Genetics And Plant Breeding - Study Mode

[#676] The concept of vertical and horizontal resistance was introduced by
Correct Answer

(B) Vander Plank (1963)

Explanation

Solution: The concept of vertical and horizontal resistance was introduced by Vander Plank (1963). The term vertical resistance, used commonly in the context of plant selection, was first used by J. E. Vanderplank to describe single-gene resistance. This contrasted with the term horizontal resistance which was used to describe many-gene resistance. In vertical resistance, there are single genes for resistance in the host plant, and there are also single genes for parasitic ability in the parasite. This phenomenon is known as the gene-for-gene relationship.

[#677] Seed multiplication ratio in paddy is
Correct Answer

(B) 1 : 80

Explanation

Solution: Seed multiplication ratio in paddy is 1 : 80. The process of seed planning involves the use of the Seed Multiplication Ratio (SMR) in computation and estimation of seed demand in the country. It is the number of seeds to be produced from a single seed when it is sown and harvested. At the time of the release of a variety, a small quantity of seed normally known as nucleus seed is available with the plant breeder.

[#678] The following amongst the molecular markers is codominant in nature
Correct Answer

(B) SSR and RFLP

Explanation

Solution: SSR and RFLP molecular markers are codominant. RFLP, as a molecular marker, is specific to a single clone/restriction enzyme combination. Most RFLP markers are co-dominant (both alleles in the heterozygous sample will be detected) and highly locus-specific. SSRs are co-dominant markers so they can distinguish heterozygotes from homozygotes. The main advantages of SSRs are their high level of polymorphism and their reliability.

[#679] Two crosses between the same pair of genotypes or phenotypes in which the sources of the gametes are reversed in one cross, is known as
Correct Answer

(C) Reciprocal cross

Explanation

Solution: Two crosses between the same pair of genotypes or phenotypes in which the sources of the gametes are reversed in one cross, is known as a Reciprocal cross. Reciprocal cross is a kind of crossing strategy, which means to make crosses between a pair of parents (A and B) by using them in turn as female parent and male parent to obtain two reciprocal crosses of A × B and B × A. Reciprocal cross is a concept of crossing a pair of parents with the sexes reversed and it results in obtaining two reciprocal crosses.

[#680] Transposable elements were discovered by
Correct Answer

(A) McClintock

Explanation

Solution: Transposable elements were discovered by McClintock. McClintock went on to discover other such mobile elements, now known as transposons. She also found that depending on where they are inserted into a chromosome these mobile elements could reversibly alter the expression of other genes. Transposable elements (TEs), also known as "jumping genes," are DNA sequences that move from one location on the genome to another.