Genetics worksheet with answers

Free printable Genetics worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
♂ Aa♀ AaAaaA

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

Aa × Aa
  1. 1a × A
  2. 2a × a
  3. 3A × A
  4. 4A × a
2.Easy
AA ♀Aa ♂AAAa????

In pea plants, purple flowers (A) are dominant over white (a). A plant with genotype AA is crossed with a plant with genotype Aa. What is the probability P that an offspring is heterozygous (Aa)?

AA × Aa
P =
3.Medium
♂♀YXD​XD​Xd​

Duchenne muscular dystrophy is X-linked recessive (allele d). A carrier mother, XDXd, has children with an unaffected father, XDY. The mother's gametes run down the side. Click the cell for an affected son.

♀ XDXd♂ XDY
  1. 1XD × Y
  2. 2XD × XD
  3. 3Xd × Y
  4. 4Xd × XD
4.Medium
♂♀YXB​Xb​XB​

red-green colour blindness is X-linked recessive (allele b). A carrier mother, XBXb, has children with an unaffected father, XBY. The mother's gametes run down the side. Click the cell for a carrier daughter.

♀ XBXb♂ XBY
  1. 1Xb × Y
  2. 2Xb × XB
  3. 3XB × Y
  4. 4XB × XB
5.Hard
♂ AaBb♀ AaBbabaBABAbAbaBabAB

Two AaBb parents are crossed. Gene A gives black fur (dominant) or white fur; gene B gives round seeds (dominant) or wrinkled seeds. Click the one cell for an offspring that is shows both white fur and wrinkled seeds.

AaBb × AaBb
  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
6.Hard
♂ AaBb♀ AaBbABAbaBabABAbabaB

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

AaBb × AaBb
  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

Answer key

  1. 1. A × A
  2. 2. P = 0.5
  3. 3. Xd × Y
  4. 4. Xb × XB
  5. 5. ab × ab
  6. 6. ab × ab

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