Science (English Medium) Class 12 - CBSE Important Questions for Biology

What are the protruding and hanging stretches of DNA produced by these restriction enzymes called? Describe their role in the formation of rDNA.

How did an American Company, Eli Lilly use the knowledge of r-DNA technology to produce human insulin?

Recombination DNA−technology is of great importance in the field of medicine. With the help of a flow chart, show how this technology has been used in preparing genetically engineered human insulins.

State the role of C-peptide in human insulin.

How have transgenic animals proved to be beneficial in production of biological products?

How have transgenic animals proved to be beneficial in chemical safety testing?

A cell-free method of amplifying DNA first developed in the mid 1980's revolutionised the field of biotechnology, Name the method and explain the basic steps of the technique involved.

What is mutualism?

Apart from being a part of the food chain, predators play other important roles. Mention any two such roles supported by examples.

State Gause’s competitive exclusion principle.

Describe the mutual relationship between fig tree and wasp and comment on the phenomenon that operates in their relationship.

Define the following term:

Commensalism

Mention any two examples where the organisms involved are commercially exploited in agriculture.

What is commensalism?

What is brood parasitism? Explain with the help of an example.

“It is often said that the pyramid of energy is always upright. On the other hand, the pyramid of biomass can be both upright and inverted.” Explain with the help if examples and sketches.

How are productivity, gross productivity, net primary productivity and secondary productivity interrelated ?

The primary productivity in an ecosystem is expressed as ______.

1. gm^-2 yr^-1
2. gm^-2 yr
3. Kcal m^-2 yr^-1
4. Kcal m^-2

Assertion (A): Decomposition process is slower if detritus is rich in lignin and cutin.

Reason (R): Decomposition is largely an oxygen requiring process.

List any four techniques where the principle of ex-situ conservation of biodiversity has been employed.