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 unravelling genetic mysteries experiments of mendel mendel's law of inheritance works of mendel

Which of the following characteristics represent inheritance of dihybrid crosses in pea :
a) Incomplete dominance
b) Dominance
c) Law of segregation 
d) Co - dominance
e) Polygenic inheritance
f) Law of independent assortment 

  1. b and f

  2. a, d and f

  3. b, c and f

  4. b , c and e
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A dihybrid cross involves the inheritance of two traits. Mendel's experiments with dihybrid crosses demonstrated the Law of Dominance (b) and the Law of Independent Assortment (f).

Multiple choice biology mendel's law of inheritance experiments of mendel works of mendel mendel's laws of inheritance

The main reason for the success of Mendel was that

  1. He made statistical analysis of the offsprings.

  2. He first took only one character at a time in his crosses.

  3. He kept pedigree records.

  4. He selected pea plants.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Main reasons for the success of Gregor Mendel: 

1. Mendel concentrated in one or few characters at a time.
2. He made controlled crosses and kept careful numerical records of the results.
3. He suggested 'factors' as a cause of characters.
4. The experimental material Pisum sativum was a wise choice.

Multiple choice biology mendel's law of inheritance experiments of mendel works of mendel mendel's laws of inheritance

Correct reason of Mendel's success was

  1. He repeated each experiment several times.

  2. Traits chosen by him had genes far apart so that linkage was absent.

  3. He kept record of all experiments.

  4. He used statistical techniques.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mendel chose seven pairs of contrasting traits, the gene for each of which is present on seven different chromosomes of pea plant. Due to the presence on different chromosomes, Mendel's trait followed independent assortment during meiosis and produced the expected parental and recombinant phenotypes. If genes of these traits would have present together showing linkage, Mendel would not have got the expected results. Repeating the experiment, keeping records and use of statistical analysis were the secondary factors; major being the chosen traits not showing linkage. 

So, the correct answer is 'Traits chosen by him had genes far apart so that linkage was absent'.

Multiple choice biology mendel's law of inheritance experiments of mendel works of mendel mendel's laws of inheritance

Mendel was lucky, because

  1. He was born in Austria which is a nice country.

  2. He used pea plant for his experiment which is rich in protein.

  3. The genes for different characters are located on different chromosomes in Pisum sativum.

  4. The Pisum sativum is short-lived plant.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Mendel was lucky because he used pea plant i.e. Pisum sativum, they are bisexual, they had pure breeding varieties with observable characters, & each character is regulated by one type of gene, whether it is tall, dwarf, round or wrinkled etc. It was an ideal choice for him.

So, the correct answer is "The genes for different characters are located on different chromosomes in Pisum sativum".

Multiple choice biology mendel's law of inheritance experiments of mendel works of mendel mendel's laws of inheritance

When two genes control a single character and have cumulative effect the ratio is _______

  1. $1:1:1:1$
  2. $1:4:6:4:1$
  3. $1:2:1$
  4. $1:6:15:20:15:6:1$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
When two genes present on the same loci give an additive or cumulative effect like the spotted and Dotted seed of Lens sps the ratio is 1:2:1
So, the correct answer is '1:2:1'
Multiple choice botany unravelling genetic mysteries experiments of mendel mendel's law of inheritance works of mendel

Successive exploitation of heterocyst depends upon the ______________.

  1. Presence of heterotic effect in the hybrid

  2. Availability of male sterility

  3. Out crossing nature of the flower

  4. Heterotic effect and availability
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The success of hybrid seed production often relies on the heterotic effect (hybrid vigor), which is the tendency of a crossbred individual to show qualities superior to those of both parents.

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

If mendel had studied the 7 traits using a plant with 12 chromosomes instead of 14 ,in what way this interpretation have been different 

  1. He would have mapped the chromosomes

  2. He would have discovered blending or incomplete dominance

  3. He would not have discovered law of independent assortement

  4. He would have discovered sex linkage
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice botany unravelling genetic mysteries experiments of mendel mendel's law of inheritance works of mendel

Choose the correct answer from the alternatives given.

Among the seven pairs of contrasting traits in pea plant as studied by Mendel, the number of traits related to flower, pod, and seed respectively were

  1. 2, 2, 2

  2. 2, 2, 1

  3. 1, 2, 2

  4. 1, 1, 2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mendel's seven traits were: flower color, flower position, stem height, pod shape, pod color, seed shape, and seed color. Categorizing these: flower (2), pod (2), and seed (2), with stem height as the remaining one.

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

Choose the correct answer from the alternatives given.


The colour based contrasting traits in seven contrasting pairs, studied by Mendel in pea plant were.

  1. 1

  2. 2

  3. 3

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

The colour based contrasting traits studied by Mender in pea plant were pod colour,  i.e., green (dominant) and yellow (recessive), flower colour, i.e., violet (dominant) and white (recessive) and seed colour, i.e., yellow (dominant) and green (recessive). 

Multiple choice biology strategies for enhancement in food production common modes of vegetative propagation plant breeding for food production tissue culture

The quickest method of plant breeding is

  1. Intoduction

  2. Selection

  3. Hybridisation

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

The correct answer is mutation breeding:

Plant breeding is the technique used to improve the variety of plants for human welfare. Introduction, selection, hybridization and mutation breeding are the main methods of crop improvement along with polyploid breeding, tissue culture and genetic engineering. Introduction is the process of introducing new plants from their old locality to the new one. Selection is the oldest method of plant improvement in which suitable varieties are selected. It is of two types-natural and artificial. Hybridization is the production of new varieties by crossing two or more plants having different genetical constitution. Mutation breeding is a quick way to introduce sudden changes in the genome of the plant.

Multiple choice botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

Chromosome theory of inheritance was proposed by

  1. Sutton $(1902)$
  2. Boveri $(1902)$
  3. Both Sutton $(1902)$ and Boveri $(1902)$
  4. Correns $(1909)$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chromosome theory of inheritance or Boveri–Sutton chromosome theory is a fundamental unifying theory of genetics which identifies chromosomes as the carriers of genetic material

So, the correct answer is 'Both Sutton (1902) and Boveri (1902)'.

Multiple choice botany bacteria bacteria - friend and foe useful and harmful bacteria bacteria; benefits and harmful effects

Grown gall disease of plants is caused by

  1. Ti-plasmid

  2. Pi-Plasmid

  3. Virus

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

Crown gall disease is a plant disease that is caused by the bacterium Agrobacterium tumefaciens. Ti plasmid is essential to cause disease. It transfers bacterial DNA into the host cell where it incorporates itself into the host genome. It results in the overgrowth appearing as knobbly swellings or galls on stems, roots, trunks, and branches. It affects mostly woody shrubs and herbaceous plants like grapes, raspberries, blackberries, and roses.

Thus, the correct answer is 'Ti-plasmid.'

Multiple choice botany biotechnology and its applications biotechnology in agriculture gm crops transgenic organisms

In tomato, genotype $aabbcc$ produces $100gm$ tomatoes and $AABBCC$ produces $160gm$ tomatoes what is the contribution of each polygenes in the production of tomatoes?

  1. $10gm$
  2. $20gm$
  3. $30gm$
  4. $40gm$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Each polygene contributes 10gm. The difference between genotypes is 160-100=60gm. This difference is distributed across 3 gene pairs (6 alleles), so each contributing allele adds 60/6=10gm. Since each gene pair has 2 contributing alleles, each polygene contributes 20gm total (2 alleles x 10gm each). However, the question asks per polygene pair, so 10gm per allele x 2 alleles per gene = 20gm per gene pair. Wait, let me recalculate: aabbcc (0 contributing alleles) = 100gm, AABBCC (6 contributing alleles) = 160gm. Each contributing allele adds (160-100)/6 = 10gm. Since each gene has 2 alleles, each gene contributes 20gm when fully dominant. But the options suggest 10gm is the expected answer.