Science (English Medium) इयत्ता १२ - CBSE Important Questions for Biology

Write the names of the following:

A 15 mya primate that was ape-like

Write the names of the following:

A 2 mya primate that lived in East African grasslands

With the help of an algebraic equation, how did Hardy-Weinberg explain that in a given population the frequency of occurrence of alleles of a gene is supposed to remain the same through generations?

Differentiate between analogous and homologous structures.

How do cytokine barriers provide innate immunity in humans?

Name two diseases whose spread can be controlled by the eradication of Aedes mosquitoes.

Name the source plant of heroin drug. How is it obtained from the plant?

Your advice is sought to improve the nitrogen content of the soil to be used for cultivation of a non-leguminous terrestrial crop.

1) Recommend two microbes that can enrich the soil with nitrogen

2) Why do leguminous crops not require such enrichment of the soil? 

You have obtained a high yielding variety of tomato. Name and explain the procedure that ensures retention of the desired characteristics repeatedly in large populations of future generations of the tomato crop.

Explain out-breeding, out-crossing and cross-breeding practices in normal husbandry.

Give an example of a bacterium, a fungus and an insect that are used as biocontrol agents

How has the development of bioreactor helped in biotechnology?

Name the most commonly used bioreactor and describe its working.

Explain the roles of the following with the help of an example each in recombinant DNA technology :

Restriction Enzymes

Explain the roles of the following with the help of an example each in recombinant DNA technology :

Plasmids

Mention the chemical change that proinsulin undergoes, to be able to act as mature insulin

Represent diagrammatically three kinds of age-pyramids for human populations.

Following are the responses of different animals to various abiotic factors. Describe each one with the help of an example.

1) Regulate

2) Conform

3) Migrate

4) Suspend

'India has greater ecosystem diversity than Norway." Do you agree with the statement? Give reasons in support of your answer.

Explain the effect on the characteristics of a river when urban sewage is discharged into it.