NEET · Biology —

Principles of Inheritance and Variation appeared 7 times across 1 year — 7.8% of Biology. This question is from Genetic Principles.

Year 2024 Total
Questions 7 7
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Match List I with List II :
List-IList-II
A. Incomplete dominanceI. Human skin colour
B. Co-dominanceII. Inheritance of flower colour in Antirrhinum sp.
C. PleiotropyIII. Phenylketonuria disease in humans
D. Polygenic inheritanceIV. ABO blood groups
Choose the correct answer from the options given below :

Solution & Explanation

Core Logic
  • Incomplete dominance (A) occurs when a heterozygote has an intermediate phenotype. Example: Flower colour in snapdragon (Antirrhinum sp.) (A-II).
  • Co-dominance (B) occurs when both alleles are fully expressed. Example: ABO blood groups, specifically individuals with AB blood group (IAIB) (B-IV).
  • Pleiotropy (C) is when a single gene influences multiple phenotypic traits. Example: Phenylketonuria (PKU) in humans leads to mental retardation and reduced hair/skin pigmentation (C-III).
  • Polygenic inheritance (D) is when a single trait is controlled by three or more genes. Example: Human skin colour is controlled by three pairs of non-allelic genes (D-I).
Step 1: Final Conclusion

The correct matches are A-II, B-IV, C-III, D-I.

Pattern Recognition

Match the most classic examples: Co-dominance = ABO blood group. Polygenic = Skin colour. Pleiotropy = PKU.

Chapter Mix

Class 12 Biology: Principles of Inheritance and Variation

Reference Study Guides

Principles Of Inheritance And Variation

More Principles of Inheritance and Variation Previous-Year Questions — Page 2

Q154 neet_2026_03_may_morning Sex Determination
In a population of a grasshopper species, the chromosome number of some members is 23 and some other members possess 24 chromosomes. The 23 and 24 chromosome-bearing members in this species are
  • A. all males
  • B. all females
  • C. females and males, respectively
  • D. males and females, respectively

Solution

Core Logic

In grasshoppers, sex determination is of the XX-XO type. Males have only one X chromosome besides the autosomes (XO), whereas females have a pair of X chromosomes besides the autosomes (XX). Therefore, an individual with 23 chromosomes (one less sex chromosome) is a male grasshopper, and the one with 24 chromosomes is a female grasshopper.

Pattern Recognition

Insects like grasshoppers follow XO male heterogamety. Males always have one chromosome less than females.

Chapter Mix

Class 12 Biology: Principles of Inheritance and Variation

Q159 neet_2026_03_may_morning Sex Determination in Honey Bee
In which animal do haploid cells divide mitotically to produce gametes?
  • A. Male honeybees
  • B. Male grasshoppers
  • C. Male earthworms
  • D. Male frogs

Solution

Core Logic

The male honeybee is haploid and females are diploid. The gamete formation in female honey bee is by meiosis, whereas male honeybees form gametes by mitosis. Thus, a haploid cell undergoes mitosis to produce gametes in male honeybees.

Pattern Recognition

Haplodiploid sex-determination system: Males (drones) develop parthenogenetically and are haploid. Therefore, they must produce sperm via mitosis to maintain the haploid state.

Chapter Mix

Class 12 Biology: Principles of Inheritance and Variation

More Principles of Inheritance and Variation Questions — neet_2026_03_may_morning

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JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)