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

What is the phenotypic ratio of a cross between two heterozygous individuals in incomplete dominance?

  1. 3:1

  2. 1:2:1

  3. 9:3:3:1

  4. 1:1
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a cross between two heterozygous individuals, the phenotypic ratio is 1:2:1, where 1 represents the homozygous dominant phenotype, 2 represents the heterozygous phenotype, and 1 represents the homozygous recessive phenotype.

Multiple choice

Incomplete dominance is observed in:

  1. Homozygous dominant individuals

  2. Heterozygous individuals

  3. Homozygous recessive individuals

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Incomplete dominance is observed in heterozygous individuals, where the two different alleles of a gene are expressed simultaneously, resulting in a phenotype that is a blend of the two homozygous phenotypes.

Multiple choice

Which of these is NOT a characteristic of incomplete dominance?

  1. The heterozygous phenotype is intermediate between the homozygous phenotypes

  2. The heterozygous phenotype is identical to one of the homozygous phenotypes

  3. The heterozygous phenotype is a blend of the two homozygous phenotypes

  4. The heterozygous genotype has equal contributions from both alleles
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In incomplete dominance, the heterozygous phenotype is a blend of the two homozygous phenotypes, not identical to one of them.

Multiple choice

In incomplete dominance, the heterozygous genotype is:

  1. RR

  2. Rr

  3. rr

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In incomplete dominance, the heterozygous genotype is Rr, where R represents the dominant allele and r represents the recessive allele.

Multiple choice

What is the probability of obtaining a heterozygous offspring from a cross between two heterozygous individuals in incomplete dominance?

  1. 1/4

  2. 1/2

  3. 3/4

  4. 1
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a cross between two heterozygous individuals, the probability of obtaining a heterozygous offspring is 1/2, as there is a 50% chance that the offspring will inherit one dominant allele and one recessive allele from each parent.

Multiple choice

What is the term used to describe the phenomenon where genes located close together on the same chromosome tend to be inherited together?

  1. Linkage

  2. Recombination

  3. Independent assortment

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

Linkage refers to the tendency of genes that are located close together on the same chromosome to be inherited together, due to their physical proximity.

Multiple choice

Which of the following is NOT a mechanism that can lead to genetic recombination?

  1. Crossing over

  2. Gene conversion

  3. Independent assortment

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

Independent assortment is the random distribution of chromosomes during meiosis, which leads to the production of gametes with different combinations of alleles. It is not a mechanism of genetic recombination.

Multiple choice

What is the term used to describe the process by which genetic material is exchanged between homologous chromosomes during meiosis?

  1. Linkage

  2. Recombination

  3. Independent assortment

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

Recombination refers to the process by which genetic material is exchanged between homologous chromosomes during meiosis, resulting in the production of gametes with new combinations of alleles.

Multiple choice

Which of the following is a measure of the genetic distance between two genes?

  1. Recombination frequency

  2. Linkage group

  3. Genetic map

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

Recombination frequency is a measure of the genetic distance between two genes, and it is calculated as the percentage of offspring that show recombinant genotypes.

Multiple choice

What is the term used to describe a group of genes that are located close together on the same chromosome and are inherited together?

  1. Linkage group

  2. Recombination group

  3. Independent assortment group

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

A linkage group is a group of genes that are located close together on the same chromosome and are inherited together due to their physical proximity.

Multiple choice

Which of the following is NOT a type of genetic recombination?

  1. Crossing over

  2. Gene conversion

  3. Transposition

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

Transduction is not a type of genetic recombination, but rather a process by which a gene is transferred from one organism to another by a virus.

Multiple choice

In a pea plant, the allele for purple flowers (P) is dominant over the allele for white flowers (p). If a homozygous purple-flowered plant (PP) is crossed with a homozygous white-flowered plant (pp), what will be the genotype and phenotype of the offspring?

  1. All offspring will be heterozygous (Pp) and have purple flowers.

  2. All offspring will be homozygous dominant (PP) and have purple flowers.

  3. All offspring will be homozygous recessive (pp) and have white flowers.

  4. Half of the offspring will be heterozygous (Pp) and have purple flowers, and the other half will be homozygous recessive (pp) and have white flowers.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since the dominant allele (P) for purple flowers masks the expression of the recessive allele (p) for white flowers, all offspring will inherit one dominant allele (P) from the purple-flowered parent and one recessive allele (p) from the white-flowered parent, resulting in a heterozygous genotype (Pp). This genotype will express the dominant trait, which is purple flowers.

Multiple choice

In humans, the allele for brown eyes (B) is dominant over the allele for blue eyes (b). If a heterozygous brown-eyed parent (Bb) is crossed with a homozygous blue-eyed parent (bb), what is the probability of having a blue-eyed child?

  1. 0%

  2. 25%

  3. 50%

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

The heterozygous brown-eyed parent (Bb) can produce two types of gametes: B (carrying the dominant allele for brown eyes) and b (carrying the recessive allele for blue eyes). The homozygous blue-eyed parent (bb) can only produce one type of gamete: b (carrying the recessive allele for blue eyes). When these gametes combine, there is a 25% chance of inheriting two recessive alleles (bb), resulting in a blue-eyed child.

Multiple choice

In a certain species of plant, the allele for red flowers (R) is dominant over the allele for white flowers (r). If a red-flowered plant (RR) is crossed with a white-flowered plant (rr), what will be the genotype and phenotype of the F1 generation?

  1. All offspring will be heterozygous (Rr) and have red flowers.

  2. All offspring will be homozygous dominant (RR) and have red flowers.

  3. All offspring will be homozygous recessive (rr) and have white flowers.

  4. Half of the offspring will be heterozygous (Rr) and have red flowers, and the other half will be homozygous recessive (rr) and have white flowers.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since the dominant allele (R) for red flowers masks the expression of the recessive allele (r) for white flowers, all offspring will inherit one dominant allele (R) from the red-flowered parent and one recessive allele (r) from the white-flowered parent, resulting in a heterozygous genotype (Rr). This genotype will express the dominant trait, which is red flowers.

Multiple choice

In a genetic cross, the genotype of an individual is determined by the:

  1. Alleles inherited from both parents.

  2. Alleles inherited from the mother only.

  3. Alleles inherited from the father only.

  4. Alleles inherited from the grandparents.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a genetic cross, each parent contributes half of the genetic material to the offspring. Therefore, the genotype of an individual is determined by the alleles inherited from both parents.