# aqa a level biology mitosis

#1
hi,

question 8aiii https://pmt.physicsandmathstutor.com...ll%20Cycle.pdf has me confused

so the mark scheme says that there will be 3 chromosomes
https://pmt.physicsandmathstutor.com...Cycle%20MS.pdf

I thought there'd be 4 because there are 4 chromosomes.

if structure a is a centromere, wouldn't the black one on the opposite side be a centromere too? that would mean there'd be 2 chromosomes in the gamete...?

Thanks
0
1 year ago
#2
So, the question is referring to how many chromosomes will there be in a gamete if this cell undergoes meiosis. Well as you know, a gamete needs to be haploid (has half the number of chromosomes) so if this cell (diploid-2n) undergoes meiosis the 4 daughter cells (gametes) will each have half the number of chromosomes than the diploid cell.

Therefore, this diploid cell has 3 pairs of chromosomes (3 black and 3 white) = 6 chromosomes. Half of 6 is 3 so the number of chromosomes in the gamete will be 3.

Btw the circle in the middle of the sticks is the centromere if you’re getting confused about that...

I hope this helps!
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