland

(d)

Shrub land

29.

Maximum growth rate occurs in

(a)

senescent phase

(b)

lag phase

(c)

exponential phase

(d)

stationary phase

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Answers Key:

1 Marks

10 x 1 = 10

()
Parasitic plants are Cuscuta and Viscum and parasitic animals are mites and lice.

()
Animals that take both animals and plant food.

()
A set of local populations connected by dispersing individuals is called metapo-pulation.

()
Brood parasitism is the phenomenon in which an organism (parasite) lays eggs on the nest of other organism (host).
Example. Eudynamys Cuckoo (koel) bird lays its eggs in the nest of its host and lets the host incubate them. The eggs of the parasitic bird resemble the host's egg in size and colour to reduce the chances of the host bird detecting the foreign eggs and ejecting them from the nest.

()
They have a thick layer of fat (blubber) below their skin, which acts as an insulator.

()
J - shaped growth curve.

()
By comouflage, they avoid being detected by their predators.

()
Commensalism.

()
Amensalism.

10.

()
Snails go into aestivation in summers.

Generic 2

5 x 2 = 10

11.

12.

Mammals from colder climates generally have shorter ears and limbs which minimise heat loss (Allen's rule).
In polar region seals have thick layer of fat (blubber) below their skin that acts as insulator and reduce loss of body heat.

13.

Mutualism is an interaction that confers benefits on both the interacting species. Two examples where organisms involved are commercially exploited in agriculture are:
(i) Mycorrhizae close mutual association between fungi and the roots of higher plants.
Fungi help the plant in absorption of nutrients, while the plant provides food for the fungus.
(ii) Lichens represent an intimate mutualistic relationship between a fungus and photo synthesising algae or cyanobacteria.
Here, the fungus helps in the absorption of nutrients and provides protection, while algae prepare the food.

14.

(i) In some shallow South American lakes, visiting flamingoes and resident fishes compete for their common food, zooplanktons.
(ii) Abingdon tortoise of Galapagos island became extinct when goats were introduced into the island,

15.

(i) The Kangaroo rat is capable of meeting its water requirement through the metabolic water, produced by oxidation of fat.
(ii) It concentrates its urine to a minimal volume.

Generic 3

5 x 3 = 15

16.

Small animals have larger surface area as compared to their volurns. Therefore they tend to lose body heat very fast when it is cold outside and thus they are unable to maintain the constant body temperature and hence not found in polar regions.

17.

(i) Clumped, uniform
(ii) Population size, population density
(iii) Biotic potential, Environmental resistance
(iv) S-shaped(sigmoid), j-shaped
(v) Intraspecific, Interspecific
(vi) Mutualism, parasitism
(vii) Lithosere, psammosere.

18.

Co-evolution of mutualists:
Evolution of the flower characteristics and its pollinator species is highly linked with each other as in wasp-fig relationship.
A given species of fig is pollinated by a specific (partner) wasp species.
The wasp pollinates the fig inflorescence while searching fon a suitable egg laying site.
The female wasp uses the ovary of flowers for oviposition (laying eggs) and the developing seeds provide nourishment to the young ones.
Later the young ones emerge from the fruits of fig.

19.

Reproductive strategies:
(i) Some organisms breed only once in their life time-e.g. Bamboo, Pacific Salmon.
(ii) Some produce a large number of small-sized offspring-Oysters.
(iii) Some breed many times during their life time-e.g. birds.
(iv) Some produce a small number of large sized offspring, e.g. Mammals.

20.

Symptoms include:
(i) nausea
(ii) fatigue, and
(iii) heart palpitations.
Adaptations are:
(i) Increase in breathing rate.
(ii) Increased production of red blood cells.
(iii) Decreasing binding capacity of haemoglobin.

Multiple Choice Question

9 x 1 = 9

21.