Biology

Genetics and Plant Breeding

1,240 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 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 dash and hyphen punctuation english

(Line1) Research shows that same sex siblings are more likely to form a bond than sib
(Line2) lings of different sexes.

Choose the option that best corrects the sentence.

  1. NO CHANGE

  2. Research shows that same-sex siblings are more likely to form a bond than sib-
    lings of different sexes.

  3. Research shows that same-sex siblings are more likely to form a bond than sib
    lings of different sexes.

  4. Research shows that same sex siblings are more likely to form a bond than sib-
    lings of different sexes.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The correct option is B because it has the hyphen in the two required places: between the pairs 'same sex' and 'sib lings'. While the first pair requires the hyphen to connect two words that act as a single unit to modify a noun (siblings), the other hyphen for 'sib lings' is used to show that the word continues onto the next line. 

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'.

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

Which of the following is not the Mendel's principle of inheritance?

  1. Law of incomplete dominance

  2. Law of dominance

  3. Law of segregation

  4. Law of independent assortment
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely expressed over its paired allele. In the early 1900s, German botanist Carl Correns (1864–1933) would conduct similar research on four o'clock plants. While Mendel's work laid a foundation, it isCorrens who is credited with the actual discovery of incomplete dominance. In his work, Correns observed a blend of colors in flower petals. So, the correct option is 'Law of incomplete dominance'.

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

$F _2$ generation in a Mendelian cross showed that both genotypic and phenotypic ratio are same as 1 : 2 : 1. It represents a case of  

  1. Monohybrid cross with complete dominance

  2. Monohybrid cross with incomplete dominance

  3. Co-dominance

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

Incomplete dominance is a type of intermediate inheritance in which one allele is not completely dominant over its paired allele. In this, the third phenotype is observed in heterozygous condition. In monohybrid cross with incomplete dominance, the phenotypic and genotypic ratio is 1:2:1, where one part is with dominant phenotype, 2 parts are with intermediate phenotype and 1 part is with recessive phenotype. For example, a snapdragon flower shows red (dominant), white (recessive) and pink (intermediate) flowers.

Thus, the correct answer is 'Monohybrid cross with incomplete dominance.'

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

In Mirabilis jalapa , the percentage of plants having pink and red flowers would be ________ when pink flower plant is test crossed.

  1. 25% pink and 25% red

  2. 50% pink and 50% red

  3. 50% pink and 0% red

  4. 0% pink and 50% red
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
 Gamete  R r 
 r Rr- Pink flower  rr- White flower 

Mirabilis jalapa is a plant showing incomplete dominance which means that when in F$ _1$ generation intermediate phenotype appears instead of the two parent phenotypes. 

While, the test cross is defined as a cross between an F$ _1$ plant and the homozygous recessive parent.
So, for plants to be pink in Mirabilis jalapa the plant has to be Rr in genotype. (where R is dominant on r while RR gives Red color and rr gives white color flowers in a plant).
Desired cross: Rr x rr 
So, the phenotype ratio is: 1:1::Pink flower:White flower
So, the correct answer is '50% pink and 50% red'.

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

Different forms of a gene are called

  1. Heterozygotes

  2. Alleles

  3. Complementary genes

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

A.Heterozygotes – Organisms with a pairs of contrasting characters are called Heterozygotes.

B.Alleles - An alternative form of a character in a pair, controlled by a single gene is called Allele. It is dominant either in homozygous or heterozygous state.

C.Complementary gene – Two genes present on separate loci that interact together to produce a dominant phenotype is called Complementary gene. In the F2 generation 9:7 ratio.

D.Supplementary gene – genes which include two pairs of non-allelic genes. Both of them are involved in affecting the same character. Out of the non-allelic genes, one gene is dominant and can express by itself. Second gene is also dominant but expresses only when it is supported by the presence of the first gene. In the F2 geneartion 9:3:4 ratio.

So, the correct option is ‘Alleles’.