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

The smallest unit of genetic material that cannot be divided but is interchangeable among units refers to Recon.
A term coined by Seymour Benzer for the smallest recombinable unit within a cistron.
A region of a gene within which there can be no crossing-over; now known to be a single nucleotide pair that is Recon.

An organism having one chromosome pair less than the normal somatic complement of the species is Nullisomic.
Nullisomic is a genetic condition involving the lack of both the normal chromosomal pairs for a species (2n-2). Humans with this condition will not survive.
Nullisomy is caused by non-disjunction, during meiosis that causes two of the gametes to have no chromosomal material, leaving the other two gametes to have double the amount of chromosomal material.

Autopolyploidy is known as Simple polyploidy.
Polyploidy is a mutation in which offspring have a multiple of some ancestral set of chromosomes. Polyploidy can occur either within a species (autopolyploidy) or between different species.
An individual or strain whose chromosome complement consists of more than two complete copies of the genome of a single ancestral species.

An exchange of genetic material between homologous chromosomes is called Crossing over.
crossing over is the exchange of genetic material during sexual reproduction between two homologous chromosome's non-sister chromatids that results in recombinant chromosomes.
It is one of the final phases of genetic recombination, which occurs in the pachytene stage of prophase I of meiosis during a process called synapsis.
The linked frequency of crossing over between two gene loci (markers) is the crossing-over value.

a. Plasma membrane is semi-permeable.
It is a type of biological or synthetic, the polymeric membrane that will allow certain molecules or ions to pass through it by osmosis.
b. Cellulose cell wall is permeable.
The cell wall of most plant cells is freely permeable to small molecules including small proteins, with size exclusion estimated to be 30 - 60 kDa.
c. DPD and water potential is closely linked.
The water potential has the same magnitude as DPD (Diffusion pressure deficit) but with a negative sign.
d. Osmotic pressure and solute potential.
Osmotic pressure is directly proportional to the solute potential. If the solute concentration of a solution increases, the potential for the water in that solution to undergo osmosis decreases.

"The ability of a gene to express itself in an individual that carries it" is defined as Penetrance.
The ability of a gene to express itself in an individual that carries it is called penetrance.
Penetrance is the percentage of animals of a specific genotype who express the phenotype associated with that underlying genotype.

The carpel is a female reproductive organ in a flower.
A carpel is the female reproductive part of the flower usually composed of the style and stigma and usually interpreted as modified leaves that bear structures called ovules, inside which egg cells ultimately form.
Carpels are thought to be phylogenetically derived from ovule-bearing leaves or leaf homologues, which evolved to form a closed structure containing the ovules.

Mass selection is rarely used in a sexually propagated species.
In mass selection, several individuals chosen based on appearance are mated; their progeny are further selected for the preferred characteristics, and the process is continued for as many generations as is desired.
It applies to both self and cross-pollinated species. It is a method of crop improvement in which plants are selected from a mixed population based on their phenotype.

When two genotypes produce the same phenotype due to different environments, it is known as Phenocopy.
A phenocopy is a phenotypic trait or disease that resembles the trait expressed by a particular genotype, but in an individual who is not a carrier of that genotype.
The phenocopy induced by the environmental conditions mimics the phenotype produced by a gene. For example, a phenocopy is observed in Himalayan rabbits which have a white-coloured coat along with a black tail, nose, and ears when raised in moderate temperatures.

The superiority of an F₁ hybrid over a standard commercial variety is called Economic heterosis.
Heterosis is the improved or increased function of any biological quality in a hybrid offspring. It refers to the superiority of F₁ over the standard commercial check variety. It is also called economic heterosis or useful heterosis and is calculated by using a formula.