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 biology mendel's law of inheritance mendel's laws laws of inheritance mendel's laws of inheritance

According to the concept of dominance, the modified allele is equivalent to the unmodified allele when?

  1. It produces normal/less efficient enzyme

  2. It produces the same phenotype/trait

  3. It results in the transformation of substrate

  4. More than one option is correct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
A gene is responsible for the appearance of a specific trait. In diploid organisms, a gene is represented by a pair of alleles. When these two alleles are not identical, one of alleles is different with modified information. Normal allele will form normal enzyme. Changed or modified allele can form three types of enzymes i.e. normal enzyme, non-functional enzyme, no enzyme at all. Enzyme is always required for the formation of substrate say ‘S’. Modified allele is almost similar to normal allele and forms the same enzyme and produces same phenotypic trait i.e., leads to the formation of substrate ‘S’. But sometimes allele formed are non­functional enzyme or no enzyme and phenotypic trait depends on functioning of un-modified allele. Functioning or unmodified allele will form the original normal phenotypic trait (due to dominant allele) and modified allele will be known as recessive allele.
So the correct option is 'it produces normal/less efficient enzyme'.
Multiple choice mendel's law of inheritance mendel's laws laws of inheritance mendel's laws of inheritance

The effect of dominant allele is studied under ______________

  1. Law of independent assortment

  2. Law of dominance

  3. Law of segregation

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

Some alleles are dominant while others are recessive. Organism with at least one dominant allele will display the effect of the dominant allele, which is studied under Law of dominance. Therefore, (b) is the correct answer.

Multiple choice mendel's law of inheritance mendel's laws laws of inheritance mendel's laws of inheritance

Assume that flower colour is controlled by a single gene. In a given plant, red flower colour is dominant over white flower colour. Two red flower bearing plants were crossed and the progeny consists of 45 plants bearing red flowers and 4 plants bearing white flowers this indicates that

  1. Both the parents are heterozygous for the gene controlling flower colour

  2. One parent is true breeding for red flowers on the other heterozygous

  3. A mutation must have occurred in the progeny which (mutation) caused the appearance of white flowers

  4. The results are not consistent with the expected ratio 3 Red : 1 White. Hence both the parents cannot be heterozygous
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ratio is totally deviated from 3(red) : 1 (white), Hence this is a case of mutation which is resulting into this outcome.

Multiple choice mendel's law of inheritance mendel's laws laws of inheritance mendel's laws of inheritance

Mendel's law of segregation states that?

  1. The alleles do not show any blending and that both the characters are recovered as such in $F _2$ generation

  2. The factors or alleles of a pair segregate from each other such that a gamete receives only one of the two factors

  3. Homozygous parent produces all gametes that are similar while heterozygous produces two kinds of gametes each having one allele with equal proportion

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice mendel's law of inheritance mendel's laws laws of inheritance mendel's laws of inheritance

Find which options are correct. According to Mendel's law of purity of gametes.
A) In $F1$ hybrid, the dominant and recessive character though remain together for long time but do not contaminate or mixed with each other.
B) The inheritance of one character is always independent to the inheritance of other character within the same individual.
C) The gamete formed contains the factors, which determines single trait pertaining to a particular character.
D) Two genes of allelomorphic pair are not related as dominant or recessive but each of them expresses itself partly.

  1. A, B and C are correct

  2. A and B are correct

  3. B and D are correct

  4. A and C are correct
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Statement A correctly describes the law of segregation, stating that alleles remain pure and unmixed in hybrids. Statement C correctly notes that each gamete receives a factor determining a single trait. Statement B describes independent assortment, and statement D describes incomplete dominance, neither of which is part of the law of purity of gametes.

Multiple choice mendel's law of inheritance mendel's laws laws of inheritance mendel's laws of inheritance

Independent segregation of genes is seen in case of _____________

  1. Law of dominance

  2. Law of segregation

  3. Law of independent assortment

  4. Both (A) and (C)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Genes for different traits can segregate independently during the formation of gametes. This is the result of Law of independent assortment which was studied Mendel. Therefore, (C) is the correct answer.

Multiple choice mendel's law of inheritance mendel's laws laws of inheritance mendel's laws of inheritance

Each gamete carries only one allele. This is proposed in which law?

  1. Law of dominance

  2. Law of segregation

  3. Law of independent assortment

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

During gamete formation, the alleles for each gene segregate from each other so that each gamete carries only one allele for each gene. This was proposed in the Law of segregation. Therefore, (b) is the correct answer.

Multiple choice mendel's law of inheritance mendel's laws laws of inheritance mendel's laws of inheritance

Which of the following follows Mendel's law of segregation?

  1. Genetic material is equally distributed during mitosis.

  2. Each gamete receives one gene for an allele.

  3. Genetic material enters only one gamete.

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

Mendel's law of Segregation: The principle of segregation describes how pairs of gene variants are separated into reproductive cells. The segregation of gene variants, called alleles, and their corresponding traits was first observed by Gregor Mendel in 1865. Mendel was studying genetics by performing mating crosses in pea plants.
Each gamete receives one gene for an allele and thus, is haploid in nature. Both male and female gametes, which are haploid will fuse and forms a diploid zygote.

So, the correct answer is 'Each gamete receives one gene for an allele.'

Multiple choice commercial applications population - the increasing numbers and rising problem impact of depletion of natural resources population growth models depletion of resources

In a population, which is in Hardy- Weinberg equilibrium the recessive allelic frequency is $0.8$, in a population of $1300$. Find out the number of dominantindividuals in that ppulation, if the gene in reference has only two alleles   

  1. $416$
  2. $468$
  3. $640$
  4. $52$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Recessive freq $= q= 0.8$
$q^2 = (0.8)^2 =0.64$  
$p^2 + q^2 = 1$  
$1 - q^2 = p^2$ 
$ p^2 = 1 - 0.64= 0.36$ 
$0.36 \times 1300 = 468$

Multiple choice commercial applications population - the increasing numbers and rising problem impact of depletion of natural resources population growth models depletion of resources

If the frequency of a dominant phenotype in a stable population is $75\%$, the frequency of recessive allele in that population would be?

  1. $0.375$
  2. $0.25$
  3. $0.75$
  4. $0.50$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If dominant phenotype percentage is given, we come to know about the percentage of homozygous recessive in population: which in this case is $25$%. Thus frequency of recessive allele is $0.50$.

So, the correct option is '0.50'.

Multiple choice commercial applications population - the increasing numbers and rising problem impact of depletion of natural resources population growth models depletion of resources

In a population $100$ individual are with recessive phenetype,with allelic frequency of $0.4$, the total population sis 

  1. $625$
  2. $400$
  3. $600$
  4. $250$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Using Hardy-Weinberg equilibrium: q^2 = 100/N. Given q = 0.4, then q^2 = 0.16. So, 0.16 = 100/N, which means N = 100 / 0.16 = 625.

Multiple choice biology cell biology and biotechnology agritourism biotechnology commercial applications of biotechnology
Multiple-choice Question

Find out the correct sentence:

  1. Hybridisation means crossing between genetically dissimilar plants

  2. Cross between two varieties is called as interspecific hybridisation

  3. Introducing genes of desired character into a plant gives genetically modified crop

  4. Cross between plants of two species is called intervarietal hybridisation
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

Hybridisation is the interbreeding between two genetically different organisms from the same or different species. When such interbreeding is between different species it is known as interspecific hybridisation. Genetically modified crops are those that are genetically engineered by introducing the genes of the desired trait (character) into the plants. When the cross is between two different varieties of the same species then it is known as intervarietal hybridisation. So, the correct options are 'Hybridisation means crossing between genetically dissimilar plants and Introducing genes of the desired character into a plant gives genetically modified crop'.

Multiple choice biology selection and evolution phylogeny cladistics speciation

An example of polygenic inheritance

  1. Epistasis

  2. Dominance

  3. Segregation

  4. Pleiotropy

  5. Independent assortment
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Polygenic inheritance occurs when one characteristic is controlled by two or more genes e.g., height, skin color, eye color and weight.
Epistasis is a 'modifier genes', occurs when two or more different gene loci contribute to the same phenotype. In epistasis, one gene locus masks or modifies the phenotype of a second gene locus. Thus, the correct answer is option A.
Multiple choice zoology applications of biotechnology genetically modified organism transgenic organisms genetic modification and biotechnology

Triticale is produced by the crossing of

  1. wheat and rye

  2. wheat and maize

  3. wheat and barlye

  4. rye and maize
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Triticale is a crop species (cereal grain) formed as a result of cross between wheat (Triticum) and rye (Secale). It combines the yield potential and grain quality of wheat with the disease and environmental tolerance (including soil conditions) of rye. So, the correct option is 'wheat and rye'.

Multiple choice pleiotropy genetics zoology

Teacher asks the student to give the best example to explain pleiotropy. The correct answer is

  1. Flower colour in snapdragon

  2. Seed coat colour of garden pea

  3. ABO blood group system of human

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

Pleiotropy occurs when one gene will code and control the phenotype or expression of several different and unrelated traits. Phenylketonuria is an autosomal recessive disorder controlled by a mutant gene present on the 12th chromosome. This mutant gene fails to code for the enzyme phenylalanine hydroxylase required for normal metabolism of amino acid phenylalanine to tyrosine. Due to this, there is an accumulation of phenylalanine in body fluids such as blood, sweat, CSF. An abnormal breakdown product phenyl ketone is found in urine A higher level of phenylalanine and pheylketone cause severe brain damage leading to mental retardation. Thus phenylketonuria is the best example to explain pleiotropy.

So, the correct answer is 'Phenylketonuria'