Enhancement of Food Production — BIOLOGY STD 12 Science — Question

Write an account of hormones secreted by the thyroid gland.

Distinguish between Hibernation and Aestivation.

Rose plants produce large, attractive bisexual flowers but they seldom produce fruits. On the other hand a tomato plant produces plenty of fruits though they have small flowers. Analyse the reasons for failure of fruit formation in rose.
Both these plants - rose and tomato - both selected by human beings for different characteristics, the rose for its flower and tomato for its fruit. Roses, being vegetatively propagated do not need to produce seeds.

Answer the following questions:
Describe the stages of oogenesis in human females.

Discuss the mode of action and advantages/ disadvantages of hormonal contraceptives.

Justify the following statement in terms of ecosystem dynamics. “Nature tends to increase the gross primary productivity, while man tends to increase the net primary productivity”.

If a desired gene is identified in an organism for some experiments, explain the process of the following:

1. Cutting this desired gene at specific location.
2. Synthesis of multiple copies of this desired gene.

1. A mere 0.1 percent impurities make domestic sewage unfit for human consumption. Categorise the types of impurities with one example each.
2. What is polyblend?
3. Why does a greenhouse warm up?

“Microbes play a dual role when used for sewage treatment as they not only help to retrieve usable water but also generate fuel”. Explain.

How can education help in building up a socially responsible and reproductively healthy society? (Enumerate the aspects that should be emphasised).