Q38:
Chromatin is multiple Nucleosomes, Nucleosome is a section which will be repeated , it’s composed of some DNA and Histone proteins (DNA wraps around them)
Chromosome Y is smaller than Chromosome X
Histone is a protein
so : Chromosome X> Chromosome Y> Nucleosome > Histone
Q 28; this is a tricky question
a cell with n=4 means, it has 4 chromosomes which aren’t paired
imagine you have 4 balloons, 1 red, 1 green, 1 yellow, 1 blue.
a cell with 2n=8 , means it has 8 chromosomes but they are paired in 4 groups:
imagine you have 8 balloons, 2 red, 2 green, 2 yellow, 2 blue.
now let’s look at the answers
A) The picture doesn’t correspond with the description, it is showing sister chromatids being pulled, this does not happen in Anaphase I, in Anaphase I, the homologous chromosomes of each Tetrad is being pulled.
B) The picture doesn’t correspond with the description, if it is Anaphase of a mitosis of a 2n=8, on either side there should be 8 chromosomes, let’s explain with the balloon colors again, on either side, there should be 2 red 2 green 2 yellow & 2 blue. meaning you should have 8 chromosomes on either side.
C) The picture doesn’t correspond with the description , the picture is showing metaphase 1 of meiosis, (Tetrads are in equatorial plane), also it just says a cell with 8 chromosomes, no specification, the cell could be either n=8 or 2n=8.
D) This needs understanding of chromatids, when we have a replicated DNA in chromosome form , we have 2 sister chromatids but one chromosome, imagine you have a balloon you clone this balloon now you have 2 balloons, you make the 2 balloons stick to each other in the middle , when you had that one balloon that’s one chromosome , one chromatid, when you had 2 balloons that’s 2 chromosomes 2 chromatids, when you made them stick to each other that’s one chromosome but 2 chromatids. the picture shows metaphase of mitosis but if it’s 4 chromatids, there should only be 2 chromosomes, not 4. in the picture there is 4 Chromosomes and 8 chromatids.
E) This cell shows prophase, we have 8 chromosomes , we have 4 pairs of look alike chromosomes ,2n=8 ( the balloon : 2 red, 2 yellow, etc.) and 16 chromatids.