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 animal tissues fluid connective tissue tissues of animals animal tissues and its type

How many possible genotypes are there for ABO blood groups in man?

  1. Three

  2. Four

  3. Six

  4. Eight
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
 Genotype   Blood types
 $I^AI^O$ or $I^AI^A$ A blood type
 $I^AI^B$  AB blood type
 $I^BI^O$ or $I^BI^B$  B blood type
 $I^OI^O$  O blood type

There are six possible genotypes for the ABO blood groups in human.
The chart here shows the different genotypes, that make up the blood groups.
Therefore, the correct answer is option C.

Multiple choice zoology biodiversity and conservation hotspots and methods of conservation biodiversity: conservation conservation of biodiversity basis of classification in animals basis of the classification of animals criteria for animal classification

Dwarfing gene of wheat is

  1. Pal - 1

  2. Atomita - 1

  3. Norin - 10

  4. Pelita - 2
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Rht - B1b and Rht - D1b are dwarfing genes, derived from Norin - 10. Norin - 10, which was a semi - dwarf variety bred in Japan and released in 1935. Norin - 10 was used in order to improve lodging resistance in winter wheat. 

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 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
C Correct answer
Explanation

The genotype AaBbCC produces gametes with various combinations of alleles. The locus CC always contributes one dominant allele. We need at least two dominant alleles total, so we need at least one dominant allele from the Aa or Bb loci. The total number of pollen grains is 40 million. Using binomial probability or branch diagrams, the fraction of pollen grains with at least two dominant alleles can be determined, resulting in 30 million.

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
C Correct answer
Explanation

Recombinant progeny are those that show non-parental combinations of traits, which here are grey vestigial and black long. The number of recombinants is 24 + 26 = 50. The total progeny is 24 + 126 + 26 + 124 = 300. The recombination frequency is (50 / 300) * 100 = 16.67 percent, which rounds to 16.7 percent.