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 not notice linkage due to

  1. segregation

  2. dominance

  3. independent assortment

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

Mendel didn't notice linkage due to independent assortment. He unknowingly chose those characters which are either on different chromosomes or lay apart on the same chromosome. The characters were assorted independently in F2 generation as they were not linked.

Multiple choice

Which of the following explanations about a dominant genetic trait subject to genomic imprinting is FALSE?

  1. In a given family, only males or females will be affected.

  2. The trait may appear to skip generations.

  3. Affected individuals will always inherit the mutation from either the mother or father, but not both.

  4. Severity of the phenotype will be independent of sex of the affected individual.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For an inherited trait subject to imprinting, the phenotype will only be expressed when it is inherited from the parent whose copy is expressed in the next generation.

Multiple choice

In a cross between a white-eyed female dragonfly and red-eyed male, how many female progenies will inherit white eyes?(White eyes are X-linked recessive)

  1. 0%

  2. 25%

  3. 50%

  4. 75%
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

All the female eggs will have X chromosome with the white-eye mutation while the sperm will posses either a normal X chromosome or a Y chromosome. By using Punnett square, we can predict the outcome of this cross. Female progenies will receive X chromosome from both the sperm and egg cells. All females receive the dominant, red-eyed allele from their fathers and the recessive, white-eyed allele from their mothers.

Multiple choice

A white-eyed female fruitfly is crossed with a red-eyed male fruitfly. Red eyes are dominant, and X-linked. What are the expected phenotypes of their children?

  1. 100% females will have red eyes while 50 % males will have red eyes, and 50% males will have white eyes.

  2. 100% females and 100% males will have white eyes.

  3. 100% females will have red eyes & 100% males will have white eyes.

  4. 100% females and 100% males will have red eyes.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As per the question, all of the females are red-eyed and heterozygous. All of the males are white-eyed and hemizygous.

Multiple choice

A human male bearing an allele for a trait on the X chromosome is termed as

  1. heterozygous

  2. homozygous

  3. hemizygous

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

Human males are termed as hemizygous for any X-chromosome genes, meaning that there are only half (hemi) as many alleles as normally present for a diploid individual. As a result, if males inherit X-linked recessive trait from their mothers, they will show the recessive phenotype.

Multiple choice

In which of the following phenotypic females does a pair of testis originate?

  1. 46, XY with X-linked androgen receptor inadequacy

  2. 45, X

  3. 46, XY with a point mutation in the HMG arena of the SRY gene.

  4. 46, XY with an interstitial deletion of Yp including the SRY gene.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The presence of a Y-chromosome predicts that testes will develop. Differentiation of external genitalia is controlled by the androgen derivative (5-alpha-dihydrotestosterone) and a defect in the androgen receptor which results in androgen insensitivity means that external male genitalia will not be stimulated to differentiate. Thus, this individual will look phenotypically female but will have undescended testes.

Multiple choice

In predetermining the phenotype for the ABO blood system

  1. blood group O is dominant at blood group A

  2. blood group B is dominant at blood group A

  3. blood type O is recessive

  4. blood type AB is recessive
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The rules of dominance for the ABO system is that both A and B are dominant over O (i.e. O is recessive) and A and B are codominant.

Multiple choice

A person's ABO blood type is typically predetermined by

  1. genetic inheritance and environmental influences during his course of life

  2. environmental factors alone

  3. the inheritance of 1 of 3 possible alleles, i.e. either A, B or O from each of the parent

  4. combination of 2 of 3 possible alleles, i.e. either A, B or O from each of the parent
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In most cases, these alleles are totally responsible for determining blood type phenotypes. The inheritance usually follows simple Mendelian patterns. However, there are rare exceptions such as Bombay Phenotype.

Multiple choice

Mr. X & Mr. Y both claimed for a child in the hospital. Which of the following would be the least likely to be accepted as legal proof of paternity?

  1. ABO blood type presumption

  2. HLA typing presumption

  3. DNA sequence comparison

  4. All will be equally accepted in the court
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Due to Bombay Phenotype and other possible exceptions, the ABO blood type system is not conclusive in determining whether or not someone could be a parent of a particular child. The other two kinds of evidence are much more reliable.

Multiple choice

Select the true statement about Rh positive people.

  1. They are either homozygous dominant (XX) or heterozygous (Xx) for this trait.

  2. They all are homozygous dominant (XX) individuals.

  3. They are all homozygous recessive (xx) individuals.

  4. They are either homozygous recessive (xx) or heterozygous (Xx) 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 DD and Dd people have Rh antigen on the surface of their red cells which make them Rh positive.