71.

Following are certain statements regarding somatic hybridization, a technique used for plant improvement.

A. Protoplasts of only sexually compatible plant species can be fused.

B, Hybrids are produced with variable and asymmetric amounts of genetic material of parental species.C. Protoplast fusion permits transfer of gene block or chromosomes.

D. Genes to be transferred need to be identified and isolated.

Which one of the following combinations of the above statements is correct?

• A and C

• B and C

• A and D

• B and D

An analysis of four microsatellite markers was carried out in a family showing a genetic disorder. The results are summarized below:

Based on the above, which of the markers shown linkage to the disorder?

• M1

• M2

• M3

• M4

A hypothetical biochemical pathway for the formation of eye color in insect is given below:

Two autosomal recessive mutants 'a' and 'b' are identified which block the pathway as shown above. Considering that the mutants are not linked, what will be the phenotype of the F₂ progeny if crosses were made between parents of the genotype aaBB × AAbb, and the F₁ progeny are intercrossed?

• 9 orange-brown : 3 orange : 3 brown : 1 colorless

• 9 orange-brown : 7 colorless

• 1 orange : 2 colorless

• 15 orange-brown : 1 colorless

A co-transduction experiment was performed to decipher order of 4 genes: a, b, c, and d. Three sets of experiments were done where transductants were selected for a (Set-1) or b (Set-2) or c (Set - 3) and screened for co-transduction of the other markers.

SET 1-

SET 2-

SET 3-

Based on the frequencies shown above, identify the most likely order in the genome.

• a b c d

• b c d a

• c d a b

• a d b c

In Neurospora, the mutant stp exhibits erratic stop-and-start growth. When a female of stp strain is crossed with a normal strain acting as a male, all progeny individuals showed stp mutant phenotype. However, the reciprocal cross resulted in all normal progeny individuals. These results can be explained on the basis of

A. maternal inheritance

B. sex limited inheritance

C. sex influenced inheritance

D. stp mutation may be located in mitochondrial DNA.

The most appropriate statement or combination of the above statements for explaining the experimental results is:

• A and C

• C only

• A and D

• B and D

Autotetraploids arise by the doubling of 2n complement to 4n. There are three different pairing possibilities at meiosis in tetraploids as given below:

A. Two bivalents

B. One quadrivalent

C. One univalent + one trivalent

Which of the above pairing can lead to production of diploid gamete?

• Only A

• B and C

• A and C

• A and B

A mutant was experimentally generated which had wings reduced to haltere like structure. The following statements are put forward regarding this phenotype:

A. ultrabithorax gene ectopically expressed in second thoracic segment.

B. antennapedia gene ectopically expressed in second thoracic segment.

C. A homeotic mutation.

D. A mutation in gap gene

The following combination of statements will be most appropriate explaining the molecular basis of mutant phenotype:

• A and B

• B and C

• C and D

• A and C

A null mutation is created in a gene which is responsible for specific phosphorylation at 6^th carbon position mannose on acid hydrolases occurring in cis-Golgi. The following statements are given towards explaining the effect of this mutation:

A. The lysosomes will be devoid of lysosomal enzymes.

B. Lysosomal enzymes will be secreted out.

C. Lysosomal enzymes will gel localized in cytoplasm.

Which statement or combination or statements will explain the effect of mutation if the acid hydrolases in the mutant do not get degraded?

• A and C

• B and C

• C only

• A and B

The degree of genetic relatedness between the offspring and their parent is

• higher than that between sister and brother.

• lower than that between sister and brother.

• the same as that between sister and brother

• dependent on the number of siblings

An interrupted mating experiment was performed between Hfr Str^S a⁺ b⁺ c⁺ and F^- Str^r a^- b^- c^- strains. The genotype of majority of streptomycin-resistant (Str^') exconjugant after 10, 20 and 30 minutes of interrupted mating is given below:

10 min	a+ b- c-
20 min	a+ b- c+
30 min	a+ b+ c-

The most probable gene order would be

• a b c

• c a b

• b a c

• a c b