Two-trait crosses with a 4 by 4 square

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   Use this

   Parent card (pea plant, genotype RrYy). Seed shape gene: alleles R (round) and r (wrinkled). Seed color gene: alleles Y (yellow) and y (green). Table: Parent card; columns gene and alleles in the plant; rows seed shape, seed color.

2. 1.

   Ari reads a parent card for one pea plant. Which choice lists all the allele combinations this plant can pass on, one allele for each gene?

   • RY, Ry, rY and ry
   • Rr and Yy, the plant's own gene pairs
   • RY, Ry and rY
   • RY and ry, with each capital kept with a capital

3. Use this

   Parent card (pea plant, genotype RrYY). Seed shape gene: alleles R (round) and r (wrinkled). Seed color gene: alleles Y (yellow) and Y (yellow). Table: Parent card; columns gene and alleles in the plant; rows seed shape, seed color.

4. 2.

   Bo reads a parent card for another pea plant. Which choice lists all the allele combinations this plant can pass on, one allele for each gene?

   • RY and rY
   • RY, Ry, rY and ry, as for a plant with Yy
   • Rr and YY, the plant's own gene pairs
   • RY and ry, with each capital kept with a capital

5. Use this

   Parent card (pea plant, genotype RrYy). The seed shape gene and the seed color gene are on different chromosomes. The combination in question is Ry: R from the seed shape gene and y from the seed color gene. Table: Parent card; columns gene and alleles in the plant; rows seed shape, seed color.

6. 3.

   The genes for seed shape and seed color are on different chromosomes. Esme asks why a plant with RrYy can pass on the combination Ry. What is the reason?

   • R stays with Y, so RY and ry are the combinations passed on
   • Ry appears because y is dominant over Y
   • The two genes sort independently, so R can go with either Y or y
   • The plant passes on Rr as one unit and Yy as one unit
7. 4.

   Jun fills in the square for RrYy × RrYy. Which genotype goes in the blank box?

   • RrYy (R: one capital, one small; Y: one capital, one small)
   • RRyy (R: two capital; Y: two small)
   • rryy (R: two small; Y: two small)
   • Rryy (R: one capital, one small; Y: two small)
8. 5.

   Kira fills in another box of the square for RrYy × RrYy. Which genotype goes in the blank box?

   • RrYY (R: one capital, one small; Y: two capital)
   • RrYy (R: one capital, one small; Y: one capital, one small)
   • rrYY (R: two small; Y: two capital)
   • RRYY (R: two capital; Y: two capital)

9. Use this

   Trait card for pea seeds, letter and seed trait. R: round (dominant). r: wrinkled (recessive). Y: yellow (dominant). y: green (recessive). Plant genotype: RrYy.

10. 6.

    Milo reads a trait card. What do the seeds of a plant with genotype RrYy look like?

    • Wrinkled and yellow
    • Wrinkled and green
    • Round and green
    • Round and yellow

11. Use this

    Trait card for pea seeds, letter and seed trait. R: round (dominant). r: wrinkled (recessive). Y: yellow (dominant). y: green (recessive). Plant genotype: rrYy.

12. 7.

    Noah reads the same trait card. What do the seeds of a plant with genotype rrYy look like?

    • Wrinkled and green
    • Round and green
    • Round and yellow
    • Wrinkled and yellow

13. Use this

    Trait card for pea seeds, letter and seed trait. R: round (dominant). r: wrinkled (recessive). Y: yellow (dominant). y: green (recessive). Plant genotype: Rryy.

14. 8.

    Pia reads the trait card once more. What do the seeds of a plant with genotype Rryy look like?

    • Round and green
    • Round and yellow
    • Wrinkled and green
    • Wrinkled and yellow
16. 9.

    Tala reads the same filled square. How many of the 16 boxes show round, yellow seeds?

    • 1 box
    • 3 boxes
    • 12 boxes
    • 9 boxes
17. 10.

    Zee reads the same filled square. How many of the 16 boxes show wrinkled, yellow seeds?

    Use the picture in question 9.

    • 1 box
    • 9 boxes
    • 3 boxes
    • 4 boxes