Question

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.

1. List your observations regarding:
   1. Colour of stem in their F₁ progeny
   2. Percentage of brown stemmed plants in F₂ progeny if F₁ plants are self pollinated.
   3. Ratio of GG and Gg in the F₂ progeny.
2. Based on the finding of this cross, what conclusion can be drawn?

Answer 1

(a)

(i) Colour of the stem in F₁ progeny: All green

(ii) Percentage of brown stem: 25%

(iii) GG : Gg is 1 : 2 

(b) It is clear from the aforementioned cross that the colour green is dominating and manifests itself in the F₁ generation. The recessive trait is the brown stem, which does not manifest itself in the F₁ generation. The law of domination is this.