Science (English Medium) इयत्ता १२ - CBSE Important Questions

Assertion (A): Synthetic oligonucleotide polymers are used during Annealing in a PCR.

Reason (R): The primers bind to the double stranded DNA at their complementary regions.

Write the scientific name of the source organism of the thermostable DNA polymerase used in PCR.

State the advantage of using Thermostable DNA polymerase.

Bioreactors are the containment vehicles of any biotechnology-based production process. For large scale production and for economic reasons the final success of biotechnological process depends on the efficiency of the bioreactor.

Answer the following questions w.r.t. the given paragraph:

1. List the operational guidelines that must be adhered to so as to achieve optimisation of the bioreactor system. Enlist any four.
2. Mention the phase of the growth we refer to in the statement "Optimisation of growth and metabolic activity of the cells".
3. Is the biological product formed in the bioreactor suitable for the intended use immediate? Give reason in support of your answer.

'EcoRI' has played a very significant role in rDNA technology.

1. Explain the convention for naming EcoRI.
2. Write the recognition site and the cleavage sites of this restriction endonuclease.

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

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?

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.