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 2,100, the share that is not threatened
   • About 3, from 0.125% of 2,400
   • About 240, from a share of 10%
   • 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?

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

7. Plant species in two woodland patches (model data)

   patch	species before	species after
   control (kept whole)	50	47
   cleared in part	50	35

8. 4.

   Jun reads the table. How many percent points more of its species did the cleared patch lose than the control?

   • 12 points: 15 lost minus 3 lost
   • 37 points: 15 of 35 is 43%, minus 6%
   • 30 points: the cleared patch's loss on its own, without taking away what the control lost
   • 24 points: 30% of the cleared patch's species were lost, against 6% in the control

9. 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

10. 5.

    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
    • 1.5 parts per billion, a fall of 93.75%
    • 3 parts per billion, a fall of 12.5%
    • 3 parts per billion, a fall of 87.5%, since it halves every 3 years

11. 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

12. 6.

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

    • 150%, and the reading is at the limit, not over it
    • 60%, and the reading is over the limit
    • 150%, and the reading is over the limit since it is 6 higher
    • 0%, since the water looks clear at both sites
13. 7.

    Noah reads the graph. Which statement describes stream A and predicts its level 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
    • 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
14. 8.

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

    • It rebuilt by about 4 thousand tonnes a year, rising back above the line by year 15
    • 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

15. Fish stock status at the end of 2023 (real data, NOAA Fisheries, 2023)

    row	count
    stocks or stock complexes managed	506
    stocks on the overfishing list	21
    stocks on the overfished list	47
    stocks rebuilt since 2000	50

16. 9.

    Ren reads the NOAA rows. Which statement about overfished stocks do they support?

    • Recovery is possible: 50 stocks were rebuilt since 2000, though 47 were still overfished
    • Overfishing has ended, since just 21 of 506 stocks are on that list
    • Most managed stocks are overfished, since 47 is more than 21
    • The 47 overfished stocks are gone for good, since stocks that small do not come back after that

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