Question

D) A and B only E) A, B, and C 25. Which of the following statements are TRUE? A) It is possible for some individuals with the sex chromosome constitution XY to appear female. B) It is possible for some individuals with the sex chromosome constitution XX to appear male. C) It is possible for some individuals with the sex chromosome constitution XXY to appear female. D) All of the above are FALSE statements. E) All of the above are TRUE statements 26. Red-green colorblindness is a recessive X-linked trait. If a woman is a carrier for the colorblind allele and marries a man with normal color vision, what is the probability of the couple having a colorblind girl? A) 0% B) 25% C) 50% D) 100% E) cannot be determined from the provided information 27. In humans, all phenotypically male individuals have a single X and a single Y chromosome, while all B) FALSE individuals with two X chromosomes are phenotypically female. A) TRUE 28. In humans, the presence of a Y chromosome in the zygote guarantees male sexual development 29.X chromosomome inactivation in mammals occurs A) TRUE B) FALSE A) in the egg of the female prior to fertilization B) in the zygote, immediately following fertilization C) in an early stage of multi-cellular embryonic development D) during puberty E) X chromosome inactivation does not occur in mammals 30. In the cases of individuals having X chromosomes carrying an SRY gene or Y chromosomes missing the SRY gene, the defect occurred during gametogenesis in A) father B) mother c) It could have occurred during either the production of the egg in the mother or during production of the sperm in the father. 31. The male hormone testosterone is also referred to as A) androgen B) estrogen C) cortisol D) esterdiol E) none of the above are correct

Answer 1

25. D, all of the statements are false, XX = female, XY = male and XXY = male with infertility and small reproductive organs.

26. A, 0 % The daughter must receive one of her X chromosomes from her normal father and will not be color-blind.

27. A, true

28. A, True

29. C, late blastula stage in mammals, in early stage of development.

30. C

31. A, androgen