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Biology

Principles of Inheritance and Variation

Mendel's laws, monohybrid and dihybrid crosses, incomplete dominance, codominance, linkage, sex determination, pedigree analysis, and genetic disorders fill this chapter. Application beats recall here: you work out cross ratios, read pedigrees, and predict offspring genotypes.

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 7 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

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 ______.
  1. A.females and males, respectively
  2. B.all males
  3. C.males and females, respectively
  4. D.all females
Answer and explanation

Answer: C

Grasshoppers follow the XO type of sex determination: males are XO (a single X and no partner sex chromosome) while females are XX. Therefore the individual with 23 chromosomes lacks the second sex chromosome and is male, while the one with 24 chromosomes is female. Hence males and females respectively.

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 12-question mock on the exam screen.

Nearby Biology chapters

Questions

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

Principles of Inheritance and Variation carried 7 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?

In the BrainIt app, free until the 2027 exam: its bank holds 50,000 past NTA questions tagged to all 83 chapters, including this one, with accuracy tracked per chapter. 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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