Question

question 1 and 2

Question 1: i) If a cell has eight chromosomes before meiosis, how many chromosomes will it have at metaphase I? ii) How many sister chromatids will it have at metaphase 1 ? iii) How many chromosomes will the cells have at metaphase II ? iv) How many sister chromatids will the cells have at metaphase II? v) How many chromosomes will the cells have after telophase II ? vi) How many cells will there be after telophase I ? vii) How many cells will there be after telophase II ? Question 2: i) During gametogenesis a sperm cell undergoes considerable structural change. What are the basics of sperm structure? How does it relate to function?

Answer 1

Answer 1:

After meiosis is complete the number of chromosomes is reduced to half. Meiosis involves two stages: Meiosis I and Meiosis II. Cells with half number of chromosomes are produced after both phases have taken place.

If a cell had 8 chromosomes before meiosis , then:

(i) At metaphase I , there will be 8 chromosomes.

(ii) Sister chromatids at metaphase I will be  (8 x 2 ) , i.e. 16 chromatids.

(iii) Chromosomes at metaphase II = 4

(iv) Sister chromatids at metaphase II = 8

(v) Chromosomes after telophase II = 4

(vi) Number of cells after telophase I = 2

(vii) Number of cells after telophase II = 4

Answer 2:

Basics of sperm structure with functional relevance:

• A sperm has a tapering head which contains  acrosome and nucleus. Acrosome releases enzymes upon encountering ovum, which makes it possible for sperm's nucleus to enter the egg cell. Nucleus of sperm fuses with egg nucleus (fertilization) and nucleus contains the genetic material which is passed to next progeny.
• At the base of head there is a neck, which leads to mid-body. Mid body is rich n mitochondria. Its function us to fuel energy as ATP for sperm mobility in the female reproductive channel.
• At the end, sperm has a thin long tail. Tail has flagella, which makes wave like motion for sperm movement.