Question

Genetics Coursework

Part A: A geneticist discovers a single primrose with yellow flowers. All other primroses have orange flowers. The geneticist crosses the yellow primrose with one of the orange primroseand obtains 66 yellow and 61 orange progeny. The geneticist crosses two of the yellow primroses from the progeny of the first cross, and obtains 89 yellow and 32 orange primroses. Explain these results by sketching the two crosses, giving the combinations of heritable factors and associated traits for parents and progeny. At the top of your answer, define the symbols used for heritable factors. For example: Let the heritable factor for orange be X. Let the heritable trait for yellow be y.

Part B: In Jimsweed, blue flowers are determined by the heritable factor B and white flowers by the heritable trait b. Blue flowers are dominant to white flowers. Self pollination in a blue plant produces 28 blue floweredprogeny and 10 white flowered progeny. What fraction of all blue flowered progeny will breed true when self pollinated?

Answer 1

Answer:

Part A.

Let the heritable factor for orange be X. Let the heritable trait for yellow be y.
the yellow primrose with one of the orange primrose and obtains 66 yellow and 61 orange progeny
Yellow flowers are heterozygous whereas orange flowers are homozygous.
Yellow is dominant allele over orange allele
xy (yellow) x xx (orange)= xx, xx, xy, xy (50% yellow, 50% orange)

xy x xy
=xx, xy, xy, yy
1 orange: 3 yellow

Part B

Answer:
blue flowers are determined by the heritable factor B and white flowers by the heritable trait b.
Bb (blue flowers) x Bb (blue flowers)
= BB, Bb, Bb, bb
3 blue: 1 white
¼ of the progeny are true breeding blue flower plant