Traits controlled by many genes, and their bell-shaped spread

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

2. 1.

   Ari reads a bar graph of bean seed masses. How many seeds have a mass of 430 mg?

   • 9 seeds
   • 17 seeds
   • 22 seeds
   • 3 seeds
3. 2.

   Esme adds two bars of the bean seed graph. How many seeds weigh 390 mg or 400 mg together?

   Use the picture in question 1.

   • 26 seeds
   • 17 seeds
   • 48 seeds
   • 12 seeds
5. 3.

   Jun reads the filled square for a model wheat cross, AaBb × AaBb. How many of the 16 boxes hold exactly 2 dark alleles?

   • 8 boxes
   • 6 boxes
   • 1 box, like a corner box
   • 4 boxes
6. 4.

   Kira reads the same square. How many of the 16 boxes hold exactly 4 dark alleles?

   Use the picture in question 3.

   • 1 box
   • 16 boxes
   • 6 boxes
   • 4 boxes
7. 5.

   Luz reads the same square again. How many of the 16 boxes hold exactly 1 dark allele?

   Use the picture in question 3.

   • 4 boxes
   • 6 boxes
   • 2 boxes, one for each genotype
   • 1 box, like the corner boxes

8. Read this first

   Wheat kernel color, 16 equally likely offspring (model data)

   dark alleles	offspring
   0	1
   1	4
   2	?
   3	4
   4	1

9. 6.

   Milo reads a count table for a model wheat cross, AaBb × AaBb. What number goes in the blank?

   • 8 offspring
   • 1 offspring
   • 6 offspring
   • 4 offspring

10. Wheat kernel color, 64 equally likely offspring (model data)

    dark alleles	offspring
    0	1
    1	6
    2	15
    3	?
    4	15
    5	6
    6	1

11. 7.

    Noah reads a count table for a model wheat cross with 3 genes. What number goes in the blank?

    • 1 offspring
    • 15 offspring
    • 20 offspring
    • 30 offspring
12. 8.

    Pia reads a second count table for the model wheat cross with 3 genes. What number goes in the blank?

    • 6 offspring
    • 20 offspring
    • 1 offspring
    • 15 offspring

13. Trait card (model data)

    trait	genes	kernel colors
    wheat kernel color	3	7

14. 9.

    Ren reads a trait card for wheat kernel color. Which choice explains why this trait is called polygenic?

    • One gene alone sets the kernel color
    • Three genes each add to the kernel color
    • The kernel color blends two parents' colors
    • The soil alone decides the kernel color
15. 10.

    Tala reads a trait card for bean seed mass. Which choice names this kind of variation?

    • Continuous variation: many small steps with no clear groups
    • Soil variation: the soil alone sets the mass
    • Discontinuous variation: two or very few clear groups
    • Blended variation: offspring mix the traits of two parents