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

If a single pair of alleles determines the number of fingers for an animal species and homozygous dominant individuals have 8 fingers, heterozygous ones have 7, and homozygous recessive ones have 6, the inheritance pattern would be referred to as

  1. genome imprinting

  2. intermediate expression

  3. pleiotropy

  4. reduced penetrance
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

Few individuals are AB blood types of the ABO blood system. They posses all the features of both type A and type B blood but they are not a blend of them. This is due to the

  1. codominance

  2. dominance

  3. blending

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

Codominant traits are the ones in which both alleles are expressed when the phenotype is heterozygous. In the case of the ABO blood type system, A and B are codominant. They are also completely dominant over O.

Multiple choice

The genes for a trait are inherited by son & daughter of a couple but only show up in the phenotype of daughter, they are referred to as

  1. sex-controlled genes

  2. codominant genes

  3. sex-limited genes

  4. sex-linked genes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Only one gender actually has sex-limited genes expressed in the phenotype, while both inherit them. The typical heavy male facial beard is an example of a trait whose inheritance follows this pattern.

Multiple choice

The monozygotic twins may not have identical phenotypes because

  1. their genotypes are different

  2. their phenotypes are effected by environment

  3. their phenotypes are independent of their genotypes

  4. they develop from different zygotes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

While monozygotic twins are identical in genetic makeup, but the individuals after conception and birth can alter their phenotypes.

Multiple choice

The interaction between different genes is termed as

  1. multiple-allelism

  2. mutation

  3. syndrome

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

It is described as the interaction between genes. It can be contrasted with dominance, which is an interaction between alleles at the same gene locus.

Multiple choice

Which of the following can be regarded as an exception to Mendel's concept that genes are passed on, unchanged, from one generation to other?

  1. Codominance

  2. Multiple-alleles

  3. Stuttering alleles

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

Stuttering or unstable alleles structurally change from generation to generation. Segments of these rare genes are doubled with each generation, resulting in an intensification of a trait. One form of muscular dystrophy apparently can follow this pattern.

Multiple choice

The same base sequencing in DNA will be similar in

  1. a male parent and his male offspring

  2. identical twins

  3. siblings

  4. a female parent and her offspring
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The identical twins will have the same base sequencing in their DNA because they originates from the same egg and sperm of the parents.

Multiple choice

Pick out the true statement regarding Gregor Mendel.

  1. His discoveries regarding genetic inheritance were eventually accepted by the scientific community in the mid 19th century.

  2. He concluded that genetic traits of parents will generally inherit in their offsprings.

  3. His postulates of gene & inheritance apply equally to plants and animals.

  4. His experimental plant was cross-pollinating.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

He gave us the basis for understanding genetic inheritance in all living things, including humans. His realization that we inherit units or genes was the key to it.

Multiple choice

According to Mendel, the characteristics of Pisum sativum were determined by

  1. inheritance of genes from both parents

  2. inheritance of genes from one parent only

  3. comparitive health of each parent plants at the time of pollination

  4. comparitive health of each parent plants at the time of fertilisation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mendel called genes as factors. In all the individuals, each inherited trait is determined by at least one gene from each parent.

Multiple choice

An allele can be described as

  1. a homozygous genotype

  2. a heterozygous genotype

  3. a substitute for a gene

  4. one of several possible forms of a gene
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An allele is an alternate form of a gene. If an individual is homozygous (YY or GG) for a trait, it has inherited the same allele from both parents. If it is heterozygous (YG), it has inherited different alleles for the trait.

Multiple choice

The concept that different pairs of alleles are passed to progenies autonomously describes Mendel's principle of

  1. independent assortment

  2. segregation

  3. unit inheritance

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

This is a definition of principle of independent assortment. Stated in other words, the genes that determine a trait assort independently of the genes for other traits. As a result, new combinations of genes, present in neither parent, are possible.

Multiple choice

In an individual, phenotype expresses

  1. genetic makeup

  2. physical appearance

  3. a recessive allele

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

Phenotype is the observable characteristic, 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

A persons's ABO blood type is generally determined by

  1. genetic factors as well as environmental factors

  2. environmental influences alone

  3. the presence of one of A, B, or O alleles inherited from the parents

  4. antibodies present in the blood
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.