Hereditary and Variation MCQs for NEET — Botany Questions with Answers

Genotype is the inheritable information carried by all living organisms. This stored information is used as a blueprint or set of instructions for building and maintaining living creature. These instructions are found in almost all cells, they are written in a coded language, they are copied at the time of cell division or reproduction and are passed from one generation to the next. These instructions are intimately involved with all aspects of the life of a cell or an organism. They control everything from the formation of protein macromolecules to the regulation of metabolism and synthesis. The genotype can be defined as the genetic makeup of a cell, an organism, or an individual usually with reference to a specific characteristic under consideration.

Mendel was performing dihybrid crosses, which are crosses between organisms that differ with regard to two traits. He discovered that the combinations of traits in the offspring of his crosses did not always match the combinations of traits in the parental organisms. From his data, he formulated the Principle of Independent Assortment.

Mendel used both emasculation and bagging techniques in his hybridization experiments. Emasculation involves removing the anthers of a flower to prevent self-pollination, while bagging involves covering the flower to prevent contamination from other pollen. This way, Mendel could control which plants were cross-pollinated.

The genotypes of the offspring can be inferred from the phenotypic ratio of tall to short plants. Given that there are 140 tall and 40 short plants, the ratio is 3:1, which is typical for a monohybrid cross of heterozygous plants (Tt) with each other. The expected genotypes would be TT, Tt, and tt.

A heterozygous tall plant (Tt) crossed with a dwarf plant (tt) will produce offspring with the following genotypes: Tt and tt. This results in a 1:1 or 50% ratio of tall to dwarf plants.

Genetic recombinations occur through meiosis and fertilization. During meiosis, homologous chromosomes exchange segments in a process known as crossing over, which creates new combinations of alleles. Fertilization then combines the genetic material from two parents, further increasing genetic diversity.

The unit of inheritance is the gene. A gene is a segment of DNA that contains the instructions for the development, functioning, growth, and reproduction of organisms. Genes are passed from parents to offspring and determine specific traits.

An allele is an alternate form of a gene that arises by mutation and is found at the same place on a chromosome. Alleles can vary in sequence and can result in different traits being expressed.

Genes do not occur in pairs in gametes. Gametes are haploid cells, meaning they contain only one set of chromosomes, and hence only one allele for each gene. In contrast, zygotes, somatic cells, and endosperm cells are diploid or triploid, containing two or more sets of chromosomes, and thus genes occur in pairs in these cells.