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. 3.

   Esme's class grows 64 plants from an Aa × Aa pea cross. About how many would you expect to be Aa?

   32

4. 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

5. 4.

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

   • About 3 to 1, so both parents were II
   • About 1 to 2 to 1 of the pod shapes
   • About 3 to 1, so both parents were Ii
   • About 1 to 1, so the parents were Ii and ii
6. 5.

   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 2
   • Zero: green-pod plants are GG
   • About 2 of every 3
   • About 1 of every 3
7. 6.

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

   • 1 in 2: two of the four boxes are Gg
   • 3 in 4: three of the four boxes are green
   • Zero: green pods mean the plant is GG
   • 2 in 3: two of the three green boxes are Gg
8. 7.

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

   • Ii: a plant with an i shows constricted pods
   • Ii: it passed an i to some offspring
   • II: it looks inflated
   • ii: constricted offspring need two ii parents
9. 8.

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

   • Both show axial flowers, since A is dominant
   • Aa plants have flowers halfway up the stem
   • Aa plants show terminal flowers, so they stand out
   • Axial plants are AA each time, so it is easy
10. 9.

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

    • 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
    • Disagree: the colors come out 1 : 1
11. 10.

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

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