d. Studying the recombination frequencies between three traits at once In humans

Question

d. Studying the recombination frequencies between three traits at once In humans which parent determines the sex of their offspring? a. The male bThe female 29 Why are X linked disorders (diseases) far more common than Y linked? The Y chromosome has more genes a. b. c. The Y chromosome has many genes that do not code for sexual traits The X chromosome only codes for feminine traits me has many genes important for things besides sex determination 30. Using the figures above which of them represents a deletion a. b. B 31.A male that has two copies of the X chromosome and one copy of the Y chromosome typically has: a. Klinefelter's syndrome b. Down syndrome c. Cancer d. Turner's syndrome on is the cret of temperatures on Anne

Explanation / Answer

Ans. #28. Correct option- a. The male

Female gamete consists of only X chromosome as sex-determining factor. The male gamete may have either X- or Y-chromosome as sex-determining factor. If a male gamete with X-chromosome fuses with a female gamete (always X-chromosome), the resultant offspring is female. . If a male gamete with Y-chromosome fuses with a female gamete (always X-chromosome), the resultant offspring is male.

Therefore, it is the male gamete that determines the sex of the resultant progeny.

#29. Correct option – d. The X chromosome has many gene for things besides sex determination.

X-chromosome has around 900 genes whereas Y-chromosome has around 36 genes on it.

Besides sex-determination, X-chromosome also encodes several genes like those green-red color vision, clotting factor VIII, IX etc. Therefore, X-linked diseases are more prevalent than Y-linked because it has relatively higher number of genes which may give disease conditions due to mutation or other chromosomal abnormalities.

#30. Correct option- a. A. Due to deletion (loss) of a region, the original chromosome (left chromosome) has become shorter (right chromosome).

# Figure B represents duplication – a region of chromosome is duplicated. So, the resultant chromosome is longer than the original one.

# Figure C represents exchange of regions between two chromosomes (similar to recombination)- so, the resultant chromosome is equal in size to that of original chromosome.

#31. Genotype of the male = 44 (autosomes) + XX + Y = 47, XXY

It is characteristic of Klinefelter syndrome (47, XXY).

So, correct option is- a. Klinefelter syndrome.

# Down syndrome is 21 trisomy, but no extra X-chromosome.

# Turner syndrome is 45,X. That is one X-chromosome is partially or completely lost.

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