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?

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

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

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 ?

When a human female reaches a certain age then vaginal bleeding occurs for a few days after regular time intervals.

(a) What is this process known as (i) in scientific terms, and (ii) in everyday language?

(b) At what approximate age this process starts in human females? What is the human female said to have attained at this stage ?

(c) After how much time is this process repeated? For how many days this process usually lasts?

(d) What does the onset of this process in human females signify?

(e) At which particular event in the life of a human female this process stops temporarily but starts again?

(f) At which approximate age of human female this process stops permanently ?