List of top Biology Questions asked in CBSE CLASS XII

Fill in the blanks.
(a)Plants are called as___because they fix carbon dioxide.
(b)In an ecosystem dominated by trees the pyramid(of numbers)is___type.
(c)In aqautic ecosystems the limiting factor for the productivity is___.
(d)Common detritivores in our ecosystem are___.
(e)The major reservior of carbon on earth is____.

List any three important characteristics of a population and explain

Select the statement which explains best parasitism.
(a) One organism is benefited.
(b) Both the organisms are benefited.
(c) One organism is benefited other is not affected.
(d) One organism is benefited other is affected.

With the help of suitable diagram describe the logistic population growth curve.

Define the following terms and give one example for each:
(a) Commensalism
(b) Parasitism
(c) Camouflage
(d) Mutualism
(e) Interspecific competition

Define population and community.

Give an example for:
(a) An endothermic animal
(b) An ectothermic animal
(c) An organism of benthic zone

Define decomposition and describe the processes and products of decomposition.

Write a short note on
(a) Adaptations of desert plants and animals
(b) Adaptations of plants to water scarcity
(c) Behavioural adaptations in animals
(d) Importance of light to plants
(e) Effect of temperature or water scarcity and the adaptations of animals.

What is the ecological principle behind the biological control method of managing with pest insects?

An orchid plant is growing on the branch of mango tree. How do you describe this interaction between the orchid and the mango tree?

Name important defence mechanisms in plants against herbivory.

If a population growing exponentially double in size in 3 years what is the intrinsic rate of increase (r) of the population?

Most living organisms cannot survive at temperature above 45°C°. How are some microbes able to live in habitats with temperatures exceeding 100°C?

Define phenotypic adaptation. Give one example.

If a marine fish is placed in a fresh water aquarium will the fish be able to survive? Why or why not?

How is diapause different from hibernation?

How do biofertilisers enrich the fertility of the soil?

Arrange the following in the decreasing order (most important first) of their importance, for the welfare of human society. Give reasons for your answer. Biogas, Citric acid, Penicillin and Curd

Find out the role of microbes in the following and discuss it with your teacher.

(a) Single cell protein(SCP)
(b) Soil