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 important for NEET aspirants, as it forms the basis for understanding genetics and heredity. This chapter is frequently tested in the NEET 2026 exam, making it essential to practice the Principles of Inheritance and Variation previous year's questions.

Q1. 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?

NEET 2025

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.

Q2. 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

Q3. 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.

Q4. 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.

Q5. In a cross between a male and female both heterozygous for the sickle cell anaemia gene, what percentage of the progeny will be diseased?

NEET 2021

Difficulty level: Difficult

Chapter: Principles of Inheritance and Variation

Option 1: 50%

Option 2: 75%

Option 3: 25%

Option 4: 100%

Solution:

Autosomal recessive inheritance is the mode of inheritance for sickle cell disease. Thus, an individual has to inherit two copies of the mutated HBB gene- one from each parent- to be affected. This will affect about 25% of the offspring when both parents are carriers (sickle cell trait). Carriers have genotype AS and are usually asymptomatic but can pass the gene to their children.

Hence, the correct answer is Option 3) 25%

Q6. Experimental verification of the chromosomal theory of inheritance was done by:

NEET 2020

Difficulty level: Medium

Chapter: Principles of Inheritance and Variation

Option 1: Mendel

Option 2: Sutton

Option 3: Boveri

Option 4: Morgan

Solution:

The Chromosomal Theory of Inheritance, crucial in biology, establishes chromosomes as the carriers of genetic information responsible for Mendelian patterns of inheritance. This theory was founded on the works of Theodor Boveri and Walter Sutton. It aligns well with Mendel's laws and is bolstered by key observations:

1. Meiosis involves homologous chromosome pairs moving independently as distinct entities.
2. Parents create gametes with half their chromosome count.
3. Despite differences in size and shape, sperm and egg chromosomes are equal in number, indicating equal genetic input.
4. Upon fertilization, gametic chromosomes unite to form offspring with a chromosome count matching their parents.

Hence, the correct answer is option 4) Morgan

Principles of Inheritance and Variation PYQ Analysis (2020-2025)

• 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 2026 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 2026 students can prepare are given below in a table:

Principles of Inheritance and Variation NEET 2026 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

1. Practising NEET PYQs on Principles of Inheritance and Variation increases confidence in complex genetics questions.

2. Understanding the NEET 2026 exam pattern through NEET PYQs reduces stress and improves focus.

3. Regular practice of principles of inheritance and variation NEET previous year question paper improves efficiency in solving questions within the time limit.