Homozygous Phenotypes

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Phenotype can depend on interactions of alleles.

The pea flowers that Mendel observed were either white or purple. One allele was dominant, but dominance does not mean that one allele “defeats” the other. incomplete dominance-in which a heterozygous phenotype is somewhere between the two homozygous phenotypes. One example of incomplete dominance is the four-o’clock plant. When plants that are homozygous for red flowers are crossed with plants that are homozygous for white flowers, the offspring have pink flowers. The pink color is a third, distinct phenotype. Neither of the original phenotypes of the plants in the parent’s generation can be seen separately in the F1 generation offspring. codominance-in which both traits are fully and separately …show more content…
For example, the sex of sea turtles depends both on genes and on environment. Female turtles make nests on beaches and bury their eggs in the sand.

Genes and environment also interact to determine human traits. Think about height. Genes give someone a tendency to be either short or tall, but they do not control everything. One twin might get more nutrients than the other because of its position in the mother’s uterus. This difference can result in height and size differences that last throughout the twins’ lives.

1.How is incomplete dominance expressed in a phenotype?

Answer-BB = black hair bb = white hair so Bb = gray hair. Incomplete dominance is similar to Codominance. Codominance would be BB = black bb = white Bb = White with black patches or black with white patches

2.Why might polygenic traits vary more in phenotype than do single- gene traits?
Answer-Consider 4 genes, A, B, C, and D. There are 2 alleles for each, A, B, C, and D and a, b, c, and d. The more dominant alleles a plant has, the taller it is. So a plant with the genotype AABBCCDD will be very tall, a plant with the genotype AaBBCCDD will be a little shorter

3.Explain how interactions between genes and the environment can affect
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