The ultimate source of allelic variation is:

(1) Recombination

(2) Natural selection

(3) Mutation

(4) Drift

Which of the following are correct regarding linked genes?

I. are located near each other on the same chromosome.

II. violate the law of independent assortment

III. segregate together during meiosis

(1) Only I and II

(2) Only I and III

(3) Only II and III

(4) I, II, III

The term "linkage" was coined by :-

1. TH Morgan

2. T Boveri

3. G Mendel

4. W Sulton

Select the correct statement from the ones given below with respect to dihybrid cross.

(1) Tightly linked genes on the same chromosome show higher recombinations

(2) Genes far apart on the same chromosome show very few recombinations

(3) Genes loosely linked on the same chromosome show similar recombinations as the tightly linked ones

(4) Tightly linked genes on the same chromosome show very few recombinations.

Linkage was described by Morgan in Drosophila. Which of the following combinations are correct?

(i) He hybridised yellow bodied, white-eyed females to brown-bodied, red eyed males and then intercrossed their F₁

(ii) The ratio of F₂ generation is same as that of 9:3:3:1 in this cross.

(iii) The parental combinations are observed more than recombinants.

(iv) According to Morgan Linkage was observed due to chemical association of genes.

(v) All the genes present on same chromosomes have same efficiency to link.

(1) (ii), (iv), (v)

(2) (i), (iii)

(3) (i), (iii), (v)

(4) (i) and (iv)

Genes tightly linked on the same chromosome show:

Continuous source of variations in sexually reproducing organisms is

1.  Disjunction of chromosomes.

2.  Crossing over between sister chromatids.

3.  Crossing over between non-sister chromatids.

4.  Mutation.

The number of linkage groups in pea is

1.  14

2.  7

3.  9

4.  24

If a chiasma forms between the loci of genes A and B in 20% of the tetrads of an individual of genotype AB/ab, the percentage of gametes expected to be Ab is:

1. 40

2. 20

3. 10

4. 5

The frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes was explained by: