Reproduction in organisms — BIOLOGY STD 12 Science — Question

In a Polymerase Chain Reaction (PCR), give the temperature required for the steps:

1. Denaturation.
2. Annealing.
3. Extension, respectively.

Public all over India is very much concerned about the deteriorating air quality in large parts of North India. Alarmed by this situation the Resident's Welfare Association of your locality organised an awareness programme entitled "Bury not burn'. They invited you, being a biology student to participate.

1. How would you justify your arguments that promote burying and discourage burning? (Give two reasons).
2. With the help of flowcharts, one for each practice, depict the chain of events that follow.

Water pollinated (hydrophilous) plants.

Answer the following questions:
Explain female heterogamety with the help of an example.

Differentiate between primary and secondary succession. Provide one example of each.

Kishor visited his village and saw some trees on the boundary of the agricultural field. He thought that these are for partioning the land and discussed the matter with his grandfather. His grandfather explained him the utility of trees to the farmers and the farmlands.

1. What are the benefits these trees impart to the farmland?
2. What are such trees called?

Refer to the diagram given below and answer the questions that follows.

1. Label the parts A and B.
2. Which part of flower develops into seed and fruit?
3. What is the function of both the labeled parts?

Two types of aquatic organisms in a lake show specific growth patterns as shown below, in brief period of time. The lake is adjacent to an agricultural land extensively supplied with fertilisers.

Answer the questions based on the facts given above:

1. Name the organisms depicting the patterns A and B.
2. State the reason for the growth pattern seen in
3. Write the effects of the growth patterns seen above.

'Predation is beneficial in long run'. Comment.

Name two acid producing bacteria.