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

Choose the incorrect pair.

  1. Diabetesis-Hexokinase

  2. Albinism-Tyrosinase

  3. Tyrosinosis-Tyrosine hydroxylase

  4. PKU-Phenylalanine hydroxylase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Deficiency or absence of both fumarylacetoacetate hydroxylase and melanylacetoacetate isomerase enzymes causes Tyrosinosis.

Multiple choice

A genetic experiment was performed to map the gene (s) for eye colour in a newly-discovered moth species. Sex determination in this moth species: XY — male and XX — female. When blue-eyed males were mated to green-eyed females, all of both male and female progeny had green eyes. When these progeny were mated among themselves, about half of the males of the resulting second generation had blue eyes; however, all females were green-eyed. Which one of the following is consistent with the above data?

  1. Multiple genes control eye colour in this moth species.

  2. Gene(s) for eye colour is located on the X chromosome.

  3. Gene(s) for eye colour is located on the Y chromosome.

  4. Gene(s) for eye colour may not be sex-linked.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In this species, males are XY and females are XX. When blue-eyed males are crossed with green-eyed females, all F1 progeny are green, indicating green is dominant. In the F2 generation, half of the males have blue eyes while all females are green-eyed, which is the classic sex-linked recessive inheritance pattern corresponding to genes on the X chromosome.

Multiple choice biology food production uses of animals agro-complimentary occupations improvement of crop production

Hybridisation refers to crossing between genetically ______ plants.

  1. Similar

  2. Dissimilar

  3. Both A or B

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

One way of incorporating desirable characters into crop varieties is by hybridisation. Hybridisation refers to crossing between genetically dissimilar plants.

Thus, the correct answer is option B.

Multiple choice biology food production uses of animals agro-complimentary occupations improvement of crop production

Which of the following is an advantage of hybrid variety of wheat?

  1. Good disease resistance

  2. Outstanding tillering

  3. More developed root system

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

Hybrid varieties of wheat are specifically bred to combine multiple beneficial traits, including disease resistance, improved growth characteristics like tillering, and better root development.

Multiple choice evs animal- the base of our life uses of animals agro-complimentary occupations improvement of crop production animal husbandry

Crossbreeding in cattle has mostly one breed __________ than the other.

  1. Dwarf

  2. Smaller

  3. Healthier

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

In cattle, there are systems of crossbreeding. In many crossbreeds, one is larger than the other. One is used when the purebred females are particularly adapted to a specific environment and are crossed with purebred bulls from another environment to produce a generation having traits of both parents. 

Multiple choice botany plant breeding biotechnology for improved food quality plant breeding for food production

Biofortification refers to the development of crop plants which are ______________.

  1. Resistant to disease

  2. Resistant to insect pests

  3. Having improved nutritional quality

  4. Having improved iron content
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Biofortification is the process of increasing the nutritional value of crops through selective breeding or genetic engineering. While it can involve iron, the term broadly refers to improving overall nutritional quality.

Multiple choice botany plant breeding biotechnology for improved food quality plant breeding for food production

Which of the following agronomic trait can be fortified in beans?

  1. Virus resistance

  2. Heat tolerance

  3. Drought tolerance

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

Biofortification is the method in which the food is added or supplemented with the required nutrients. It is a process of breeding crops with higher levels of vitamins, minerals, proteins, and fat content. The beans are fortified with iron, proteins and other nutrients. In order to obtain more yield, breeding of the plant is performed to obtain the resistant variety of plants. Resistance to virus, heat and drought tolerance are some of the characteristics which are selected for breeding.

Thus, the correct answer is option D. 

Multiple choice botany classical genetics non mendelian inheritance deviation from mendelism genetics

When both the alleles are equally expressed in hybrid, the phenomenon is known as

  1. Dominance

  2. Bivalence

  3. Codominance

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

Genes are units of hereditary information that are located on segments of chromosomes. The genes for a specific trait may exist in different forms known as alleles. An example of an allele or a gene is flower color. A flower may have alleles that make it red or pink and so on. Alleles that always show up when they are present are known as dominant alleles. Alleles that are masked or hidden by dominant alleles are known as recessive alleles. In some situations both alleles are expressed equally. A genetic scenario where neither allele is dominant or recessive and both get expressed is known as 'codominance'.
Blood types are excellent examples of codominance. 

Multiple choice botany classical genetics non mendelian inheritance deviation from mendelism genetics

In a cross between a red flowered plant and a white flowered plant, all offsprings produced bear pink flowers. This is because

  1. Red is dominant

  2. White is dominant

  3. Pink is dominant

  4. Red and white exhibit incomplete dominance

  5. Red and white exhibit codominance
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When a red flowered plant is crossed with a white flowered plant, ideally the offsprings should bear either red and white flower. However, in the case where the trait  flower color exhibits incomplete dominance, all the offsprings will give forth pink colored flowers due to the blending of traits.

Multiple choice botany classical genetics non mendelian inheritance deviation from mendelism genetics

Phenotypic and genotypic ratio in F$ _2$ generation in incomplete dominance is

  1. 1 : 2 : 1 and 1 : 2 : 1

  2. 9 : 6 and 1 : 2 : 1

  3. 9 : 6 and 3 : 1

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

Incomplete dominance is the condition when none of factors of a gene is dominant, the phenotype of heterozygous dominant individual is blend of dominant and recessive traits. For example flower colour in Mirabilis jalapa shows incomplete dominance and the monohybrid cross between two pure varieties gives 1 : 2 : 1 phenotypic ratio in F$ _2$ generation which is 3 : 1 in otherwise dominant traits. This is because the heterozygous genotypes do not show the dominant trait but they are blend of dominant and recessive phenotype. A cross between two pure breeding genotypes that differ in two pairs of trait (dihybrid cross) followed by selfing of F$ _1$ hybrid gives 9 : 3 : 3 : 1 phenotypic ratio and 1 : 2 : 1 : 4 : 1 : 1 : 2 : 1 : 2 : 1 genotypic ratio. Option B and C show both dihybrid (9 : 6), a dihybrid cross gives total 16 types which make these two options wrong.

Multiple choice botany classical genetics non mendelian inheritance deviation from mendelism genetics

What would be the proportion of dwarf plant with pink flowers. If heterozygous tall plant with pink flower is test crossed ? A plant taken for test cross character of length showing complete dominance and character of flower colour showing incompete dominance

  1. $4/16$
  2. $6/16$
  3. $3/16$

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Heterozygous tall plant with pink flower is test crossed with homozygous recessive partner, as a result of which different phenotypes are produced in the F1 offspring. The cross is between TtPp and ttpp which is shown in the Punnett Square.


 Male/Female  TP Tp  tP  tp 
 tp  TtPp  Ttpp  ttPp ttpp 

The percentage of dwarf plant with pink flowers (ttPp) is thus 4/16 or 1/4.

So the correct option is '4/16'.

Multiple choice botany classical genetics non mendelian inheritance deviation from mendelism genetics

Dominant and recessive alleles express themselves together in

  1. Dominance

  2. Co-dominance

  3. Pseudodominance

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Codominance occurs when two alleles are equally dominant, and both appear in a phenotype. The classic example is human blood type, in which the A and B alleles are codominant, so anyone with both will have the phenotype AB.

Multiple choice botany classical genetics non mendelian inheritance deviation from mendelism genetics

Choose the correct answer from the alternatives given.
The allele for pea comb (P) in chickens is completely dominant to the allele for single comb (p). The alleles for black feather colour (B), and white feather colour (B) show codominance, so that BB individuals possess blue feathers. If chickens heterozygous for both pairs of genes are mated, what proportion of offspring are expected to be pea combed and white feathered? 

  1. 9 / 16

  2. 3 / 16

  3. 1 / 16

  4. 2 / 16
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a cross of PpBb and PpBb,

The individuals with Pea-comb and white feathers include PPbb, Ppbb and Ppbb.
So, the correct option is '3/16'.