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. |
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. |
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. |
All the following are mechanisms of sex determination in living organisms except:
1. The Z-W system
2. The X-O system
3. The haplo-diploid system
4. The parthenogenetic system
Pedigree analysis rather than conventional methods are used to study genetic traits because:
I. | Number of progeny is limited |
II. | Choice matings are not possible |
III. | Sexual dimorphism is seen in humans |
1. | I only | 2. | II only |
3. | III only | 4. | Both I and II |
Match the disorder in Column I with the location of the gene causing it in Column II and select the correct option from the codes given:
|
COLUMN I |
|
COLUMN II |
A. |
Sickle cell anaemia |
a. |
Chromosome 11 |
B. |
Phenylketonuria |
b. |
Chromosome 12 |
C. |
Cystic fibrosis |
c. |
Chromosome 7 |
D. |
Huntington’s disease |
d. |
Chromosome 4 |
Codes:
A | B | C | D | |
1. | a | b | c | d |
2. | b | a | c | d |
3. | a | b | d | c |
4. | b | a | d | c |
The pedigree shown below cannot be:
I. | Autosomal dominant disorder |
II. | Autosomal recessive disorder |
III. | Sex-linked dominant disorder |
IV. | Sex-linked recessive disorder |
V. | Holandric disorder |
1. | I, II, and III only | 2. | I, II, III, and V only |
3. | I, III, IV, and V only | 4. | I, II, III, IV and V |
The recombination frequencies for four different linked genes of Drosophila are shown in the figure:
The order of the four genes will be:
1. | rb-cn-vg-b | 2. | vg-b-rb-cn |
3. | cn-rb-b-vg | 4. | b-rb-cn-vg |
Given below are different levels of organization of genetic material. Arrange them in the correct descending order of their size:
1. | Genome, chromosome, gene, nucleotide |
2. | Gene, chromosome, nucleotide, genome |
3. | Chromosome, gene, genome, nucleotide |
4. | Chromosome, genome, nucleotide, gene |