Sexual Reproduction in Flowering Plants — BIOLOGY STD 12 Science — Question

Branching descent and natural selection are the two key concepts of Darwinian Theory of Evolution. Explain each concept with the help of a suitable example.

Highlight the differences and a similarity between the following population interactions: competition, predation and commensalism.

Name the type of curve that characterizes most populations growing in favourable environment. Define carrying capacity.

Name the two different categories of microbes naturally occurring in sewage water. Explain their role in cleaning sewage water into usable water.

Double fertilisation is reported in plants of both, castor and groundnut. However, the mature seeds of groundnut are non-albuminous and castor are albuminous. Explain the post-fertilisation events that are responsible for it.

State the stage at which oogonia reach their maximum number.

What is meant by emasculation? When and why does a plant breeder employ this technique?

Answer the following questions:
How does a farmer use the dormancy of seeds to his advantage?

1. Give the scientific name of the soil bacterium which produces crystal (Cry) proteins.
2. How are these proteins useful in agriculture?
3. What do the differently written terms ‘Cry’ and ‘cry’ represent respectively?

Your school has been selected by the Department of Education to organise and host an interschool seminar on 'Reproductive Health-Problems and Practices'. However, many parents are reluctant to permit their wards to attend it. Their argument is that the topic is 'too embarrassing'. Put forth four arguments with appropriate reasons and explanations to justify the topic to be very essential and timely.