Male-Female determining chromosome:

Male-Female determining chromosome:

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Every living being has a definite number of chromosomes. In human beings there are 23 pairs of chromosome. Among them 22. pairs are similar in both
male and female, these are Autosomes, AA. Members of the remaining pair of chromosome are different in male and female. This pair of chromosome determines the sex of human beings.
As they determine the sex, so they are
called X and y sex chromosome or sex determining chromosome. One of the sex chromosomes is X chromosome and the other is Y chromosome. If the sex chromosome pair is XY, the child will be male (son), and if it is XX, the child will be female (daughter). In Drosophylla (a fly) also XX indicate female and XY male. So in case of determining the sex, the role of X and Y
chromosome is vital.
Whether the child will be a son or daughter:
Now we will discuss whether the father or mother is responsible for the birth of a son or daughter. Both male and female have 44 autosomes, A and a pair of sex chromosome. Sex chromosome of a female is XX and that of the male is XY. The male gamete (sperm) bears X and Y chromosome. But the female gamete (egg) bears X and X. If the X bearing egg of the female is united (fertilize) with Y bearing sperm of
the male, the child will have XY. A child having such chromosomes
will be a male child. It is seen that if there is no Y chromosome, the
child will never be a son. There is no Y chromosome in a female; Y chromosome is present only in male. So if a couple do not have any
male child, the husband is responsible not the wife. A figure on this issue
shows:
The role of sex chromosome in determining sex of the child (i.e. whether the child will be a son or a daughter) is known to you. Now work with this grid. Write which child will be a son and which one a daughter.

Exercise

Multiple choic Questions
1. In which stage the nucleus enlarges in size?
a. Prophase

b. Metaphase
c. Anaphase

d. Telophase
2. By the Process of Mitosis living organisms generally?

i. Ensure the distribution of equal number of chromosomes.
ii. Ensure the equality of properties.
iii. Produced haploid gamete.
Which one of the following is correct?
a. i & ii

b. i & iii
c. ii & iii

d. i, ii & iii

Answer the question no 3 and 4 on the basis of the above diagram.
3. What is the position of father's or mother's chromosomes in the
diagram?
a. Haploid
c. Triploid
4. What type of sex chromosomes will be in the gamete D & daughter H?

D H

a X XY

b X XX

c Y XX

d Y XY

Creative questions
Various type of cell division are seen in all cases starting from prokaryotic
organism to multicellular organism. Someone of these increases the body shape,
some one create germ cells and someone increases the number by the process of
binary fission. Diagram of 1st stage of one type of cell division is given below.

a. In which process of cell division prokaryotic organisms generally multiplied

b. Explain the process of cell division of plant root.

c. Draw a labelled diagram of the stage 2 and describe one characteristic.

d. Analyse with example what will be the probable consequence is the process
of division of stage no. 2 is not under control in a living organism. @@@@ IMPORTANT@@@@

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