Q. No.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
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
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. |
All progenies of a cross between a tall plant and a short plant are intermediate in size between the two parental plants. When these progenies are allowed to self-pollinate, plants produced followed a normal distribution. This most likely is due to:
| 1. | Overdominance | 2. | Epistasis |
| 3. | Polygenic inheritance | 4. | Incomplete dominance |
A true breeding red striped tree frog is crossed with a true breeding plain green frog. All progeny have red stripes. This is because:
| 1. | Stripes are dominant to plain green coloration. |
| 2. | Striped frogs are camouflaged better. |
| 3. | Plain green frogs are easily predated upon. |
| 4. | Striped frogs are more common. |
A plant breeder is raising many varieties of plants. As a part of the breeding program, he raises pure line varieties by continuous inbreeding over several generations – one with red flowers and another with white flowers. How can Mendel's laws be demonstrated by hybridization between these varieties?
| 1. | Set up a monohybrid cross and determine if your F2 results are predicted by a 3:1 ratio based on the law of segregation. |
| 2. | Set up a dihybrid cross and determine if your F2 results are predicted by a 9:3:3:1 ratio based on the law of independent assortment. |
| 3. | Set a test cross to demonstrate that your traits breed true. |
| 4. | Set up a two-point test cross to demonstrate that your genes are linked. |
Consider three genes: X, Y, and Z. The recombination frequency between X-Y, X-Z, and Y-Z gene pairs was found to be 50%, 25%, and 50%, respectively. What would be the right inference?
| 1. | genes X and Y are on the same chromosome |
| 2. | genes X and Z are on different chromosomes |
| 3. | genes Y and Z are on different chromosomes |
| 4. | All three genes are located on the same chromosome |
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