Q3 of 33 Page 18

"Gametes must be produced by meiosis for sexual reproduction". Why is it so?

Meiosis is a reduction division as it reduces the number of chromosomes to half, hence the gametes produced through meiosis are haploid. This is essential because when the male and female gametes fuse during the process of fertilization, the normal diploid number of chromosomes is regained.


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1

State the difference between

Haploid and diploid

 2

"First meiotic division is the reduction division".

What does the word 'reduction' refer to in this statement?

 4

Mention whether the following statements are true (T) or false (F). Give reason in support of your answer.

(a) As you grow from childhood to adulthood, your skin cells divide only to replace such cells that are lost from the surface. (T/F)


(b) The unfertilized human egg has half the number of chromosomes of the body cells. (T/F)


(c) The nuclear membrane in a mitotically dividing cell remains intact up to the metaphase and disappears only in the telophase. (T/F)


(d) Mitotic cell division can be a mode of reproduction. (T/F)


(e) Crossing-over between chromatids can occur only between homologous chromosomes. (T/F)

 1

The diagram below represents a stage during cell division. Study the same and then answer the questions that follow:


(a) Name the parts labelled 1, 2 and 3.


(b) Identify the above stage and give a reason to support your answer.


(c) Mention where in the body this type of cell division occurs.


(d) Name the stage prior to this stage and draw a diagram to represent the same.