Read data on a helpful trait spreading through a population

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Dark moths in three generations (model data)

   moths	generation 1	generation 2	generation 3
   dark	24	54	96
   all moths	80	120	160

2. 1.

   Ari reads the table. What percent of the moths in generation 3 are dark?

   • 120%: 96 ÷ 80, using the generation 1 total
   • 96%: the count of 96, written as a percent of the moths
   • 60%: 96 ÷ 160 = 0.60
   • 40%: the light moths, 64 of 160

3. Two plate samples (model data)

   sample	resistant	all bacteria
   sample A	400	8,000
   sample B	600	20,000

4. 2.

   Bo compares two plate samples. Which sample has the larger percent of resistant bacteria?

   • Neither sample: the totals differ, so the percents cannot be compared
   • Sample B: it has 600 resistant bacteria, more than the 400 in sample A
   • Sample A: 5%, compared with 3% for sample B
   • Sample B: it has 20,000 bacteria in total, more than sample A

5. Purple plants in three generations (model data)

   plants	generation 1	generation 2	generation 3
   purple	20	40	9
   all plants	40	100	30

6. 3.

   Esme reads the table. In which generation are purple plants the largest share of all plants?

   • Generation 1: 20 of 40 is 50%, above 40% and 30%
   • Generation 3: 9 purple of 30 plants is 90%
   • Generation 2: it has the most purple plants, 40
   • Generation 2: it has the most plants in total, 100

7. Resistant bacteria per 100 bacteria (model data)

   round	resistant per 100
   round 1	20
   round 2	30

8. 4.

   Jun reads the table. By what percent did the resistant share rise from round 1 to round 2?

   • 33%: the rise of 10 points is a third of the new 30
   • 10%: the rise in percent points, called a percent
   • 50%: the rise of 10 points is half of the 20 you started with
   • 30%: the share in round 2, not the change

9. Dark moths per 100 moths (model data)

   generation	dark moths per 100
   generation 1	40
   generation 2	60

10. 5.

    Kira reads the table. Which sentence describes the change from generation 1 to generation 2 correctly?

    • It rose 20 percent points, which is a 20% increase on 40
    • It rose 20 percent points, which is a 33% increase on 60
    • It rose 20 percent points, which is a 50% increase on 40
    • It rose 50 percent points, which is a 20% increase on 40

11. Light moths per 100 moths (model data)

    generation	light moths per 100
    generation 1	50
    generation 2	20

12. 6.

    Luz reads the table. By what percent did the light share fall from generation 1 to generation 2?

    • 60%: the fall of 30 points is 60% of the 50 you started with
    • 40%: the share left, 20 of the 50 you started with
    • 150%: the fall of 30 points is 150% of the new 20
    • 30%: the fall in percent points, called a percent

13. Moths before breeding: each survivor leaves 2 young like itself (model data)

    moth color	generation 1	survive to breed (percent)
    dark	50	60
    light	50	20

14. 7.

    Milo predicts generation 2 from the rule in the title. What percent of generation 2 will be dark?

    • 30%: the count of dark survivors, written as a percent
    • 50%: both colors started with 50 moths
    • 60%: the survival percent of the dark moths
    • 75%: 30 dark survivors out of 40 survivors

15. Bacteria in a flask before an antibiotic, per 10,000 bacteria (model data)

    bacteria	before	survive the antibiotic (percent)
    resistant	1,000	90
    not resistant	9,000	10

16. 8.

    Noah predicts the survivors. After the antibiotic, what percent of the surviving bacteria are resistant?

    • 50%: 900 resistant survivors and 900 other survivors
    • 90%: the survival percent of the resistant bacteria
    • 100%: the antibiotic made the other survivors resistant too
    • 10%: the starting share, since survival does not change a share

17. Moths on cleaned trunks: each survivor leaves 3 young like itself (model data)

    moth color	generation 5	survive to breed (percent)
    dark	50	20
    light	50	60

18. 9.

    The trunks were cleaned, so light moths now survive better. Pia predicts generation 6. What percent will be dark?

    • 0%: dark moths turn light on cleaned trunks
    • 75%: the light moths' share of the survivors
    • 20%: the survival percent of the dark moths
    • 25%: 10 dark survivors out of 40 survivors

19. Dark moths in a small woodland of 20 moths (model data)

    generation	dark moths	dark percent
    generation 1	10	50
    generation 2	11	55
    generation 3	9	45
    generation 4	10	50

20. 10.

    Ren reads the dark share across four generations of one small woodland. Which explanation fits the data?

    • Selection: the share fell from 55% to 45%, so light moths are favored
    • Neither: the share cannot change while the total stays at 20 moths
    • Selection: the share rose from 50% to 55%, so dark moths are favored
    • Chance: the share goes up and down and ends where it began