Genetics And Plant Breeding MCQ Question and Answer | Agriculture MCQ Question

'Colchicine' is generally used for Chromosome doubling.
Colchicine is an important mutagen that works by preventing the formation of microtubules and doubles the number of chromosomes.
It is commonly used to develop polyploid plants and functions as a mitotic poison by producing many mutagenic effects on plants.

Abscisic acid is produced during water stress and causes the closure of stomata.
Abscisic acid (ABA) is a plant hormone involved in the response of plants to reduced water availability.
Reduction of guard cell turgor by ABA diminishes the aperture of the stomatal pore and thereby contributes to the ability of the plant to conserve water during periods of drought.

Inbred maize lines are maintained by Self-pollination.
Inbred lines have been a rich resource for fundamental and applied investigations in maize. They constitute a sampling of the genetic diversity in Zea mays L. that has been captured and partitioned into an array of uniform, reproducible genotypes.
The nucleus seed of inbred lines can be maintained by self-pollination, sib-pollination, or a combination of the two procedures.

Genomic imprinting occurs in Plants, Animals, and Humans.
Genomic imprinting is a process of silencing genes through DNA methylation. The repressed allele is methylated, while the active allele is unmethylated.
Genomic imprinting refers to a form of epigenetic gene regulation whereby alleles are differentially expressed in a parent-of-origin-dependent manner.
Imprinting evolved independently in flowering plants and therian mammals in association with the elaboration of viviparity and a placental habit.

Hutchinson proposed Phylogenetic classification.
A system of plant taxonomy by John Hutchinson, the Hutchinson system, was published as The families of flowering plants, arranged according to a new system based on their probable phylogeny (two volumes) in three editions; 1^st edition 1926 - 1934; 2^nd edition 1959; 3^rd edition, 1973.
Hutchinson divided the Phylum Angiospermae into two Subphyla Dicotyledones and Monocotyledones. The Dicotyledones are further divided into two divisions-Lignosae (arboreal) and Herbaceae (herbaceous).

A plant having both male and female flowers is known to be Monoecious.
It is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant.
It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is connected to anemophily.

Jagannath is the following rice variety that has been developed through induced mutagenesis.
Jagannath possesses important low land variety characteristics. The short height of the variety may be due to the involvement of more than one dominant gene.
Semi-dwarf, strongly photosensitive high seed dormancy. Days to 50% flowering 120 days.
It is fairly resistant to stem borer. Board Spectrum of field resistance to major pests and diseases.

In a cross, if we get 8 types of gametes from both male and female parents, the resultant selfing will produce a ratio of 27 : 9 : 9 : 9 : 3 : 3 : 3 : 1.

Conditions for Hardy-Weinberg law to operate are Population size should be large, Open pollination should occur, and Selection should not be carried out.
The Hardy-Weinberg principle, states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.
Small population sizes can cause a random change in allele frequencies. This is due to a sampling effect and is called genetic drift.
Selection, in general, causes allele frequencies to change, often quite rapidly. While directional selection eventually leads to the loss of all alleles except the favoured one.

Folded fiber model of chromosome organisation was proposed by DuPraw.
Based on an electron microscopic examination of the chromosome, DUPRAW (1968) proposed a “folded fiber model” of the metaphase chromosome structure.
According to this, the fundamental elements of the chromosomes are long DNA-protein fibers with diameters of about 23 nm.