Identify the condition where the following karyotype is expected:
1. Klinefelter’s syndrome
2. Cri du chat syndrome
3. Turner’s syndrome
4. Down’s syndrome
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Which of the following experiments can show a gene to be located on the X-chromosome?
I. set up reciprocal crosses
II. set up two point test cross
1. Only I
2. Only II
3. Neither I nor II
4. Both I & II
A man and woman who both have normal pigmentation but both having an albino parent have two children both with normal pigmentation. What is the probability that their child might be an albino?
1. 0
2. ¼
2. ½
3. ¾
Identify the chromosomal aberration:
1. | Inversion | 2. | Reciprocal translocation |
3. | Deletion | 4. | Duplication |
Sons inherit the following exclusively from their mothers:
I. SR Y gene
II. X chromosome
III. Mitochnodrial DNA
1. Only II
2. Only I and III
3. Only II and III
4. Only III
Identify the chromosomal aberration:
1. Inversion
2. Translocation
3. Deletion
4. Duplication
A couple comes to you for genetic counselling. Both have a sister affected with albinism but all other members are normal. Your advice regarding the risk of their child being affected with albinism would be:
1. | They must both be heterozygotes so their risk of having an affected child is ¼. |
2. | They might both be heterozygotes so they should get tested to see if they carry the disease allele or not. |
3. | Since neither one of them is affected, they are not at risk of having an affected child. |
4. | You can't give them any firm answers because you don't know their genotypes. |
Two genes are linked. The frequency of recombinants formed between the two loci will be:
1. different between males and females.
2. determined by their relative dominance.
3. the same as if they were not linked.
4. proportional to the distance between them.
Linkage maps:
1. | always have a total of 100 map units. |
2. | can be used to pinpoint the precise physical position of a gene on a chromosome. |
3. | are a genetic map based on recombination frequencies. |
4. | reflect the frequency of crossing over between X and Y chromosomes. |
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Sex-linked recessive traits are more common in males of the species than females. This is because:
1. | males are hemizygous for the X chromosome. |
2. | male hormones such as testosterone often exacerbate the effects of mutations on the X chromosome. |
3. | female hormones such as estrogen often compensate for the effects of mutations on the X. |
4. | X chromosomes in males generally have more mutations than X chromosomes in females. |