Occasionally, chromosomes fail to separate during meiosis leading to daughter ca

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% 4

Explanation / Answer

18).B.Nondisjucntion

failure of chromosomal separation in anaphase of either meiosis or mitosis resulting in abnormal number of chromosomes in the daughter cells,

19. C. 1600; 800

Explanation:

One primary spermatocyte a diploid cell --->two haploid secondary spermatocytes----> four sperm cells.

One secondary spermatocyte----------> two sperm cells

400 primary spermatocytes---> 4 x 400= 1600 sperm cells

400 secondary spermatocytes---> 4 x 200 = 800 sperm cells

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