Biology

Genetics and Plant Breeding

1,240 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

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.

Multiple choice

Which of the following shows an incomplete dominance?

  1. Flower colour in Pisum sativum

  2. Flower colour in Mirabilis jalapa

  3. Flower colour in Lathyrus odoratus

  4. Eye colour in Drosophila melanogaster
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Flower colour in Mirabilis jalapa shows incomplete dominance

Multiple choice

In epistatic type of inheritance

  1. the behaviour of two genes is entirely independent

  2. one gene alters the effect of the other

  3. a portion of a chromosome is deleted

  4. a portion of a chromosome is inverted
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In epistatic type of inheritance, one gene alters the effect of the other.

Multiple choice

In the F2 generation of a dihybrid cross

  1. four phenotypes appear in the ratio 9 : 3 : 3 : 1, if the loci are linked

  2. four phenotypes appear in the ratio 9 : 3 : 3 : 1, if the loci are unlinked

  3. two phenotypes appear in the ratio 3 : 1, if the loci are unlinked

  4. 3 phenotypes appear in the ratio 1 : 2 : 1, if the loci are unlinked
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the F2 generation of a dihybrid cross, four phenotypes appear in the ratio 9:3:3:1, if the loci are unlinked.