Coat colour in Shorthorn cattle is controlled by a gene with two alleles.
The CRC^RCR allele codes for red hair and the CWC^WCW allele codes for white hair.
When a homozygous red-haired cow is crossed with a homozygous white-haired bull, the offspring (calves) have a roan coat.
This coat colour is seen because of codominance, resulting in a mixture of red and white hairs.
Use the symbols CRC^RCR and CWC^WCW to show how the red-haired parent and the white-haired parent can produce a roan calf.
Parents:
Gametes:
Offspring genotype:
The roan calf is later mated with another roan individual. Give the possible genotypes and phenotypes of their offspring.
A roan individual is mated with a white-haired individual. What is the probability of producing a white-haired offspring?
Stem height in pea plants is also controlled by a gene that has two alleles. The stem height can either be tall or dwarf. Explain how the genetic control of stem height in pea plants differs from the genetic control of coat colour in Shorthorn cattle.
Cattle usually produce a single offspring from each mating. Scientists often study genetics using model organisms such as fruit flies (Drosophila melanogaster). Suggest one advantage of using fruit flies rather than cattle to study genetics.
