Biodiversity and why it keeps ecosystems steady

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Trees counted in two woodlands (model data)

   species	woodland P trees	woodland Q trees
   oak	25	85
   maple	25	5
   birch	25	5
   elm	25	5
   total trees	100	100

2. 1.

   Bo reads the table. Which statement about the diversity of the two woodlands is correct?

   • The woodlands are equally diverse: each has 4 species and 100 trees
   • Woodland P is less diverse: each of its 4 species has just 25 trees
   • Woodland Q is more diverse: it has one species with most of its trees, 85
   • Woodland P is more diverse: both have 4 species, but P has its trees spread evenly

3. Plants counted in one meadow (model data)

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

4. 2.

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

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

5. Three model communities (model data)

   community	species	share of the commonest species (%)
   X	8	90
   Y	8	15
   Z	4	25

6. 3.

   Milo reads the table. Which community is the most diverse?

   • Community Z: its species are the most evenly shared, 25% each
   • Community X: its commonest species has the biggest share, 90%
   • Communities X and Y tie: each has 8 species
   • Community Y: it has 8 species and none of them dominates

7. Growth in two plots (model data)

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

8. 4.

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

   • It fell 75%: 360 ÷ 480, the share left
   • It fell 0%: a plot with many species does not change
   • It fell 33%: 120 ÷ 360
   • It fell 25%: 120 ÷ 480
9. 5.

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

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

10. 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

11. 6.

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

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

12. 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

13. 7.

    Luz reads the table. Which statement fits the table?

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

14. 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

15. 8.

    Esme reads the table for two populations of one wildflower species. Which has more genetic 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
    • Neither: genes inside one species do not count as diversity
    • The same: both populations are one species, so their species diversity is equal

16. 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

17. 9.

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

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

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

    version of the gene	plants
    version 1	60
    version 2	40

19. 10.

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

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