Biodiversity and why it keeps ecosystems steady
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Bo reads the graph. Year 2 was a dry year. Which statement matches the graph?
- The one-species plot was less resistant: it fell 50% against 25%, and both were back to normal in year 3
- The many-species plot was not affected: its line stays near the top
- The two plots were equally affected: each lost 200 grams per square meter, so diversity made no difference
- The many-species plot recovered faster: it fell less in year 2
Read this first
Growth in two plots (model data)
plot species normal dry year a year later M 24 600 450 570 N 1 500 250 475 Esme reads the table. For plot M, what percent of normal growth was reached in the dry year and a year later?
- 25% in the dry year and 95% a year later
- 75% in the dry year and 127% a year later
- 75% in the dry year and 95% a year later
- 75% in the dry year and 5% a year later
Two nature areas (model data)
area different ecosystems different species A 2 14 B 1 20 Kira reads the table. Which statement about the kinds of diversity is correct?
- Area B has more ecosystem diversity, since it has more species, 20 against 14 in area A
- Area A has more species diversity, since it has more ecosystems, 2 against 1 in area B
- Area B is more diverse overall, since it has more species, 20 against 14 in area A
- Area A has more ecosystem diversity, 2 against 1; area B has more species, 20 against 14
Growth in a dry year and a wet year (model data)
plot species normal dry year wet year K 16 600 450 750 L 1 400 200 600 Luz reads the table. Which statement describes the pattern in both the dry year and the wet year?
- Plot K changed less because it recovered faster after each year
- Plot L changed by more, so it was the more resistant plot
- Plot K changed by 25% and plot L by 50% in each year, so more species meant a smaller change
- Plot L changed more in the dry year alone; in the wet year both plots changed by the same 25%
Growth in two plots (model data)
plot normal dry year a year later R 500 375 500 S 500 250 500 Ren says plot R recovered better because it fell less. Which reply uses the table correctly?
- Plot S recovered better, because it gained more: 250 grams per square meter, against 125 for plot R
- Plot R recovered better, because a plot that falls less comes back faster
- Both plots were back at 500 a year later, so they recovered alike; plot R was more resistant
- Plot S did not recover, because it fell by 50% in the dry year
Two model forests (model data)
measure forest F1 forest F2 species 10 10 trees of the commonest species 20 190 trees of the other species together 180 10 trees in all 200 200 Zee reads the table. Which statement about the diversity of the two forests is correct?
- Forest F1 is more diverse, because it has more species than forest F2
- Forest F2 is more diverse, because one species has 190 trees, the most of any species in either forest
- Forest F1 is more diverse: its trees are evenly spread, 20 in the commonest species against 190 in F2
- The forests are equally diverse, because both have 10 species
Notebook
Notes on a many-species plot (classmate's notebook), 4 lines. Columns: line, entry. Line 1: Growth was 640 before the dry year and 480 in the dry year. Line 2: The fall is 640 − 480 = 160. Line 3: The percent fall is 160 ÷ 480 = 33%. Line 4: A 33% fall is less than 50%, so the plot resisted well.
Pia reads a classmate’s notebook about a many-species plot. Which line has the mistake?
- Line 3: divide the fall by the starting growth, 160 ÷ 640 = 25%
- Line 2: the fall should be 640 + 480, the two numbers added
- Line 4: a 33% fall is more than 50%, so the plot resisted poorly
- Line 1: the dry-year growth should be larger than the start
Notebook
Notes on two wildflower populations (classmate's notebook), 4 lines. Columns: line, entry. Line 1: Population X has 5 versions of one gene among its 100 plants. Line 2: Population Y has 1 version of that gene among its 100 plants. Line 3: Both populations have 100 plants of one species. Line 4: So the two populations have the same diversity.
Jun reads a classmate’s notebook about two wildflower populations. Which line has the mistake?
- Line 3: two populations with 100 plants each must be different species
- Line 2: 1 version means Y has no genes to compare
- Line 1: 5 versions of a gene cannot occur inside one species of 100 plants
- Line 4: the populations differ in genetic diversity, 5 versions against 1
Notebook
Notes on two plots in a dry year (classmate's notebook), 4 lines. Columns: line, entry. Line 1: Plot A, with 16 species, fell from 500 to 375, and plot B, with 1 species, fell from 500 to 250. Line 2: So plot A fell 25% and plot B fell 50%. Line 3: A year later both plots were back at 500. Line 4: Plot A fell less, so it also recovered faster.
Noah reads a classmate’s notebook about two plots in a dry year. Which line has the mistake?
- Line 4: both plots were back at 500 a year later, so recovery was alike
- Line 1: plot A has 16 species, so it should not fall in the dry year
- Line 2: the falls should be divided by the dry-year growth, 125 ÷ 375 = 33%
- Line 3: a plot cannot return to exactly 500 after a dry year
Growth in four plots in a dry year (model data)
plot species normal dry year A 1 400 192 B 2 300 159 C 16 900 657 D 32 700 532 Milo reads the table. Which claim goes with the right reason?
- Claim: more species meant more resistance. Reason: plot C had the most growth in the dry year, 657, more than any other plot
- Claim: more species meant more resistance. Reason: C and D lost 27% and 24%, against 52% and 47%
- Claim: species made no difference. Reason: each plot lost some growth in the dry year
- Claim: fewer species meant more resistance. Reason: plot B lost the fewest grams, 141