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

Kavita is homozygous normal but her husband is heterozygous for a genetically inherited recessive trait. The probability of having a normal child is

  1. 1 out of 4

  2. 2 out of 4

  3. 3 out of 4

  4. 4 out of 4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

All of the children will be healthy since none of them can be homozygous recessive (aa). However, there will be a 50% chance at each birth that the children will be carriers (Aa). The remaining 50% will be homozygous dominant (AA).

Multiple choice

Down's syndrome is a genetically inherited dominant trait. If two parents are heterozygous for it, what are the chances that they will have a child who has this trait in his or her phenotype?

  1. 25%

  2. 50%

  3. 75%

  4. 100%
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

There is a 50% chance that the children will be heterozygous (Aa) and a 25% chance that they will be homozygous dominant (AA). Children with either of these genotypes will have this trait expressed in their phenotypes.

Multiple choice

Select the CORRECT explanations regarding Mendel, the father of genetics.

  1. His ideas and concepts regarding genetic inheritance were accepted by the scientific community when he published them in late 19th century.

  2. He believed that genetic characters of parents will typically come in their offsprings.

  3. His concept about genetics are applicable to both plants and animals.

  4. He was an English scientist who carried out research with Charles Darwin in the field of genetics & evolution.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

He gave us the concept of unit inheritance as the basis for understanding genetic inheritance in all living things, including humans.

Multiple choice

The phenotype is defined as

  1. genetic makeup

  2. physical appearance

  3. recessive allele

  4. dominant allele
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Phenotype includes the observable characteristics, including physical appearance. It results from the genotype and environmental influences. A phenotype includes not only easily measured traits like hair colour but also less apparent ones such as blood type.

Multiple choice

T. duran was evolved from

  1. T. speltoids

  2. T. monococcum

  3. T. beoticum

  4. T. turgidum
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

T. durans evolved from T. turgidum. 

Multiple choice

At a particular locus, frequency of ‘A’ allele is 0.6 and that of ‘a’ is 0.4. What would be the frequency of heterozygotes in a random mating population at equilibrium?

  1. 0.24

  2. 0.16

  3. 0.48

  4. 0.36
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  The genotype proportions p2, 2pq, and q2 are called the Hardy-Weinberg proportions.Two alleles denoted A and a with frequencies f(A) = p and f(a) = q, respectively,Expected genotype frequencies are-  f(AA) = p2 for the AA homozygotes,  f(aa) = q2 for the aa homozygotes, and f(Aa) = 2pq for the heterozygotes. So, the frequency of heterozygotes = 2pq= 2 X 0.6 X 0.4 = 0.48 

Multiple choice

In order to find out the different types of gametes produced by a pea plant having the genotype AaBb, it should be crossed to a plant with the genotype

  1. AaBb

  2. aabb

  3. AABB

  4. aaBB
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 In order to find out the different types of gametes produced by a pea plant having the genotype AaBb, it should be crossed to a plant with the homozygous recessive genotype.It is called Test Cross.So, in above options, it should be crossed with aabb double recessive plant.

Multiple choice

A woman with normal vision, but whose father was colour blind, marries a colour blind man. Suppose that the fourth child of this couple was a boy. This boy

  1. must have normal colour vision.

  2. may be colour blind or may be of normal vision.

  3. will be partially colour blind since he is heterozygous for the colour blind mutant allele.

  4. must be colour blind.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 A woman with normal vision, but whose father was colour blind, marries a colour blind man. Suppose that the fourth child of this couple was a boy. This boy may be colour blind or may be of normal vision.

Multiple choice

Raman is Rh positive. Which among the following best describes him?

  1. He is either homozygous dominant (DD) or heterozygous (Dd) for this trait.

  2. He will be homozygous dominant (DD).

  3. He will be homozygous recessive (dd).

  4. He may be either homozygous recessive (dd) or heterozygous (Dd) for this trait.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Rh blood factor is a dominant trait. Therefore, both homozygous dominant (DD) and heterozygous (Dd) people have Rh antigens on the surface of their red cells, which make them Rh positive.

Multiple choice

If there is a single pair of alleles that controls the number of toes for an insect species and homozygous dominant individuals have 7 toes, heterozygous ones have 6 and homozygous recessive ones have 5, the inheritance pattern would be referred to as

  1. genome imprinting

  2. intermediate expression

  3. pleiotropy

  4. codominance
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This hypothetical example would be an example of the intermediate expression of a trait. Apparently, this is rare. For most genes, it is expected that individuals with heterozygous genotypes will have phenotypes like homozygous dominant individuals.

Multiple choice

A study of a disorder reveals that monozygotic twins are concordant 30-40% of the time, whereas full siblings are concordant 20% of the time. Which of the following is the best interpretation of this finding?

  1. The trait has no genetic component.

  2. The trait is completely determined by genetics.

  3. Genes contribute to the trait, but are not deterministic.

  4. The trait must be due to the biology of twinning.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

There is an increased twin concordance, suggestive of a genetic contribution, but since twins are not fully concordant, other non-genetic factors must also be involved.