🧬 Principles of Inheritance and Variation
🌟 Mendel's Experiments + Monohybrid Cross + Law of Dominance + Law of Segregation + Test Cross
(NCERT Line-by-Line | Hindi + English | NEET Focus | Learn With Afsa Notes)
📖 Introduction
What is Genetics?
English:
Genetics is the branch of biology that deals with inheritance and variation.
Hindi:
आनुवंशिकी (Genetics) जीवविज्ञान की वह शाखा है जो वंशागति (Inheritance) और विभिन्नता (Variation) का अध्ययन करती है।
Important Scientists
Gregor Johann Mendel
👉 Known as Father of Genetics
Why?
Because he performed hybridization experiments on pea plants and established the basic laws of inheritance.
📌 NCERT Highlight:
Mendel is called the Father of Genetics.
🔴 PYQ Favourite
🌱 Why Mendel Chose Pea Plant?
Scientific Name:
Pisum sativum
Reasons:
✅ Easy to grow
✅ Short life cycle
✅ Naturally self-pollinating
✅ Produces many seeds
✅ Clear contrasting characters
🧬 Important Terms
Character
A heritable feature.
Example:
Height of plant
Trait
Different forms of a character.
Example:
Character = Height
Traits =
- Tall
- Dwarf
📌 NEET Trap: Character ≠ Trait
Gene
Unit of inheritance.
Hindi:
वंशागति की इकाई
Alleles
Alternative forms of a gene.
Example:
T = Tall
t = Dwarf
Both are alleles.
Homozygous
Both alleles same.
Examples:
TT
tt
Heterozygous
Different alleles.
Example:
Tt
Genotype
Genetic makeup.
Example:
TT, Tt, tt
Phenotype
Physical appearance.
Example:
Tall or Dwarf
🌿 Mendel's Seven Contrasting Characters
| Character | Dominant | Recessive |
|---|---|---|
| Stem height | Tall | Dwarf |
| Flower colour | Violet | White |
| Seed shape | Round | Wrinkled |
| Seed colour | Yellow | Green |
| Pod shape | Inflated | Constricted |
| Pod colour | Green | Yellow |
| Flower position | Axial | Terminal |
📌 Learn these. Frequently asked in NEET.
🌟 Monohybrid Cross
Definition
Cross involving one character only.
Example
Tall × Dwarf
Mendel's Experiment
P Generation
TT × tt
Tall × Dwarf
Gametes
TT → T
tt → t
F₁ Generation
All offspring:
Tt
All Tall
Observation
No dwarf plants appeared.
Conclusion
Tallness dominates over dwarfness.
Hence:
Tall = Dominant
Dwarf = Recessive
🌟 Law of Dominance
Statement
When two contrasting factors are present together, only one expresses itself while the other remains hidden.
Example
Tt
Tall trait expressed
Dwarf trait hidden
Important Points
Dominant allele:
T
Recessive allele:
t
📌 NCERT Highlight
Characters are controlled by discrete units called factors.
(Factors = Genes)
🔴 Repeated NEET Question
🌟 Selfing of F₁ Generation
Cross
Tt × Tt
Punnett Square
| T | t | |
|---|---|---|
| T | TT | Tt |
| t | Tt | tt |
F₂ Generation
Genotypes:
TT = 1
Tt = 2
tt = 1
Genotypic Ratio
1 : 2 : 1
Phenotypic Ratio
Tall = 3
Dwarf = 1
3 : 1
📌 Most Repeated NEET Ratio
Phenotypic Ratio = 3:1
Genotypic Ratio = 1:2:1
🌟 Law of Segregation
Also called:
Law of Purity of Gametes
Statement
The two alleles of a gene separate during gamete formation.
Example
Tt
Gametes formed:
T and t
Not Tt
Why Important?
Because alleles do not mix permanently.
They separate and remain pure.
📌 NCERT Highlight
Alleles segregate during gamete formation.
🔴 Extremely Important NEET Question
🌟 Test Cross
Definition
Cross between an individual having dominant phenotype and a homozygous recessive parent.
Example
T? × tt
Case 1
TT × tt
All offspring Tall
Case 2
Tt × tt
Tall : Dwarf
1 : 1
Use
To determine unknown genotype.
📌 NEET Favourite
Test Cross Ratio:
1 : 1
🌟 Back Cross
Cross of F₁ with either parent.
Example
Tt × TT
or
Tt × tt
📌 Test Cross is a type of Back Cross.
🟨 NCERT Special Concepts
Factors
Mendel called genes as:
Factors
True Breeding
Plants that produce offspring identical to themselves.
Example:
TT
tt
Hybrid
Offspring produced from genetically different parents.
Example:
Tt
🎯 PYQ Analysis
Most Asked Areas
🔥 Father of Genetics
🔥 Pisum sativum
🔥 Dominance
🔥 Segregation
🔥 Monohybrid Ratio
🔥 Test Cross
🔥 Homozygous vs Heterozygous
🔥 Genotype vs Phenotype
📌 NCERT One-Liners
✅ Gregor Mendel = Father of Genetics
✅ Pisum sativum = Pea plant
✅ Gene = Unit of inheritance
✅ Alleles = Alternative forms of gene
✅ TT = Homozygous dominant
✅ tt = Homozygous recessive
✅ Tt = Heterozygous
✅ Monohybrid ratio = 3:1
✅ Genotypic ratio = 1:2:1
✅ Segregation = Purity of gametes
✅ Test cross = Unknown dominant × recessive
🚨 NEET Traps
Trap 1
Phenotype ≠ Genotype
Tall can be:
TT or Tt
Trap 2
Test Cross Ratio
Always:
1 : 1
(if parent is heterozygous)
Trap 3
Law of Dominance ≠ Law of Segregation
Dominance → Expression
Segregation → Separation
🧠 Quick Revision Mind Map
Genetics ↓ Mendel ↓ Pea Plant ↓ Genes → Alleles ↓ TT / Tt / tt ↓ Monohybrid Cross ↓ F₁ = All Tall ↓ F₂ = 3:1 ↓ Law of Dominance ↓ Law of Segregation ↓ Test Cross → 1:1
✨ Expected NEET Questions
- Why did Mendel choose pea plant?
- Define allele with example.
- Differentiate genotype and phenotype.
- State Law of Dominance.
- State Law of Segregation.
- Explain monohybrid cross.
- What is a test cross?
- Why is segregation called purity of gametes?
- Give genotypic ratio of monohybrid cross.
- Give phenotypic ratio of monohybrid cross
-
🌱 Dihybrid Cross
Definition
English:
A cross involving two pairs of contrasting characters simultaneously.
Hindi:
ऐसा संकरण जिसमें दो विपरीत लक्षणों का एक साथ अध्ययन किया जाता है।
Mendel's Dihybrid Experiment
Parents (P Generation)
Round Yellow Seeds × Wrinkled Green Seeds
Genotype:
RRYY × rryy
Dominant Traits
✅ Round (R)
✅ Yellow (Y)
Recessive Traits
✅ Wrinkled (r)
✅ Green (y)
F₁ Generation
All offspring:
RrYy
Phenotype:
Round Yellow
📌 Both dominant characters appear.
Selfing of F₁
Cross
RrYy × RrYy
Gametes Produced
RY
Ry
rY
ry
F₂ Phenotypic Ratio
9 : 3 : 3 : 1
Phenotype Ratio Round Yellow 9 Round Green 3 Wrinkled Yellow 3 Wrinkled Green 1
📌 Most Important NEET Ratio
Dihybrid Ratio = 9 : 3 : 3 : 1
🌟 Law of Independent Assortment
Statement
English:
When two pairs of traits are considered, segregation of one pair is independent of the other pair.
Hindi:
जब दो जोड़ी लक्षणों का अध्ययन किया जाता है, तो एक जोड़ी के एलील का पृथक्करण दूसरी जोड़ी से स्वतंत्र होता है।
Example
Seed Shape: R / r
Seed Colour: Y / y
Both assort independently.
📌 NCERT Highlight
Factors for different traits assort independently.
Difference Between Segregation & Independent Assortment
Segregation Independent Assortment One gene involved Two genes involved Alleles separate Gene pairs separate independently Monohybrid cross Dihybrid cross 🔴 PYQ Favourite
🌸 Incomplete Dominance
Definition
When neither allele is completely dominant over the other.
Hindi:
जब कोई भी एलील पूरी तरह प्रभावी न हो।
Example
Snapdragon (Dog Flower)
Parents
Red Flower = RR
White Flower = rr
F₁ Generation
Rr
Pink Flower
📌 New phenotype appears.
F₂ Generation
Genotype Ratio RR 1 Rr 2 rr 1
Phenotypic Ratio
1 : 2 : 1
Genotypic Ratio
1 : 2 : 1
📌 NEET Favourite
In incomplete dominance:
Phenotypic ratio = Genotypic ratio
🌟 Why Important?
In Mendel:
Phenotype = 3:1
In Incomplete Dominance:
Phenotype = 1:2:1
🌟 Codominance
Definition
Both alleles express themselves equally in heterozygous condition.
Hindi:
दोनों एलील एक साथ और पूर्ण रूप से अभिव्यक्त होते हैं।
Example
Human Blood Group
Alleles:
IA
IB
i
Genotypes
Genotype Blood Group IAIA A IAi A IBIB B IBi B IAIB AB ii O
Important Point
IA and IB are codominant.
Both express together.
Result:
Blood Group AB
📌 Most Repeated NEET Question
AB blood group is example of:
Codominance
🌟 Multiple Alleles
Definition
More than two alleles of a gene present in population.
Hindi:
किसी जीन के दो से अधिक एलील का जनसंख्या में पाया जाना।
Example
ABO Blood Group
Three Alleles:
IA
IB
i
📌 Important
A person can carry only two alleles at a time.
Although population contains three.
ABO Blood Group System
Discovered by:
Karl Landsteiner
📌 Repeated NEET Question
Blood Group A
Genotype:
IAIA
or
IAi
Blood Group B
Genotype:
IBIB
or
IBi
Blood Group AB
Genotype:
IAIB
Blood Group O
Genotype:
ii
Universal Donor
O Blood Group
Universal Recipient
AB Blood Group
📌 Frequently Asked
🌟 Pleiotropy
Definition
One gene affects multiple traits.
Hindi:
एक जीन कई लक्षणों को प्रभावित करता है।
Example
Sickle Cell Anaemia
One mutation causes many effects.
📌 NCERT Important
🌟 Comparison Table
Feature Dominance Incomplete Dominance Codominance Expression One allele dominant Intermediate phenotype Both alleles express Example Pea Plant Snapdragon AB Blood Group F₂ Ratio 3:1 1:2:1 1:2:1
🎯 PYQ Analysis
Most Asked Topics:
🔥 Dihybrid Ratio
🔥 Independent Assortment
🔥 Snapdragon
🔥 Codominance
🔥 ABO Blood Group
🔥 Karl Landsteiner
🔥 Multiple Alleles
🔥 Universal Donor
🔥 Universal Recipient
📌 NCERT One-Liners
✅ Dihybrid Ratio = 9:3:3:1
✅ Law of Independent Assortment from Dihybrid Cross
✅ Snapdragon = Incomplete Dominance
✅ AB Blood Group = Codominance
✅ ABO System = Multiple Alleles
✅ Karl Landsteiner discovered blood groups
✅ IA and IB are codominant
✅ i is recessive
✅ Universal Donor = O
✅ Universal Recipient = AB
🚨 NEET Traps
Trap 1
Incomplete Dominance ≠ Codominance
Incomplete Dominance → Blending
Codominance → Both traits expressed
Trap 2
AB blood group is NOT incomplete dominance
Correct Answer:
Codominance
Trap 3
Universal donor:
O
Not AB
Trap 4
Universal recipient:
AB
Not O
🧠 Quick Revision Mind Map
Dihybrid Cross ↓ RrYy × RrYy ↓ 9 : 3 : 3 : 1 ↓ Independent Assortment ↓ Snapdragon ↓ Incomplete Dominance ↓ Pink Flower ↓ 1 : 2 : 1 ↓ AB Blood Group ↓ Codominance ↓ Multiple Alleles ↓ IA, IB, i
✨ Expected NEET Questions
- State Law of Independent Assortment.
- Explain Dihybrid Cross.
- Why is Snapdragon an example of incomplete dominance?
- Differentiate codominance and incomplete dominance.
- Explain ABO blood group inheritance.
- What are multiple alleles?
- Who discovered ABO blood groups?
- Why is AB blood group called universal recipient?
- Why is O blood group called universal donor?
- Give phenotypic ratio of a dihybrid cross
🌟 Chromosomal Theory of Inheritance
Introduction
After Mendel's work, scientists wanted to know:
👉 Where are genes present?
👉 How are they inherited?
This led to the Chromosomal Theory of Inheritance.
Scientists
Walter Sutton
Theodore Boveri
📌 NCERT Highlight
Both independently proposed the Chromosomal Theory of Inheritance.
Statement
English:
Genes are located on chromosomes and chromosomes are the carriers of hereditary information.
Hindi:
जीन गुणसूत्रों (Chromosomes) पर स्थित होते हैं तथा गुणसूत्र वंशागति की जानकारी को एक पीढ़ी से दूसरी पीढ़ी तक ले जाते हैं।
Similarities Between Genes and Chromosomes
Genes
✔ Occur in pairs
✔ Segregate during gamete formation
✔ Recombine during fertilization
Chromosomes
✔ Occur in pairs
✔ Separate during meiosis
✔ Rejoin during fertilization
📌 PYQ Favourite
Chromosomal Theory provides physical basis of Mendel's laws.
🌟 Thomas Hunt Morgan
Contribution
Performed experiments on:
Fruit Fly
Scientific Name:
Drosophila melanogaster
Why Drosophila?
✅ Small size
✅ Easy culture
✅ Short life cycle
✅ Large number of offspring
📌 Frequently Asked in NEET
🌟 Linkage
Definition
Genes located on the same chromosome tend to be inherited together.
Hindi:
एक ही गुणसूत्र पर स्थित जीन साथ-साथ विरासत में जाते हैं।
Example
Genes on same chromosome.
They do not assort independently.
📌 Important
Linkage violates Mendel's Independent Assortment.
Types of Linkage
Complete Linkage
No crossing over.
Parental combinations only.
Incomplete Linkage
Crossing over occurs.
Both parental and recombinant types formed.
🌟 Recombination
Definition
Formation of new gene combinations.
Hindi:
नए जीन संयोजनों का निर्माण।
Cause
Crossing Over
Occurs during:
Pachytene stage of Prophase-I (Meiosis)
📌 Very Important NEET Question
Recombination Frequency
Used to determine distance between genes.
Higher recombination = Greater distance
📌 Morgan discovered linkage and recombination.
🌟 Sex Determination
Meaning
Process by which sex of offspring is determined.
Human Sex Determination
XX – XY Type
Female
XX
Male
XY
Gametes Produced
Female:
Only X
Male:
X and Y
Fertilization
Female Egg Male Sperm Child X X Girl (XX) X Y Boy (XY)
Result
50% Boys
50% Girls
📌 NCERT Highlight
Father determines the sex of child.
🔴 Most Repeated NEET Question
🚨 Common Myth
Mother is NOT responsible for child's sex.
Correct:
Father decides sex.
🌟 Birds
ZW – ZZ System
Female
ZW
Male
ZZ
📌 In Birds
Female determines sex.
🌟 Honey Bee
Haplodiploidy
Male
Haploid (n)
Produced from unfertilized eggs.
Female
Diploid (2n)
Produced from fertilized eggs.
📌 Very Important PYQ
🌟 Pedigree Analysis
Definition
Study of inheritance of traits through generations.
Hindi:
पीढ़ी दर पीढ़ी लक्षणों के संचरण का अध्ययन।
Why Pedigree?
Human crosses cannot be performed experimentally.
Hence pedigree charts are used.
Standard Symbols
Square
Male
Circle
Female
Shaded Symbol
Affected individual
Unshaded Symbol
Normal individual
Horizontal Line
Marriage
Vertical Line
Offspring
📌 Learn these symbols carefully.
Uses of Pedigree
✅ Identify inheritance pattern
✅ Genetic counseling
✅ Disease prediction
Types of Inheritance
Autosomal Dominant
Autosomal Recessive
Sex-linked
📌 Pedigree-based questions are common in NEET.
🌟 Sex-Linked Inheritance
Definition
Genes located on sex chromosomes.
Usually X chromosome.
Examples
Colour Blindness
Haemophilia
📌 Repeated NEET Questions
Colour Blindness
Person cannot distinguish certain colours.
Usually:
Red-Green colour blindness
Inheritance
X-linked recessive
Genotypes
Normal Male
XY
Affected Male
XᶜY
Normal Female
XX
Carrier Female
XᴺXᶜ
Affected Female
XᶜXᶜ
📌 Females can be carriers.
Males cannot be carriers.
NEET Favourite.
Haemophilia
Definition
Blood clotting disorder.
Blood fails to clot normally.
Cause
Deficiency of clotting factors.
Inheritance
X-linked recessive.
📌 Royal Disease
Known as:
Royal Disease of Europe
🎯 PYQ Analysis
Most Asked Topics
🔥 Chromosomal Theory
🔥 Sutton and Boveri
🔥 Drosophila
🔥 Linkage
🔥 Recombination
🔥 Crossing Over
🔥 Human Sex Determination
🔥 Honey Bee Sex Determination
🔥 Pedigree Symbols
🔥 Colour Blindness
🔥 Haemophilia
📌 NCERT One-Liners
✅ Sutton and Boveri → Chromosomal Theory
✅ Drosophila → Morgan's experiments
✅ Linkage → Same chromosome inheritance
✅ Recombination → New combinations
✅ Crossing over → Pachytene stage
✅ Human female → XX
✅ Human male → XY
✅ Father determines sex
✅ Bird female → ZW
✅ Honey bee male → Haploid
✅ Honey bee female → Diploid
✅ Colour blindness → X-linked recessive
✅ Haemophilia → X-linked recessive
🚨 NEET Traps
Trap 1
Who determines sex?
❌ Mother
✅ Father
Trap 2
Male honey bee is:
✅ Haploid
Not diploid
Trap 3
Colour blind female genotype:
✅ XᶜXᶜ
Not XᴺXᶜ
Trap 4
Crossing over occurs in:
✅ Pachytene
Not Metaphase
🧠 Quick Revision Mind Map
Chromosomal Theory ↓ Sutton + Boveri ↓ Morgan ↓ Drosophila ↓ Linkage ↓ Recombination ↓ Crossing Over ↓ Pachytene ↓ Sex Determination ↓ XX–XY ↓ ZW–ZZ ↓ Haplodiploidy ↓ Pedigree Analysis ↓ Colour Blindness ↓ Haemophilia
✨ Expected NEET Questions
- State Chromosomal Theory of Inheritance.
- Why did Morgan use Drosophila?
- Define linkage and recombination.
- What is crossing over?
- Explain XX–XY sex determination.
- Explain haplodiploidy in honey bees.
- Draw pedigree symbols.
- Explain colour blindness inheritance.
- Explain haemophilia inheritance.
- Why is father responsible for determining sex?
-
🌟 Mutation
Definition
English:
Sudden heritable change in genetic material is called mutation.
Hindi:
आनुवंशिक पदार्थ (DNA/Gene) में अचानक होने वाला वंशानुगत परिवर्तन Mutation कहलाता है।
Who Proposed Mutation Theory?
Hugo de Vries
📌 NCERT Important
Based on experiments on:
Evening Primrose
(Oenothera lamarckiana)
Types of Mutation
1. Gene Mutation
Change in DNA sequence of a gene.
Example
Sickle Cell Anaemia
2. Chromosomal Mutation
Change in chromosome number or structure.
Example
Down Syndrome
📌 NEET Favourite
🌟 Genetic Disorders
Definition
Diseases caused by mutation in genes.
🌟 Sickle Cell Anaemia
Cause
Mutation in β-globin gene.
Chromosome
Chromosome 11
📌 Frequently Asked
Defect
Glutamic acid replaced by Valine.
Position
6th amino acid of β-chain
📌 NCERT Highlight
Normal:
GAG → Glutamic acid
Mutated:
GUG → Valine
Inheritance
Autosomal Recessive
Symptoms
✅ Sickle-shaped RBCs
✅ Reduced oxygen transport
✅ Anaemia
📌 Most Repeated NEET Question
🌟 Thalassemia
Definition
Inherited disorder of haemoglobin synthesis.
Cause
Reduced or absent synthesis of globin chains.
Types
α-Thalassemia
Defect in alpha chain.
β-Thalassemia
Defect in beta chain.
📌 NEET Favourite
Difference
Sickle Cell Thalassemia Structural defect Reduced synthesis Amino acid substitution Quantitative defect Point mutation Globin chain deficiency
🌟 Chromosomal Disorders
Caused by abnormal chromosome number.
Aneuploidy
Definition
Gain or loss of one or more chromosomes.
Hindi:
एक या अधिक गुणसूत्रों की संख्या में असामान्यता।
Cause
Nondisjunction
Failure of chromosomes to separate during meiosis.
📌 Extremely Important
🌟 Down Syndrome
Chromosome Number
47
Cause
Extra copy of chromosome 21
Trisomy 21
📌 Most Repeated NEET Question
Karyotype
2n + 1
Features
✅ Short stature
✅ Furrowed tongue
✅ Broad palm
✅ Intellectual disability
📌 NCERT Line
Mongolian facial appearance
🌟 Klinefelter Syndrome
Chromosome Number
47
Karyotype
XXY
Affected Individual
Male
Features
✅ Sterile male
✅ Feminine characteristics
✅ Enlarged breasts (Gynecomastia)
📌 Very Important PYQ
🌟 Turner Syndrome
Chromosome Number
45
Karyotype
XO
Affected Individual
Female
Features
✅ Sterile female
✅ Rudimentary ovaries
✅ Short stature
📌 Frequently Asked
Quick Comparison
Disorder Karyotype Sex Down Syndrome 47 (+21) Male/Female Klinefelter XXY Male Turner XO Female
🌟 Pedigree-Based Disorders
Autosomal Recessive
Examples:
✅ Sickle Cell Anaemia
✅ Thalassemia
X-linked Recessive
Examples:
✅ Haemophilia
✅ Colour Blindness
📌 Learn classification.
🌟 Human Genome Project (NCERT)
Objective
To identify all human genes.
Total Base Pairs
≈ 3.2 billion
Number of Genes
≈ 20,000–25,000
📌 NEET Direct Questions Asked
🌟 DNA Fingerprinting
Developed By
Alec Jeffreys
Uses
✅ Criminal identification
✅ Paternity disputes
✅ Forensic science
📌 PYQ Favourite
🎯 Complete NCERT Highlights
✅ Gregor Mendel = Father of Genetics
✅ Pisum sativum = Pea plant
✅ Monohybrid ratio = 3:1
✅ Dihybrid ratio = 9:3:3:1
✅ Segregation = Purity of Gametes
✅ Independent Assortment = Dihybrid Cross
✅ Snapdragon = Incomplete Dominance
✅ AB Blood Group = Codominance
✅ ABO = Multiple Alleles
✅ Sutton + Boveri = Chromosomal Theory
✅ Morgan = Linkage
✅ Drosophila melanogaster = Fruit Fly
✅ Crossing Over = Pachytene
✅ Father determines sex
✅ Colour Blindness = X-linked Recessive
✅ Haemophilia = X-linked Recessive
✅ Sickle Cell = Autosomal Recessive
✅ Down Syndrome = Trisomy 21
✅ Klinefelter = XXY
✅ Turner = XO
✅ DNA Fingerprinting = Alec Jeffreys
🚨 Ultimate NEET Traps
Trap 1
Down Syndrome
✅ Trisomy 21
❌ Trisomy 18
Trap 2
Klinefelter
✅ XXY Male
Trap 3
Turner
✅ XO Female
Trap 4
Sickle Cell
✅ Autosomal Recessive
Not Sex-linked
Trap 5
DNA Fingerprinting
✅ Alec Jeffreys
Not Watson
🧠 Complete One-Shot Mind Map
Mendel ↓ Monohybrid ↓ 3:1 ↓ Dihybrid ↓ 9:3:3:1 ↓ Dominance ↓ Segregation ↓ Independent Assortment ↓ Incomplete Dominance ↓ Codominance ↓ ABO Blood Group ↓ Chromosomal Theory ↓ Sutton + Boveri ↓ Morgan ↓ Linkage ↓ Recombination ↓ Sex Determination ↓ Pedigree ↓ Colour Blindness ↓ Haemophilia ↓ Mutation ↓ Sickle Cell ↓ Thalassemia ↓ Down Syndrome ↓ Klinefelter ↓ Turner Syndrome ↓ DNA Fingerprinting
🔥 NEET PYQ Weightage
Topic Expected Questions Mendelism 2–3 Blood Group 1 Linkage & Recombination 1 Sex Determination 1 Pedigree 1 Genetic Disorders 1–2 Chromosomal Disorders 1–2 📌 Chapter Complete
Principles of Inheritance and Variation se har saal NEET mein lagbhag 5–8 questions aate hain. Is chapter mein ratios, blood groups, sex determination, linkage aur genetic disorders sabse zyada important hain.
