Question

How do organisms, whether reproduced asexually or
sexually maintain a constant chromosome number
through several generations? Explain with the help of
suitable example

Answer 1

Organism maintain a constant chromosome number through several generations due to following reasons:

1. Each cell ( diploid ) has two copies of a chromosome ( homologous ).
2. One from male parent ( paternal side ) and other from female parent ( maternal side ).
3. Each gamete will have single copy of a chromosome.
4. Both fuse ( gametes from male parent and female parent ) to restore normal number.

Example.

( 2n ) ( 2n )

male parent female parent

| |

| |

| |

( n ) ( n )

gamete from gamete from

male female

\ /

\ /

\ /

\ /

\ /

\ /

( 2n )

zygote

Answer 2

Answer:

Explanation: The gametes are special types of cells called reproductive cells which contain only half the amount of DNA ( half the number of chromosomes) as compared to the normal body cells of an organism. So when male gamete combines withe female gamete during sexual reproduction then the new cell zygote will have the normal amount of DNA or chromosomes in it

Example: both the human sperm and human egg has 23 chromosomes. So when a sperm answer egg fuse together during fertilization then the zygote formed will be 23+23 =46, which is the normal number of chromosomes

Hope it helps.