How people affect biodiversity

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Fish stocks with a known status, end of 2023 (real data, NOAA Fisheries, 2023)

   list	stocks with a known status	stocks flagged
   overfishing	364	21
   overfished	263	47

2. 1.

   Ari reads the NOAA table. Which list flagged the larger share of the stocks with a known status?

   • Both flag about the same share: 47 of 506 and 21 of 506
   • Overfishing: 21 of 364 is 5.8%, which is larger than 47 of 263
   • Overfished: 17.9% (47 of 263) against 5.8% (21 of 364), about 3 times as large
   • Overfished: 47 stocks against 21, about 2 times as large, since the counts decide the answer

3. Threatened species worldwide (real data, IPBES 2019)

   measure	value
   animal and plant species threatened with extinction	around 1 million
   estimated animal and plant species on Earth	8 million

4. 2.

   Bo applies the global share to a model park with 2,400 species. About how many would be threatened at the same share?

   • About 3, from 0.125% of 2,400
   • About 240, from a share of 10%
   • About 2,100, the share that is not threatened
   • About 300: 1 million of 8 million is 12.5%, and 12.5% of 2,400 is 300

5. Species lost from one wetland, by driver (model data)

   driver	species lost where it acted
   habitat loss	14
   invasive species	9
   pollution	7
   total species lost	20

6. 3.

   Esme reads the wetland table. Why do the driver counts add to more than 20, and what is the best reading?

   • Habitat loss was the main cause: 14 of the 20 species lost is 70%, the largest share
   • Some species had more than one driver, so the counts overlap and cannot be added
   • The total should be 30, so 10 lost species were left out
   • The table has an error, because each species lost has a single cause

7. Pesticide level in one model stream after a ban (model data)

   year after the ban	level (parts per billion)
   0	24
   3	12
   6	6

8. 4.

   Kira reads the table. What is the level at year 9, and by what percent did it fall from year 0?

   • 0 parts per billion, since a ban removes the pesticide
   • 3 parts per billion, a fall of 87.5%, since it halves every 3 years
   • 1.5 parts per billion, a fall of 93.75%
   • 3 parts per billion, a fall of 12.5%

9. Two sites on one model stream (model data)

   site	water looks	nitrate (milligrams per liter)	limit (milligrams per liter)
   site 1 (upstream)	clear	4	10
   site 2 (downstream)	clear	10	10

10. 5.

    Luz reads the table. By what percent did nitrate rise downstream, and is it over the limit?

    • 150%, and the reading is over the limit since it is 6 higher
    • 150%, and the reading is at the limit, not over it
    • 60%, and the reading is over the limit
    • 0%, since the water looks clear at both sites

11. Three model rivers (model data)

    river	driver acting	plant species before	plant species after
    river 1	a dam	40	34
    river 2	a pesticide	40	36
    river 3	a dam and a pesticide	40	27

12. 6.

    Milo reads the table. Which statement does the evidence support?

    • The effects simply add, since 6 + 4 is close to 13
    • Both drivers matter: rivers 1 and 2 lost 6 and 4, but the river with both lost 13
    • The pesticide has no effect, since river 2 lost just 4 of 40
    • The dam is the one cause, since both rivers with a dam lost more species than river 2
13. 7.

    Noah reads the graph. Which statement describes stream A and predicts its level at year 8?

    • Stream A falls 3 every 2 years, so it reaches 0 at year 8
    • Stream A halves every 2 years, so it should be about 1.5 parts per billion at year 8
    • Stream A reaches 0 by year 8, because the ban stopped the pollutant from entering the stream
    • Stream B also falls, to about 12 parts per billion by year 8
14. 8.

    Pia reads the graph. Which statement does it support about the stock after year 10?

    • It rebuilt by about 40 thousand tonnes a year, the size of the line
    • It stayed above the overfished line the whole twenty years
    • It was extinct at year 10, then a new stock took over
    • It rebuilt by about 4 thousand tonnes a year, rising back above the line by year 15

15. Four plans for testing the farm's pesticide (model data)

    plan	what is done
    plan A	count insects and test the pesticide at sites above and below the farm, before and after spraying
    plan B	ask neighbors whether the water looks clean
    plan C	count insects once, at one site below the farm
    plan D	test the pesticide at one site after the insects have fallen

16. 9.

    Tala wants to test whether a farm's pesticide lowered a stream's insect count. Which plan gives the best evidence?

    • Plan C: a single count below the farm shows the pesticide's effect
    • Plan D: a pesticide reading after the loss shows what caused the loss
    • Plan A: it measures both, with sites above the farm as a comparison
    • Plan B: how clear the water looks shows whether a pesticide is present

17. Warming and elevation (IPCC finding and a model rule)

    item	value
    warming, 2011–2020 compared with 1850–1900 (IPCC)	1.1 °C
    model rule: air cools for each 1,000 m uphill	6.5 °C

18. 10.

    Zee uses the model rule. About how far uphill must a plant move to keep the same temperature after 1.1 °C of warming?

    • About 5.9 km uphill: 6.5 ÷ 1.1
    • About 170 m uphill: 1.1 ÷ 6.5 × 1,000
    • About 1,100 m uphill, from 1.1 × 1,000
    • About 7 m uphill: 1.1 × 6.5