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

Eye color is an inherited trait.

  1. true

  2. false
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Eye color is a classic example of a polygenic trait determined by the DNA inherited from biological parents.

Multiple choice

Your weight is based only on inheritance (DNA).

  1. true

  2. false
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

While genetics play a role in body composition, weight is also significantly influenced by environmental factors such as diet, exercise, and lifestyle choices.

Multiple choice

Height is an inherited trait.

  1. true

  2. false
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Height is a complex trait heavily influenced by the genes inherited from parents, making it an inherited trait.

Multiple choice

another name for homozygous

  1. heterozygous

  2. purebred

  3. hybrid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Purebred is a term often used in breeding to describe an organism that is homozygous for a specific trait, meaning it will consistently pass that trait to its offspring.

Multiple choice

another name for heterozygous

  1. homozygous

  2. purebred

  3. hybrid
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A hybrid is the offspring of two different varieties or species, and in genetics, it refers to an organism that is heterozygous for the trait being studied.

Multiple choice

the actual genes or alleles of the organism

  1. genotype

  2. phenotype

  3. recessive

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

The genotype is the set of genes in our DNA which is responsible for a particular trait, whereas the phenotype is the physical expression of those genes.

Multiple choice

the weaker allele

  1. dominant

  2. recessive

  3. phenotype

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

A recessive allele is one that is masked by a dominant allele, often described as the weaker allele in basic genetic models. Phenotype and genotype refer to the physical expression and genetic makeup, respectively, rather than the strength of an allele.

Multiple choice

the stronger allele

  1. dominant

  2. recessive

  3. phenotype

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

A dominant allele is one that expresses its trait even when only one copy is present, making it the stronger allele in simple Mendelian inheritance. Recessive alleles are masked, while genotype and phenotype are broader genetic terms.

Multiple choice

Genes code for

  1. allele

  2. traits

  3. chromosome

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

Genes are the functional units of heredity that code for specific proteins, which result in observable traits. Alleles are variants of genes, while chromosomes and the double helix are structures containing DNA.

Multiple choice

Why does your identical twin look exactly like you?

  1. Twins are made from the same zygote.

  2. Your twin shares the same DNA as you

  3. Your parents had your sibling cloned to look like you

  4. How do I know? I don't have a twin!
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Identical twins are monozygotic, meaning they develop from a single fertilized egg that splits into two. Consequently, they share the same genetic material (DNA).

Multiple choice botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

Linked gene are separated by

  1. Crossing over

  2. Mutation

  3. Both A and B

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

Recombination can occur between any two genes on a chromosome, the amount of crossing over is a function of how close the genes are to each other on the chromosome. If two genes are far apart, for example at opposite ends of the chromosome, crossover and non-crossover events will occur in equal frequency. Genes that are closer together undergo fewer crossing over events and non-crossover gametes will exceed than the number of crossover gametes.

Multiple choice botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

Which of the following statements is not true of two genes that show 50% recombination frequency ?

  1. The genes may be on different chromosomes

  2. The genes are tightly linked

  3. The genes show independent assortment

  4. If the genes are present on the same chromosome, they undergo more than one crossovers in every meiosis.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The genes that are not tightly linked to each other do not show 50% of recombination frequency. Genetic linkage is the process in which genes are located close to each other on chromosomes are inherited together. When 2 genes are located far from each other or are located on different chromosomes have 50% of recombination rates.

So, option B is the correct answer.

Multiple choice botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

What is not true of two genes that show $50\%$ recombination frequency?

  1. They undergo more than one crossovers in every meiosis

  2. The genes are present on different chromosomes

  3. The genes are tightly linked

  4. The genes show independent assortment
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The tightly linked genes on chromosomes show 100% parental types and 0% recombinants. Two genes that undergo independent assortment indicated by a recombination frequency of 50% are either on non-homologous chromosomes are located far apart on a single chromosome. As the distance between two genes increases, crossover frequency increases. More recombinant gametes, fever parental gametes.

So, the correct answer is 'The genes are tightly linked'.