CBSE Class 10 Science 2022 · Paper 31/1/2 · Question 11

Heredity 3 marks Medium

A cross was made between green-stemmed tomato plants denoted by (GG) and purple-stemmed tomato plants denoted as (gg) to obtain

F_{1}

progeny.

(a)What colour of the stem would you expect in their $F_{1}$ progeny and why ?
(b)Give the percentage of purple-stemmed plants if $F_{1}$ plants are allowed to self-pollinate to produce $F_{2}$ progeny.
(c)Write the ratio between GG and gg plants in the $F_{2}$ progeny ?

Answer

All $F_{1}$ plants are green ( $G g$ ) as $G$ is dominant; $25%$ of $F_{2}$ are purple, and $GG : g g = 1 : 1$ .

(a) All the

F_{1}

plants will have green stems. Each receives G from the green parent and g from the purple parent, so each is Gg; G, the allele for green, is dominant (it is written with the capital letter), so one copy of it is enough for a green stem, and the purple trait stays hidden. (b)

25%

. Self-pollinating Gg gives GG, Gg, Gg and gg; only gg, one in four, has a purple stem. (c)

GG : gg = 1 : 1

(the

F_{2}

genotypes are

1 GG : 2 Gg : 1 gg

🔒 Step-by-step solution

From the board paper

CBSE Class 10 Science 2022 · Paper 31/1/2, Question 11 — all 15 questions with answers →

CBSE Class 10 Science 2022 · Paper 31/1/2 · Question 11

Answer

From the board paper

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