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.

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

   50
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, which show terminal flowers
   • 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
6. 5.

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

   • Zero: green pods mean the plant is GG
   • 1 in 2: two of the four boxes are Gg
   • 2 in 3: two of the three green boxes are Gg
   • 3 in 4: three of the four boxes are green
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: a plant with an i shows constricted pods
   • ii: constricted offspring need two ii parents
   • Ii: it passed an i to some offspring
   • 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?

   • Aa plants have flowers halfway up the stem
   • Both show axial flowers, since A is dominant
   • Axial plants are AA each time, so it is easy
   • 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?

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

    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 plants have yellow pods
    • Disagree: GG and Gg both have green pods
    • 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: Ii pods are half constricted
    • Disagree: Ii plants show a 1 : 2 : 1 look
    • Disagree: I is dominant, so Ii pods are inflated
    • Agree: any i makes the pods constricted