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

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   Bo reads a bar graph for a second lot of bean seeds. Which mass has the most seeds?

   • 24 seeds, the height of the tallest bar
   • 540 mg
   • 500 mg, the lightest class
   • 530 mg
2. 2.

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

   • 48 seeds
   • 12 seeds
   • 26 seeds
   • 17 seeds
4. 3.

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

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

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

6. Read this first

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

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

7. 5.

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

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

8. 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

9. 6.

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

   • 1 offspring
   • 20 offspring
   • 30 offspring
   • 15 offspring
10. 7.

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

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

11. Trait card (model data)

    trait	genes	kernel colors
    wheat kernel color	3	7

12. 8.

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

    • The kernel color blends two parents' colors
    • Three genes each add to the kernel color
    • The soil alone decides the kernel color
    • One gene alone sets the kernel color
13. 9.

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

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

14. Use this

    Counts of offspring by dark alleles (model data). Columns: dark alleles | table P (of 4) | table Q (of 16). Row 1: 0 | 1 | 1. Row 2: 1 | 2 | 4. Row 3: 2 | 1 | 6. Row 4: 3 | - | 4. Row 5: 4 | - | 1.

15. 10.

    Zee compares two count tables. One comes from a cross with 1 gene and one from a cross with 2 genes. Which choice names the 2-gene table?

    • Table Q, since 5 classes need 2 genes
    • Table P, since a trait is controlled by one gene
    • Table P, since 3 classes are enough for 2 genes
    • Table Q, since 16 offspring means 16 classes