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7th grade Genotype, phenotype and offspring ratios worksheet

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Genotype, phenotype and offspring ratios

Grade 7 Science Worksheet - Building Confidence

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Circle the best answer.

  1. Esme's trait card shows a pea plant with flowers at the stem tips (terminal) and the letters aa. Which label is right?

    • Genotype aa; phenotype terminal flowers
    • Genotype terminal flowers; phenotype aa
    • Genotype aa; phenotype axial flowers
    • Genotype Aa; phenotype terminal flowers
  2. Pea pod shape, I = inflated (dominant), i = constricted (recessive). Gene pair: II; trait: ?. Jun's pea plant has the letters II for pod shape. Which word fits II?

    • Homozygous recessive: two small letters
    • Phenotype: the look of the pods
    • Homozygous dominant: two capital letters
    • Heterozygous: two different letters
  3. Pea pod shape, I = inflated (dominant), i = constricted (recessive). Gene pair: ii; trait: ?. Kira's pea plant has the letters ii for pod shape. Which word fits ii?

    • Homozygous recessive: two small letters
    • Phenotype: the letters are what you see
    • Homozygous dominant: two capital letters
    • Heterozygous: one of each letter
  4. Pea flower position, A = axial (dominant), a = terminal (recessive). Gene pair: Aa; trait: ?. Luz's pea plant has the letters Aa for flower position. Which word fits Aa?

    • Phenotype, since the letters show the look
    • Homozygous recessive, as it has an a
    • Homozygous dominant, as it looks axial
    • Heterozygous: two different letters
  5. Pea pod color, G = green (dominant), g = yellow (recessive). Gene pair: Gg; trait: ?. Milo reads a trait card: a pea plant with the letters Gg. What color are its pods?

    • Yellow, since it carries a g
    • Yellow-green, a mix of both
    • Green, since G is dominant
    • Half green and half yellow pods
  6. Pea pod shape, I = inflated (dominant), i = constricted (recessive). Gene pair: Ii; trait: ?. Noah reads a trait card: a pea plant with the letters Ii. What shape are its pods?

    • Inflated, since I is dominant
    • Constricted, since it carries an i
    • Partly inflated and partly pinched
    • Constricted, since i is written last
  7. Pea flower position, A = axial (dominant), a = terminal (recessive). Gene pair: aa; trait: ?. Pia reads a trait card: a pea plant with the letters aa. Where do its flowers grow?

    • Along the stem (axial), as axial is dominant
    • Both along the stem and at the tips
    • Nowhere: aa plants have no flowers
    • At the stem tips (terminal)
  8. Ren fills a Punnett square for Gg × Gg pea plants. How many of the four boxes are heterozygous (Gg)?

    • 4: each box has a G or g
    • 2: the two Gg boxes
    • 3: each box that has a G
    • 1: just the GG box
  9. Tala fills a Punnett square for II × Ii pea plants. How many of the four boxes are homozygous (II)?

    • 1: just the top-left box
    • 4: each box looks inflated
    • 2: the two II boxes
    • 0: no box has two of one letter
  10. Zee fills a Punnett square for Aa × Aa pea plants. How many of the four boxes are homozygous (AA or aa)?

    • 3: the boxes that look axial
    • 1: just the AA box
    • 0: each box has an A
    • 2: the AA box and the aa box
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7th grade Genotype, phenotype and offspring ratios worksheet – printable
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About this worksheet

Genotype, phenotype and offspring ratios. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can tell a genotype (letter pair) from a phenotype (the trait you see) and name homozygous and heterozygous pairs.
  • I can give a genotype ratio (1 : 2 : 1) and a phenotype ratio (3 : 1) from the same square, and a genotype's chance as a fraction in simplest form.
  • I can predict how many of many offspring have one genotype, and explain why a dominant look can hide a recessive letter.

Standard: MS-LS3-2

Words to know

genotype: The letter pair for a gene, such as Gg

phenotype: The trait you can see, such as green pods

homozygous: Two of the same letter: GG or gg

heterozygous: Two different letters: Gg

genotype ratio: How many boxes have each letter pair, such as 1 GG : 2 Gg : 1 gg

phenotype ratio: How many boxes show each look, such as 3 green : 1 yellow

axial / terminal: Flowers along the stem / flowers at the stem tip

Common mistakes

Your child swapped genotype and phenotype. The genotype is the letter pair (Gg); the phenotype is the trait you can see (green pods).

Your child thought a plant with one recessive letter (such as Gg) shows the recessive trait. One dominant letter is enough for the dominant trait to show.

Your child gave a ratio of looks when asked for letter pairs, or the other way round. Gg × Gg gives 1 GG : 2 Gg : 1 gg, which is 3 green : 1 yellow.

Questions parents ask

What is the most common mistake with genotype, phenotype and offspring ratios?

Your child swapped genotype and phenotype. The genotype is the letter pair (Gg); the phenotype is the trait you can see (green pods).

Are these 7th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

More grade 7 science

See all grade 7 science

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