Biology (Theory) Official Board Paper 2021-2022 ISC (Science) ISC Class 12 Question Paper Solution

Write the scientific name of the causative agent of the following disease:

Typhoid

Hybrids are usually superior to their parents. This phenomenon is called ______.

Hybrid depression

Inbreeding depression

Heterosis

Transgenesis

Assertion: Motor vehicles equipped with catalytic converter should use unleaded petrol.

Reason: The catalyst used in the catalytic converter gets inactivated by the lead in the petrol.

Both assertion and reason are true and reason is the correct explanation of assertion.

Both assertion and reason are true but reason is not the correct explanation of assertion.

Assertion is true but reason is false.

Both assertion and reason are false.

Give one significant contribution of S. Cohen.

Expand CNG.

Cancer causing agents are called ______.

Why is the pyramid of energy never inverted?

A person in good health visits a garden where flowers are in bloom. While returning from the garden, he suddenly starts sneezing and wheezing.

1. Name and define the response of the person’s immune system in the above case.
2. State the type of antibody which is produced against such a response.

Write the role of ‘ori site’ in the cloning vector pBR322.

Write the role of ‘restriction sites’ in the cloning vector pBR322.

Define Allen’s rule.

 Define the Standing crop.

The Net primary productivity of a terrestrial ecosystem is 1500 kg per meter square per year, and the respiratory loss of the ecosystem is 1200 kg per meter square per year. Calculate the gross primary productivity of the given ecosystem.

In an ecosystem, a food chain follows the following pattern:

Grass → Insects → Snake → Peacock.

If 2000 J of energy is available at the level of producers in this food chain, how much energy would be available to the peacock?

Explain the significance of bagging in the process of artificial hybridisation of plants.

Explain the significance of emasculation in the process of artificial hybridisation of plants.

What is PCR?

Describe the steps of PCR technique.

What is a Ti plasmid?

Name the organism in which Ti plasmid is found.

In an ecosystem, is the climax stage achieved more quickly during the primary succession or during the secondary succession? Give a reason to justify your answer.

The following diagram represents the population growth curves of two different species, A and B, living together in an area. Answer the following questions based on it.

1. What type of growth patterns are exhibited by the species A and B?
2. Give mathematically equations to represent the growth curves of species A and species B separately.
3. In the diagram, what does the horizontal line K represent?

With reference to inbreeding of cattle, answer the following question:

Define inbreeding

With reference to inbreeding of cattle, answer the following question:

Suggest one advantage of the inbreeding process.

With reference to inbreeding of cattle, answer the following question:

Suggest one disadvantage of the inbreeding process.

Draw a well-labelled diagram of a stirred-tank bioreactor.

What is eutrophication?

Explain the consequences of eutrophication on the life of plants and animals in an aquatic ecosystem.

Define a biogeochemical cycle.

Give a graphic representation of the phosphorus cycle in nature (ecosystem).