Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions

A sexually transmitted disease symptomised by the development of chancre on the genitals is caused by the infection of ______.

The characters which appear in the first filial generation are called ______.

Which of the following trait is controlled by dominant autosomal genes?

Which one is not a sexually transmitted disease?

Disease or infections which are transmitted through sexual intercourse are collectively called ______.

The best method to determine the homozygous and heterozygous of an individual is ______.

Hepatitis-B, AIDS and genital herpes are the STDs that can be cured.

STDs can be considered as self-invited diseases. Comment.

Suggest the reproduction-related aspects in which counselling should be provided at the school level.

STDs are a threat to reproductive health. Describe any two such diseases and suggest preventive measures.

Mycorrhiza does not help the host plant in ______.

Which one of the following is not a nitrogen-fixing organism?

Why are blue green algae not popular as biofertilisers?

How do mycorrhizal fungi help the plants harbouring them?

Why are cyanobacteria considered useful in paddy fields?

Give two examples of biofertilizer.

Pyramid of numbers is ______.

What does the base tier of the ecological pyramid represent?

Name any two organisms which can occupy more than one trophic level in an ecosystem.

Organisms at a higher trophic level have less energy available. Comment.