Genetic problems --
1. Chin fissure is controlled by a dominant allele and a smooth chin by a recessive allele. If the parents were heterozygous for the trait, the chance of producing a child with a chin fissure would be ______.
2. (Assume a simple/dominant recessive relationship). If you cross two green pea plants. One plant is homozgyous and one is heterozygous. What fraction of their progeny (offspring) will be homozygous dominant, heterozygous or homozygous receissive? In other words, what is the genotypic ratio?
3. Albinism (lack of skin pigmentation) is caused by a recessive autosomal allele. A man and a woman, both normally pigmented, have an albino child. The mother is now pregnant again, and her doctor tells her she is carrying fraternal twins (resulting from two eggs between fertilized by separate sperm). What is the probability that both twins will have normal pigmentation?
4. In snapdragons plant color shows an incomplete dominance. Heterozygous plants have pink flowers, where as the two homozygotes have red flowers or white flowers. Two pink flowers are crossed. What proportion of their progeny would you predict would be pink? NOTE YOU DO NOT NEED TO KNOW THE INCOMPLETE DOMINANCE FOR EXAM TWO.
5. If two heterozygous parents, CcDd, were crossed there are ____ possible combinations of GENOTYPES in the offspring? _____ possible phenotypes?
6. If tall is dominant to short, and purple flowers are dominant to white flowers, what is the phenotypic ratio of the potential offspring if you cross a short, white flower with a homozygous dominant tall, heterozygous purple flower?
7. Black fur in mice is dominant to brown fur (B – dominant allele, b-recessive allele). Short tails are dominant to long tails (T – dominant allele, t-recessive allele). What fraction of the progeny of the cross BbTt * BBTt will have black fur and long tails?