NEET · Biology —

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

Year 2024 Total
Questions 7 7
Practice all Principles of Inheritance and Variation questions → View full NEET weightage & trends →

Which one of the following disorders is caused by the substitution of Glutamic acid (Glu) by Valine (Val) at the sixth position of the beta globin chain of the haemoglobin molecule?

Solution & Explanation

Core Logic

Sickle-cell anaemia is an autosome-linked recessive trait. At the molecular level, it is caused by a point mutation leading to a single amino acid substitution: Glutamic acid (Glu) is replaced by Valine (Val) at the sixth position of the beta-globin chain of the haemoglobin molecule. This occurs due to a single base substitution at the sixth codon of the beta-globin gene from GAG to GUG.

Step 1: Final Conclusion

This specific substitution is the classic hallmark of Sickle-cell anaemia.

Pattern Recognition

GAG to GUG -> Glu to Val -> position 6 of beta-globin = Sickle-cell anaemia. Universally tested standard fact.

Chapter Mix

Class 12 Biology: Principles of Inheritance and Variation Class 12 Biology: Molecular Basis of Inheritance

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

Practice all Principles of Inheritance and Variation previous-year questions →

Rankbit System
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%)