Enhancement of Food Production — BIOLOGY STD 12 Science — Question

Explain about artificial methods of vegetative reproduction.

1. Mature seeds of legumes are non-albuminous.Then, can it be considered that double fertilization does not occur in legumes? Explain your answer.
2. Write one similarity and one difference between autogamy and geitonogamy.

Define Hamburger’s phenomenon. Add a note on it.

Study the given pedigree chart and answer the questions that follow:
Is the trait sex–linked or autosomal?

Give reasons: Missing of menses is the first indication of pregnancy.

Mention the six harmful effects of noise on human health.

A group of youth were having a 'rave party' in an isolated area and was raided by police. Packets of ‘smack’ and syringes with needles were found littered around.

1. Why is taking ‘smack’ considered an abuse?
2. Write the chemical name of ‘smack’ and the name of its source plant.
3. Syringes and needles used by the youth for taking the drug could prove to be very fatal. Why?

What are the most important ecological services whose value cannot be determined?

The cytological observations made in a number of insects led to the development of the concept of genetic/ chromosomal basis of sex-determination mechanism. Honey bee is an interesting example to study the mechanism of sex-determination. Study the schematic cross between the male and the female honey bees given below and answer the questions that follow:

1. Identify the cell divisions ‘A’ and ‘B’ that lead to gamete formation in female and male honey bees respectively.
2. Name the process ‘C’ that leads to the development of male honey bee (drone).

Enlist the various connective tissue layers in a nerve along with their location.