NEET · Biology —

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

Year 2024 Total
Questions 7 7
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What is the probability of having children with 'O' blood group, where both mother and father are heterozygous for 'A' and 'B' blood group, respectively?

Solution & Explanation

Core Logic

The genotypes of the parents are:

  • Mother: Heterozygous 'A' blood group arrow IAi
  • Father: Heterozygous 'B' blood group arrow IBi

    • When calculating the genetic cross via Punnett square:

  • Gametes from mother: IA and i
  • Gametes from father: IB and i

    • The possible offspring genotypes are:

  • IAIB (Blood group AB)
  • IAi (Blood group A)
  • IBi (Blood group B)
  • ii (Blood group O)
Step 1: Final Conclusion

Out of 4 possible combinations, only 1 results in blood group 'O'. Therefore, the probability is 1/4 or 25%.

Pattern Recognition

Heterozygous A (AO) × Heterozygous B (BO) yields all four blood types in equal 1:1:1:1 ratio (25% each).

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%)