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Principles of Inheritance and Variation: Class-XII


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MCQs on Principles of Inheritance and Variation: Class-XII for NEET Practice


Match List-I (Sex Chromosome Complement) with List-II (Organism/Sex):

List-IList-II
A. Autosomes + XXI. Human/Drosophila female
B. Autosomes + XYII. Human/Drosophila male
C. Autosomes + ZWIII. Female bird
D. Autosomes + ZZIV. Male bird
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: Human/Drosophila females have XX. Human/Drosophila males have XY. Female birds exhibit ZW chromosomes (female heterogamety). Male birds exhibit ZZ chromosomes.

Match List-I (Mendelian Trait Pair) with List-II (Dominant/Recessive):

List-IList-II
A. Seed colourI. Yellow (Dominant) / Green (Recessive)
B. Seed shapeII. Round (Dominant) / Wrinkled (Recessive)
C. Pod shapeIII. Inflated (Dominant) / Constricted (Recessive)
D. Flower positionIV. Axial (Dominant) / Terminal (Recessive)
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: Seed colour contrast is Yellow/Green. Seed shape contrast is Round/Wrinkled. Pod shape contrast is Inflated/Constricted. Flower position contrast is Axial/Terminal. Yellow, Round, Inflated, and Axial are the dominant traits, respectively.

Match List-I (Honey Bee Sex Determination) with List-II (Chromosome Status/Mechanism):

List-IList-II
A. Female (Queen/Worker)I. Diploid (32 chromosomes)
B. Male (Drone)II. Haploid (16 chromosomes)
C. Development of MaleIII. Parthenogenesis (unfertilised egg)
D. Sperm production in malesIV. Mitosis
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: Females are diploid (32 chromosomes). Males are haploid (16 chromosomes). Males develop from unfertilised eggs via parthenogenesis. Males produce sperm by mitosis.

Match List-I (Mechanism of Change in Chromosome Number) with List-II (Description/Cause):

List-IList-II
A. AneuploidyI. Failure of chromatid segregation during cell division cycle
B. TrisomyII. Presence of an additional copy of a chromosome
C. MonosomyIII. Lack of one of any one pair of chromosomes
D. PolyploidyIV. Failure of cytokinesis after telophase stage of cell division
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: Aneuploidy results from failure of chromatid segregation. Trisomy means an additional copy of a chromosome. Monosomy means lacking one chromosome of a pair. Polyploidy results from the failure of cytokinesis after telophase, increasing the whole set of chromosomes.

Match List-I (Genetic Disorder Type) with List-II (Example/Defining Cause):

List-IList-II
A. Mendelian DisorderI. Determined by alteration or mutation in a single gene
B. Chromosomal DisorderII. Caused due to absence or excess of one or more chromosomes
C. ThalassemiaIII. Quantitative problem of synthesizing too few globin molecules
D. Sickle-cell anaemiaIV. Qualitative problem of synthesizing an incorrectly functioning globin
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: Mendelian disorders are caused by single gene mutations. Chromosomal disorders are caused by abnormal chromosome arrangements or numbers. Thalassemia is a quantitative problem (too few globin molecules). Sickle-cell anaemia is a qualitative problem (incorrectly functioning globin).

Match List-I (Genetics Pioneer) with List-II (Key Area of Work):

List-IList-II
A. Gregor MendelI. Used statistical analysis and mathematical logic in biology
B. T.H. MorganII. Coined the terms linkage and recombination
C. Watson and CrickIII. Proposed the complementary double-helical configuration of DNA
D. W. SuttonIV. United chromosomal segregation with Mendelian principles
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: Mendel was the first to use statistical analysis in biology. Morgan coined the terms linkage and recombination. Watson and Crick proposed the DNA double-helical configuration. Sutton united chromosomal segregation with Mendelian principles.

Match List-I (Mendelian Observation) with List-II (Resulting Concept/Law):

List-IList-II
A. F1 always resembled one parentI. Dominance
B. Recovery of both traits in F2 (3:1)II. Segregation
C. Dihybrid F2 ratio (9:3:3:1)III. Independent Assortment
D. Crossing F2 tall plant with dwarf plantIV. Test Cross
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: F1 resembling one parent supports the Law of Dominance. Recovery of both traits in F2 supports the Law of Segregation. The 9:3:3:1 ratio in dihybrid crosses supports the Law of Independent Assortment. Crossing an F2 dominant phenotype with the recessive parent is a Test Cross.

Match List-I (Human Disorder Symptom) with List-II (Condition):

List-IList-II
A. Broad flat face, furrowed tongue, mental retardationI. Down’s Syndrome
B. Gynaecomastia, overall masculine development, sterilityII. Klinefelter’s Syndrome
C. Rudimentary ovaries, lack of secondary sexual characters, sterilityIII. Turner’s Syndrome
D. Accumulation of phenylpyruvic acid in brainIV. Phenylketonuria
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 symptoms include short stature, small round head, furrowed tongue, and mental retardation. Klinefelter’s Syndrome symptoms include masculine development and gynaecomastia (development of breast). Turner’s Syndrome symptoms include rudimentary ovaries and sterility in females. Phenylketonuria is characterized by the accumulation of phenylalanine derivatives in the brain, leading to mental retardation.

Match List-I (Concept/Term) with List-II (Mendel’s Idea):

List-IList-II
A. Units of inheritanceI. Factors
B. Opposing traitsII. Manifested as contrasting pairs (e.g., Tall/Dwarf)
C. True-breeding lineIII. Stable trait inheritance over several generations through self-pollination
D. Basis of heredityIV. Inheritance
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: Mendel called units of inheritance 'factors'. He investigated characters manifested as two opposing traits. A true-breeding line shows stable trait inheritance after continuous self-pollination. Inheritance is the basis of heredity.

Match List-I (Mendelian Trait) with List-II (Allelic Pair in True Breeding Variety):

List-IList-II
A. Tall plantI. TT
B. Dwarf plantII. tt
C. Homozygous dominantIII. Capital letters (e.g., RR)
D. HeterozygousIV. Dissimilar alleles (e.g., 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-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: True breeding tall plant is homozygous TT. True breeding dwarf plant is homozygous tt. Homozygous dominant uses capital letters. Heterozygous means dissimilar alleles.