Biology

Genetics and Plant Breeding

1,177 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 pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

When a red flowered plant was cross pollinated by white flowered one and the offspring were self pollinated to obtain a phenotypic ratio of 1:2:1, it has to be a case of -

  1. Incomplete dominance

  2. Co-dominance

  3. Recessive epistasis

  4. Pleurotropic effect of genes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Incomplete dominance or blending dominance is a type of inheritance where the hybrid is not related to either of the parents but exhibit a blending of characters of the two parents.

It shows the ratio of 1:2:1 instead of the normal 3:1 phenotypic ratio.
So, the correct option is 'incomplete dominance'


Multiple choice botany pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

By cross pollinating certain tobacco species, some fertile hybrids were obtained by

  1. Mendel

  2. Morgan

  3. Kolreuter

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

In tobacco, due to the continuous self-pollination, homozygosity increases. It results in the occurrence of inbreeding depression, and the plants are called Inbred lines. When these inbred lines are subjected to hybridization, fertile hybrids are obtained. This is called Hybrid vigour or heterosis. This was developed by Kolreuter.

So, the correct option is ‘Kolreuter’.

Multiple choice botany pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

Cross pollination produces

  1. Similar offspring

  2. Weaker progeny

  3. Better progeny

  4. Male progeny
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Cross pollination is the transfer of pollen grains from the anther of one flower to the stigma of another flower borne on a separate plant. Cross pollination results in mixing or combination of characters, and thus improve the vigour and quality of species.
Cross pollination results in better progeny because:
1. Two genetically different pants are involved.
2. There is recombination in cross pollination which increase the vigour.
3. Fertility is increased.
So, the correct answer is C.
Multiple choice expression of gene inherited changes biology

Inheritance of a character is also affected by the promoter and regulatory sequences of a structural gene. Hence, sometimes the regulatory sequences are loosely defined as 

  1. Structural gene

  2. Regulatory gene

  3. Promoter gene

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A regulatory gene is a gene involved in controlling the expression of one or more other genes. Regulatory sequences encode regulatory genes. Sometimes the regulatory sequences are loosely defined as regulatory genes because the regulatory sequences of a structural gene affect the inheritance of a character.
So, the correct answer is 'Regulatory gene'.
Multiple choice bio-chemistry immunology blood group blood groups and compatibility advance blood groups and transfusion

Choose the correct answer from the alternatives given.
Which of the following is an example of codominance?

  1. Pink flowers of snapdragon

  2. The ABO blood groups in humans

  3. Sex-linkage in humans

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Pink flowers of Snapdragon is a heterozygote phenotype and an intermediate phenotype of the two homozygous phenotypes from which it originates. It is an example of incomplete dominance.
  • Codominance is seen when both the alleles are expressed simultaneously and neither of the alleles is dominant over the other. In human ABO blood grouping system both the alleles I$^A$ and I$^B$ are codominant and hence in the AB blood group individuals both the antigens, A and B are seen. So, the human ABO blood grouping is an example of codominance.
  • The expression of the sex chromosomes in humans differ in males and females and hence are said to be sex-linked.
So, the correct option is 'The ABO blood groups in humans'.
Multiple choice photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

When two hybrids Ttrr & Rrtt are crossed, the phenotypic ratio of offspring shall be?

  1. $3:1$
  2. $1:1:1:1$
  3. $1:1$
  4. $9:3:3:1$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • When Ttrr x Rrtt is performed, 4 types of phenotypes are obtained in equal numbers. (1:1:1:1)
  • The gametes for Ttrr are Tr and tr and for Rrtt are Rt and rt.
  • The possible genotypes are TtRr, Ttrr, ttRr, ttrr which are all different phenotypically.
  • So. the correct answer is '1:1:1:1'.
Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

Suppose two species A and B share 94% of their DNA with each other and species C shares 75% of DNA sequence with and B. What inference can be drawn from it ?

  1. Species A and B share more recent common ancestor with each other than either shares with C.

  2. Species C evolved more recently than species A and B.

  3. Species C is more closely related to species B than to species A.

  4. Species A and B have common ancestor but neither have common ancestor with species C.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Higher DNA sequence similarity indicates a more recent common ancestor. Since A and B share 94% and C shares less with them, A and B are more closely related.

Multiple choice botany flower taxonomic description of flower technical terms related to flowers basics of leaf and flower

Which one of the following is the modern approach is plant taxonomy?

  1. t-RNA analysis

  2. DNA fingerprinting

  3. Numerical taxonomy

  4. r-RNA analysis
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Numerical taxonomy, which uses mathematical and statistical methods to evaluate observable characteristics and classify organisms, represents a modern computational approach compared to classical systems.

Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Match the following.

A. IAA (i) Herring sperm DNA
B. ABA (ii) Bolting
C. Ethylene (iii) Stomatal closure
D. GA (iv) Weed-free lawns
E. Cytokinins (v) Ripening of fruits

  1. A-(iv), B-(iii), C-(v), D-(ii), E-(i)

  2. A-(v), B-(iii), C-(iv), D-(ii), E-(i)

  3. A-(iv), B-(i), C-(iv), D-(iii), E-(ii)

  4. A-(v), B-(iii), C-(ii), D-(i), E-(iv)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

IAA is an auxin but has potential role of herbicide and weedicide. ABA is stress inducing plant growth regular. It can induce closure of stomata, Ethylene on other hand increases climactic rate and hence used for fruit ripening, GA or gibberlic acid are known to cause bolting in crucifers. Cytokinins were first isolated from Herring sperm DNA.

Thus, the correct answer is 'A-(iv), B-(iii), C-(v), D-(ii), E-(i).'

Multiple choice zoology inherited changes compatibility of blood groups blood group blood groups and compatibility advance

Several copies of genes carrying the contrasting characters are mainly included in which of the following laws?

  1. Law of independent assortment

  2. Law of segregation

  3. Multiple allelism

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Alleles are alternative forms of a gene. They are responsible for differences in phenotypic expression of a given trait. When a gene exists in three or more allelic forms it is called multiple allele. 
For example, ABO blood group system in humans is controlled by three alleles  I$^A$, I$^B$, and  I$^O$
IA and IB are codominant and make type A and type B antigens, respectively. IO is the recessive allele and produces no antigen.The blood groups arising from the different possible genotypes is given below.
Genotype                         Blood Group
I$^A$ I$^A$                        A
I$^A$ I$^O$                       A
I$^B$ I$^B$                        B
I$^B$ I$^O$                       B
I$^A$ I$^B$                      AB
I$^O$ I$^O$                      O
So, the correct answer is 'Multiple allelism'
Multiple choice zoology inherited changes compatibility of blood groups blood group blood groups and compatibility advance

If both parents are albino, all the offspring shall be

  1. Albino

  2. Some albino, some normal

  3. Homozygous normal

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

Albinism is a autosomal genetical recessive gene disorder. It occurs in homozygous recessive state. The gene for albinism is a. it does not produce the enzyme tyrosinase, but is normal Allele A is does. Thus only homozygous individuals (aa) is affected. When both parents are albinic, all the offsprings also albinic generally.

So, the correct option is ‘Albino’.

Multiple choice zoology inherited changes compatibility of blood groups blood group blood groups and compatibility advance

When the heterozygote in a population have a reproductive advantage, one can predict that _________________.

  1. They will produce only heterozygous offspring

  2. The individuals that are homozygous recessive will take over

  3. Both homozygous dominant and homozygous recessive individuals will continue to appear in future generations

  4. Homozygous dominant and homozygous recessive individuals will be completely eliminated
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When heterozygotes have a selective or reproductive advantage (overdominance or heterozygote advantage), alleles for both dominant and recessive traits are maintained in the gene pool, ensuring both homozygous genotypes continue to appear in future generations.

Multiple choice zoology inherited changes compatibility of blood groups blood group blood groups and compatibility advance

Multiple gene inheritance takes into account ______________.

  1. Discontinuous traits

  2. Continuous traits

  3. Co-dominance

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

Multiple gene inheritance, also known as polygenic inheritance, involves traits controlled by two or more genes that typically show a continuous range of variation (continuous traits) rather than distinct categories.