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 improvement in food resources crop variety improvement improvement if crop varieties improvement in crop variety

The science of improving crop varieties is called as____________________

  1. Crop improvement

  2. Selection

  3. Introduction

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

  • Plant breeding is the art and science of changing the traits of plants in order to produce desired characteristics. 
  • Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable characteristics for propagation, to more complex molecular techniques. 
  • Plant breeding aims to improve the characteristics of the plant so that they become more desirable agronomically and economically. 
  • Thus, the chief objective of plant breeding is to develop such improved varieties of crop plants that will be commercially successful. 
  • Generally, a successful variety is one with a total balance of traits that makes it more profitable for growers. 
  • Quality characters vary from one crop to another, e.g., grain size, colour, milling and baking qualities in wheat (Triticum aestivum), cooking quality in rice (Oryza sativa), malting quality in barley (Hordeum vulgare), size, colour, and flavour of fruits, keeping quality of vegetables, protein content in cereals and legumes, lysine content in cereals, methionine and tryptophan contents in pulses, etc.

Therefore, the correct answer is option D.

Multiple choice biology improvement in food resources crop variety improvement improvement if crop varieties improvement in crop variety

The aim of plant breeding is to produce_____________

  1. Disease-free varieties

  2. High-yielding varieties

  3. Early-maturing varieties

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

  • Plant breeding aims to improve the characteristics of the plant so that they become more desirable agronomically and economically. 
  • Thus, the chief objective of plant breeding is to develop such improved varieties of crop plants that will be commercially successful. 

Therefore, the correct answer is option D.

Multiple choice biology animals in daily life introduction to reproduction poultry farming food from animals

Breeding in Fowl is done between :

  1. Six month old hen and cock.

  2. One year old hen and two year old cock.

  3. Two year old hen and one year old cock.

  4. Two year old hen and cock.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Answer C) Two year old hen and are year old cock usually a rooter reacts its mortality of 5 moths old. But young rooters are not wood 10 breed because they are case effective. So the rooter of an year old is used for breeding.
A hen also grows and molecular of an age of 6 months But the hen is allowed to grow fully and matured. Hence, two year old hen is used.
Multiple choice biology fruit and seed morphology of the fruit fruit plants: structure and function

Fruit shape in shephered's purse(Capsella bursa) is of two types-triangular and top-shaped. Triangular fruit shape(T) is dominant over top-shape (t). Following table summarises the results of several crosses.

Cross Result
Strain 1 x tt All triangular
Strain 2 x tt 1 triangular : 1 top-shaped
Strain 3 x tt All top-shaped
Strain 4 x tt 3 triangular: 1 top-shaped

Which pair of strains possess the genotype Tt?

  1. Strains 2 and 3

  2. Strains 2 and 4

  3. Strains 1 and 3

  4. Strains 1 and 4
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice evs modern agriculture agricultural practices in india different types of farming and agriculture various agricultural practices

WhIch of the following is necessary for Improvement of the quality of crops?
1. Introduction
2. Hybridisation
3. Selection
4. Segregation

  1. 1, 2 and 3

  2. 1, 2, 3 and 4

  3. 2, 3 and 4

  4. 2 and 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Development of the new variety of plant processing desirable characters from existing ones is known as plant breeding.
Plant introduction means introducing a plant having desirable characters which are a genetic improvement, high yield, disease resistance and vigorous growth from a region of a country where growth naturally to a region or a country where does not occur earlier.
Then the pure line selection is done.
Hybridization is a method of reducing new crop varieties in which two or more plants of unlike genetical constituents are fused together.

So, the correct option is '1, 2 and 3'



Multiple choice botany modes of reproduction why do plants reproduce? reproduction and variation the life cycle of plants

Characters that are transmitted from parents to offspring during reproduction show

  1. Only similarities with parents

  2. Only variations with parents

  3. Both similarities and variations with parents

  4. Neither similarities nor variations
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Character that are transmitted from parent to offspring during reproduction are similar to parent but they may vary due to mutation, crossing over and genetic recombination.
Multiple choice botany classical genetics incomplete dominance deviation from mendelism inheritance

Phenotypic and genotypic ratio is similar in case of?

  1. Complete dominance

  2. Incomplete dominance

  3. Over dominance

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

In complete dominance, the dominant allele fully masks the recessive allele. Therefore, the phenotype of the heterozygote is identical to the homozygous dominant, making the phenotypic and genotypic ratios identical in a monohybrid cross (3:1 vs 1:2:1 is not the case here, but rather the expression of traits).

Multiple choice botany classical genetics incomplete dominance deviation from mendelism inheritance

The segregration of alleles is a random process and so there is a _______ chance of a gametes containing either allele.

  1. $25\%$
  2. $50\%$
  3. $75\%$
  4. $100\%$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to Mendel"s law of segregation, alleles segregate from one another so that the gametes will have only one copy of the particular gene. In a diploid organism, there are two alleles for a particular gene, which segregate and only one of each allele can be present in a gamete, therefore, since there are two alleles for a gene, chances of a gamete containing either of the allele is 50%. 

So, the correct option  is '50%'.

Multiple choice botany classical genetics incomplete dominance deviation from mendelism inheritance

When the phenotypic and genotypic ratios resemble in the F$ _2$ generation, it is an example of

  1. Independent assortment

  2. Qualitative inheritance

  3. Segregation of factors

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

Incomplete dominance: It is a type of intragenic (or interallellic) interaction where both the alleles of a given trait express as a blend (mixture) as against a normal Mendelian pattern where one allele is dominant over the other. As a resulting of this blending, an intermediate character is expressed. This situation occurs due to the fact that the dominant gene is not in a position to completely suppress the expression of recessive gene. With the result, the heterozygous offspring will be phenotypically and genotypically different from either of the homozygous parent.

Multiple choice botany classical genetics incomplete dominance deviation from mendelism inheritance

When a hybrid plant with pink (Rr) flower of Mirabilis is crossed with white flower, the expected phenotype ratio is

  1. red : pink : white, 1 : 2 : 1

  2. pink : white, 1 : 1

  3. red : pink, 1 : 1

  4. red : white, 3 : 1
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Hybrid - Rr pink flower and white flower - rr
Genotypes: Rr            x      rr
Gametes:     R, r                 r
Offspring:      Rr, rr
The ratio of pink flower: white flower = 1:1

Multiple choice botany classical genetics incomplete dominance deviation from mendelism inheritance

RR(red) is crossed with rr (white). All Rr offsprings are pink. This indicates that R gene is

  1. Hybrid

  2. Incompletely dominant

  3. Recessive

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

Incomplete dominance refers to a genetic situation in which one allele does not completely dominate another allele and, therefore, results in a new phenotype. It shows that the dominant allele is incompletely dominant.
Examples of incomplete dominance are:

1. A snapdragon flower that is pink as a result of cross-pollination between a red flower and a white flower when neither the white or the red alleles are dominant.
2. A brown fur coat on a rabbit as a result of one rabbit's red allele and one rabbit's white allele not dominating.

Multiple choice botany classical genetics incomplete dominance deviation from mendelism inheritance

Which one of the following represents a deviation from Mendelian concepts?

  1. Segregation

  2. Independent assessment

  3. Purity of gametes

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

Incomplete dominance is the only option which does not obey Mendel's principles. Mendel postulated law of segregation, independent assortment, dominance, purity of gametes, etc. According to Mendel's theories, the alleles constituting the genes will separate and segregate during meiosis for the formation of gametes. It produces the expression of either dominant or recessive - dominant expresses in both homo and heterozygous conditions, recessive expresses only in homozygous condition. But incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a third phenotype in which the expresses physical trait is a combination of the dominant and recessive phenotypes.

Multiple choice botany classical genetics incomplete dominance deviation from mendelism inheritance

If in snapdragon, a homozygous dominant red-flowered plant is crossed with a homozygous recessive white flowered plant, the offspring would be

  1. Half red-flowered

  2. Half white-flowered

  3. All red-flowered

  4. Pink-flowered
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Homozygous dominant red flowered plant- RR
Homozygous recessive white flowered plant- rr
Genotypes:  RR     x     rr
Gametes:     R             r
F$ _{1}$:   Rr (pink-coloured flower)
This is an example of incomplete dominance.

Thus, the correct answer is option D.