Biology Term Paper 1

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  • Topic: Blood type, Allele, Red blood cell
  • Pages : 2 (528 words )
  • Download(s) : 516
  • Published : October 21, 2010
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Genetics Problems

1. Brown eyes are dominant over blue. What are the chances that the first child of a marriage of two hybrid (heterozygous) brown-eyed parents will be blue-eyed? What are the chances of the second child being blue-eyed? BB


There is a 25% chance that the first child will be blue-eyed and a 75% chance the child will be brown-eyed. There is a 50% chance that the trait for brown eyes will overpower the recessive trait for blue eyes.

2.In humans, color-blindness is recessive and sex-linked. A man of normal vision whose father was color-blind, marries a woman of normal vision whose mother was color-blind. What kind of vision would be expected in their offspring? What kind of vision did the wife's father have?

The mother and father both have a 50% chance of passing on their gene to their children. If the child is male he will be color-blind because the trait that is passed on is sex-linked on the X chromosome. A female must inherit 2 copies of the gene, while a male only needs 1 copy to carry the trait. This means that the wife’s father must not have been colorblind because her mother is colorblind.

3. In snapdragons flower color is inherited via incomplete dominance.What would the expected colors be (in percentages) if a red snapdragon is crossed with a white snapdragon? Rr

If a true white snapdragon crossed with a true red snapdragon their offspring would be 100% pink. 4.In humans, blood types A and B are codominant with type O being recessive. List the blood types of the offspring of a father with blood type AB and a mother with type O. 50% of the children are predicted to have blood type A and the other 50% type B. The offspring will neither be AB or O.

5.An individual that does not have the sickling gene mates with an individual with one copy of it (sickle cell trait).  What percent of their offspring would have sickle cell disease?  and sickle cell trait?

6. An Rh + woman  (her mother is Rh-)...
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