10 minutes maximum! Can you do it in 5?
Q1-2. Maize seeds can have a variety of colours and shapes:
Pollen from a pure breeding plant that produces purple seeds is used to fertilize ovules on a plant that was grown from a yellow seed. The seeds produced from the cross are grown, and all the ‘corn on the cobs’ produced were purple.
|1. Which is the dominant allele?
|2. The purple seeds from the first cross were planted. When these heterozygous plants were mature they were crossed with each other. What would be the ratio of purple to yellow seeds on the corn cobs?
3-5: White rabbits lack pigment in their hair and in their skin. They are called albino.
Albinism is caused by a recessive allele a. The dominant allele A causes the rabbit to have normal pigmentation and be brown.
|3. What is the genotype of an albino rabbit?
|4. Two rabbits heterozygous for fur colour mate and produce several offspring.
What proportion of the offspring are expected to be albino?
|5. What proportion of the offspring will be homozygous dominant for brown fur?
6-10: Cystic fibrosis is an inherited disorder that affects the lungs and the gut. It is carried on a recessive allele.
Here is a family pedigree for a family with carriers of cystic fibrosis:
|6. What is the probability that Sam has cystic fibrosis?
|7. What is the probability that Sam’s sister will be a carrier for cystic fibrosis?
|8. What is Jane’s phenotype?
9. The allele for cystic fibrosis may have been caused by a mutation. A mutation is ...
|10. Which of the following is unlikely to cause a mutation?