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?

   • 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
   • The woodlands are equally diverse: each has 4 species and 100 trees
   • 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
   • 75%: 120 out of 160, the two largest counts
   • 60%: 120 out of 200 plants
   • 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 Y: it has 8 species and none of them dominates
   • Communities X and Y tie: each has 8 species
   • Community X: its commonest species has the biggest share, 90%
   • Community Z: its species are the most evenly shared, 25% each

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 25%: 120 ÷ 480
   • It fell 75%: 360 ÷ 480, the share left
   • It fell 33%: 120 ÷ 360
   • It fell 0%: a plot with many species does not change
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 25%: 160 ÷ 640, the change of plot E
   • It fell 92%: 120 ÷ 130
   • It fell 52%: 130 ÷ 250, the share left
10. 6.

    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

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?

    • 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
    • Population P: its plants carry 4 versions of the gene, against 1 in Q

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

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