Question

Match the column:

(a) Pachytene	(i) Pairing of homologous chromosomes
(b) Metaphase I	(ii) Terminalisation of chiasmata
(c) Diakinesis	(iii) Cross-over takes place
(d) Zygotene	(iv) Chromosomes align at equatorial plate

• A. a- iv, b-iii, c-ii, d-i
• B. a- iii, b-iv, c-ii, d-i
• C. a- i, b-iv, c-ii, d-iii
• D. a- ii, b-iv, c-iii, d-i

Answer 1

Answer: (B)

a- iii, b-iv, c-ii, d-i

• During pachytene, the homologous chromosomes thicken and become recombinant. Crossing over of segments of genetic information occurs between non-sister chromatids of homologous chromosomes, forming exchange sites called chiasmata and resulting in recombination
• During metaphase, the kinetochore microtubules pull the sister chromatids back and forth until they align along the equator of the cell, called the equatorial plate.
• Diakinesis. the final stage in the first meiotic prophase in gametogenesis, in which the chromosomes achieve their maximum thickness. The chiasmata and nucleolus disappear, the nuclear membrane degenerates, and the spindle fibres form in preparation for the formation of dyads.
• Zygotene is the sub-stage where synapsis between homologous chromosomes begins. It is also known as zygonema. These synapsis can form up and down the chromosomes allowing numerous points of contact called 'synaptonemal complex', this can be compared to a zipper structure, due to the coils of chromatin.

So, the correct answer is 'B'.