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

Brown heart disease is caused due to deficiency of Boron.
Boron regulates pentose phosphate pathway, and increases sugar translocation in plants. Due to deficiency of boron growth of roots stops and the disease 'brown heart'.
Boron deficiency affects vegetative and reproductive growth of plants resulting in inhibition of cell expansion, death of meristem and reduced fertility. Plants contain B both in a water-soluble and insoluble form.

a. Theory of epigenesis is proposed by Wolf. Epigenesis is, the thesis that every developing entity starts from unformed material, with form emerging gradually, over time, in the process of development.
b. Theory of pangenes is given by Charles Darwin. In 1868 Charles Darwin proposed Pangenesis, a developmental theory of heredity. He suggested that all cells in an organism are capable of shedding minute particles he called gemmules, which are able to circulate throughout the body and finally congregate in the gonads.
c. Theory of acquired character is given by Lamarck. Lamarck is best known for his Theory of Inheritance of Acquired Characteristics, first presented in 1801. If an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring.
d. The germplasm theory is proposed by August Weismann. August Weismann proposed the germ plasm theory in the 19^th century, before the foundation of modern genetics.

Reciprocal recurrent selection is used when a character is governed by Additive genes and Non-additive genes.
RRS is a cyclical breeding procedure designed to improve the cross of two populations from different heterotic groups by using both general and specific combining ability.
This method is equally effective with incomplete, complete and overdominance. This method is used when a character is governed by both additive and non additive gene action.

The following statements regarding synthetic varieties are correct:
2. Open pollinated materials are also used as parental lines.
4. Parental lines are always tested for their combining ability.
A synthetic variety is developed by intercrossing several genotypes of known superior combining ability i.e., genotypes that are known to give superior hybrid performance when crossed in all combinations.
Synthetic variety is a variety that is developed by inter-mating in all possible combinations some inbred lines with good general combining ability and mixing their seeds.

Emasculation of flower is necessary for hybridization in Self-pollinated plants.
Self pollination is condition in which pollen from the same plant or same flower fertilizes the ovule of the same flower. In such cases, for hybridization, emasculation is necessary.
Emasculation is the removal of anther or stamen or the pollen of bisexual flowers.

An example of blending of alleles is paramutation in Maize.
A paramutation is an interaction between two alleles at a single locus, whereby one allele induces a heritable change in the other allele.
The first formal description of paramutation was given by R. A. Brink at the University of Wisconsin-Madison in the 1950s, who did his work in maize (Zea mays).
He noticed that specific weakly expressed alleles of the red1 (r1) locus in maize, which encodes a transcription factor that confers red pigment to corn kernels, can heritably change specific strongly expressed alleles to a weaker expression state.

In hexaploid wheat the haploid (n) and basic (x) no. of chromosomes are n = 21, x = 7.
Hexaploid wheat possesses 42 chromosomes derived from its three ancestral genomes. The 21 pairs of chromosomes can be further divided into seven groups of six chromosomes (one chromosome pair being derived from each of the three ancestral genomes), based on the similarity of their gene order.

The seeds don't require certification are Breeder seed.
Breeder seed shall be genetically so pure as to guarantee that in the subsequent generation, certified foundation seed class shall confirm to the prescribed standards of genetic purity.
This is hundred percent physical and genetic pure seed for production of foundation seed.
A golden yellow colour certificate is issued for this category of seed by the producing breeder.

The F2 ratio in complementary gene action is 9 : 7.
Complementary gene action is when two different genes work together to contribute to one single trait. These two genes are involved in a specific pathway, like a biochemical reaction, and produce functional products required to produce a certain trait.
A dihybrid cross of complementary genes in F2 generation gives phenotypic ratio as 9 : 7.

The homozygous line developed through repeated selfing in cross-pollinated crop is Inbred.
An inbred line is the progeny of a single self-pollinated plant. It is the result of repeated selfing as a result all the alleles in an inbred are in the homozygous form.
In the Inbred Development Phase, the breeder begins by crossing two plants with different traits, such as yield, size, shape, color, taste, or disease resistance. The objective is to combine valuable traits from each parent to generate and select offspring containing the best characteristics of both parents.