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.

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

   32

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

   In Luz's table, terminal flowers vanish in the first generation and return in the second. Which explanation fits?

   • The first plants were AA, then later changed to Aa
   • The two flower positions blended, then split apart again
   • The first plants were Aa; two Aa parents gave some aa
   • The first plants were Aa, which show terminal flowers
6. 5.

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

   • 2 in 3: two of the three green boxes are 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
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 passed an i to some offspring
   • Ii: a plant with an i shows constricted pods
   • ii: constricted offspring need two ii parents
   • II: it looks inflated
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
   • 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
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: each genotype has its own pod color
   • Agree: genotype and phenotype ratios are the same
10. 9.

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

    • Disagree: GG and Gg both have green pods
    • Disagree: Gg plants have yellow pods
    • Agree: the look shows the two letters
    • Agree: a green-pod plant is GG, as green is dominant
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: Ii plants show a 1 : 2 : 1 look
    • Agree: Ii pods are half constricted
    • Disagree: I is dominant, so Ii pods are inflated