Principles of Inheritance and Variation NEET Previous Year Question Paper(PYQ)

Principles of Inheritance and Variation NEET Previous Year Questions

The Principles of Inheritance and Variation chapter is one of the most important topics in NEET Biology, with questions consistently asked on Mendelian inheritance, chromosomal theory of inheritance, pedigree analysis, genetic disorders, linkage, and recombination. Solving NEET previous year questions (PYQs) helps candidates understand the latest question trends, improve conceptual clarity, and identify frequently tested topics. Along with previous year questions, aspirants can also practise the Principles of Inheritance and Variation RE-NEET 2026 questions to gain exposure to the latest exam-level questions and improve their preparation for NEET 2027.

NEET 2026

Q1. Given below are two statements: one is labelled as Assertion (A) and the other as Reason (R).

Assertion (A): In Mendel's monohybrid cross, all the F₁ plants were tall and none were dwarf.

Reason (R): Tallness is the dominant trait, while dwarfness is the recessive trait in pea plants.

Options:

1. Assertion (A) is incorrect, but Reason (R) is correct.
2. Both Assertion (A) and Reason (R) are correct, and Reason (R) is the correct explanation of Assertion (A).
3. Both Assertion (A) and Reason (R) are correct, but Reason (R) is not the correct explanation of Assertion (A).
4. Assertion (A) is correct, but Reason (R) is incorrect.

Correct Answer: Option 2

Explanation: In Mendel's monohybrid cross, crossing pure tall (TT) with pure dwarf (tt) plants produced all tall (Tt) offspring in the F₁ generation because the tall allele is dominant over the dwarf allele.

Q 2. A person has blood group O. Which of the following parental genotype combinations cannot produce a child with blood group O?

Options:

1. Father: IᴬIᴮ and Mother: Iᴬi
2. Father: Iᴬi and Mother: Iᴮi
3. Father: Iᴬi and Mother: Iᴬi
4. Father: Iᴮi and Mother: Iᴮi

Correct Answer: Option 1

Explanation: Blood group O has the genotype ii, so each parent must contribute an i allele. A father with genotype IᴬIᴮ does not carry the i allele, making it impossible for the child to inherit the ii genotype.

Q3. Given below are two statements:

Statement I: Down syndrome is caused by the absence of one X chromosome.

Statement II: Turner syndrome is caused by the presence of an extra chromosome.

Options:

1. Statement I is incorrect, but Statement II is correct.
2. Both Statement I and Statement II are correct.
3. Both Statement I and Statement II are incorrect.
4. Statement I is correct, but Statement II is incorrect.

Correct Answer: Option 3

Explanation: Down syndrome is caused by trisomy 21 (an extra copy of chromosome 21), whereas Turner syndrome results from monosomy X (45, X), where one X chromosome is absent. Therefore, both statements are incorrect.

NEET 2025

Q4. Genes R and Y follow independent assortment. If RRYY produces round yellow seeds and rryy produces wrinkled green seeds, what will be the phenotypic ratio of the F₂ generation?

Difficulty Level: Medium

Option 1) Phenotypic ratio 9:7

Option 2) Phenotypic ratio 1:2:1

Option 3) Phenotypic ratio 3:1

Option 4) Phenotypic ratio 9:3:3:1

Solution:

Given -

• Parent 1: RRYY
• Parent 2: rryy

The F₁ generation will all be heterozygous RrYy and will display the dominant traits - round yellow seeds. Now,

• Parent 1: RrYy
• Parent 2: RrYy

The gametes for F₂ from each parent will be: RY, Ry, rY, ry.

After fertilisation, the phenotypes:

1. Round Yellow (RRYY, RRYy, RrYY, RrYy): 9
2. Round Green (RRyy, Rryy): 3
3. Wrinkled Yellow (rrYY, rrYy): 3
4. Wrinkled Green (rryy): 1

Hence, the correct answer is option 4) Phenotypic ratio 9:3:3:1.

Q5. In a plant, the black seed colour (BB/Bb) is dominant over the white seed colour (bb). To find out the genotype of the black seed plant, which of the following genotypes will you cross?

NEET 2024

Difficulty level: Medium

Chapter: Principles of Inheritance and Variation

Option 1: BB

Option 2: bb

Option 3: Bb

Option 4: BB/Bb

Solution:

In a test cross, an organism with an unknown genotype is mated with an organism with a known genotype to ascertain the genotype of the unknown organism. The test cross is said to have been created by Gregor Mendel. To determine the genotype of a black seed colour at F₂, the black seed from F₂ is crossed with the white seed colour. This is called a test cross. To determine the genotype of the black seed (BB/Bb), we need to cross them with the white seed (bb)

Hence, the correct answer is Option (2) b

Q6. Broad palm with single palm crease is visible in a person suffering from –

NEET 2023

Difficulty level: Medium

Chapter: Principles of Inheritance and Variation

Option 1: Down's syndrome

Option 2: Turner's syndrome

Option 3: Klinefelter's syndrome

Option 4: Thalassemia

Solution:

A broad palm with a single palm crease, also known as a simian crease or a single transverse palmar crease, is commonly seen in individuals with Down syndrome. Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21. This condition is characterized by various physical and intellectual disabilities, and certain physical features are often associated with it.

One of the common physical features observed in individuals with Down syndrome is a single transverse palmar crease, where the normal two creases in the palm fuse into one. This can give the appearance of a broad palm with a single crease extending across the palm.

Therefore, the correct answer is Option (1) Down syndrome.

Q7. Which of the following occurs due to the presence of an autosome-linked dominant trait?

NEET 2022

Difficulty level: Easy

Chapter: Principles of Inheritance and Variation

Option 1: Myotonic Dystrophy

Option 2: Haemophilia

Option 3: Thalassemia

Option 4: Sickle cell anaemia

Solution:

Hemophilia is a disorder in which blood doesn’t clot normally, and it is an X-linked recessive disorder.

Thalassemia is a blood disorder involving a lower-than-normal amount of an oxygen-carrying protein. It is an autosomal recessive disorder.

Sickle cell anaemia is a group of disorders that causes red blood cells to become misshapen and break down. It is an autosomal recessive disorder.

Myotonic dystrophy is an autosomal dominant disorder,i.e., it occurs due to the presence of an autosomal-linked dominant trail.

Hence, the correct answer is option 1) Myotonic dystrophy.

Principles of Inheritance and Variation PYQ Analysis (2020-2026)

• Marks Contribution: Approximately 8-12 marks in the NEET Biology paper.

• Number of Questions: Typically 2-3 questions per exam, with some questions integrating diagram-based or pedigree-oriented questions.

High Scoring NEET 2027 Topics of Principles of Inheritance and Variation

Every year, 2-3 questions are consistently asked from Principles of Inheritance and Variation. The diagram-based questions are common as well. The most important topics that NEET 2027 students can prepare are given below in a table:

Principles of Inheritance and Variation NEET 2027 Preparation Strategy

Below are ten important points for preparing Principles of Inheritance and Variation NEET questions:

1. Pay attention to learning Mendel's laws, genetic disorders, and patterns of inheritance to solve Principles of Inheritance and Variation NEET questions.

2. Practice Principles of Inheritance and Variation NEET questions from last year's papers to get used to the pattern and difficulty of the exam.

3. Practice Principles of Inheritance and Variation NEET previous year question paper consistently to build confidence and lower exam anxiety.

4. Identify and concentrate on commonly asked subjects in Principles of Inheritance and Variation NEET questions, including linkage and gene expression.

5. Practice a range of Principles of Inheritance and Variation NEET questions to enhance problem-solving and time-management skills.

6. Refer to NCERT notes as a basis for learning, as they include key concepts examined in Principles of Inheritance and Variation NEET pyq.

7. Use online platforms such as Careers360 for explanations and practice Principles of Inheritance and Variation NEET questions.

8. Compare your performance on Principles of Inheritance and Variation NEET questions to determine weak points and work on enhancing them.

9. Practice solving principles of inheritance and variation NEET pyq in a timed manner to optimize speed during the exam.

10. Practice principles of inheritance and variation NEET previous year question paper for rapid revision to ensure that you have mastered all major concepts before the exam.

Common Mistakes in Preparing For Principles of Inheritance and Variation NEET Previous Year Questions

Some common mistakes students make while preparing for NEET 2026 Principles of Inheritance and Variation questions:

Confusion in Mendelian Ratios

Students often mix up Mendelian ratios like 3:1, 9:3:3:1, and 1:2:1, leading to errors in solving inheritance problems. Misinterpreting test cross and back cross is another common mistake. Understanding the concept behind these ratios rather than just memorizing them can help in answering questions accurately.

Ignoring Non-Mendelian Inheritance

Many students focus only on Mendel’s laws and ignore topics like incomplete dominance, codominance, multiple alleles, and epistasis. However, NEET frequently asks about exceptions to Mendelian inheritance, especially blood group inheritance and coat colour genetics in animals.

Errors in Linkage and Recombination

Candidates often misinterpret Morgan’s experiment on linkage and recombination. Confusing crossing over with independent assortment and failing to calculate recombination frequency correctly can lead to wrong answers. Practising chromosome maps and numerical problems is essential to avoid these errors.

Difficulty in Pedigree Analysis

Many students struggle with interpreting pedigree charts, especially in identifying autosomal vs. sex-linked disorders. Misreading dominant and recessive traits can result in incorrect answers. A structured approach using flowcharts and practice questions can help in mastering pedigree analysis effectively.

Advantages of Practising Principles of Inheritance and Variation NEET PYQs

• Strengthens conceptual understanding: Regular practice of NEET PYQs helps build a strong foundation in genetics, heredity, and inheritance, making complex concepts easier to understand.
• Familiarises you with recent exam trends: Solving previous year questions and the latest RE-NEET 2026 questions helps candidates understand evolving question patterns, frequently tested concepts, and the level of difficulty expected in NEET 2027.
• Improves speed and accuracy: Consistent practice enhances problem-solving skills, reduces errors, and enables candidates to solve genetics-based questions more efficiently within the exam time limit.