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Principles of Inheritance and Variation

A Biology chapter of the NEET syllabus, and how to practise it for the computer-based exam.

Exam rules change between cycles. Confirm dates, syllabus and pattern against NTA's official site. We are not NTA.

Weightage: what the paper actually did

Principles of Inheritance and Variation carried 10 questions in the NEET 2026 paper. One paper is a data point, not a destiny: NTA moves weight between chapters every cycle, which is why the weightage tables deserve care. The stable facts are the paper's shape: 180 questions, 720 marks, +4 right, −1 wrong.

Sample PYQs from this chapter

Real questions NTA asked from Principles of Inheritance and Variation, with the answer and the working. Try before you peek.

Question 1 · NEET 2026

The sixth mutant codon of beta globin gene causing polymerization of Haemoglobin and change in RBC shape is ______.
  1. A.GUG
  2. B.AUG
  3. C.GAG
  4. D.CAG
Answer and explanation

Answer: A

In sickle cell anaemia the sixth codon of the β\beta-globin gene changes from GAG to GUG, so glutamic acid is replaced by valine. This substitution makes haemoglobin polymerize at low oxygen tension and distorts the RBC into a sickle shape, so the mutant codon is GUG.

Question 2 · NEET 2026

Given below are two statements : Statement I: Down's syndrome is caused by the absence of one of the X-chromosomes. Statement II: Turner's syndrome is caused by the presence of an additional copy of the chromosomes. In the light of the above statements, choose the correct answer from the options given below :
  1. A.Both Statement I and Statement II are correct
  2. B.Both Statement I and Statement II are incorrect
  3. C.Statement I is correct but Statement II is incorrect
  4. D.Statement I is incorrect but Statement II is correct
Answer and explanation

Answer: B

Both statements have been swapped. Down's syndrome is an AUTOSOMAL trisomy - an extra copy of chromosome 21, giving 47 chromosomes - and has nothing to do with the X chromosome. Turner's syndrome is the opposite kind of error: a MISSING X, giving the 45,X karyotype in a phenotypic female with rudimentary ovaries. So the descriptions belong to each other's conditions, and neither statement as written is correct. NCERT Class 12, Principles of Inheritance and Variation.

How to practise Principles of Inheritance and Variation

Chapter by chapter, against real past-paper questions, on a screen: NEET is computer based from 2027. Read the chapter once, then attempt its PYQs until your accuracy stops climbing, and let the wrong answers tell you which lines to reread. If the chapter keeps refusing to stick, that has its own guide. There is also a free NEET mini mock with answers.

Nearby Biology chapters

Questions

How many questions did Principles of Inheritance and Variation have in NEET 2026?

Principles of Inheritance and Variation carried 10 questions in the NEET 2026 paper. Weightage shifts between cycles, so treat it as a probability, not a promise.

Where can I practise Principles of Inheritance and Variation PYQs for NEET?

Explore available chapter-wise NEET practice in BrainIt, free until the 2027 exam. Review explanations and track chapter accuracy to guide your revision. Sample questions from this chapter are on this page.

Is Principles of Inheritance and Variation important for NEET 2027?

It is part of the Biology syllabus the paper draws from, and NEET 2027 is computer based, so practise it on a screen. Your own accuracy in the chapter matters more than any weightage table: a heavy chapter you already score well on needs less time than a light one you keep missing.

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