Principles of Inheritance
Dihybrid cross
Do traits ko ek saath follow karo, to F₂ ek 9 : 3 : 3 : 1 pattern me aate hain. Ye do genes ke freely mix hone ka sign hai.
Pure round-yellow (RRYY) ko pure wrinkled-green (rryy) se cross karo. F₁ saare RrYy hote hain, round aur yellow. Inhe self-cross karo, to F₂ split hote hain 9 round-yellow : 3 round-green : 3 wrinkled-yellow : 1 wrinkled-green.
Do naye mixes, round-green aur wrinkled-yellow, prove karte hain ki do genes apne aap alag hue.
Yahaan students galti karte hain
9 : 3 : 3 : 1 tabhi chalta hai jab do genes unlinked hon aur har ek simple dominance dikhaye. Agar genes linked hain, ya incomplete dominance hai, to ratio badal jaata hai. Ye fixed number nahi hai; in conditions par depend karta hai.
Yaad rakho
9 : 3 : 3 : 1 bas do 3 : 1 crosses ka multiplication hai.
Exam me kaise kaam aata hai: ise (3 : 1) × (3 : 1) ki tarah dekho, to saare solah boxes banaye bina ratio nikaal loge.
Ek quick check
Dihybrid cross (RrYy × RrYy) ka F₂ look ratio hota hai:
- A3 : 1
- B1 : 2 : 1
- C9 : 3 : 3 : 1
- D1 : 1 : 1 : 1