Genotype, phenotype and offspring ratios

Answer Key - Grade 7 Science Worksheet

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

1. 1.

   Bo makes a Punnett square for Ii × Ii pea plants. As a fraction in simplest form, what is the chance an offspring is II?

   1/4
2. 2.

   Esme makes a Punnett square for AA × Aa pea plants. As a fraction in simplest form, what is the chance an offspring is AA?

   1/2
3. 3.

   Jun studies a Gg × Gg pea cross. What is the ratio of genotypes in the offspring?

   • 1 GG : 1 Gg : 1 gg
   • 1 GG : 2 Gg : 1 gg
   • 2 GG : 2 gg
   • 3 green : 1 yellow
4. 4.

   Kira studies an Ii × ii pea cross. What is the ratio of genotypes in the offspring?

   • 1 inflated : 1 constricted
   • 3 Ii : 1 ii
   • 1 Ii : 1 ii
   • 1 II : 2 Ii : 1 ii
5. 5.

   Luz studies an AA × Aa pea cross. What is the ratio of genotypes in the offspring?

   • Each offspring axial
   • 1 AA : 2 Aa : 1 aa
   • 3 AA : 1 aa
   • 1 AA : 1 Aa
6. 6.

   Milo studies the same kind of cross, Gg × Gg. What ratio of pod colors is expected?

   • 3 green : 1 yellow
   • 1 green : 3 yellow
   • 1 green : 1 yellow
   • 1 GG : 2 Gg : 1 gg
7. 7.

   Noah studies an Ii × ii pea cross. What ratio of pod shapes is expected?

   • 1 inflated : 1 constricted
   • 3 inflated : 1 constricted
   • Each pod constricted, as each box has an i
   • 1 Ii : 1 ii
8. 8.

   Pia studies an AA × aa pea cross. What flower positions are expected in the offspring?

   • All Aa, with no look given
   • 3 axial : 1 terminal
   • All axial, each plant Aa
   • All terminal, since each plant carries a
9. 9.

   Tala's pea plant has narrow, constricted pods. Which genotype must it have?

   • II, since it has two letters
   • Ii or ii, since each has an i
   • ii, since constricted is recessive
   • Ii, since it is mixed
10. 10.

    Zee crosses two pea plants with axial flowers, and some offspring have terminal flowers. What are the parents' genotypes?

    • AA and AA, since both look axial
    • AA and Aa, since one looks axial
    • Aa and Aa
    • aa and aa