Genetics And Plant Breeding - Study Mode

[#346] In a random mating population allele frequency between generations are
Correct Answer

(C) Constant

Explanation

Solution: In a random mating, population allele frequency between generations is Constant. Allele frequencies in a population will not change from generation to generation. In a large, random-mating population that is not affected by the evolutionary processes of mutation, migration, or selection, both the allele frequencies and the genotype frequencies are constant from generation to generation.

[#347] Exception to Mendel's law
Correct Answer

(D) Mirabilis

Explanation

Solution: The exception to Mendel's law is Mirabilis. Mendel described dominance but not incomplete dominance. Had he worked with Mirabilis jalapa rather than pea he would have pondered the cross of a plant with red flowers by one with white flowers. All progeny were pink flowered, an intermediate phenotype. An individual who is heterozygous for a gene has two different alleles, but it is not always sufficient to produce an intermediate phenotype.

[#348] Introduction are used as
Correct Answer

(D) None of the above

Explanation

Solution: The introduction of new plant species/varieties into new areas is an integral part of plant breeding. The transfer of specific genes from wild species to cultivated genotypes through genetic engineering can be regarded as domestication. The introduction is not used as a direct variety, a variety after selection, or a parent of a hybrid.

[#349] Wobble hypothesis was given by
Correct Answer

(B) Crick

Explanation

Solution: The wobble hypothesis was given by Crick. In 1966, Francis Crick hypothesized that the cell's limited number of tRNAs decoded the genome by recognizing more than one codon. The ambiguity of that recognition resided in the third base pair, giving rise to the Wobble Hypothesis. The Wobble hypothesis proposes that normal base pairing can occur between nitrogen bases in positions 1 and 2 of the codon and the corresponding bases in the anticodon.

[#350] Match the following columns: Column I Column II a. Pure lines 1. Incomplete dominance b. Mirabilis jalapa 2. Johannsen c. Pleiotropy 3. Sickle-cell anaemia d. Co-dominance 4. Human blood groups
Correct Answer

(C) a-2, b-1, c-3, d-4

Explanation

Solution: a. Pure lines is the term proposed by Johannsen. A pure line means those breeds of organisms that have been generated through repeated self-fertilization and have become homozygous for a particular trait. b. Mirabilis Jalapa shows incomplete dominance because the genes for red and white colour mix in F1 to form pink hybrids. Both the pure characters reappear in the F2 generation. c. Pleiotropy is observed in sickle cell anaemia. Changes in one gene can cause changes in two or more phenotypic features, a phenomenon known as pleiotropy. d. Co-dominance in Human blood groups. Human blood type is determined by codominant alleles. The IA and IB alleles are codominant, and the i allele is recessive. The possible human phenotypes for the blood group are type A, type B, type AB and type O.