When the F1 generation resembles both parents, as in the ABO blood grouping in humans, this phenomenon is called:

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

• Incomplete dominance
• Co-dominance
• Pleiotropy
• Polygenic inheritance
Correct Option: B  [ Co-dominance ]

Remark: In the case of co-dominance, the F1 generation resembles both parents. A good example is ABO blood grouping where alleles IA and IB are present together and both express their own types of sugars.

How many alleles for the I gene control the ABO blood groups in the human population?

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

• One
• Two
• Three
• Four
Correct Option: C  [ Three ]

Remark: The ABO blood groups are controlled by the gene I, which has three alleles: IA, IB, and i. This is also an example of multiple alleles.

Genetics is the branch of biology that deals with the inheritance, as well as the ___________ of characters from parents to offspring.

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

• segregation
• variation
• domestication
• mutation
Correct Option: B  [ variation ]

Remark: Genetics deals with the inheritance, as well as the variation of characters from parents to offspring.

___________ is the process by which characters are passed on from parent to progeny; it is the basis of heredity.

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

• Variation
• Genetics
• Inheritance
• Mutation
Correct Option: C  [ Inheritance ]

Remark: Inheritance is the process by which characters are passed on from parent to progeny; it is the basis of heredity.

Gregor Mendel conducted hybridisation experiments on garden peas for ___________ years.

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

• five
• seven
• ten
• three
Correct Option: B  [ seven ]

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

Mendel applied statistical analysis and mathematical logic to problems in biology for the first time during his investigations into ___________ patterns.

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

• molecular
• evolutionary
• genetic disorder
• inheritance
Correct Option: D  [ inheritance ]

Remark: During Mendel’s investigations into inheritance patterns it was for the first time that statistical analysis and mathematical logic were applied to problems in biology.

A true-breeding line is one that, having undergone continuous self-pollination, shows the stable trait inheritance and expression for several generations; Mendel selected ___________ true-breeding pea plant varieties.

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

• 7
• 12
• 14
• 20
Correct Option: C  [ 14 ]

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

In Mendel's monohybrid cross of tall (TT) and dwarf (tt) pea plants, all the F1 progeny plants were ___________.

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

• dwarf
• intermediate
• tall
• short
Correct Option: C  [ tall ]

Remark: Mendel observed that all the F1 progeny plants were tall, like one of its parents.

When Mendel self-pollinated the F1 tall plants, the proportion of dwarf plants in the Filial 2 (F2) generation was ___________ of the total plants.

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

• 1/2
• 3/4th
• 1/4th
• 1/3rd
Correct Option: C  [ 1/4th ]

Remark: The proportion of plants that were dwarf were 1/4th of the F2 plants.

Which of Mendel's Laws states that the alleles for a gene segregate (separate) from each other during gamete formation, such that each gamete receives only one allele?

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

• Law of Dominance
• Law of Independent Assortment
• Law of Segregation
• Law of Purity
Correct Option: C  [ Law of Segregation ]

Remark: The Law of Segregation (Mendel's First Law) states that the two alleles for a trait carried by a diploid organism separate during meiosis, ensuring gametes are haploid for that trait.