Chapter 21: Like Father, Like Daughter
किसकी झलक? किसकी पूंछ? (ग्रेगर मेंडल, मटर के प्रयोग एवं आनुवंशिकी)
Don't Let a 20-Minute Bubbling Delay Cost You CTET Qualification
In offline CTET exams, bubbling 150 bubbles takes 18 to 22 minutes of mechanical time. A single misaligned row can trigger an 8-question domino error. Practice bubble-filling this chapter's solved MCQs inside Mentora's official OMR simulator.
- Inherited Biological Traits: Features like eye color, skin complexion, hair curliness, height, and attached/free earlobes are passed down genetically from biological parents and ancestors.
- Acquired Habits vs Genetics: Habits, language accents, table manners, singing skills, and schooling are acquired from family environment, NOT inherited genetically.
- Gregor Johann Mendel (1822–1884): Born into a poor farming family in Austria; became a monk in a monastery at Brno. Conducted scientific experiments for 7 years on 28,000 pea plants (Pisum sativum).
- Mendel's Pea Plant Discoveries: Pea plants possess traits that come in distinct pairs — seeds are either rough OR smooth (never medium-rough); seeds are either yellow OR green; plant stems are either tall OR dwarf.
- Dominance Principle: When crossing yellow and green seeded pea plants, the next generation produces predominantly yellow seeds because yellow is the dominant trait.
- Polio is NOT Hereditary: Polio is an infectious disease caused by a virus (Poliovirus); it is NOT passed down genetically from parents to children.
- Trap: CBSE states Polio is inherited genetically from parents. Correct: Polio is NOT hereditary; it is caused by a virus.
- Trap: CBSE states Mendel conducted experiments on 10,000 plants or rose bushes. Correct: Exactly **28,000 pea plants** over **7 years**.
- Trap: CBSE claims Mendel was born in Germany or England. Correct: He was born in **Austria**.
NCERT Core Facts: Gregor Mendel's Pea Genetics & Nature vs Nurture
Class 5 Chapter 21 introduces elementary principles of genetics, identical twins, and the landmark monastery research of Gregor Johann Mendel.
1. Gregor Johann Mendel (1822–1884)
- Background: Born into a poor peasant family in Austria. Longed to study at university but lacked money; entered an Augustinian monastery in Brno.
- The Research:
- Over a period of 7 years, Mendel painstakingly cross-pollinated and observed 28,000 pea plants in the monastery gardens.
- His findings laid the foundational laws of modern genetics, though his genius went unrecognized until decades after his death.
2. Key Discoveries in Pea Plant Inheritance
| Pea Trait | Observable Paired Varieties | Inheritance Behavior |
|---|---|---|
| Seed Surface | Smooth vs Rough | Seeds are either smooth or rough; never in-between. |
| Seed Color | Yellow vs Green | Crossing yellow and green varieties yields next generation with mostly Yellow seeds (dominant trait). |
| Plant Height | Tall vs Dwarf | Offspring inherit distinct tall or short stems. |
3. High-Yield CTET Trap: Polio is NOT Hereditary
- In this chapter, a girl named Saroja worries that since her legs were affected by Polio in early childhood, her future children will also be born with polio.
- The doctor explicitly clarifies:
- Polio is NOT hereditary (*यह आनुवंशिक नहीं है*).
- Polio is caused by a microscopic virus attacking motor nerves.
- Pulse Polio vaccination protects children from infection.
Test Your Mastery: Like Father, Like Daughter
Authentic CBSE exam questions tested directly from this NCERT chapter.
Gregor Johann Mendel conducted his pioneering scientific experiments on heredity using 28,000 plants of which species?
ग्रेगर जोहान मेंडल ने आनुवंशिकता पर अपने अग्रणी वैज्ञानिक प्रयोग किस प्रजाति के 28,000 पौधों पर किए?
Which of the following conditions or traits is NOT inherited genetically from parents to offspring?
निम्नलिखित में से कौन सी स्थिति या लक्षण माता-पिता से संतानों में आनुवंशिक रूप से स्थानांतरित नहीं होता है?
For how many years did Gregor Mendel conduct his breeding experiments in the monastery garden in Austria?
ग्रेगर मेंडल ने ऑस्ट्रिया में मठ के बगीचे में कितने वर्षों तक अपने प्रजनन प्रयोग किए?
On how many pea plants did Gregor Mendel conduct his experiments and for how long?
On 28,000 pea plants over a period of 7 years in Austria.
Is Polio a hereditary condition according to NCERT?
No, Polio is an infectious disease caused by a virus (Poliovirus); it is not inherited from parents.
Which traits in pea plants did Mendel study?
Pairs of traits: seed surface (rough or smooth), seed color (yellow or green), and plant height (tall or dwarf).