NEET MCQs Practice on Principles of Inheritance and Variation Class-XII Biology, Free unlimited practice on Principles of Inheritance and Variation Class-XII Biology Mcqs

A change in a single base pair of DNA, such as causing sickle cell anemia, is known as a _______ mutation.

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

Point
Frame-shift
Chromosomal
Aneuploidy

Correct Option: A [ Point ]

Remark: Mutation due to change in a single base pair of DNA is known as point mutation.

The analysis of traits in several generations of a family, used to trace the inheritance of a specific trait or disease, is called the _______.

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

Pedigree analysis
Test cross
Karyotyping
Linkage mapping

Correct Option: A [ Pedigree analysis ]

Remark: Analysis of traits in several generations of a family, used to trace the inheritance of a specific trait, abnormality or disease, is called the pedigree analysis.

Down's syndrome is a chromosomal disorder caused due to the presence of an additional copy of chromosome number _______ (trisomy).

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

21
18
13
X

Correct Option: A [ 21 ]

Remark: Down’s Syndrome is caused by the presence of an additional copy of the chromosome number 21 (trisomy of 21).

Match List-I (Mendelian Concepts) with List-II (Explanation/Example):

List-I	List-II
A. Law of Dominance	I. F1 generation resembles only one parent
B. Law of Segregation	II. Alleles do not show blending and segregate during gamete formation
C. Co-dominance	III. F1 generation resembles both parents
D. Incomplete Dominance	IV. F1 phenotype is in between the two parents

Choose the correct answer from the options given below:

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

A-I, B-II, C-III, D-IV
A-II, B-I, C-IV, D-III
A-III, B-IV, C-I, D-II
A-IV, B-III, C-II, D-I

Correct Option: A [ A-I, B-II, C-III, D-IV ]

Remark: The Law of Dominance explains the F1 resembling one parent. The Law of Segregation ensures alleles do not blend. Co-dominance results in the F1 resembling both parents (e.g., ABO blood group I^A I^B). Incomplete dominance produces an intermediate phenotype (e.g., pink Snapdragon flowers).

Match List-I (Genetic Terms) with List-II (Definition):

List-I	List-II
A. Alleles	I. Slightly different forms of the same gene
B. Genotype	II. Allelic composition of an organism (e.g., Tt)
C. Phenotype	III. Descriptive appearance (e.g., Tall)
D. Homozygous	IV. Allelic pair of genes are identical (e.g., TT or tt)

Choose the correct answer from the options given below:

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

A-I, B-II, C-III, D-IV
A-II, B-III, C-I, D-IV
A-III, B-I, C-IV, D-II
A-IV, B-I, C-II, D-III

Correct Option: A [ A-I, B-II, C-III, D-IV ]

Remark: Alleles are slightly different forms of the same gene. Genotype refers to the composition like TT or tt. Phenotype refers to the descriptive appearance like tall or dwarf. Homozygous refers to identical allelic pairs.

Match List-I (Sex Determination Organism) with List-II (Mechanism/Feature):

List-I	List-II
A. Grasshopper	I. XO type of sex determination
B. Birds	II. Female heterogamety (ZW)
C. Humans/Drosophila	III. XY type of sex determination
D. Male Heterogamety	IV. Males produce two different types of gametes

Choose the correct answer from the options given below:

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

A-I, B-II, C-III, D-IV
A-III, B-I, C-II, D-IV
A-I, B-IV, C-III, D-II
A-II, B-III, C-I, D-IV

Correct Option: A [ A-I, B-II, C-III, D-IV ]

Remark: Grasshopper is an example of XO type sex determination. In birds, females are heterogametic (ZW). Humans and Drosophila show XY type sex determination. Male heterogamety involves males producing two different types of gametes (X/O or X/Y).

Match List-I (Genetic Disorder) with List-II (Key Feature):

List-I	List-II
A. Haemophilia	I. X-linked recessive disease resulting in non-stop bleeding
B. Sickle-cell anaemia	II. Caused by single base substitution (GAG to GUG)
C. Colour Blindness	III. Due to mutation in genes present on the X chromosome, affecting red/green cones
D. Phenylketonuria	IV. Autosomal recessive trait leading to mental retardation and metabolic error

Choose the correct answer from the options given below:

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

A-I, B-II, C-III, D-IV
A-II, B-I, C-IV, D-III
A-IV, B-III, C-II, D-I
A-III, B-IV, C-I, D-II

Correct Option: A [ A-I, B-II, C-III, D-IV ]

Remark: Haemophilia is an X-linked recessive disease affecting blood clotting. Sickle-cell anaemia is caused by a point mutation (single base substitution GAG to GUG). Colour blindness is an X-linked recessive disorder due to defects in cone cells. Phenylketonuria is an inborn error of metabolism (autosomal recessive) resulting in mental retardation.

Match List-I (Chromosomal Disorder) with List-II (Karyotype/Cause):

List-I	List-II
A. Down’s Syndrome	I. Trisomy of chromosome 21
B. Klinefelter’s Syndrome	II. Karyotype 47, XXY
C. Turner’s Syndrome	III. Karyotype 45, X0
D. Polyploidy	IV. Increase in a whole set of chromosomes (often seen in plants)

Choose the correct answer from the options given below:

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

A-I, B-II, C-III, D-IV
A-II, B-I, C-IV, D-III
A-III, B-IV, C-I, D-II
A-IV, B-III, C-II, D-I

Correct Option: A [ A-I, B-II, C-III, D-IV ]

Remark: Down’s Syndrome is caused by trisomy of chromosome 21. Klinefelter’s Syndrome is 47, XXY. Turner’s Syndrome is 45, X0. Polyploidy is the increase in a whole set of chromosomes, typically due to failure of cytokinesis.

Match List-I (Scientist) with List-II (Key Contribution):

List-I	List-II
A. T.H. Morgan	I. Experimental verification of Chromosomal Theory using Drosophila
B. Sutton & Boveri	II. Proposed the Chromosomal Theory of Inheritance
C. Alfred Sturtevant	III. Used recombination frequency to map gene distance
D. Henking	IV. Discovered the 'X body' during spermatogenesis in insects

Choose the correct answer from the options given below:

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

A-I, B-II, C-III, D-IV
A-II, B-I, C-IV, D-III
A-III, B-IV, C-I, D-II
A-IV, B-III, C-II, D-I

Correct Option: A [ A-I, B-II, C-III, D-IV ]

Remark: T.H. Morgan provided experimental verification of the chromosomal theory. Sutton and Boveri formulated the chromosomal theory of inheritance. Sturtevant used recombination frequency to map gene positions. Henking discovered the X body (later X-chromosome) in insects.

Match List-I (Type of Mutation/Variation) with List-II (Description):

List-I	List-II
A. Mutation	I. Phenomenon resulting in alteration of DNA sequences
B. Point Mutation	II. Change in a single base pair of DNA
C. Aneuploidy	III. Gain or loss of a chromosome(s) due to failure of segregation
D. Chromosomal Aberrations	IV. Loss (deletions) or gain (duplication/insertion) of a segment of DNA

Choose the correct answer from the options given below:

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

A-I, B-II, C-III, D-IV
A-III, B-I, C-II, D-IV
A-II, B-IV, C-I, D-III
A-IV, B-III, C-II, D-I

Correct Option: A [ A-I, B-II, C-III, D-IV ]

Remark: Mutation is the alteration of DNA sequences. Point mutation is a change in a single base pair (e.g., sickle cell anemia). Aneuploidy is the gain or loss of a chromosome. Chromosomal aberrations involve alteration in chromosomes due to loss or gain of DNA segments.

Principles of Inheritance and Variation: Class-XII

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