Principles of Inheritance
Test cross
Ek tall pea plant TT ho ya Tt, dono ek jaise dikhte hain. Test cross batata hai ki wo kaunsa hai.
Jab plant dominant trait dikhata hai, tum dekh kar nahi bata sakte ki uske paas ek dominant copy hai ya do. Isliye use ek pure recessive plant (tt) se cross karte ho aur offspring answer de dete hain.
Agar saare offspring tall hain, to parent TT tha (pure). Agar lagbhag aadhe tall aur aadhe short hain, to parent Tt tha (carrier).
Short offspring hi clue hain. Ye tabhi aa sakte hain jab tall parent ek hidden recessive copy rakh raha ho.
Yahaan students galti karte hain
Test cross hamesha 1 : 1 ratio nahi deta. 1 : 1 tabhi aata hai jab unknown parent Tt ho. Agar wo TT hai, to har offspring tall hoga. Jo ratio actually aaye use padho, wahi answer hai, koi fixed rule nahi.
Ek quick check
Ek tall plant ko short (tt) plant se cross kiya. Aadhe offspring short hain. Tall parent tha:
- ATT
- BTt
- Ctt
- DBata nahi sakte