91.

Somatic embryogenesis is an important exercise in micropropogation and genetic engineering of plants. The following steps are considered as critical for achieving somatic embryogenesis:

A. Reducing the concentration of sucrose in the medium by half.

B. Addition of the hormone, 2, 4-dichlorophenoxyacetic acid, to induce somatic embryos.

C. Reduce agar concentration to 0.6% (w/v).

D. Use maltose in place of sucrose as a carbon source.

Which one of the following combinations is correct?

• A and C

• B and D

• A and B

• C and D

Of the following, which one of the individuals will NOT necessarily carry the allele responsible for the mentioned trait?

• A woman in a family where an autosomal dominant trait is segregating and her mother and son are affected.

• A daughter of a man who is affected by an X-linked dominant trait.

• A father of a child who is affected with an autosomal recessive trait.

• A father of a boy affected with X-linked recessive trait.

Three somatic hybrid cell lines, designated as X, Y and Z, have been scored for the presence or absence of chromosomes 1 through 8, as well as for their ability to produce the hypothetical gene product A, B, C, and D as shown in the following table:

Which of the following option has most appropriately assigned chromosomes for each of the given genes?

• Gene A on chromosome 5, Gene B on chromosome 3, Gene C on chromosome 8 and Gene D on chromosome 1.

• Gene A on chromosome 5 and Gene B on chromosome 3 only.

• Gene D on chromosome 8, Gene C on chromosome 1, Gene B on chromosome 5 and Gene A on chromosome 4.

• Gene A on chromosome 5, gene B on chromosome 3, and Gene D on chromosome 1.

Consider the following hypothetical pathway:

H allele converts X substance to H substance.

h allele cannot convert X to H substance and leads to phenotype 'O'.

A allele converts H substance leading to A phenotype.

a allele cannot convert H substance.

B allele converts H substance leading to B phenotype.

b allele cannot convert H substance.

An individual with A phenotype, when crossed with that of B phenotype, has a progeny with O phenotype. Which one of the following crosses can lead to the above observation?

• Aahh × BbHH

• AaHh × BBHh

• AaHh × BBHH

• AAHH × BbHh

Two siblings who inherit 50% of the genome from the mother and 50% from the father show lot of phenotypic differences. Which one of the following events during gametogenesis of the parents will maximally contribute to this difference?

• Mutation

• Recombination

• Independent assortment

• Environment

The following pedigree chart shows the inheritance of a given trait

The trait can be called

• autosomal dominant

• autosomal recessive

• X-linked dominant

• sex limited

Mutation in a gene 'X' leads to lethality in a haploid organism. Which one of the following is best suited to analyze the function of gene 'X'?

• Pleiotropic mutants

• Temperature-sensitive mutants

• Recessive mutants

• Mutants with low temperature

Following is a hypothetical biochemical pathway responsible for pigmentation of leaves. The pathway is controlled b two independently assorting genes 'A' and 'B' encoding enzymes as shown below. Mutant alleles 'a' and 'b' code for non-functional proteins.

What is the expected progeny after selfing a plant with the genotype AaBb?

• Green (9) : White (4) : Yellow (3)

• Green (9) : Yellow (4) : White (3)

• Green (9) : Yellow (6) : White (1)

• Green (9): White (7)

Consider an autosomal locus with two alleles A₁ and A₂ at frequencies of 0.6 and 0.4 respectively. Each generation, A₁ mutates to A₂ at a rate of μ = 1 × 10^-5 while A₂ mutates to A₁ at a rate of 2 × 10^-5. Assume that the population is infinitely large and no other evolutionary force is acting. The equilibrium frequency of allele A₁ is

• 1.0

• 0.5

• 0.67

• 0.33

For two species A and B in competition, the carrying capacities and competition coefficients are-

K_A = 150; K_B = 200

α = 1.0; β = 1.3

According to the Lotka-Volterra model of interspecific competition, the outcome of the competition will be

• Species A wins

• Species B wins

• Both species reach a stable equilibrium.

• Both species reach an unstable equilibrium.