punnet squares (1 Viewer)

[stressedadfff]

hey guys can anyone please explain A to me, i keep getting confused

 

[Leadmen4y]

Given the capital letter "G" denoting Green & lowercase "g" denoting Yellow, 1:0 ratio in F1 with only colour being green, as well as the monohybrid cross in F2 which resulted in Mendel's ratio of 3:1 (approximately, it was something like 3.24ish, it is important to note that inheritance is all chance and won't always be exact), it is safe to assume that F1 alleles are respectively homozygous dominant for green (GG) and also homozygous, though recessive for yellow (gg). Hence, F1's punnet square cross would be GG x gg, and all of F1 generation would be heterozygous for green (Gg). In F2, it is simply Mendel's classic monohybrid cross (Gg x Gg), with resulting phenotypes being both green and yellow as shown in the table. However, the question asks for genotype, so we have 3 possible genotypes with 2 coding for green (Gg & GG) and a single genotype for yellow (gg), in the ratio of 2 (Gg) : 1 (GG) : 1 (gg).

 

[stressedadfff]

thanks!

 

[Eagle Mum]

@Leadmen4y, most of the statements in your response are spot on and quite impressive, but I suggest a slight change: ‘it is appropriate to infer that F1 alleles are derived, by both maternal and paternal contributions, from the parental generation of pure plants lines which were respectively homozygous dominant for green (GG) and also homozygous, though recessive, for yellow (gg)’.

I think you have fully understood the whole experiment as you correctly state later that all of the F1 generation would be heterozygous for green (Gg), but the above sentence was just a mis-statement because it pertains to the parental (P) generation (not mentioned in the question), not the F1 generation.

You probably don’t even have to include this statement for an answer which would still gain full marks, but if you do, mis-statements can cause loss of mark(s).

 

[Leadmen4y]

@Leadmen4y, most of the statements in your response are spot on and quite impressive, but I suggest a slight change: ‘it is appropriate to infer that F1 alleles are derived, by both maternal and paternal contributions, from the parental generation of pure plants lines which were respectively homozygous dominant for green (GG) and also homozygous, though recessive, for yellow (gg)’.

I think you have fully understood the whole experiment as you correctly state later that all of the F1 generation would be heterozygous for green (Gg), but the above sentence was just a mis-statement because it pertains to the parental (P) generation (not mentioned in the question), not the F1 generation.

You probably don’t even have to include this statement for an answer which would still gain full marks, but if you do, mis-statements can cause loss of mark(s).

Oh right, yes that was the gap in my knowledge, forgot about P. I definitely felt like something was off when I first written it too, but couldn't figure it out myself, thank you Eagle Mum for the correction!