Confused about genetics!

richngill at my-dejanews.com richngill at my-dejanews.com
Mon Apr 26 11:10:00 EST 1999


Hello all... I've just been tring to get to grips with genetics by reading
about Mendel and his sweet peas. I can't get to grips with the following
question / statement:

"A flower has variation in 2 characteristics: stem length (tall or short) and
distribution of clorophyll in leaves (normal, absent or variegated). In an
experiment, plants with tall stems and green leaves were bred true for these
characters and crossed with plants with short stems and variegated leaves.
The progeny of the cross had tall stems and green leaves and plants with tall
stems and variegated leaves in the ratio 1:1"

I spent ages working out the 9:3:3:1 phenotypes of F2 generation plants in
the hope that the seemingly odd result of 1:1 was due to linkage and
cross-over during meiosis... then I realised the question is talking about F1
generations!!

If the tall green leafed plant is bred true I assume it will have the
following genotype: TTCC (TT for tall and CC for normal chlorophyll) and the
short variegated variety will have a genotype: ttcc. So - all I can come up
with is and F1 generation consisting of TtCc & TtCc (all tall green plants!!)

Can anyone please tell me where I have gone wrong?

Thanks very much,

Rich

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