Chapter 12: End-Chapter Review Worksheet 1. A trait lik e white eyes instead of

Question

Chapter 12: End-Chapter Review Worksheet 1. A trait lik e white eyes instead of red eyes in fruit flies or color blindness instead of normal vision in humans is more commonly seen in males than in females. When that type of inheritance pattern emerges, it is a good indication that the trait is caused by a. a recessive X-linked gene b. an autosomal recessive trait c. a dominant X-linked gene 2. An X-linked carrier isa a. b. c. d. e. heterozygous male homozygous male heterozygous female homozygous female homozygous recessive female 3. Which of the following is correct regarding the sex chromosomes? a. The X chromosome carries more genes for nonsexual traits than does the Y chromosome b, X and Y are different in size but carry nearly equal numbers of genes. c. The Y chromosome carries a greater number of genes than does the X. d. The X chromosome carries only gender-related genes Hemophilia is a sex-linked disorder. Which is the best prediction of the offspring if the mother is a carrier and the father has hemophilia? 4. a. All sons will have hemophilia, and all daughters will be normal b. All sons and daughters will have hemophilia. C. Fifty percent of the sons will have hemophilia, and 50% of the daughters will have hemophilia. d. Twenty-five percent of the daughters will have hemophilia, and all the sons will have hemophilia.

Explanation / Answer

1) X- linked recessive This is the only inheritance pattern where males commonely effected than females.

2) A heterozygous female. Because males have only one X chromosomes so carriers are not possible,males can be either effected or normal.(XY normal, xY effected) females (XX normal, xX carrier, xx effected).

3) option a is correct The X- chromosome carries more genes for nonsexual traits than does the y chromosome.

4) xY * xX (effected father and carrier mother )

xx (effected female), xX (carrier female), xY (effected male), XY(normal male)

So from the above cross we conclude that 50% of the males are effected and 50% females are effected

  

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