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?

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

2. Read this first

   Bees on one hillside during one year (model data)

   count	bees
   at the start of the year	250
   births	40
   deaths	15
   immigrants (moved in)	10
   emigrants (moved out)	5

3. 2.

   Bo reads the table. What is the change in the number of bees, and the change for each bee at the start?

   • +25 bees, or 0.10 per bee: 25 ÷ 250
   • +30 bees, or 0.12 per bee: 30 ÷ 250
   • +30 bees, or 30 per bee: the count as a rate
   • +50 bees, or 0.20 per bee: 50 ÷ 250

4. One field of plants over two years (model data)

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

5. 3.

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

   • It rose, from 5 to 10 plants per square meter: 400 ÷ 40
   • 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 fell, from 5 to 4 plants per square meter, as the area grew faster

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?

   • Total births rose from 40 to 80, so births per plant rose with density too
   • 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

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?

   • 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
   • 250 ducks, and 0.2 ducks per hectare: 50 ÷ 250

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 2: 9 deaths + 11 emigrants remove 19 turtles altogether, not 20 turtles
    • Line 3: the change must count the moves too, 25 − 20 = 5, not 9
    • 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 2: 210 of 300 seedlings is 21%, not 70%
    • Line 4: the same share cannot survive in plots of different density

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

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

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

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