Heredity and Evolution Class 10 Notes (Hindi + English) | आसान भाषा में पूरा अध्याय, उदाहरण सहित

Heredity and Evolution Class 10 Notes: Class 10 Science का Chapter “Heredity and Evolution (अनुवांशिकता एवं विकास)” बोर्ड परीक्षा के लिए बेहद महत्वपूर्ण है। इस अध्याय में हम समझते हैं कि बच्चों में माता-पिता के गुण कैसे आते हैं और समय के साथ जीवों में बदलाव कैसे होता है। इस टॉपिक में Mendel के नियम, genes, DNA, dominant और recessive traits, natural selection और evolution theory जैसे महत्वपूर्ण concepts शामिल हैं।

अगर आप इस chapter को आसान भाषा में और clear concepts के साथ समझना चाहते हैं, तो ये notes आपके लिए बिल्कुल perfect हैं। यहां आपको Hindi और English दोनों में सरल explanation, examples और exam-oriented points मिलेंगे, जिससे आपकी तैयारी और भी मजबूत हो जाएगी। For Objective Questions, Visit Learneasily8.

Heredity and Evolution Class 10 Notes: Start Now

Heredity (अनुवांशिकता) वह प्रक्रिया है जिसके द्वारा जीव अपने माता-पिता से गुण (traits) प्राप्त करते हैं।
Evolution (विकास) वह प्रक्रिया है जिसमें जीवों में समय के साथ परिवर्तन होते हैं और नई प्रजातियाँ (species) बनती हैं।

Example:

• A child having eye color like parents → Heredity
• Human evolving from primitive organisms → Evolution

Important Terms (महत्वपूर्ण शब्दावली)

• Trait (लक्षण): किसी जीव की विशेषता (जैसे height, color)
• Gene (जीन): DNA का वह भाग जो traits को नियंत्रित करता है
• Chromosome (गुणसूत्र): DNA से बने धागे जैसी संरचना
• DNA: Genetic material (आनुवांशिक पदार्थ)

👉 Humans have 23 pairs of chromosomes

Read More: Class 10 Life Processes Case Study Questions | जीवन प्रक्रियाएँ केस स्टडी प्रश्न (CBSE Board Pattern)

Mendel’s Experiment (मेंडल के प्रयोग)

Gregor Mendel को Genetics का जनक कहा जाता है।

उन्होंने pea plant (मटर) पर प्रयोग किया और inheritance के नियम दिए।

Traits Studied:

• Tall (लंबा) vs Short (बौना)
• Round seed vs Wrinkled seed

Laws of Inheritance (वंशागति के नियम)

(1) Law of Dominance (प्रभाविता का नियम)

• Dominant trait हमेशा दिखाई देता है
• Recessive trait छिपा रहता है

👉 Example:
T (Tall) > t (Short)

(2) Law of Segregation (विभाजन का नियम)

• Traits अलग-अलग होकर अगली पीढ़ी में जाते हैं

Monohybrid Cross (एक गुण संकरण)

👉 Cross between Tall (TT) and Short (tt)

Result:

• All plants become Tall (Tt)

👉 Next generation (Tt × Tt):

Genotype	Result
TT	Tall
Tt	Tall
tt	Short

👉 Ratio:

• Phenotypic ratio = 3:1
• Genotypic ratio = 1:2:1

Sex Determination in Humans (लिंग निर्धारण)

Humans have:

• Female = XX
• Male = XY

👉 Father decides the sex of child

Father	Mother	Child
X	X	Girl
Y	X	Boy

Evolution (विकास)

Evolution means gradual changes over time.

👉 Theory given by Charles Darwin

Natural Selection (प्राकृतिक चयन)

• Nature selects the fittest organisms
• Survival of the fittest

👉 Example:

• Giraffes with long neck survived better

Acquired vs Inherited Traits

Type	Meaning	Example
Acquired Traits	जीवन में सीखे गए	Bodybuilding
Inherited Traits	जन्म से मिले	Eye color

👉 Acquired traits are NOT inherited

Speciation (नई प्रजाति का निर्माण)

When new species are formed due to:

• Geographical isolation
• Genetic variation

👉 Example:
Darwin’s finches (different beaks)

Homologous & Analogous Organs

🔹 Homologous Organs

• Same structure, different function
  👉 Example: Human hand & Whale flipper

🔹 Analogous Organs

• Different structure, same function
  👉 Example: Bird wings & Insect wings

Fossils (जीवाश्म)

• Remains of dead organisms
• Help to study evolution

👉 Example: Dinosaur fossils

Evolution by Stages

• Fish → Amphibians → Reptiles → Birds → Mammals

👉 Humans evolved from ape-like ancestors

Important Examples for Exam

✔ Tallness in plants
✔ Blood group inheritance
✔ Eye color
✔ Darwin’s finches
✔ Industrial melanism

Key Points (Exam Revision)

✅ Traits are controlled by genes
✅ Mendel gave laws of inheritance
✅ Dominant trait expressed more
✅ Evolution occurs due to variation
✅ Natural selection is key factor
✅ Fossils provide evidence
✅ Speciation leads to new species

Frequently Asked Questions (FAQs)

Q1: What is heredity?

👉 Transfer of traits from parents to offspring

Q2: Who is father of genetics?

👉 Gregor Mendel

Q3: What is evolution?

👉 Gradual change in organisms over time

Q4: Who gave theory of evolution?

👉 Charles Darwin

Q5: What is dominant trait?

👉 Trait that expresses itself in presence

Heredity and Evolution Class 10 Notes: Conclusion

Heredity और Evolution biology के सबसे महत्वपूर्ण topics हैं।
ये हमें बताते हैं कि traits कैसे inherit होते हैं और जीव समय के साथ कैसे बदलते हैं।

👉 Board exam के लिए यह chapter बहुत महत्वपूर्ण है, इसलिए examples और laws को अच्छे से समझना जरूरी है।

Assertion–Reason Questions

👉 Instructions:
For each question, choose the correct option:
A. Both Assertion (A) and Reason (R) are true and R is the correct explanation of A
B. Both A and R are true but R is NOT the correct explanation of A
C. A is true but R is false
D. A is false but R is true

Q1. Assertion (A): Traits are controlled by genes.
Reason (R): Genes are segments of DNA present on chromosomes.

Answer: A

Q2. Assertion (A): Dominant traits are always expressed in an organism.
Reason (R): Dominant traits mask the effect of recessive traits.

Answer: A

Q3. Assertion (A): Acquired traits are inherited by offspring.
Reason (R): Traits developed during lifetime are passed to next generation.

Answer: D

Q4. Assertion (A): Evolution is a gradual process.
Reason (R): It occurs due to accumulation of variations over generations.

Answer: A

Q5. Assertion (A): Only variations that are useful to organisms are selected by nature.
Reason (R): Natural selection favors organisms with advantageous traits.

Answer: A

Q6. Assertion (A): Fossils provide evidence for evolution.
Reason (R): Fossils are preserved remains of organisms from the past.

Answer: A

Q7. Assertion (A): Speciation occurs due to geographical isolation.
Reason (R): Isolated populations do not interbreed and evolve separately.

Answer: A

Q8. Assertion (A): Homologous organs have similar structure.
Reason (R): They perform the same function in all organisms.

Answer: C

Q9. Assertion (A): Analogous organs have different structures.
Reason (R): They perform similar functions.

Answer: A

Q10. Assertion (A): Mendel used pea plants for his experiments.
Reason (R): Pea plants have easily observable contrasting traits.

Answer: A

Q11. Assertion (A): Male determines the sex of the child in humans.
Reason (R): Male has XY chromosomes while female has XX.

Answer: A

Q12. Assertion (A): Variations are important for survival.
Reason (R): Variations help organisms adapt to changing environment.

Answer: A

Q13. Assertion (A): All inherited traits are useful.
Reason (R): Some inherited traits may not have survival advantage.

Answer: D

Q14. Assertion (A): DNA carries genetic information.
Reason (R): DNA controls the formation of proteins.

Answer: A

Q15. Assertion (A): Evolution explains diversity of life on Earth.
Reason (R): Different species arise due to accumulation of variations.

Answer: A

MCQs (Multiple Choice Questions)

Q1. The basic unit of heredity is:
A. Cell
B. Tissue
C. Gene
D. Organ
Answer: C

Q2. Who is known as the Father of Genetics?
A. Charles Darwin
B. Gregor Mendel
C. Isaac Newton
D. Einstein
Answer: B

Q3. Which of the following is a dominant trait?
A. Short height
B. Blue eyes
C. Tallness
D. Wrinkled seed
Answer: C

Q4. How many pairs of chromosomes are present in humans?
A. 21
B. 22
C. 23
D. 24
Answer: C

Q5. Evolution was proposed by:
A. Gregor Mendel
B. Charles Darwin
C. Pasteur
D. Newton
Answer: B

Q6. Which process leads to evolution?
A. Respiration
B. Variation
C. Digestion
D. Circulation
Answer: B

Q7. Homologous organs show:
A. Same function
B. Same structure
C. No similarity
D. Same size
Answer: B

Q8. Analogous organs show:
A. Same origin
B. Same structure
C. Same function
D. Same DNA
Answer: C

Q9. Fossils are:
A. Living organisms
B. Dead remains of organisms
C. Cells
D. Genes
Answer: B

Q10. Sex of a child is determined by:
A. Mother
B. Father
C. Both equally
D. Environment
Answer: B

Q11. Which of the following is NOT inherited?
A. Eye color
B. Height
C. Bodybuilding muscles
D. Blood group
Answer: C

Q12. Natural selection means:
A. Artificial breeding
B. Survival of the fittest
C. Random selection
D. Mutation only
Answer: B

Q13. Which is an example of acquired trait?
A. Hair color
B. Skin color
C. Learning skills
D. Blood group
Answer: C

Q14. DNA is found in:
A. Cytoplasm
B. Nucleus
C. Cell wall
D. Ribosome
Answer: B

Q15

Speciation leads to:
A. Death
B. New species
C. Mutation only
D. Extinction
Answer: B

Case Study Questions (Board Pattern)

Case Study 1: Mendel’s Experiment

A scientist crossed tall (TT) pea plants with short (tt) plants. All offspring in first generation were tall.

Q1: What is the genotype of offspring?
Answer: Tt

Q2: Which trait is dominant?
Answer: Tall

Q3: What will be ratio in next generation?
Answer: 3:1

Case Study 2: Evolution

A group of giraffes showed variation in neck length. Those with longer neck survived better.

Q1: Which concept is shown here?
Answer: Natural selection

Q2: Who proposed this theory?
Answer: Charles Darwin

Q3: Why did long-neck giraffes survive?
Answer: They could reach food easily

Case Study 3: Sex Determination

In humans, females have XX chromosomes and males have XY chromosomes.

Q1: Who determines the sex of child?
Answer: Male

Q2: Which chromosome forms a male child?
Answer: Y chromosome