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

a. B-chromosomes are extrachromosomal. B chromosomes are extra chromosomes to the standard complement that occur in many organisms. They can originate in several ways including derivation from autosomes and sex chromosomes in intra- and interspecies crosses.
b. Mitosis is also known as Equational division. Mitosis is the process of cell division wherein the chromosomes replicate and get equally distributed into two daughter cells, therefore it is also known as equational division.
c. Meiosis is also known as Reduction. Meiosis is sometimes called "reduction division" because it reduces the number of chromosomes to half the normal number.
d. The colourless plastids are known as Leucoplasts. Leucoplasts are colourless plastids and mainly help in the storage of food compounds like starch, proteins or fats.

The concept of the single-seed descent method was developed by Goulden (1939).
SSD is the modification of the bulk method. It is first proposed by Goulden (1939) and later modified by Brim (1966).
Instead of bulking a whole seed lot of selected plants, a single seed is selected randomly from each selected plant to make bulk.
The SSD method consists of advancing hybrid populations by taking a single seed from each plant and compositing the seeds to perpetuate the next generation.

When an embryo originates from an unfertilized egg, is known as Parthenogenesis.
It is a natural form of asexual reproduction in which the growth and development of embryos occur in a gamete (egg or sperm) without combining with another gamete.
In plants, parthenogenesis is a component process of apomixis. In algae, parthenogenesis can mean the development of an embryo from either an individual sperm or an individual egg.

In the mutation breeding programme, the mutant population can be selected in the F2 generation.
Mutation breeding refers to the method of using artificial mutagenesis to obtain new biological cultivars, mainly through chemical or radiation mutagenesis.
In order to generate mutants with desirable traits to be bred with other cultivars. Plants created using mutagenesis are sometimes called mutagenic plants or mutagenic seeds.

The pure line is the progeny of a selfed homozygous plant.
The pure line is the progeny of a single self-fertilized homozygous plant. The concept of pure line was proposed by Johannsen on the basis of the studies with beans variety.
He obtained the seeds from the market and observed that the lot consisted of larger as well as smaller seeds. Progeny of larger seeds produced larger seeds and the progenies of smaller seeds produced small seeds only.

Over time there is a loss in vigour and productivity of clones. The phenomenon is known as Clonal degeneration.
The loss in vigour and productivity of clones with time is known as clonal degeneration and it may be due to mutation and infection of viruses and bacteria.
It is when cannabis clones lose their uniqueness in producing certain properties or compounds, including cannabinoids and terpenes.

For vigour test, the Paper piercing method was proposed by Fritz, in 1965.
Seed vigour is an important quality parameter that needs to be assessed to supplement germination and viability tests to gain insight into the performance of a seed lot in the field or storage.
The principle of the paper piercing test is similar to that of the brick gravel test. High vigour seed lots are expected to produce strong seedlings which can pierce a particular type of paper while seedlings of poor vigour lots may not be able to pierce the paper. Therefore, the seedlings which emerge by piercing the paper.

Self-incompatibility was first reported by Koelreuter.
Self-incompatibility (SI) is a general name for several genetic mechanisms that prevent self-fertilization in sexually reproducing organisms and thus encourage outcrossing and allogamy.
Self- incompatibility was first reported by Koelreuter in the middle of the eighteenth century. It has been extensively studied in different plant families after the first discussion on self-incompatibility by Darwin (1877). The term self-incompatibility is given by Stout in 1917.

When the pollen from one plant falls on the stigma of another flower of the same plant is Geitonogamy.
Geitonogamy is when pollen is exported using a vector (pollinator or wind) out of one flower but only to another flower on the same plant. It is a form of self-fertilization.
In flowering plants, pollen is transferred from one flower to another flower on the same plant, and in animal-pollinated systems, this is accomplished by a pollinator visiting multiple flowers on the same plant.

In tobacco, Nicotiana dighila originated from a cross between N. tabacum and N. glutinosa.
tobacco plants are cultivated as ornamental garden plants. N. tabacum is grown worldwide for the cultivation of tobacco leaves used for manufacturing and producing tobacco products.
Nicotiana tabacum, or cultivated tobacco, is an annually grown herbaceous plant of the Nicotiana genus.
N. glutinosa is a Dicotyledon and is from the family of Solanaceae. The use of N. glutinosa in tobamoviruses allowed for the death of lesions within the plant.