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

In a couple, if a woman is homozygous normal (XX ) and her husband is heterozygous ( Xx) for a genetically inherited recessive disease, what is the probability that they will have a healthy offspring?

  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 (xx). However, there will be a 50% chance at each birth that the children will be carriers (Xx). The remaining 50% will be homozygous dominant (XX).

Multiple choice

In a couple, if both mother & father are heterozygous (Xx) for a genetically inherited dominant defect, what is the feasibility that they will have a child together 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

Which of the following statements is TRUE?

  1. With the exception of monozygotic twins, each of us is unique in terms of the combination of tens of thousands of genetically inherited peculiar qualities that we possess.

  2. Blackish skin is found only among Africans and people whose ancestors came from Africa in recent centuries.

  3. Non-African people with black skin colour posses a close common ancestry with Africans.

  4. The personal physical qualities of an individual are determined by the genetic inheritance.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Except for monozygotic (identical) twins, it is highly likely that every one of us is genetically different from every other human whoever lived.

Multiple choice

On what factor does the strength of linkage depend?

  1. Size of genes

  2. Distance between the genes

  3. Types of nucleotides in the gene

  4. Length of chromosome
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The strength of linkage depends upon the distance between the genes. Distance between the genes is inversely proportional to strength, i.e. D is proportional to 1/S, where D is the distance and S is the strength of linkage.

Multiple choice

In which of the following is complete linkage observed?

  1. Drosophila males

  2. Maize

  3. Pea plant

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

Complete linkage is observed in Drosophila males. In complete linkage, the genes located on the same chromosome do not separate and are inherited together over the generations due to the absence of crossing over.

Multiple choice

Incomplete linkage is due to

  1. epistasis

  2. mutation

  3. cross over

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

Genes present in the same chromosome have a tendency to separate due to crossing over and hence produce recombinant progeny besides the parental type. The number of recombinant individuals is usually less than the number expected in independent assortment. In independent assortment, all the four types (two parental types and two recombinant types) are each 25%. In case of linkage, each of the two parental types is more than 25% while each of the recombinant types is less than 25%.

Multiple choice

"The genes or alleles coming from two different parents tend to enter different gametes and to be inherited independently."

Which phenomenon is defined by the definition mentioned in the passage?

  1. Genetic coupling

  2. Genetic repulsion

  3. Genetic recombination

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

Genetic repulsion is defined as, the genes or alleles coming from two different parents tend to enter different gametes and to be inherited independently.