Human Reproduction — BIOLOGY STD 12 Science — Question

a. Draw the embryo sac of a flowering plant and label the following:
i. Central cell
ii. Chalazal end
iii. Synergids
b. Name the cell and explain the process it undergoes to develop into an embryo sac.
c. Explain the development of endosperm in coconut.

1. Draw a labelled longitudinal view of an albuminous seed.
2. How are seeds advantageous to flowering plants?

Write the important characteristic of cromagnon man and also clarify that it was closest ancestor of modern man?

1. What is an age pyramid?
2. Explain with the help of figures, the three different types of age pyramids represented by human population.

1. Why are catalytic converters recommended for vehicles?
2. Why should such vehicles use only unleaded petrol?
3. Why is CNG preferred to diesel as a fuel in vehicles?

1. Work out a dihybrid cross upto F, generation between pea plants bearing violet-coloured axial flowers and white-coloured terminal flowers. Give their phenotypic ratio.
2. State the Mendel's law of inheritance that was derived from such a cross.

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

Write a short note on electronic waste. List the various sources of e-wastes and the problems associated with its disposa

Explain the ways by which solid waste can be disposed.

A flower of brinjal plant following the process of sexual reproduction produces 360 viable seeds.
Answer the following questions giving reasons:
How many megaspore mother cells are involved?