Biotechnology: Principles and Processes — BIOLOGY STD 12 Science — Question

What is menstrual cycle? Write name of any two stages of menstrual cycle.

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

Regulation of lac operon can be visualised as regulation of enzyme synthesis by its substrate. Explain the statement.

Describe convergent evolution, taking an example from plants.

OR

Convergent evolution leads to analogous structures. Explain with the help of an example.

What is adaptation? Describe it with example.

What does secondary productivity in an ecosystem indicate? List any two factors by which productivity is limited in an aquatic ecosystem.

A new type of drug, PTC 124, enables translation to continue through the nonsense codon. Trials in mice homozygous for a CFTR allele containing the nonsense codon have found that animals treated with PTC 124 produce normal CFTR protein in their cells. The drug is taken orally and is readily taken up into cells all over the body.
Using your knowledge of the progress towards successful gene therapy for cystic fibrosis, suggest why PTC 124 could be simpler and more reliable treatment for this disease.

Cervix contains the largest and the strongest sphincter in its wall. Give reason.

A3' ............ 5'B
C5’ ........... 3'D.
AB and CD represent two strands of a DNA molecule. When this molecule undergoes replication, forming a replication fork between A and C in the above.

1. Name the templete strand for replication.
2. Using which strand as the templete, will there be continuous synthesis of a complementary DNA strand
3. Complementary to which strand will okazaki segments get synthesised, discontinuous synthesis occurs.
4. What are templete strands and Okazaki pieces?
5. In which direction is a new strand synthesised?

What is primary productivity. How does it differ from net primary productivity.