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?

(a) Observations:

• (i) Colour of stem in $F_1$ progeny: All plants will have green stems (genotype $Gg$).
• (ii) Percentage of brown stemmed plants in $F_2$ progeny: $25\%$ of the plants will have brown stems (genotype $gg$).
• (iii) Ratio of $GG$ and $Gg$ in the $F_2$ progeny: The ratio is $1:2$ (since the genotypic distribution is $1\ GG : 2\ Gg : 1\ gg$).

(b) Conclusion:

Based on these findings, we can conclude that:

1. The green stem trait ($G$) is dominant because it expresses itself in both homozygous ($GG$) and heterozygous ($Gg$) conditions.
2. The brown stem trait ($g$) is recessive because it is suppressed in the $F_1$ generation ($Gg$) and only expresses itself in the homozygous recessive condition ($gg$).
3. Traits are controlled by two copies of genes (factors) in sexually reproducing organisms, which segregate during gamete formation and recombine randomly during fertilization.