NCERT Question 1 - Chapter 9 Class 10 - Heredity and Evolution

A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers

with short pea plants bearing white flowers. The progeny all bore violet flowers,

but almost half of them were short. This suggests that the genetic make-up of the

tall parent can be depicted as

1. TTWW
2. TTww
3. TtWW
4. TtWw

Answer:

Four traits are present in the parent generation: Tall (T), Short (t), Violet flowers (W), White flowers (w)

• Since the recessive trait (short pea plants) appears in the progeny, there is the presence of the recessive allele . 
• But since the parent is tall , there is an allele for the tall trait as well. 

Therefore, the genotype for height is heterozygous dominant (Tt) .

• Since all plants bear Violet flowers (which is the dominant trait), allele from the recessive trait (white) is absent . 

Therefore  the genotype for flower colour is homozygous dominant (WW) .

So, the answer is (c) TtWW