Genotype, phenotype and offspring ratios

Answer Key - Grade 7 Science Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   Ari's class grows 48 plants from a Gg × Gg pea cross. About how many would you expect to be Gg?

   24
2. 2.

   Bo reads about 200 plants from an Ii × Ii pea cross. About how many would you expect to be II?

   50

3. Read this first

   Mendel's results, as reported by OpenStax Biology 2e Table 12.1

   trait	first generation	second generation
   pod shape	100 percent inflated	882 inflated and 299 constricted

4. 3.

   Jun reads Mendel's second-generation counts for pod shape. About what ratio is this, and what were the parents' genotypes?

   • About 1 to 1, so the parents were Ii and ii
   • About 1 to 2 to 1 of the pod shapes
   • About 3 to 1, so both parents were II
   • About 3 to 1, so both parents were Ii
5. 4.

   Kira reads Mendel's counts for pod color. Of the 428 green-pod plants, about what share would you expect to be Gg?

   • About 1 of every 3
   • Zero: green-pod plants are GG
   • About 1 of every 2
   • About 2 of every 3
6. 5.

   From a Gg × Gg cross, Milo picks one green-pod offspring at random. What is the chance it is Gg?

   • 3 in 4: three of the four boxes are green
   • 2 in 3: two of the three green boxes are Gg
   • Zero: green pods mean the plant is GG
   • 1 in 2: two of the four boxes are Gg
7. 6.

   Noah crosses an inflated-pod plant with an ii plant. Some offspring have constricted pods. What is the inflated plant's genotype?

   • II: it looks inflated
   • ii: constricted offspring need two ii parents
   • Ii: a plant with an i shows constricted pods
   • Ii: it passed an i to some offspring
8. 7.

   Pia's class garden wants pea plants that are AA. Why can't the class tell AA from Aa just by looking?

   • Axial plants are AA each time, so it is easy
   • Aa plants have flowers halfway up the stem
   • Both show axial flowers, since A is dominant
   • Aa plants show terminal flowers, so they stand out
9. 8.

   Ren says a Gg × Gg cross gives a 1 : 2 : 1 ratio of pod colors. Agree or disagree?

   • Disagree: the colors come out 1 : 1
   • Disagree: 1 : 2 : 1 is genotypes; colors are 3 : 1
   • Agree: genotype and phenotype ratios are the same
   • Agree: each genotype has its own pod color
10. 9.

    Tala says two pea plants with the same phenotype must have the same genotype. Agree or disagree?

    • Agree: a green-pod plant is GG, as green is dominant
    • Agree: the look shows the two letters
    • Disagree: GG and Gg both have green pods
    • Disagree: Gg plants have yellow pods
11. 10.

    Zee says an Ii pea plant has constricted pods because it carries an i. Agree or disagree?

    • Agree: any i makes the pods constricted
    • Disagree: I is dominant, so Ii pods are inflated
    • Disagree: Ii plants show a 1 : 2 : 1 look
    • Agree: Ii pods are half constricted