Biodiversity and why it keeps ecosystems steady

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Plants counted in one meadow (model data)

   species	plants
   clover	120
   yarrow	40
   plantain	20
   dandelion	20
   total plants	200

2. 1.

   Kira reads the table. What share of the plants in the meadow belongs to the most common species?

   • 75%: 120 out of 160, the two largest counts
   • 60%: 120 out of 200 plants
   • 20%: 40 out of 200 plants, the second species
   • 25%: 4 species share the plants evenly

3. Growth in two plots (model data)

   plot	species	before the dry year	during the dry year
   D	16	480	360
   L	1	320	160

4. 2.

   Jun reads the table. By what percent did the growth of plot D change in the dry year?

   • It fell 33%: 120 ÷ 360
   • It fell 75%: 360 ÷ 480, the share left
   • It fell 0%: a plot with many species does not change
   • It fell 25%: 120 ÷ 480
5. 3.

   Noah reads the table. By what percent did the growth of plot F change in the dry year?

   • It fell 92%: 120 ÷ 130
   • It fell 52%: 130 ÷ 250, the share left
   • It fell 25%: 160 ÷ 640, the change of plot E
   • It fell 48%: 120 ÷ 250
6. 4.

   Zee reads the table. Which plot’s growth changed by the larger percent in the dry year?

   • Plot G: it lost more growth, 200 grams against 150 grams
   • Plot H: it fell 50%, against 25% for plot G
   • Neither: the two plots changed by the same percent
   • Plot G: it had more growth left, 600 against 150

7. Growth in one plot (model data)

   time	growth (grams per square meter)
   before the dry year	400
   during the dry year	300
   a year later	390

8. 5.

   Resistance is how little a plot changes during an event. Pia reads the table. Which comparison shows the plot’s resistance?

   • A year later against before: 390 against 400
   • A year later against the dry year: 390 against 300
   • Growth before the dry year, by itself: 400
   • The dry year against before: 300 against 400

9. Growth in two plots (model data)

   plot	before the dry year	during the dry year	a year later
   many-species plot	400	300	380
   one-species plot	400	200	380

10. 6.

    Ari reads the table. Which statement does the table support?

    • The many-species plot recovered faster because it fell less in the dry year
    • The many-species plot did not change during the dry year, so it had nothing to recover
    • The one-species plot recovered more because it rose 180 grams, against 80
    • Both plots reached 380 a year later, so recovery here did not depend on diversity

11. Growth in four plots (model data)

    plot	species	normal	dry year	a year later
    P1	1	300	150	300
    P2	2	500	260	500
    P3	16	1000	750	1000
    P4	32	800	624	800

12. 7.

    Luz reads the table. Which statement fits the table?

    • Plots with more species recovered faster, since they lost less in the dry year
    • The four plots were equally resistant because all ended at their normal growth
    • Plot P1 was the most resistant because it lost the fewest grams, 150
    • Plot P4 was the most resistant, losing 22%, and all four plots were back to normal a year later

13. Gene versions in two wildflower populations (model data)

    version of the gene	population P plants	population Q plants
    version 1	40	100
    version 2	30	0
    version 3	20	0
    version 4	10	0

14. 8.

    Esme reads the table for two populations of one wildflower species. Which has more genetic diversity?

    • Neither: genes inside one species do not count as diversity
    • Population P: its plants carry 4 versions of the gene, against 1 in Q
    • Population Q: it has the most plants with one version, 100
    • The same: both populations are one species, so their species diversity is equal

15. Dry-year growth by gene version (model data)

    gene version	growth per plant (grams)	population P plants	population Q plants
    version A	20	90	100
    version D	50	10	0

16. 9.

    Kira reads the model data. Which population grew more in total in the dry year?

    • Population Q: 2,000 grams, against 1,800 for P
    • The same, 2,000 grams: each population has 100 plants
    • Population P: 2,300 grams, against 2,000 for Q
    • Population P: 3,500 grams, counting 35 grams for each plant

17. Gene versions in one clover population (model data)

    version of the gene	plants
    version 1	60
    version 2	40

18. 10.

    Tala reads the table for a clover population. Which change would raise its genetic diversity?

    • Adding plants of a different species to the meadow
    • Adding a pond beside the meadow
    • Adding plants that carry a new version of the gene
    • Adding more plants of the two versions already there