NEET 2026 (Phase 1) · BiologyPrevious Year Question
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?
- A.Thalassemia
- B.Sickle-cell anaemia✓
- C.Phenylketonuria
- D.Haemophilia
Correct Answer
(B) Sickle-cell anaemia
Solution & Explanation
Answer: (B) Sickle-cell anaemia Solution: Sickle-cell anaemia is caused by the substitution of the amino acid Glutamic acid (Glu) by Valine (Val) at the sixth position of the beta globin chain of haemoglobin. This single amino acid change results from a point mutation and alters the haemoglobin molecule. Thalassemia, phenylketonuria and haemophilia have different molecular bases. NCERT Reference: NCERT Class XII, Ch 4, p.75, lines 3-4: "(Glu) by Valine (Val) at the sixth position of the beta globin chain of the" (continuation of "The defect is caused by the substitution of Glutamic acid" on p.74, line 27)
🎯
Practice NEET 2026 (Phase 1) Biology — free, with instant solutions
10,000+ NEET PYQs solved step-by-step, chapter-wise, in the MedicNEET app.
More NEET PYQ solutions
BiolExploration of molecular, genetic and species level diversity for novel products of economic importance is known as:BiolSelect the correct statements regarding cell membrane in eukaryotic cell. A. Membrane of human RBCs has approximately 52% protein. B. Major phospholipids are arranged in a bilayer. C. Extensions of the plasma membrane into the cell form mesosomes. D. Tails towards the inner part of lipids are hydrophobic and thus protected from aqueous medium. E. Glycocalyx is present on the outer surface of the plasma membrane. Choose the correct answer from the options given below:BiolWhich one of the following is the site for active ribosomal RNA synthesis?BiolChoose the correct statements regarding cell organelles and their inclusions. A. The endomembrane system includes Golgi complex, endoplasmic reticulum and mitochondria. B. Rough endoplasmic reticulum bears ribosomes on its surface. C. Both mitochondria and plastids have circular DNA. D. A network of microtubules, microfilaments and intermediate filaments present in the cytoplasm is called cytoskeleton. E. Mitochondrion is a single membrane-bound structure. Choose the correct answer from the options given below :BiolNon-membrane bound cell organelles found in both prokaryotic and eukaryotic cells are ______.BiolThe main criteria used for Five Kingdom Classification proposed By R.H. Whittaker (1969) included : A. Cell structure B. Body organization C. Presence of flagellum D. Reproduction E. Phylogenetic relationships Choose the correct answer from the options given below :BiolSince the origin and diversification of life on Earth, there have been five episodes of mass extinction of species. How is the sixth extinction, which is in progress, different from the previous episodes? (NEET 2026)BiolWhich of the following statements are correct? A. The Amazon rainforest being cut and cleared for cultivation of soyabeans is an example of habitat loss. B. Steller's sea cow and passenger pigeon became extinct due to over-exploitation by humans. C. The Nile perch introduced into Lake Victoria in East Africa helped in population growth of cichlid fish in the lake. D. Water hyacinth is an invasive species. E. When a species becomes extinct, the plant and animal species associated with it are not affected. Choose the correct answer from the options given below: (NEET 2026)