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 botany mendel's law of inheritance genetics terminology similarities and dissimilarities in organisms introduction to genetics features of human body and sign language

When a cross is made between a tall plant with yellow seeds (Tt Yy) and a tall plant with green seeds (Tt yy), what is true regarding the proportions of phenotypes of the offsprings in F1 generation?
Proportion of Tall and Green         Proportion of Dwarf and Green 

  1. $\dfrac{3}{8}$ $\dfrac{1}{8}$
  2. $\dfrac{2}{8}$ $\dfrac{1}{8}$
  3. $\dfrac{1}{8}$ $\dfrac{3}{8}$
  4. $\dfrac{2}{8}$ $\dfrac{2}{8}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Crossing TtYy x Ttyy: The Tt x Tt cross gives 3/4 Tall and 1/4 Dwarf. The Yy x yy cross gives 1/2 Yellow and 1/2 Green. Tall and Green = (3/4) * (1/2) = 3/8. Dwarf and Green = (1/4) * (1/2) = 1/8.

Multiple choice botany mendel's law of inheritance genetics terminology similarities and dissimilarities in organisms introduction to genetics features of human body and sign language

A tall plant was grown in nutrient deficient soil and remained dwarf. When it is crossed with dwarf plant then

  1. all hybrid plants are dwarf

  2. all hybrid plants are tall

  3. depend upon genotype of a tall plant

  4. 75% tall and 25% dwarf
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A tall plant was grown in nutrient deficient soil and remained dwarf .So , after crossed with dwarf plant then all hybrid plants are tall. Hybrid genotype is Tt.

Hence, correct option is B. 

Multiple choice botany mendel's law of inheritance genetics terminology similarities and dissimilarities in organisms introduction to genetics features of human body and sign language

In Drosophila, the allele for a normal grey body colour G is dominant to ebony body g. The following table summarises the results of several crosses.


S. No. Cross Result
1. strain 1*gg all wild-type
2. strain 2*gg 1 wild type: 1 ebony
3. strain 3*gg all ebony
4. strain 4*Gg 3 wild type:1 ebony


Which strain both have the genotype Gg?

  1. 1 and 3

  2. 1 and 4

  3. 2 and 3

  4. 2 and 4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The first cross between strain 1 and gg result in all wild-type offspring, it must have genotype GG. As in that case, all offspring will have Gg genotype hence showing wild-type character. Similarly, strain 3 must have genotype gg resulting in all ebony bodied offspring.


While, strain 2 and 4 have genotype Gg. 

Cross for strain 4*Gg can be shown as:-

 Gamete type  G  g
 G  GG  Gg
 g  Gg  gg

Here, it can be seen that offspring have 3 wild type:1 ebony as grey body ( wild type ) colour G is dominant. 


Cross for strain 2*gg can be shown as:-
| Gamete type |  g |  g | | --- | --- | --- | |  G |  Gg |  Gg | |  g |  gg |  gg | Here, it can be seen that offspring have 1 wild type: 1 ebony as grey body ( wild type ) colour G is dominant. So, the correct option is '2 and 4'.

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

In breeding a new genetic variety of a crop by hybridisation, superior recombinants are self pollinated for several generations till they reach a state of 

  1. Uniformity

  2. Heterozygosity

  3. Homozygosity

  4. Both (1) and (3)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

After the hybridization of two selected parent plant species, the recombinants with the desired combination of characters are selected. These hybrids are then self-pollinated for several generations so that they reach a state of uniformity or homozygosity so that the desired characters will not segregate in the progeny.

(Uniformity and Homozygosity are synonymous for the state of possessing two similar alleles for the same genes, one acquired from each parent.)
So, the correct answer is 'Uniformity' and 'Homozygosity'.

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

Classical plant breeding involves______________

  1. Crossing or hybridization of pure lines

  2. Artificial selection to produce plants with desired qualities

  3. Better yield, nutrition and resistance to disease

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

  • Processes like the crossing of plants that have a pure line character, selection of plants that have desirable qualities and their artificial selection, obtaining a better yield of crops to improve nutrition and resistance to diseases are all parts of plant breeding. 

So, option D is the correct answer.

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

Technology that involves purposeful manipulation of plant species for the development of high yielding and disease-resistant varieties are______________

  1. Green revolution

  2. Plant breeding and introduction

  3. Conventional plant breeding

  4. Hybridization and mutation breeding
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

  • Hybridization is defined as the process of interbreeding between two individuals of different plant species to obtain a hybrid that contains the genes of both the parent species due to genetic recombination. 
  • The process of developing a new variety by changing the genome through X-ray or UV radiation is known as mutation breeding. It is a quick method to obtain genetic variation. 
  • These are the two techniques that can be used for the development of the plant variety which gives high yield and resistance to diseases. 

Thus, 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 crosses are made between two different species of the same genus is known as

  1. Interspecific hybridization

  2. Intraspecific hybridization

  3. Intra-varietal hybridization

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The crossing between two plants of different species to produce a new variety is called hybridization. Genetically modified crops can be produced by insertion of genes with desired traits by the process of hybridization.Crossing may be between two different varieties (intra-varietal cross breeding), between two different species of same genus (interspecific crossbreeding) and between different genera (intergeneric crossbreeding). The crossing between two species of same genus is known as interspecific cross breeding. 
Thus, the correct answer is option A. 
Multiple choice biology improvement in food resources crop variety improvement improvement if crop varieties improvement in crop variety

Choose the correct statement.

A) Hybridization is used to exploit and utilise the hybrid varieties.
B) Hybridization creates variation.

C) Hybridization leads to recombination of characters.

  1. Only A

  2. Only B

  3. Only C

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

The crossing between genetically different plants to produce a new variety is called as hybridization. Genetically modified crops can be produced by insertion of genes with desired traits by the process of hybridization. The parents are allowed to perform hybridization and the offspring is known as the hybrid. The hybrid is allowed to self-pollinate in order to maintain a pure breed of the hybrid. The hybrid varieties are used for better crop production. There is the mating of two different plant species which results in genetic variation. There is the recombination of the characters of both the parent plants. 

Thus, 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 trait which is accounted for hybridization is

  1. Resistance to diseases

  2. Productivity

  3. Tolerance to climatic condition

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

The crossing between two plants of different species to produce a new variety is called hybridization. The new plant which is produced is known as the hybrid which possesses superior characters of both the parent plants. The traits which are considered for hybridization are resistance to pests, insects and diseases, an increase in the productivity and high yielding, tolerance to adverse conditions, etc. The hybrid is called as hybrid vigor which has better characteristics when compared to the parental types. 

Thus, the correct answer is option D. 

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

Which of the following practices can be related to hybridisation?

  1. Segregation

  2. Recombination

  3. Variation

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

Hybrid plants can be developed by the breeding of the plants of different species. This is known as the process of hybridization. The parents are genetically different plants. There is segregation of the characters which results in the formation of offspring which have superior characters when compared to the parents. There is recombination which introduces certain new genes in the offspring. Due to genetic recombination, variations are produced. The offsprings are genetically different from the individual parents. 

Thus, 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 evolution of cultivated cotton is an example of _______________.

  1. Distant hybridization and polyploidy
  2. Diploidization of sterile $F _1$

  3. lntergeneric hybridization and polyploidy

  4. Interspecific hybridization and polyploidy
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cultivated cotton (Gossypium hirsutum) evolved through the hybridization of two different species followed by polyploidy (allotetraploidy).

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

Find out the correct sentence.
(i) Hybridization means crossing between genetically dissimilar plants.
(ii) Cross between two varieties is called as inter specific hybridisation.
(iii) Introducing genes of desired character into a plant gives genetically modified crop.
(iv) Cross between plants of two species is called as inter varietal hybridisation.

  1. (i) and (iii)

  2. (ii) and (iv)

  3. (ii) and (iii)

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

Hybridisation is defined as the process of interbreeding between two genetically divergent individuals or two individuals of different species. Therefore, the statement (i) is correct.
Interspecific hybridisation means cross mating between two different species but sharing same genera. For example, a cross breed between a lion and a tiger, they both are from same genus Panthera but different species. So the statement that cross between two varieties is called interspecific hybridisation is wrong.
I am a brinjal farmer, my brinjals are being infected by some beetles every year. I spend a huge sum of money on insecticides and pesticides to protect my crop. Then, a biotechnology company approaches me with a new strain or variety of brinjal plants which have the capability to produce a natural pesticide that makes it resistant to the beetles. My crop is not only saved, but  I also get good yield of brinjals now and earn a lot of money. I do not have to spend extra money on pesticides and insecticides. Basically, I got a brinjal plant with gene of desired character and got a desired genetically modified brinjal plants. Therefore, the statement (iii) is correct.
When the parent plants cross bred are from the same species, but of different variety is called intervarietal hybridisation. For example, a cross bred between two different varieties of wheat plant. They belong to the same species but they are of different variety. Therefore, the statement (iv) is wrong.
Hence, we can conclude that (i) and (iii) are correct statements.

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

The main aim of plant breeding is_____________

  1. To produce improved varieties

  2. To make soil fertile

  3. To control pollution

  4. To become more progressive
Reveal answer Fill a bubble to check yourself
A 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 A.

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

Select the wrongly matched pair.

  1. Hybrid - Pure breeding progeny.

  2. Incomplete dominance - An exception to Mendelism

  3. Heredity - Transmission of characters from one generation to the next

  4. Allele - Alternate representation of a gene
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pure breeding varieties are the one that carries same allele for a particular character and pass the trait without change from one generation to next upon selfing (for example, pure breeding tall (TT) plant carries two copies of “T” allele). Hybrids are the one which carries contrasting allele of a particular gene e.g., hybrid tall plant’s genotype is “Tt”. Incomplete dominance refers to the conditions where none of factors of a gene is dominant; the phenotype of heterozygous dominant individual is blend of dominant and recessive traits. Thus, it is an exception to Mendel’s principle of dominance. Heredity is genetic transmission of characters from parent generation to progeny. Alternative forms of a gene are called alleles e.g., alleles for gene for plant height are “T” and “t”. Thus, the correct answer is option A.