Control and Co-ordination — BIOLOGY STD 12 Science — Question

1. Why is RNA called an 'adapter'?
2. Draw and label a secondary structure of RNA. How does the actual structure of RNA look like?

This sludge can be used as an inoculum or as a source of biogas. Explain.

Given below are the events that are observed in an artificial hybridisation programme. Selection of parents → Emasculation → Bagging → Collection of pollen from other male plant → Dusting of pollen on stigma — Rebagging.
While, planning for crop improvement involving dioecious plants, which of the above mentioned steps would not be relevant?

Mention the role of the following in E.coli cloning vector pBR 322.

1. Selectable marker.
2. ori.
3. rop.

"A population has been exhibiting genetic equilibrium."
Answer the following with regard to the above statement.

1. Explain the above statement.
2. Name the underlying principle.
3. List any two factors which would upset the genetic equilibrium of the population.
4. Take up any one such factor and explain how the gene pool will change due to factor.

Outline how restriction enzymes are used for removing sections of DNA from a chromosome.

In haploid organisms that undergo sexual reproduction, name the stage in the life cycle when meiosis occurs. Give reasons for your answer.

Name the specific enzyme responsible for nucleotide polymerisation in DNA replication. Write two characteristic features of this enzyme. Name the region on E.coli DNA, where this enzyme can initiate replication.

Explain the following sequence of succession after a forest fire.

What are the two spatial patterns in an ecosystem? Describe them briefly.