Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

Make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination.

Apart from plants and animals, microbes form a permanent biotic component in an ecosystem. While plants have been referred to as autotrophs and animals as heterotrophs, what are microbes referred to as? How do the microbes fulfil their energy requirements?

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

In a sea shore, the benthic animals live in sandy, muddy and rocky substrata and accordingly developed the following adaptations.

1. Burrowing.
2. Building cubes.
3. Holdfasts/ peduncle.

Find the suitable substratum against each adaptation.

How many eggs are released by a human ovary in a month? How many eggs do you think would have been released if the mother gave birth to identical twins? Would your answer change if the twins born were fraternal?

Why medical termination of pregnancy is done? Is MTP legalised in India?

In a typical nucleus some regions of chromatin are stained light and others dark. Explain why it is so and what is its significance.

What is cleavage?

Why are adolescents especially advised not to smoke? How does smoking affect the functioning of the body?