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?

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

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?

   • Sample B: it has 20,000 bacteria in total, more than sample A
   • Sample A: 5%, compared with 3% for sample B
   • 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

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

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?

   • 10%: the rise in percent points, called a percent
   • 33%: the rise of 10 points is a third of the new 30
   • 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 50 percent points, which is a 20% increase on 40
    • It rose 20 percent points, which is a 50% increase on 40
    • It rose 20 percent points, which is a 33% increase on 60
    • It rose 20 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
    • 30%: the fall in percent points, called a percent
    • 150%: the fall of 30 points is 150% of the new 20

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?

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

15. 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

16. 8.

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

    • Selection: the share rose from 50% to 55%, so dark moths are favored
    • 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
    • Chance: the share goes up and down and ends where it began
17. 9.

    Tala reads the bars for a garden of 10 plants. Which explanation fits the data best?

    • Selection: tall plants went up and down, so each generation favors a new height
    • Selection: tall plants rose from 4 to 6 out of 10 in generations 3 to 5
    • Chance: in 10 plants, a change of one plant moves the share by 10 points
    • Each plant grew taller or shorter between generations, which moved the bars

18. Resistant bacteria per 10,000 bacteria after repeated antibiotic rounds (model data)

    round	resistant per 10,000
    round 0	6
    round 1	150
    round 2	2,700
    round 3	8,800

19. 10.

    Zee reads the table of rounds. Which explanation fits the data best?

    • Chance: the share jumps around between rounds with no steady direction
    • The antibiotic caused resistance, raising it from 6 to 8,800 per 10,000
    • Selection: resistant bacteria were already there and left more offspring each round
    • Each bacterium became a little more resistant in each round of the antibiotic