Occasionally, chromosomes fail to separate during meiosis leading to daughter ca
ID: 164856 • Letter: O
Question
Occasionally, chromosomes fail to separate during meiosis leading to daughter called have an abnormal number of chromosomes This phenomenon is called epistasis nondisjunction crossing over pleiotropy chromosome inactivation In a healthy male, how many sperm cells would be expected to form from (a) 400 primary spermatocytes? (b) 400 secondary spermatocytes? (a) 800, (b) 800 (a) 1600, (b) 1600 (a) 1600. (b) 800 (a) 400. (b) 400 (a) 400. (b) 800 In a healthy female, how many secondary oocytes would be expected to form from 100 primary oocytes1 How many first polar bodies would be expected from 100 primary oocytes? 200; 50 100; 50 200; 200 100; 100 50; 50 The sex of birds, some insects, and other organisms is determined by a ZW chromosomal arrangement in which the males have like sex chromosomes (ZZ) and females are ZW (similar to AT in humans) Assume that a recessive lethal allele on the Z chromosome causes death of an embryo in birds What sex ratio would result in the offspring if a cross wore made between a male heterozygous for the lethal allele and a normal female? 4:1 male to female 2:1 male to female 3:1 male to female 1:2 male to female 1:1 male to female A recessive gene for red-green color blindness is located on the X chromosome in humans Assume that a woman with normal vision (her father is color-blind) marries a color-blind male. What is the likelihood that this couple's first son will be color-blind? 0% 25% 50% 75% 100% 4Explanation / Answer
The answer for 1st question is option B that is non- disjunction.
In the Non- disjunction their is a failure of homologus chromosomes or sister chromatids to get separated during meiosis I or II or in mitosis too. That leads to the unequal number of chromosome distribution in the daughter cells. That is also called as "Aneuploidy".
2nd- In the process of Spermatogenesis, it starts with the diploid spermatogonium(2n) that gets divide mitotically and gives 2 diplod primary spermatocytes (2n).Then (2n) primary spermatocyte undergoes meiosis I to produce 2 haploid (n) secondary spermatocytes. In meiosis II the secondary spermatocytes produce 4 haploid (n) spermatids.
So the answer for 400 primary spermatocyte would be 1600, and for 400 secondary spermatocytes would be 800. The option C is the answer.
3rd- The answer for this one is D.
In the process of oogenesis, the diploid (2n) oogonium undergoes mitosis to form diploid (2n) primary oocyte. then primary oocyte undergoes meiosis I to produce one haploid (n) secondary oocyte and a first polar body. So if you consider 100 primary oocytes, then it will give 100 secondary oocytes and 100 polar bodies.
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