Principles of Inheritance
Law of Dominance
Jab gene ke do alag versions saath ho, to aksar sirf ek dikhta hai. Wo dominant hai. Jo chhup jaata hai wo recessive hai.
Ek pure tall pea ko pure short pea se cross karo, to next generation ke saare plants tall hote hain. ‘Short’ wala instruction gaya nahi, bas chhup gaya. Ek allele plant me dikhta hai (dominant). Doosra tab tak chhupa rehta hai jab tak ek dominant copy present hai (recessive).
Recessive trait tabhi dikhta hai jab dono copies recessive hon.
Yahaan students galti karte hain
Dominant ka matlab strong, zyada common, ya better nahi hota. Sirf itna ki ‘jo dono present hone par dikhe’. Bahut se dominant traits rare hote hain, aur bahut se recessive common. Dominance ka matlab hai kya dikhta hai, taakat nahi.
Yaad rakho
Dominant wo jo dikhta hai. Recessive tab tak chhupta hai jab tak akela na ho.
Exam me kaise kaam aata hai: isiliye monohybrid cross ke F₁ saare ek jaise dikhte hain, aur recessive trait ek generation skip karke baad me wapas aa sakta hai.
Ek quick check
Pure tall (TT) pea ko pure short (tt) pea se cross kiya. F₁ plants honge:
- ASaare short
- BSaare tall
- CAadhe tall, aadhe short
- DSaare medium height