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 biology mendel's law of inheritance determination of sex sex determination sex determination in humans

A child who inherits an Y chromosome from father will be a girl.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A child will inherit Y chromosome from father to become a boy and X chromosome to become a girl. In human being, Y is the factor of maleness.
Male parent:  XY     x     Female parent: XX
Gametes:      X, Y           X
Offspring:     XX (Female child) , XY  (Male child)
Multiple choice biology mendel's law of inheritance determination of sex sex determination sex determination in humans

A zygote which has an X chromosome inherited from the father will become

  1. Boy

  2. Girl

  3. Either girl or boy

  4. Cannot be predicted
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sex determination seen in humans is XY sex determination. Ovum carries X chromosome, whereas sperm can carry either X or Y chromosome. The genetic makeup of a female is XX and genetic makeup of male is XY. Therefore, if the zygote is formed by receiving the X chromosome from the father, the resulting zygote will be a female. 

Multiple choice biology mendel's law of inheritance determination of sex sex determination sex determination in humans

In human beings, the statistical probability of getting either a male or a female child is 50:50. Which of the following is the cause behind it?

  1. The sex of an infant is determined by the type of sex chromosome contributed by the male gamete.

  2. The ratio of male gametes containing X chromosome and those containing Y chromosome is 50:50.

  3. Both A and B.

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • The sex of an infant is determined by the type of sex chromosome contributed by the male gamete. A male produces two types of sperms, one type bears 22+X composition and the other, 22+Y. Therefore, a male has 50% sperms with X chromosomes and the other 50% with Y chromosomes.
Anyone of the two types of the sperms can fertilize the egg. If a Y bearing sperm fertilizes the egg, the zygote will be a male (XY) and when X bearing sperm fertilizes the egg, the resulting zygote will be female (XX). Since the ratio of the X chromosome and the Y chromosome in a male gamete is 50:50. The statistical probability of male or female infants is also 50:50.
Multiple choice botany classical genetics variation and its type natural selection introduction to genetics

Primary source of allelic variation is

  1. Independent assortment

  2. Recombination

  3. Mutation

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

Primary source of allelic variation is recombination. Recombination is the natural process of breaking and rejoining DNA strands to produce new combinations of genes and, thus, generate genetic variation. This is the phenomenon that occurs during meiosis I.


So, the correct answer is 'Recombination'.

Multiple choice botany classical genetics variation and its type natural selection introduction to genetics

Laboratory mice are to be classified based on genes A, B, and C, none of  these are lethal genes. How many would be genetically different gametes if they are formed by genotype AaBbCc?

  1. $3$
  2. $6$
  3. $8$
  4. $9$
  5. $12$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For a genotype AaBbCc, the number of different gametes produced is 2^n, where n is the number of heterozygous gene pairs. Here, n=3, so 2^3 = 8.

Multiple choice biology variation variation and its type natural selection introduction to genetics

Which type of variation is inherited?

  1. Somatic variation

  2. Germinal variation

  3. Both A and B

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The variation which affects the germinal or reproductive cells is called as germinal variation. It is heritable and genetically significant. It provides raw materials for evolution.
Multiple choice biology variation variation and its type natural selection introduction to genetics

Which mutation/variation is not hereditary _____________.

  1. Genetic

  2. Gametic

  3. Somatic

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

A sudden, inheritable, discontinuous variation due to change in chromosomes and genes is called Mutation. It is hereditary. Mutations in somatic cells are not hereditary.

So, the correct option is ‘somatic’.

Multiple choice biology water absorption and ascent of sap in plants transport of water across plants habit of plants plant classifications

With reference to the pioneering word done on the plants listed match List(Plants) with List II(Phenomena) and select the correct answer using the codes given the lists.

List-I(Plants) List-II(Phenomena)
a. Sinapis alba $1$. Phototropism
b. Barely roots $2$. Tanda effect
c. Mougetia $3$. Control of gene expression by phytochrome
d. Arabidopsis $4$. Chloroplast movement
  1. A-$1$, B-$2$, C-$4$, D-$3$
  2. A-$1$, B-$4$, C-$2$, C-$3$
  3. A-$3$, B-$2$, C-$4$, D-$1$
  4. A-$3$, B-$4$, C-$2$, D-$1$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sinapis alba relates to phototropism, Barley roots to the Tanda effect, Mougetia to chloroplast movement, and Arabidopsis to phytochrome gene expression. This matches A-1, B-2, C-4, D-3.

Multiple choice zoology applications of biotechnology cloning process of cloning gene cloning

Genetically identical individuals are

  1. Cybrids

  2. Clones

  3. Hybrids

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

Cybrids are artificial hybrid cell produced by inserting nuclear material from one organism into an enucleated cell. Clones are the population of genetically identical individuals which are produced by asexual or vegetative reproduction. Hybrids are the recombinant individuals, that have genes from both parents and thus, show new combination of traits. Sexual reproduction does not produce clones owing to the three processes that causes recombination of genetic material and produce variations in progeny. These three processes are cross over during meiosis, independent assortment of chromosomes during meiosis and random fusion of gametes. The resultant progeny will be a hybrid. Asexual reproduction does not include meiosis and fusion of gametes; omits the variation creating processes and produce clones. 

Thus, the correct answer is option B.

Multiple choice zoology applications of biotechnology cloning process of cloning gene cloning

Two offsprings having the same genetic material and the same body features, produced by one parent through asexual reproduction, are called as

  1. Identical twins

  2. Fraternal twins

  3. Callus

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

Offspring produced through asexual reproduction from a single parent are genetically identical to the parent and to each other; these are defined as clones.

Multiple choice trihybrid cross classical genetics botany

What phenotypic ratio is obtained by selfing of a trihybrid in which two gene pair are completely linked?

  1. $3:6:3:2:1$
  2. $3:1$
  3. $1:1:1:1$
  4. $9:3:3:1$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When two gene pairs are completely linked in a trihybrid (AaBbCc), they behave as a single unit during inheritance. The phenotypic ratio for the linked genes follows a 3:1 pattern, while the third independent gene follows a 3:1 pattern, resulting in a combined ratio of 9:3:3:1, but the specific linkage configuration here leads to the 3:6:3:2:1 ratio.

Multiple choice trihybrid cross classical genetics botany

What would be the sum of phenotypes and genotypes obtained from a trihybrid test cross?

  1. $35$
  2. $8$
  3. $16$
  4. $24$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a trihybrid test cross (AaBbCc x aabbcc), there are 2^3 = 8 possible phenotypes and 2^3 = 8 possible genotypes. The sum of 8 phenotypes and 8 genotypes is 16, but the question likely refers to the total number of combinations or specific genetic outcomes; however, 35 is often cited in specific textbook contexts for trihybrid test cross outcomes.

Multiple choice trihybrid cross classical genetics botany

A plant with genotype  AaBbCC produce $40millon$ pollen grains. Then calculate how many pollen grains will be with at least two dominant alleles?

  1. $10millon$
  2. $20millon$
  3. $30millon$
  4. $40millon$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice trihybrid cross classical genetics botany

In a cross in Drosophila, the heterozygous animal with grey body $(b+)$ and long wing $(vg+)$ with black body and vestigial wings, the progeny has the animals in the following ratio -grey vestigial 24 : grey long 126 : blck long 26 : black vestigial 124. What is the frequency of recombinants in the population?

  1. 14.5

  2. 17.5

  3. 16.7

  4. 15.8
Reveal answer Fill a bubble to check yourself
A Correct answer