Biology

Genetics and Plant Breeding

1,177 Questions

Genetics and Plant Breeding explores the principles of heredity, chromosomal inheritance, and hybridization techniques. It includes key concepts like Mendelian genetics, gene linkage, and polygenic inheritance. This topic is essential for students tackling advanced biology or botany sections in competitive examinations.

Mendelian InheritanceChromosome TheoryGene LinkagePolygenic InheritancePlant HybridizationPopulation Genetics Equilibrium

Genetics and Plant Breeding Questions

Multiple choice

With respect to X-linked genes, males are said to be

  1. heterozygous

  2. hemizygous

  3. homozygous

  4. both homozygous and hemizygous

  5. both homozygous and heterozygous
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

With respect to X-linked genes males are said to be hemizygous. Having some single copies of genes in an otherwise diploid cell or organism is hemizygous.

Multiple choice

Which among the following are not the advantages of the cross-pollination?

  1. Specificity and cost effectiveness

  2. Production of disease resistant varities

  3. Production of higher yielding varieties

  4. Introduction of Genetic variations
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is not economical. Plants waste a lot of energy and food materials in unnecessary adaptations and devices to bring about pollination. It is uncertain because a factor of chance is always involved.

Multiple choice

Mendel did experiments with _________.

  1. pisum sativum

  2. hibiscus rosa-sinensis

  3. nelumbo nucifera

  4. mirabilis jalapa
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

While Mendel's research was with plants, the basic underlying principles of heredity that he discovered also apply to people and other animals.Through the selective cross-breeding of common pea plants (Pisum sativum) over many generations, Mendel discovered that certain traits show up in offspring without any blending of parent characteristics.

Multiple choice

The true breeding organisms are ______________.

  1. homozygous

  2. heterozygous

  3. nullizygous

  4. hemizygous
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A cell is said to be homozygous for a particular gene when identical alleles of the gene are present on both homologous chromosomes. The cell or organism in question is called a homozygote. True breeding organisms are always homozygous for the traits that are to be held constant.

Multiple choice

Induced polyploidy

  1. has played significant role in evolution

  2. is caused by certain mutagens

  3. is responsible for flowering of plants under non-inductive conditions

  4. is a technique that can make sterile hybrid to produce flowers
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Induced polyploidy can make sterile hybrids fertile by restoring chromosome pairing during meiosis. When two different species are crossed, the resulting hybrid is often sterile because chromosomes cannot pair properly during meiosis. Doubling the chromosomes (polyploidy) allows each chromosome to find a homologous partner, restoring fertility and enabling flowering and seed production in previously sterile hybrids.

Multiple choice

In Neurospora, tetrad analysis revealed that the percentage of mycelia regarding different combination of alleles A, a, B and b was AB = 35%, Ab = 15%, aB = 14%, ab = 36%. It means that

  1. two genes show independent assortment

  2. two genes show incomplete linkage

  3. two genes show complete linkage

  4. two genes are located on different chromosomes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The tetrad analysis shows parental combinations (AB and ab) at 71% and recombinant combinations (Ab and aB) at 29%. This deviation from the 50:50 ratio expected for independent assortment indicates linkage, but the presence of 29% recombinants shows the linkage is incomplete (complete linkage would produce 0% recombinants). Therefore, the genes are linked but not completely so.