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 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
A Correct answer
Multiple choice biology the age of adolescence menstruation in females changes at puberty what happens if an egg is not fertilized?

Sexual dimorphism is the 

  1. Genotypic difference

  2. Phenotypic difference

  3. Neurological difference

  4. Both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Sexual dimorphism refers to the condition where the two sexes of the same species show different characteristics apart from the differences in their sex organs.
  • As both sexes consist of different chromosome pattern ( for e.g. XX AND XY in human beings), they differ genotypically.
  • Those observable characters which are visible to us and helps us in knowing the sex of any animal/plant without knowing their chromosome pattern are essentially what phenotypic difference is about.
  • So, the correct answer is 'Both A and B'.
Multiple choice evs production of food from animals dairy farm management cattle farming uses of animals contribution of louis pasteur discoveries by louis pasteur discovery of microorganisms

In cattles, when red one is crossed with white coloured then an intermediate or rather roan coloured offspring is formed. It is an example of.

  1. Incomplete dominance

  2. Dominance simply

  3. Co-dominance

  4. No genetic relation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Incomplete dominance occurs when the phenotype of the heterozygote is intermediate between the phenotypes of the two homozygotes. Crossing red and white cattle to produce roan (a mix of red and white hairs) is a classic example of co-dominance, but in many textbooks, this specific scenario is often used to illustrate incomplete dominance or co-dominance depending on the definition of the trait.

Multiple choice botany heredity: from parents to offsprings experiments of mendel mendel's law of inheritance works of mendel

It is said that Mendel proposed that the factor controlling any character is discrete and independent. His proposition was based on the

  1. Results of $F _3$ generation of a cross

  2. Observations that the offspring of a cross made between the plants having two contrasting characters shows only one character without any blending
  3. Self pollination of $F _1$ offsprings
  4. Cross pollination of $F _1$ generation with recessive parent
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mendel crossed two parent plants having contrasting characters. He found that in the first filial generation, F1 generation, the dominant of the two expressed while the recessive is suppressed. Apart from this,  When the f1 generation is self crossed, in the F2 generation, these recessive characters appear again. Therefore, it is not that they have disappeared. 

So, option B is the correct answer.

Multiple choice botany unravelling genetic mysteries experiments of mendel mendel's law of inheritance works of mendel

Which of these is not a part of Mendel's laws

  1. Law of independent assortment

  2. Law of segregation

  3. Law of dominance

  4. Law of linkage
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Linkage is the tendency of two or more genes to inherit together as a pair and not to sort out independently.
Thus, linkage is not applicable according to Mendelian principles.
Linkgae is strictly against Law of independent assortment where Mendel explains that the characters are sorted out independently while forming gametes.

Multiple choice botany heredity: from parents to offsprings experiments of mendel mendel's law of inheritance works of mendel

Mendel's law of heredity can be explained with the support of  

  1. Mitosis

  2. Meiosis

  3. Both mitosis and meiosis

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

Meiosis is otherwise called as Reductional division where the ploidy level of the organism is halved. Meiosis occurs in sex cells where Law of Independent assortment is well applicable. Because during meiosis, the hereditary units are inherited independently and segregated in chromosomes. One allele of a trait segregates and moves to the chromosomes such that the offspring can acquire characters from any one parent. Thus the law of Segregation also is proved well by the process of Meiosis. The expression of phenotype very well depends on Mendel's law of dominance. The dominant character is expressed in both homozygous and heterozygous forms. Whereas recessive characters are expressed only in homozygous forms.

Multiple choice botany heredity: from parents to offsprings experiments of mendel mendel's law of inheritance works of mendel

Heterozygous tall plant is selfed. It produces both tall and dwarf plants. This confirmed Mendel's law

  1. Law of dominance

  2. Law of segregation

  3. Law of independent assortment

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

 According to the law of seggregation  alleles of a trait that remain together in an individual do not mix but rather keep their identity intact. They separate during gamete formation and get randomly distributed only to get paired again in the offspring’s as per the principle of probability. This results in a phenotypic trait in the 3:1 ratio in the F2 generation i.e when a heterozygous plant is crosssed. So, the correct answer is 'Law of segregation'.

Multiple choice botany heredity: from parents to offsprings experiments of mendel mendel's law of inheritance works of mendel

In a population of $400$ individuals, the frequency of a recessive allele is $40%$. Find out which of these represents the total number of individuals with dominant phenotype?

  1. $144$
  2. $192$
  3. $256$
  4. $336$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • In the population of 400 individuals if 40% is recessive allele and 60% will be dominant (144).

So, the correct option is '144'.

Multiple choice botany heredity: from parents to offsprings experiments of mendel mendel's law of inheritance works of mendel

Which one of the following ratio/s represent variation in phenotypic ratio of monohybrid $F _2$ and incomplete dominance $F _2$ results, with regard to Mendelian inheritance.

  1. $1:2:1$
  2. $3:1$
  3. $9:3:3:1$
  4. Both $2$ and $3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Incomplete dominance F2 phenotypic ratio is 1:2:1, and the genotypic ratio of a monohybrid F2 is also 1:2:1.

Multiple choice botany heredity: from parents to offsprings experiments of mendel mendel's law of inheritance works of mendel

Which of the following law of genetics has been proved to be true in all cases? 

  1. Law of Segregation

  2. Law of Independent assortment

  3. Law of Dominance

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

Law of segregation or law of purity of gametes holds in all situations whereas Law of independent assortment is violated in case of linkage and law of dominance is violated when codominance and incomplete dominance takes place.

Multiple choice botany heredity: from parents to offsprings experiments of mendel mendel's law of inheritance works of mendel

Mendelian laws of heredity include

  1. Gene linkage, segregation and independent assortment

  2. Gene linkage, dominance and independent assortment

  3. Segregation, dominance and independent assortment

  4. Segregation, independent assortment and recombination
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Mendel's law of heredity explains that there is some factor that inherits the characters from one generation to next. To explain this  he gave 3 laws which are :
1. Law of dominance
2. Law of purity of gametes (Principle of segregation)
3. Law of independent assortment

Thus, the correct answer is option C.

Multiple choice botany heredity: from parents to offsprings experiments of mendel mendel's law of inheritance works of mendel

Dihybrid cross proves the law of

  1. Segregation

  2. Purity of gametes

  3. Dominance

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

Dihybrid cross proves the law of independent assortment. Mendel found that each pair of alleles segregates independently of the other pairs of alleles during gamete formation. This is known as Law of independent assortment. Dihybrid cross - cross between two parents that differ by two pairs of alleles (AABB X aabb). The formation of gametes is an application of this law.