Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions for Biology

Explain the process of replication of a retrovirus after it gains entry into the human body.

Correct the following statement:

All sexually transmitted diseases are completely curable.

Explain the law of dominance using a monohybrid cross.

What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?

Microbes can be used to decrease the use of chemical fertilisers and pesticides. Explain how this can be accomplished.

Find out the role of microbes in the following:

Soil

How do biofertilisers enrich the fertility of the soil?

In an ecosystem dominated by trees, the pyramid (of numbers) is ______ type.

Distinguish between upright and inverted pyramids.

Distinguish between a food chain and a food web.

Describe with examples of pyramids of number and biomass.

Discuss briefly Defunct ships and e-wastes.

Discuss briefly the following:

Municipal solid wastes

How does the application of the fungal genus, Glomus, to the agricultural farm increase the farm output? 

1. What precaution(s) would you recommend to a patient requiring repeated blood transfusion?
2. If the advise is not followed by the patient, there is an apprehension that the patient might contract a disease that would destroy the immune system of his/her body. Explain with the help of schematic diagram only how the immune system would get affected and destroyed.

How does the application of cyanobacteria help improve agricultural output?

Write the complete name of the diagnostic test for AIDS.

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? 

Define biofertilizers. Give two types of fungal biofertilizers

“The pyramid of biomass is not always upright.” Explain the statement.