CBSE Class 10 Science 2020 · Paper 31/3/1 · Question 21

Heredity 3 marks Medium

A green stemmed rose plant denoted by GG and a brown stemmed rose plant denoted by gg are allowed to undergo a cross with each other. (a) List your observations regarding

(i)Colour of stem in their $F_{1}$ progeny
(ii)Percentage of brown stemmed plants in $F_{2}$ progeny if $F_{1}$ plants are self pollinated.
(iii)Ratio of GG and Gg in the $F_{2}$ progeny. (b) Based on the findings of this cross, what conclusion can be drawn ?

Answer

$F_{1}$ is all green ( $G g$ ); $25%$ of $F_{2}$ are brown and $GG : G g = 1 : 2$ ; green is dominant, brown recessive.

(a) (i) All the

F_{1}

plants have green stems (genotype Gg). (ii)

25%

of the

F_{2}

plants have brown stems (gg is

1

box in

4

). (iii) GG : Gg

= 1 : 2

in the

F_{2}

progeny. (b) Green stem colour is the dominant trait and brown the recessive trait: the trait expressed in the

F_{1}

progeny is dominant, while the trait that is not expressed in

F_{1}

but reappears in the

F_{2}

progeny is recessive.

🔒 Step-by-step solution

CBSE Class 10 Science 2020 · Paper 31/3/1 · Question 21

Answer

From the board papers

More questions from Heredity