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

Principles of Inheritance and Variation NEET Previous Year Questions with Solutions

The NEET PYQs provided below will help students understand some basic principles of the chapter Principles of Inheritance and Variation. Some of the topics covered include Mendelian inheritance, inheritance of blood group, and chromosomal disorders.
This section consists of NEET previous year questions along with solutions on a year-wise basis for practising important concepts of Principles of Inheritance and Variation for NEET 2027 preparation.

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 some important points for preparing for Principles of Inheritance and Variation NEET questions:

• Start with NCERT. Study concepts, examples, tables, and diagrams carefully.
• Learn to solve genetic cross problems. Practice solving monohybrid, dihybrid, test crosses, and other inheritance problems.
• Prepare a revision sheet on genetics. It should include ratios, modes of inheritance, genetic disorders, and chromosome abnormalities.
• Practise chapter-wise PYQs. Try to attempt PYQs without seeing the answer key.
• Check your mistakes. Check for errors due to concept, calculation, and assumption mistakes.
• Attempt difficult PYQs again. Try to solve NEET PYQs that you attempted incorrectly or made guesses on.
• Practise mixed questions. Prepare some questions on genetics with molecular biology and evolution after mastering the chapter.

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

Mistakes by the students while preparing for NEET 2027 Principles of Inheritance and Variation:

Inaccurate Interpretation of Mendelian Ratio

Students tend to confuse different ratios such as 3:1, 9:3:3:1 and 1:2:1, resulting in incorrect solutions to the problems of inheritance. Mistakes made while understanding test cross and back cross are also common. It will be easier to solve the questions on inheritance if one understands the concept of the ratio and doesn't just rely on memory.

Ignoring Non-Mendelian Inheritance

The majority of the students prepare on the basis of Mendel's laws and ignore the non-Mendelian topics such as incomplete dominance, codominance, multiple alleles, and epistasis. But questions regarding exceptions to Mendelism, especially the inheritance of blood groups and coat colour of animals, are very frequent in NEET.

Misinterpretations of Linkage and Recombination

Students misinterpret the experiment done by Morgan on linkage and recombination. Confusion regarding crossing over vs. independent assortment and miscalculations of recombination frequency cause incorrect answers to the questions.

Pedigree Analysis Problem

There are some difficulties in solving pedigree analysis problems, as many students find it difficult to differentiate between sex-linked and autosomal traits. Miscalculating dominant and recessive traits may lead to errors. A well-structured process involving the use of flowcharts and NEET PYQs will help in doing a better pedigree analysis.

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 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.