The diagrams show animal cells from organisms that sexually reproduce. Each diagram shows a single cell containing chromosomes during cell division.
Which one of the following diagrams has a correct description for a cell from an organism with a haploid number of 4?
[Assume that the sex of the organism is inherited in the same way as in humans.]
The correct answer is E.
What are chromatids ?
Chromatin is the general packaging of DNA around histone proteins – this DNA arrangement helps condense DNA to fit within the cell’s nucleus. Throughout most of the cell cycle, DNA is packaged in the form of chromatin. However, chromatin exists in an additional level of an organization known as a chromosome during mitosis and meiosis.
Chromosomes are an even denser chromatin packaging visible with a light microscope, particularly during metaphase. Chromosomes can exist in duplicated or unduplicated states. At the beginning of mitosis, for example, a chromosome consists of two sister chromatids – chromatids are used to describe the chromosome in its duplicated form.
Here is a simple table to show you the number of chromosomes and chromatids during each phase of mitosis and meiosis :
Answering the question
A diploid cell has 2 complete sets of chromosomes, usually written as being a 2n cell, as opposed to a haploid cell, that only has 1 set of each chromosome, and written as a n cell.
In this case, it is said that n = 4 which means that the mother cell is 2n = 8.
All of these cells are undergoing a process of cell division (either mitosis or meiosis). Both of these processes are precedented by a replication of DNA, which means that there would be 16 chromatides.
From that only, we can determine that E is the answer.
Hey, can someone help reexplain the logic to get to the answer for this question to me?
Are the mitosis options instantly ruled out because the question talks about sexual reproduction?
Im struggling to go through the process of eliminating the other options to get to the correct answer (E)
Hey when I first saw the question, my thought process was
Question talks about sexual reproduction = meiosis, B C D is might not be correct.
Leaves to A and E.
Question says n = 4, 2n = 8 is also possible. 8 chromosomes, 16 chromatids.
(A) mentions first division of meiosis = meiosis 1 = homologous chromosomes separate. The picture seems wrong, eliminate A.
Something like this.
+) please correct me if im wrong! 
Yeah, thats what I have ended up thinking but I was just really unsure about the first point you put when I first approached the question Thank you though!
