The phenomenon of pleiotropism refers to:

NEET-2023 [Principles-of-Inheritance-and-Variation] [class-xii ]

• more than two genes affecting a single character.
• presence of several alleles of a single gene controlling a single crossover
• presence of two alleles, each of the two genes controlling a single trait
• a single gene affecting multiple phenotypic expression.
Correct Option: D  [ a single gene affecting multiple phenotypic expression. ]

Remark:

Frequency of recombination between gene pairs on same chromosome as a measure of the distance between genes to map their position on chromosome, was used for the first time by:

NEET-2023 [Principles-of-Inheritance-and-Variation] [class-xii ]

• Henking
• Thomas Hunt Morgan
• Sutton and Boveri
• Alfred Sturtevant
Correct Option: D  [ Alfred Sturtevant ]

Remark:

Which of the following statements are correct about Klinefelter's Syndrome?
A. This disorder was first described by Langdon Down (1866).
B. Such an individual has overall masculine development. However, the feminine development is also expressed.
C. The affected individual is short stature.
D. Physical, psychomotor and mental development is retarded. E. Such individuals are sterile.
Choose the correct answer from the options given below:

NEET-2023 [Principles-of-Inheritance-and-Variation] [class-xii ]

• A and E only
• A and B only
• C and D only
• B and E only
Correct Option: D  [ B and E only ]

Remark:

Given below are two statements:
Statement I: Mendel studied seven pairs of contrasting traits in pea plants and proposed the Laws of Inheritance.
Statement II: Seven characters examined by Mendel in his experiment on pea plants were seed shape and colour, flower colour, pod shape and colour, flower position and stem height.
In the light of the above statements, choose the correct answer from the options given below:

NEET-2022 [Principles-of-Inheritance-and-Variation] [class-xii ]

• Both Statement I and Statement II are correct
• Both Statement I and Statement II are incorrect
• Statement I is correct but Statement II is incorrect
• Statement I is incorrect but Statement II is correct
Correct Option: A  [ Both Statement I and Statement II are correct ]

Remark:

XO type of sex determination can be found in:

NEET-2022 [Principles-of-Inheritance-and-Variation] [class-xii ]

• Drosophila
• Birds
• Grasshoppers
• Monkeys
Correct Option: C  [ Grasshoppers ]

Remark:

Which of the following occurs due to the presence of autosome linked dominant trait?

NEET-2022 [Principles-of-Inheritance-and-Variation] [class-xii ]

• Sickle cell anaemia
• Myotonic dystrophy
• Haemophilia
• Thalessemia
Correct Option: B  [ Myotonic dystrophy ]

Remark:

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Mendel’s law of Independent assortment does not hold good for the genes that are located closely on the same chromosome.
Reason (R): Closely located genes assort independently.
In the light of the above statements, choose the correct answer from the options given below:

NEET-2022 [Principles-of-Inheritance-and-Variation] [class-xii ]

• Both (A) and (R) are correct and (R) is the correct explanation of (A)
• Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• (A) is correct but (R) is not correct
• (A) is not correct but (R) is correct
Correct Option: C  [ (A) is correct but (R) is not correct ]

Remark:

The production of gametes by the parents, formation of zygotes, the F1 and F2 plants, can be understood from a diagram called:

NEET-2021 [Principles-of-Inheritance-and-Variation] [class-xii ]

• Bullet square
• Punch square
• Punnett square
• Net square
Correct Option: C  [ Punnett square ]

Remark:

How many true breeding pea plant varieties did Mendel select as pairs, which were similar except in one character with contrasting traits?

NEET-(Sept)2020 [Principles-of-Inheritance-and-Variation] [class-xii ]

• 4
• 2
• 14
• 8
Correct Option: C  [ 14 ]

Remark:

Identify the wrong statement with reference to the gene 'I' that controls ABO blood groups.

NEET-(Sept)2020 [Principles-of-Inheritance-and-Variation] [class-xii ]

• The gene (I) has three alleles.
• A person will have only two of the three alleles.
• When I^A and I^B are present together, they express same type of sugar.
• Allele 'i' does not produce any sugar.
Correct Option: C  [ When I^A and I^B are present together, they express same type of sugar. ]

Remark: