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Grade 9 Genetics Basics (Mixed) Worksheet with Answers

Grade 9 (US) · Year 10 (UK) · Class 9 (India) · Biology

Unit 2: GeneticsInheritanceNGSS HS-LS3-2

A mixed set on genetics vocabulary and Punnett square crosses. This free high school worksheet has 12 questions and a full answer key. Print it or save it as a PDF — every answer is checked by code, not guessed.

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Genetics Basics (Mixed)

Grade 9 · Biology

Score___ / 12

Name

Class

Date

Learning goal: Inheritance · NGSS HS-LS3-2

Directions: This worksheet has 2 parts. Read the instructions at the start of each part.

Example

Cross YY × YY. What percentage of offspring are expected to show the dominant trait?

Answer: 100%

RememberGenetics words

B dominantshows if presentcapital letterb recessiveshows only as bblower-case letterBB, bbhomozygoustwo the sameBbheterozygousone of eachGenotypethe letters: BbPhenotypewhat you see: brown
Part A

Match each clue to the right word. Write the letter in the box.

  1. 1What do we call an organism with two identical alleles for a trait?
  2. 2What shape is a DNA molecule?
  3. 3What is the term for an organism's genetic makeup?
  4. 4What do we call an organism with two different alleles for a trait?
  • AHeterozygous
  • BDouble helix
  • CGenotype
  • DHomozygous
Part B

Answer each question. Use full sentences where you can.

  1. 5

    Use a Punnett square to cross WW × WW. What is the expected genotype ratio (out of 4)?

    WWWW
  2. 6

    Cross BB × Bb. What is the expected ratio of dominant to recessive phenotypes?

    BBBb
  3. 7

    Cross bb × Bb. What is the expected ratio of dominant to recessive phenotypes?

    bbBb
  4. 8

    Cross pp × pp. What percentage of offspring are expected to show the dominant trait?

    pppp
  5. 9

    Use a Punnett square to cross BB × Bb. What is the expected genotype ratio (out of 4)?

    BBBb
  6. 10

    Cross Ww × WW. What is the expected ratio of dominant to recessive phenotypes?

    WwWW
  7. 11

    Use a Punnett square to cross Yy × yy. What is the expected genotype ratio (out of 4)?

    Yyyy
  8. 12

    Cross Ww × WW. What percentage of offspring are expected to show the dominant trait?

    WwWW

★ Challenge corner for fast finishers

You are in a closed room with a candle, a match and a lamp. What do you light first?

How did I do?

Teacher's comments

Free printable worksheets with answer keys · aethelsystems.com/worksheets/biology/9/genetics_basics

Answer key (click to show)
  1. 1.D — homozygous
  2. 2.B — a double helix
  3. 3.C — genotype
  4. 4.A — heterozygous
  5. 5.4 WW
  6. 6.all dominant (4 : 0)
  7. 7.2 : 2
  8. 8.0%
  9. 9.2 BB : 2 Bb
  10. 10.all dominant (4 : 0)
  11. 11.2 Yy : 2 yy
  12. 12.100%
  13. ★the match (challenge corner)

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