Farm Genetics
Codominance
Name ________________________
Old MacDonald had a farm, and he sure did have a lot of animals! On his farm he had
some cows, which were red, white and roan. Use the information provided and your
knowledge of codominance to complete each section below.
1. Write the correct genotype for each if R represents a red gene and W represents a white
gene.
Red: _______
Roan: ________
White: _______
2. What would happen if Old MacDonald crossed a red cow with at white bull? Complete
the Punnett square to determine the chances of each color calf.
(a) Give the genotypes and phenotypes for the
offspring.
(b)How many of the calves are red? _____%
(c) How many of the calves are roan? _____%
(d) How many of the calves are white? _____%
3. What would happen if Old MacDonald crossed two roan cattle together? Complete the
Punnett square to show the chances of each color calf.
(a) Give the genotypes and phenotypes for the
offspring.
(b)How many of the calves are red? _____%
(c) How many of the calves are roan? _____%
(d) How many of the calves are white? _____%
4. What would happen if Old MacDonald crossed a roan cow with at white bull? Complete
the Punnett square to determine the chances of each color calf.
(a) Give the genotypes and phenotypes for the
offspring.
(b)How many of the calves are red? _____%
(c) How many of the calves are roan? _____%
(d) How many of the calves are white? _____
On his farm he also had some chickens. Most of his chickens are black (BB) or white
(WW), but he is finding that some of the chickens are checkered. How is this happening?
Use what you know about codominance to complete each section below.
5. What would happen if Old MacDonald crossed two checkered chickens together?
Complete the Punnett square to help you determine the probability of each chick.
(a) Give the genotypes and phenotypes for the
offspring.
(b)How many of the chicks are white? _____%
(c) How many of the chicks are checkered?
_____%
(d) How many of the chicks are black? _____%
6. What would happen if a white chicken crossed with a checkered rooster? Compete the
Punnett square to help you determine the probably of each chick.
(a) Give the genotypes and phenotypes for the
offspring.
(b)How many of the chicks are white? _____%
(c) How many of the chicks are checkered?
_____%
(d) How many of the chicks are black? _____%
7. What would happen if Old MacDonald crossed a white chicken with a black rooster?
Complete the Punnett square to help you answer the question.
If 100 chicks were produced from this cross, how
many would you expect for each?
White: ______
Black: ______
Checkered: ______