The phenomenon where a single gene product may produce more than one effect, such as the gene controlling starch synthesis in pea seeds also influencing seed shape, is called _______.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Pleiotropy
• Aneuploidy
• Co-dominance
• Linkage
Correct Option: A  [ Pleiotropy ]

Remark: A single gene can exhibit multiple phenotypic expression, and such a gene is called a pleiotropic gene, seen in cases like Phenylketonuria.

Mendel applied _______ analysis and mathematical logic for the first time to problems in biology.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Statistical
• Genetic
• Molecular
• Cytological
Correct Option: A  [ Statistical ]

Remark: Mendel's investigations were unique because statistical analysis and mathematical logic were applied to problems in biology for the first time.

Mendel conducted hybridisation experiments on garden peas for _______ years (1856–1863).

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Seven
• Five
• Ten
• Three
Correct Option: A  [ Seven ]

Remark: Gregor Mendel conducted hybridisation experiments on garden peas for seven years (1856–1863).

Mendel selected _______ true-breeding pea plant varieties, as pairs which were similar except for one character with contrasting traits.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• 14
• 7
• 21
• 10
Correct Option: A  [ 14 ]

Remark: Mendel selected 14 true-breeding pea plant varieties, as pairs which were similar except for one character with contrasting traits.

Mendel observed that in the F₁ progeny, the trait of the other parent was not seen, and the F₁ always resembled _______.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Either one of the parents
• Both parents
• An intermediate phenotype
• A blended form
Correct Option: A  [ Either one of the parents ]

Remark: Mendel found that the F₁ always resembled either one of the parents, and that the trait of the other parent was not seen in them.

The tall and dwarf traits studied by Mendel were identical to their parental type and did not show any _______ in the F₂ generation.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Blending
• Mutation
• Recombination
• Segregation
Correct Option: A  [ Blending ]

Remark: The tall and dwarf traits were identical to their parental type and did not show any blending.

Mendel called the stable units passed down from parent to offspring as 'factors'; today we call them as _______.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Genes
• Alleles
• Chromosomes
• Genomes
Correct Option: A  [ Genes ]

Remark: Mendel called the stable units passed down from parent to offspring as 'factors'. Now we call them as genes.

If alphabetical symbols are used for genes, the _______ letter is used for the trait expressed at the F₁ stage.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Capital
• Small
• Greek
• Roman
Correct Option: A  [ Capital ]

Remark: The capital letter is used for the trait expressed at the F₁ stage and the small alphabet for the other trait.

In a pair of dissimilar factors, the factor that dominates the other (as in the F₁) is called the _______ factor.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Dominant
• Recessive
• Homozygous
• Heterozygous
Correct Option: A  [ Dominant ]

Remark: In a pair of dissimilar factors, one dominates the other (as in the F₁) and hence is called the dominant factor.

Mendel's Second Law is known as the Law of _______.

[Principles-of-Inheritance-and-Variation] [class-xii ]

• Segregation
• Dominance
• Purity of Gametes
• Independent Assortment
Correct Option: A  [ Segregation ]

Remark: Mendel's two general rules are the First Law or Law of Dominance and the Second Law or Law of Segregation.