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 botany classical genetics incomplete dominance deviation from mendelism inheritance

The inheritance of flower color in Antirrhinum (dog flower) is an example of

  1. incomplete dominance

  2. co-dominance

  3. multiple alleles

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

In the dog flower Antirrhinum there are two types of flower color in pure state: red and white. When the two types of plants are crossed, the hybrid or plants of generation have pink flowers. This is due to a phenomenon called the incomplete dominance in which one allele for a specific trait is not completely expressed over its paired allele. This results in a third phenotype in which the expressed physical trait is a combination of the phenotypes of both alleles ( in this case the red and white color and incompletely dominant and hence the third color pink is observed when they mix).

So, the correct answer is 'Incomplete dominance'.

Multiple choice botany classical genetics incomplete dominance deviation from mendelism inheritance

What percentage of progenies would have broad leaves and pink flower in F2 generation of Snapdragon if the first trait follows the law of dominance and the other shows incomplete dominance?

  1. 37.5%

  2. 56.25%

  3. 62.5%

  4. 12.5%
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Assume that the broad shape of leaves is governed by alleles B,b where 'B' represents dominant allele for broad leaves. Similarly, 'R' and 'r' are alleles for the colour of the flower. 'RR' progenies show red colour,' rr' progenies show white colour and 'Rr' progenies show pink colour due to incomplete domination.


Dihybrid cross for F2 generation in Snapdragon can be shown as below - 

 Gamete type  BR  Br  bR  br
 BR  BBRR  BBRr  BbRR   BbRr
 Br  BBRr BBrr   BbRr  Bbrr
 bR  BbRR   BbRr bbRR   bbRr
 br   BbRr  Bbrr  bbRr  bbrr
We can see, 6 out of 16 ( Genotypes BbRr and BBRr ) progenies will have broad leaves and pink flower which is equal to 37.5%.
So, the correct option is '37.5%'.

Multiple choice bio-chemistry immunity and blood groups active and passive immunity acquired immunity innate and acquired immunity

Find the correct statement with respect to HLA system. 

  1. Each individual inherit one pair of haplotype from each parent.

  2. Siblings will have identical haplotype.

  3. MHC - 1 protein present on all cells including erythrocytes.

  4. Macrophages, B-cells, dendritic cells have MHC - II protein on its surface.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

a) HLA system is also called as human leukocyte antigen system. It is a gene complex which encodes for the major histocompatibility complex (MHC) in humans. HLA haplotype is the set of histocompatibility genes that are on the same chromosome and are inherited together. Each individual inherits one pair of HLA haplotypes from each parent. 

b) Each parent has 2 HLA haplotypes on the chromosomes. Hence, there are 1 in 4 chance siblings will have identical haplotype. 
c) MHC I protein is present on all nucleated cells. Since erythrocytes are enucleated, they do not have MHC I proteins on them. 
MHC II protein is present on surface of marcophages, monocytes and dendritic cells. These are responsible for antigen presentation to T cells.
Thus, the correct answer is 'Each individual inherit one pair of the haplotype from each parent.'

Multiple choice zoology the paths traversed by life mutational theory of evolution theories of evolution other theories of evolution

Mutations were first reported by De Vries in

  1. Pea

  2. Datura

  3. Oenothera lamarckiana

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

De Vries discovered new forms among a display of the evening primrose (Oenothera lamarckiana) growing wild in an abandoned potato field. Taking seeds from these, he found that they produced many new varieties in his experimental gardens; he introduced the term mutations for these suddenly appearing variations.

So, the correct answer is 'Oenothera lamarckiana'.

Multiple choice zoology immune system active and passive immunity immunity related disorders and problems diseases and immunity

Graft between individuals of different species is called 

  1. Xenograft

  2. Isograft

  3. Autograft

  4. Allograft
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Grafting refers to a surgical procedure to move tissue from one site to another on the body, or from another creature, without bringing its own blood supply with it. Instead, a new blood supply grows in after it is placed.
  • There are 4 types of grafting techniques. They are Allograft, Autograft, Isograft and Xenograft.
  • Xenograft is the Grafting between two individuals of different species. Most commonly from animal to man such as pig heart valve used to replace human.
  • Hence Graft between individuals of different species is called  Xenograft.
  • So, the correct answer is 'Xenograft'.
Multiple choice zoology immune system active and passive immunity immunity related disorders and problems diseases and immunity

Number of haplotypes present in an individual is 

  1. One

  2. Two

  3. Six

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

A haplotype (haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. It is used in the collection of specific alleles (that is, specific DNA sequences) in a cluster of tightly linked genes on a chromosome that are likely to be inherited together. An individual will have two haplotypes, although at a population level there may be numerous haplotypes for any given stretch of chromosomal DNA.

So, the correct answer is 'Two'.

Multiple choice zoology immune system active and passive immunity immunity related disorders and problems diseases and immunity

Haplotypes are identical in

  1. Identical twins

  2. Brothers and sisters

  3. Children and parents

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

A haplotype (haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. It is used in the collection of specific alleles (that is, specific DNA sequences) in a cluster of tightly linked genes on a chromosome that are likely to be inherited together. The dizygotic twin pairs share two HLA haplotypes more often than ordinary siblings and thus might be genetically more alike.

So, the correct answer is 'Identical twins'.

Multiple choice zoology immune system active and passive immunity immunity related disorders and problems diseases and immunity

Haplotype is

  1. A single genome

  2. Major histocompatability compklex

  3. Chain of HLA alleles inherited together

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

A haplotype (haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. It is used in the collection of specific alleles (that is, specific DNA sequences) in a cluster of tightly linked genes on a chromosome that are likely to be inherited together.

So, the correct answer is 'Chain of HLA alleles inherited together'.

Multiple choice zoology why do we fall ill health introduction to health health and its maintenance

John, a male hemophiliac, marries Jane, a normal woman, and together they have four children, two boys (Mark and Mike) and two girls (Molly and Mary). None of the children display the symptoms of hemophilia. Mark, Mike, Molly, and Mary all marry normal individuals and have children. None of Mark's or Mike's children, male or female, display symptoms of hemophilia, but the sons of Molly and Mary all display symptoms of hemophilia while the daughters of Molly and Mary do not. Which of the following individuals are heterozygous for hemophilia?

  1. John, Mark, and Mike

  2. Mark, Mike, Molly, and Mary

  3. John and Jane

  4. Molly and Mary

  5. Mark and Mike
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Hemophilia is sex linked recessive disorder. Gene responsible for it present on X chromosome and only expresses in dominant state. Out of four children of john (hemophiliac male) and Jane (normal woman), both the girls Molly and Mary become heterozygous for hemophilia as they got hemophiliac X chromosome from father only, which they pass on to their children resulting sons with hemophilia expressed and daughters are either normal heterozygous for hemophilia. The boys Mark and Mike are normal as they don't get hemophiliac X chromosome from father and when they married with normal individuals, all their children would be normal. Thus, the correct answer is ' Molly and Mary.'

Multiple choice zoology why do we fall ill health introduction to health health and its maintenance

John, a male hemophiliac, marries Jane, a normal woman, and together they have four children, two boys (Mark and Mike) and two girls (Molly and Mary). None of the children display the symptoms of hemophilia. Mark, Mike, Molly, and Mary all marry normal individuals and have children. None of Mark's or Mike's children, male or female, display symptoms of hemophilia, but the sons of Molly and Mary all display symptoms of hemophilia while the daughters of Molly and Mary do not. If one of Mike's daughters marries a normal man, what is the probability that one of their children will display symptoms of hemophilia?

  1. 0%

  2. 25%

  3. 50%

  4. 75%

  5. 100%
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Haemophilia is a sex-linked recessive disorder. Gene responsible for it present on X chromosome and only expresses in a dominant state. Out of four children of John (haemophiliac male) and Jane (normal woman), both the girls Molly and Mary become a carrier for haemophilia as they got haemophiliac X chromosome from John, which they pass on to their children resulting sons with haemophilia expressed and daughters are either normal or carrier. The boys Mark and Mike are normal as they don't get haemophiliac X chromosome from father and when they married with normal individuals, all children would be normal. Thus, the correct answer is '0%.'
Multiple choice botany plant breeding method of plant breeding for crop improvement plant breeding for food production biotechnology

Wide hybridisation has been used for producing

  1. Haploids

  2. Dihaploids from tetraploids

  3. Trihaploids from hexaploids

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

Wide hybridization can be used to transfer the desirable variability. It is used for producing haploids, diploids from tetraploids and trihaploids from hexaploids.

So, the correct answer is 'All the above.'

Multiple choice botany plant breeding method of plant breeding for crop improvement plant breeding for food production biotechnology

First artificial hybrid was obtained by crossing sweet william and carnation in $1717$ by 

  1. G.J Mendel

  2. M.S Swaminathan

  3. P.Maheshwari

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

A. G.J Mendal is known for his discovery of fundamental laws of inheritance.

B. M.S Swaminathan is responsible for introducing and further developing high-yielding varieties of wheat in India.
C. P. Maheshwari was the first person to to grow a plant after natural fertilization in a test tube containing artificial culture medium.
D. Thomas Fairchild was responsible for first artificial hybrid.
So, the correct answer is 'Thomas Fairchild'.