The normal body cell of an organism contains 28 pairs of chromosomes. The number of chromosomes present in its germ cell will be :

The male gametes in a flower and in a human are produced respectively in:

The ratio of number of chromosomes in a human zygote and a human sperm is:

The flask-shaped organ A at the centre of a flower is surrounded by a number of little stalks B having swollen tops which lie just inside the ring of petals.

(a) Name A. What are the various parts of A?

(b) Which part of A contains gametes?

(c) Name B. What is the swollen top of B known as ?

(d) What does the swollen top of B contain ?

(e) Out of A and B, which one is (i) male part, and (ii) female part of the flower?

When an insect sits on the flower of a plant then some particles A present in the top of little stalks in the flower attach to its body hair. When this insect now sits on the flower of another similar plant, then particles A attached to the hair of insect are put on the top of a flask-shaped organ at the centre of flower. The particle A grows a long tube B from the top of flask-shaped organ through which C moves down and reaches the bottom part of flask-shaped organ. Here C fuses with the nucleus of D contained in structure E. The fusion of C and D forms a new cell F which grows and develops into a seed of the plant.

(a) What are particles A ? What is the process of transferring A from one flower to another flower of similar plant by the insect known as ?

(b) What is the name of tube B?

(c) What is C which moves down through the tube B?

(d) Name D and E.

(e) What is F ?