Blended and both-showing traits

Grade 9 Science Worksheet

Circle the best answer.

1. 1.

   Ari crosses two pink snapdragons. What is the ratio of red to pink to white flowers in the offspring?

   • 2 red : 1 pink : 1 white
   • 1 red : 2 pink : 1 white
   • 3 red : 0 pink : 1 white
   • 0 red : 4 pink : 0 white
2. 2.

   Bo crosses a pink snapdragon with a white one. What is the ratio of pink to white flowers in the offspring?

   • 1 red : 1 white
   • 3 pink : 1 white
   • 4 pink : 0 white
   • 1 pink : 1 white
3. 3.

   Esme crosses a roan parent with a red parent in a model cross. What is the ratio of red to roan calves?

   • 2 red : 1 roan
   • 1 red : 1 roan
   • 3 red : 1 roan
   • 4 red : 0 roan

4. Read this first

   Table

   Four traits and their heterozygote looks (model), 4 rows. Columns: trait, what the heterozygote shows. Row 1: pea seed shape, round seeds, as one allele hides the other. Row 2: snapdragon flower color, pink flowers, in between red and white. Row 3: roan cattle coat, red hairs and white hairs together. Row 4: ABO blood type AB, both the A form and the B form.

5. 4.

   Luz reads a card of four traits. Which row shows incomplete dominance?

   • Row 1: the pea seed shape
   • Row 4: ABO blood type AB
   • Row 3: the roan cattle coat
   • Row 2: snapdragon flowers
6. 5.

   Milo plans 200 seedlings from the cross in the square (model data). About how many should have red flowers?

   • About 50, one quarter of 200
   • About 150, three quarters of 200
   • About 0, since the red allele is blended away
   • About 100, the two pink boxes together
7. 6.

   Noah expects 120 calves from the cross in the square (model data). About how many should be roan?

   • About 30, one quarter of 120
   • About 120, since a roan parent passes on its roan look
   • About 90, three quarters of 120
   • About 60, half of 120
8. 7.

   Pia expects about 90 pink seedlings from the cross in the square (model data). About how many seedlings is that in all?

   • About 120, since pink is three quarters
   • About 180, since pink is half
   • About 360, since pink is one quarter
   • About 270, since 90 is multiplied by 3

9. Table

   Two crosses of heterozygous parents (model), 2 rows. Columns: cross, the four boxes, the four looks. Row 1: pea Vv × Vv, VV, Vv, Vv and vv, violet, violet, violet and white. Row 2: snapdragon RW × RW, RR, RW, RW and WW, red, pink, pink and white.

10. 8.

    Ren compares two crosses of heterozygous parents. How do the ratios of looks compare?

    • Pea 3 violet : 1 white; snapdragon 1 red : 2 pink : 1 white
    • Pea 1 violet : 2 mixed : 1 white; snapdragon 3 : 1
    • Pea 3 : 1; snapdragon 3 : 1, since both crosses use two heterozygous parents
    • Pea 1 : 2 : 1; snapdragon 1 : 2 : 1, since both have the same boxes

11. Genotype ratio and ratio of looks (model)

    cross	genotype ratio	ratio of looks
    pea Vv × Vv	1 : 2 : 1	3 : 1
    snapdragon RW × RW	1 : 2 : 1	1 : 2 : 1

12. 9.

    Tala reads a table of two crosses. Why does the snapdragon ratio of looks match its ratio of genotypes?

    • Each genotype has its own look, so 3 genotypes give 3 looks
    • Red is dominant, so RR and RW look the same
    • The alleles blend into one pink allele that is passed on
    • Snapdragons have three alleles, one for each look

13. Three patterns of dominance (model)

    pattern	heterozygote example	heterozygote look
    complete dominance	pea Vv	violet
    incomplete dominance	snapdragon RW	pink
    codominance	roan cattle RW	red hairs and white hairs

14. 10.

    Zee crosses two heterozygous parents in each pattern. What is true for all three patterns?

    • The heterozygote hides one of its alleles
    • The heterozygote shows one mixed color
    • The genotypes come out 1 : 2 : 1
    • The ratio of looks is 3 : 1