Lizards phenotype and genotypes

Suppose that on Venus Lizards exist with three genes controlling spotted skin color. The gene for brown spots (S^B) is dominant to both the gene for green spots (S^G) and the gene for orange spots (S^O). The gene for green spots is also dominant to the gene for orange spots. Assume that the inheritance of spotted skin color in lizards on Venus occurs in the same way as on Earth.

QUESTION 1: What are the possible genotypes of a green spotted lizard? (1 mark)


QUESTION 2: What is the name given to this type of genetic inheritance? (1 mark)


QUESTION 3: If a brown-spotted lizard carrying the gene for green spots is crossed with a heterozygous green-spotted lizard carrying the gene for orange spots, what are the expected probabilities of the phenotypes in the offspring? (1 mark: parental cross ; 2 marks: genotypes)


QUESTION 4: Of the total 20 offspring produced, how many offspring from the above cross would have green spots? (1 mark)