Births, deaths, immigration and emigration

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Noah reads the graph of one plot. What is the density of seedlings at year 4?

   • 3.5 seedlings per square meter: 70 ÷ 20, the count at year 3
   • 5 seedlings per square meter: 100 ÷ 20
   • 0.2 seedlings per square meter: 20 ÷ 100
   • 100 seedlings per square meter: the count at year 4

2. Read this first

   One field of plants over two years (model data)

   measure	year 1	year 2
   plants	200	400
   area (square meters)	40	100

3. 2.

   Esme reads the table. What happened to the density of plants from year 1 to year 2?

   • It doubled, from 200 to 400 plants, because the count of plants doubled in a year
   • It stayed at 5 plants per square meter, as both numbers grew
   • It rose, from 5 to 10 plants per square meter: 400 ÷ 40
   • It fell, from 5 to 4 plants per square meter, as the area grew faster

4. Two plots of seedlings in a normal year and a drought year (model data)

   plot	percent that survive in a normal year	percent that survive in a drought year
   sparse plot, 10 seedlings per square meter	90	63
   crowded plot, 50 seedlings per square meter	60	42

5. 3.

   Jun reads the table of two plots of seedlings. Which statement fits the data?

   • Crowding lowers survival in both years; the drought cut each plot by the same 30%
   • The drought cut a larger share from the crowded plot, since it ended lower, at 42%
   • The drought cut a larger share from the sparse plot, since it fell 27 points against 18
   • Crowding does not matter: both plots were cut by the same drought

6. Plots of 10 square meters at four densities (model data)

   plants per square meter	plants	births per plant	total births
   5	50	0.8	40
   10	100	0.6	60
   20	200	0.4	80
   40	400	0.2	80

7. 4.

   Kira reads the table of plots, each 10 square meters. Which statement fits the data?

   • Births per plant fall because of a flood, a density-independent factor
   • Births per plant fall as density rises, so total births must fall too
   • Births per plant fall as density rises, even though total births rose from 40 to 80
   • Total births rose from 40 to 80, so births per plant rose with density too

8. Mark and recapture on a lake of 50 hectares (model data)

   step	ducks
   marked and released in the first catch	40
   caught in the second catch	50
   marked ducks in the second catch	8

9. 5.

   Luz reads the model data for one lake. What are the estimated number of ducks and the density?

   • 250 ducks, and 0.2 ducks per hectare: 50 ÷ 250
   • 6.4 ducks, and 0.13 ducks per hectare: flipped
   • 250 ducks, and 250 ducks per hectare: the count as density
   • 250 ducks, and 5 ducks per hectare: 250 ÷ 50

10. Notebook

    Notes on turtles on one island (classmate's notebook), 4 lines. Columns: line, entry. Line 1: Births, 18, and immigrants, 7, add 25 turtles. Line 2: Deaths, 9, and emigrants, 11, remove 20 turtles. Line 3: So the change is births minus deaths, 18 − 9 = 9. Line 4: The change is positive, so the number of turtles rose.

11. 6.

    Ari reads a classmate's notebook about turtles. Which line has the mistake?

    • Line 3: the change must count the moves too, 25 − 20 = 5, not 9
    • Line 2: 9 deaths + 11 emigrants remove 19 turtles altogether, not 20 turtles
    • Line 1: 18 births + 7 immigrants add 24 turtles altogether, not 25 turtles
    • Line 4: a change of 9 means the number of turtles fell

12. Notebook

    Notes on a drought and two plots (classmate's notebook), 4 lines. Columns: line, entry. Line 1: After a drought, 56 of 80 seedlings in the sparse plot survived, which is 70%. Line 2: In the crowded plot, 210 of 300 seedlings survived, which is 70%. Line 3: More seedlings did not survive in the crowded plot, 90 against 24, so drought is density-dependent. Line 4: In both plots the drought left the same share, 70%.

13. 7.

    Pia reads a classmate's notebook about a drought. Which line has the mistake?

    • Line 1: 56 of 80 seedlings is 7%, not 70%
    • Line 3: both plots kept 70%, so the drought is density-independent
    • Line 4: the same share cannot survive in plots of different density
    • Line 2: 210 of 300 seedlings is 21%, not 70%

14. Two ponds of frogs during one year (model data)

    pond	frogs at the start	births
    A	500	50
    B	80	16

15. 8.

    Ren reads the table. Which claim goes with the right reason?

    • Claim: pond B has the higher rate per frog. Reason: it has fewer frogs, 80 against 500
    • Claim: pond B has the higher rate per frog. Reason: 16 ÷ 80 is 0.20, against 0.10
    • Claim: the ponds have the same rate. Reason: each pond had births in the year
    • Claim: pond A has the higher rate per frog. Reason: it had more births, 50 against 16
16. 9.

    Tala reads the graph. Which claim goes with the right reason?

    • Claim: growth is speeding up. Reason: the line keeps climbing from 100 to 190
    • Claim: the population is still growing. Reason: each yearly change is above 0, but smaller, 30 to 6
    • Claim: the population has stopped changing. Reason: the line flattens near 190
    • Claim: the population is shrinking. Reason: the yearly gains get smaller, from 30 to 6

17. Mark and recapture on two lakes (model data)

    lake	marked ducks released	ducks in the second catch	marked ducks in the second catch
    A	50	80	10
    B	50	80	20

18. 10.

    Zee reads the table. Which claim goes with the right reason?

    • Claim: lake B has more ducks. Reason: (50 × 20) ÷ 80 gives the larger number
    • Claim: the lakes are the same size. Reason: 50 ducks were marked in each
    • Claim: lake A has more ducks. Reason: 10 of 80 caught were marked, against 20 of 80
    • Claim: lake B has more ducks. Reason: more marked ducks were caught there, 20 against 10