Genetics worksheet with answers

Two Aa parents are crossed. A gives purple flowers and is dominant over a, which gives white flowers. Click the cell of the Punnett square for an offspring with white flowers.

1. 1A × a
2. 2A × A
3. 3a × a
4. 4a × A

Two Bb parents are crossed. B gives black fur and is dominant over b, which gives white fur. Click the cell for an offspring that has black fur and is homozygous.

1. 1b × B
2. 2b × b
3. 3B × B
4. 4B × b

red-green colour blindness is X-linked recessive (allele b). A carrier mother, X^BX^b, has children with an unaffected father, X^BY. The mother's gametes run down the side. Click the cell for an affected son.

1. 1X^b × X^B
2. 2X^b × Y
3. 3X^B × X^B
4. 4X^B × Y

Tall (A) is dominant over short (a), and round seeds (B) over wrinkled (b). The genes are on different chromosomes. For the cross AaBb × AaBb, what is the probability P that an offspring is tall, round seeds?

Two AaBb parents are crossed. Gene A gives tall plants (dominant) or short plants; gene B gives round seeds (dominant) or wrinkled seeds. Click the one cell for an offspring that is homozygous for tall plants and for round seeds.

1. 1aB × AB
2. 2aB × ab
3. 3aB × Ab
4. 4aB × aB
5. 5ab × AB
6. 6ab × ab
7. 7ab × Ab
8. 8ab × aB
9. 9Ab × AB
10. 10Ab × ab
11. 11Ab × Ab
12. 12Ab × aB
13. 13AB × AB
14. 14AB × ab
15. 15AB × Ab
16. 16AB × aB

In a population of 2000 in Hardy–Weinberg equilibrium, 1% show a recessive trait. How many individuals N are expected to be homozygous dominant?