Analyze Ecosystem Change Data

Help Questions

Middle School Life Science › Analyze Ecosystem Change Data

Questions 1 - 10
1

Ecosystem changes can affect populations. A desert area had a baseline condition in Years 1–2. In Year 3, several wetter-than-usual seasons occurred (changed condition), increasing plant growth. Use the data to answer: Which prediction about future population change is supported by the trend in the data?

Data:

  • Plant cover (%): 15, 16, 30, 38, 36 (Years 1–5)
  • Kangaroo rats (count): 40, 42, 55, 70, 68 (Years 1–5)
  • Hawks (count): 6, 6, 7, 9, 9 (Years 1–5)

Because kangaroo rats increased from Year 2 to Year 4, they will increase forever at the same rate no matter what happens.

Population changes are random, so no prediction can be supported even when trends appear in the data.

If higher plant cover continues, kangaroo rat numbers will likely stay higher than the baseline years, and hawk numbers may also stay higher.

If plant cover stays high, all animal populations must decrease because plants take up space animals need.

Explanation

The core skill is analyzing data to understand how changes in an ecosystem affect populations of organisms. Ecosystems can change due to climatic shifts like wetter seasons increasing plant growth in a desert. Data, such as plant cover and counts of kangaroo rats and hawks over years, show population responses by indicating increases in herbivores and predators following vegetation growth. To check predictions, extrapolate trends if conditions persist, basing them on observed patterns. A common misconception is that populations will grow indefinitely, but they stabilize based on resources. By examining such data, we can explain ecosystem dynamics, including resource-driven population changes. Ultimately, this aids in forecasting biodiversity in arid ecosystems like deserts.

2

Ecosystem changes can affect populations. A pond was measured for 5 years. Years 1–2 are the baseline condition (no fertilizer runoff). Starting in Year 3, fertilizer runoff increased algae growth (changed condition). Use the data to answer: Which conclusion is supported by the data and evidence?

Data (average counts per survey):

  • Algae coverage (%): Year 1 = 10, Year 2 = 12, Year 3 = 40, Year 4 = 55, Year 5 = 50
  • Minnows (fish): Year 1 = 120, Year 2 = 115, Year 3 = 90, Year 4 = 60, Year 5 = 65
  • Dragonfly nymphs: Year 1 = 30, Year 2 = 28, Year 3 = 26, Year 4 = 20, Year 5 = 22

Because algae increased in Year 3, the runoff is the only possible cause of every population change in the pond.

Minnow numbers changed randomly, so there is no evidence that the ecosystem change affected any population.

The data support that increased algae after Year 3 is associated with decreases in minnows and dragonfly nymphs over time.

All pond populations respond identically to increased algae, so minnows and dragonfly nymphs should both increase after Year 3.

Explanation

The core skill is analyzing data to understand how changes in an ecosystem affect populations of organisms. Ecosystems can change due to factors like fertilizer runoff increasing algae growth in a pond, which alters the habitat and resources available to other species. Data, such as yearly counts of algae coverage, minnows, and dragonfly nymphs, show population responses by revealing trends like decreases in animal populations following the algae increase. To check conclusions, compare baseline data from before the change (Years 1–2) with data after (Years 3–5) to identify supported associations without assuming causation. A common misconception is that all populations must respond identically to a change, but species like minnows and nymphs can both decline even if they have different roles. By examining such data, we can explain ecosystem dynamics, including how one change can ripple through food webs. Ultimately, this analysis helps us understand and predict shifts in biodiversity within aquatic ecosystems like ponds.

3

Ecosystem changes can affect populations. A forest had a baseline condition in Years 1–2. In Year 3, an invasive insect arrived and reduced the number of oak trees (changed condition). Use the table to answer: Which conclusion is supported by the data and evidence?

Table:

Year 1: Oak trees = 100, Caterpillars = 200, Woodpeckers = 12

Year 2: Oak trees = 98, Caterpillars = 195, Woodpeckers = 11

Year 3: Oak trees = 70, Caterpillars = 140, Woodpeckers = 10

Year 4: Oak trees = 55, Caterpillars = 110, Woodpeckers = 8

Year 5: Oak trees = 60, Caterpillars = 120, Woodpeckers = 9

The data support that decreases in oak trees after Year 3 are followed by decreases in caterpillars and woodpeckers over time.

Since oak trees increased from Year 4 to Year 5, the invasive insect must have disappeared completely and can never return.

Because oak trees decreased after Year 3, caterpillars and woodpeckers must both increase to keep the forest balanced.

Oak trees dropped in Year 3, so caterpillars should drop to zero immediately in Year 3 if they depend on oaks.

Explanation

The core skill is analyzing data to understand how changes in an ecosystem affect populations of organisms. Ecosystems can change due to invasive species like insects reducing oak trees in a forest, which disrupts food chains. Data, such as counts of oak trees, caterpillars, and woodpeckers over years, show population responses by revealing cascading decreases following the tree decline. To check conclusions, trace patterns from the initial change through dependent species, ensuring data support gradual rather than abrupt shifts. A common misconception is that dependent populations drop to zero immediately, but they can decline over time as resources dwindle. By examining such data, we can explain ecosystem dynamics, including trophic level interactions. Ultimately, this analysis reveals how forests maintain balance amid disturbances.

4

Ecosystem changes can affect populations. A lake had a baseline condition in Years 1–2. In Year 3, anglers removed many large predator fish (changed condition). Use the data to answer: Which statement about ecosystem change is supported by the data and evidence?

Data (average counts per survey):

  • Predator fish: 30, 28, 12, 10, 11 (Years 1–5)
  • Small fish: 200, 210, 260, 320, 310 (Years 1–5)
  • Zooplankton: 150, 145, 130, 90, 95 (Years 1–5)

After predator fish decreased, small fish increased over time while zooplankton decreased over time.

Because predators decreased in Year 3, zooplankton must increase immediately in Year 3.

The small fish increase proves predators were removed, so the population data are not needed.

All three populations should decrease together because any ecosystem change affects every species the same way.

Explanation

The core skill is analyzing data to understand how changes in an ecosystem affect populations of organisms. Ecosystems can change due to actions like removing predator fish from a lake, which alters predation pressures. Data, such as counts of predators, small fish, and zooplankton over time, show population responses by showing increases in prey and decreases in their food sources. To check statements, compare multi-level trends post-change against baseline, identifying supported chain reactions. A common misconception is that all populations change in the same direction, but removals can cause increases at one level and decreases at another. By examining such data, we can explain ecosystem dynamics, like food web balances. Ultimately, this helps predict outcomes in aquatic ecosystems like lakes.

5

Ecosystem changes can affect populations. A city park pond had a baseline condition in Years 1–2. In Year 3, more people began feeding ducks (changed condition), increasing available food for ducks. Use the data to answer: Which claim about population response is incorrect?

Data:

  • Duck food added (kg/week): 0, 0, 15, 20, 18 (Years 1–5)
  • Ducks (count): 25, 26, 40, 55, 50 (Years 1–5)
  • Aquatic plants (% cover): 45, 44, 38, 25, 28 (Years 1–5)

Because ducks increased, aquatic plants must also increase since all populations rise together when food increases.

Duck numbers increased after food was added, while aquatic plant cover decreased over the same period.

Aquatic plant cover decreased from Year 2 to Year 4, but it shows a small increase in Year 5, so change is not always one-directional.

The data show changes over time after Year 3 that could be evidence of ecosystem change affecting populations.

Explanation

The core skill is analyzing data to understand how changes in an ecosystem affect populations of organisms. Ecosystems can change due to human behaviors like feeding ducks in a city park pond, increasing available food. Data, such as food amounts and counts of ducks plus plant cover, show population responses by indicating increases in consumers and decreases in resources. To check claims, identify if trends support linked changes or reveal opposing directions. A common misconception is that all populations increase together with added resources, but overconsumption can harm producers. By examining such data, we can explain ecosystem dynamics, like consumer-producer balances. Ultimately, this reveals impacts in managed ecosystems like urban ponds.

6

Ecosystem changes can affect populations. A meadow had a baseline condition in Years 1–2. In Year 3, a new irrigation system increased soil moisture (changed condition). A student makes a claim: “Because soil moisture increased, every plant and animal population must increase.” Use the data to evaluate the claim: Which conclusion is supported by the data and evidence?

Data:

  • Soil moisture (%): 12, 11, 20, 24, 23 (Years 1–5)
  • Clover plants (count): 50, 52, 80, 95, 90 (Years 1–5)
  • Ground-nesting bees (count): 40, 39, 30, 22, 25 (Years 1–5)

The student’s claim is correct because bees decreased, which proves irrigation always harms all insects.

The student’s claim is supported because soil moisture increased and at least one population increased.

The student’s claim is supported because the ecosystem controls every population completely, so organisms cannot respond differently.

The student’s claim is not supported because clover increased while ground-nesting bees decreased after the change, showing different responses.

Explanation

The core skill is analyzing data to understand how changes in an ecosystem affect populations of organisms. Ecosystems can change due to interventions like irrigation increasing soil moisture in a meadow. Data, such as moisture levels and counts of clover and bees over time, show population responses by revealing increases in some species and decreases in others. To evaluate claims, assess if data support uniform effects or varied responses across organisms. A common misconception is that changes benefit all populations equally, but species can react differently based on needs. By examining such data, we can explain ecosystem dynamics, such as habitat preferences. Ultimately, this clarifies adaptation in grassland ecosystems like meadows.

7

Ecosystem changes can affect populations. A bay had a baseline condition in Years 1–2. In Year 3, a new wastewater treatment system reduced pollution (changed condition). Use the data to answer: Which statement about ecosystem change is supported by the data and evidence?

Data:

  • Pollution index (lower is cleaner): 70, 68, 40, 30, 28 (Years 1–5)
  • Seagrass area (hectares): 12, 13, 18, 25, 27 (Years 1–5)
  • Jellyfish (count): 90, 88, 70, 55, 50 (Years 1–5)

Because the bay got cleaner, jellyfish should disappear immediately in Year 3 if pollution affects them.

The data show no relationship because some numbers go up and others go down, so the ecosystem change had no effect.

Seagrass increased, so the wastewater system must have been designed specifically to make seagrass grow.

As pollution decreased after Year 3, seagrass increased and jellyfish decreased over time compared with the baseline years.

Explanation

The core skill is analyzing data to understand how changes in an ecosystem affect populations of organisms. Ecosystems can change due to improvements like reduced pollution in a bay from better wastewater treatment. Data, such as pollution indices and areas of seagrass plus jellyfish counts, show population responses by demonstrating increases in sensitive species and decreases in pollution-tolerant ones. To check statements, align trends with the direction of change, avoiding assumptions of immediate effects. A common misconception is that cleaner conditions eliminate species instantly, but populations adjust gradually. By examining such data, we can explain ecosystem dynamics, including recovery processes. Ultimately, this supports conservation in marine ecosystems like bays.

8

Ecosystem changes can affect populations. A river section had a baseline condition (cool water) in Years 1–2. In Year 3, shade trees along the bank were removed, and the water warmed (changed condition). Use the data to answer: Which claim about population response is incorrect?

Data:

  • Water temperature (°C): Year 1 = 14, Year 2 = 14, Year 3 = 17, Year 4 = 18, Year 5 = 18
  • Trout (count): Year 1 = 45, Year 2 = 44, Year 3 = 35, Year 4 = 22, Year 5 = 20
  • Carp (count): Year 1 = 10, Year 2 = 12, Year 3 = 18, Year 4 = 25, Year 5 = 27

Carp numbers increased over time after the ecosystem change to warmer water.

Because the water warmed in Year 3, trout must increase in Year 3 immediately if temperature affects them.

Different species can respond differently to the same ecosystem change.

Trout numbers decreased over time after the ecosystem change to warmer water.

Explanation

The core skill is analyzing data to understand how changes in an ecosystem affect populations of organisms. Ecosystems can change due to factors like removal of shade trees warming river water, which impacts temperature-sensitive species differently. Data, such as temperature readings and counts of trout and carp over time, show population responses by demonstrating decreases in cold-water fish and increases in warm-water fish after the change. To check claims, verify if they align with actual trends, such as gradual population shifts rather than immediate changes. A common misconception is that affected populations must show instant responses in the year of change, but effects can appear over time as conditions persist. By examining such data, we can explain ecosystem dynamics, including how abiotic factors like temperature influence species distribution. Ultimately, this analysis aids in understanding adaptation and survival in aquatic ecosystems like rivers.

9

Ecosystem changes can affect populations. A grassland was measured before and after a new well increased water available for plants.

Baseline condition: Year 1–2 (normal rainfall, no well) Changed condition: Year 3–4 (extra watering from the well)

Population data:

  • Wildflowers (plants per 10 m$^2$): Year 1 = 12, Year 2 = 11, Year 3 = 20, Year 4 = 24
  • Rabbits (rabbits per km$^2$): Year 1 = 18, Year 2 = 17, Year 3 = 22, Year 4 = 29
  • Hawks (hawks per 10 km$^2$): Year 1 = 6, Year 2 = 6, Year 3 = 6, Year 4 = 7

Which statement about ecosystem change is supported by the data?

The well caused hawks to stay exactly the same forever, proving ecosystem changes cannot affect predators.

Because wildflowers increased, the well must be the only cause of every population change in the grassland.

The extra water is followed by increases in wildflowers and rabbits, while hawks change little at first, showing different population responses over time.

All populations respond identically to extra water, so wildflowers, rabbits, and hawks should increase by the same percent each year.

Explanation

The core skill is analyzing data to understand how ecosystem changes affect populations over time. Ecosystems can change due to additions like a new well providing extra water to a grassland. Data, such as densities of wildflowers, rabbits, and hawks, show population responses with some increasing immediately while others lag behind. To check, examine patterns before and after the change, noting differential responses across trophic levels. A common misconception is that all species respond identically in percentage change, but food chain positions influence outcomes. By examining such data, we can explain how resource availability affects producers and then consumers. Ultimately, this helps us understand ecosystem dynamics and predict cascading effects from modifications.

10

Ecosystem changes can affect populations. A lake was monitored. Years 1–2 were baseline with normal nutrient levels. In Year 3 (changed condition), fertilizer from nearby lawns washed into the lake.

Population data:

  • Algae (water clarity index; higher number = clearer water): Year 1 = 8, Year 2 = 8, Year 3 = 5, Year 4 = 4
  • Snails (snails per square meter): Year 1 = 30, Year 2 = 29, Year 3 = 24, Year 4 = 20

Which conclusion is supported by the data?

The fertilizer runoff proves snails will never increase again in any future year.

Because fertilizer entered the lake, snails should have increased immediately; since they did not, the data must be wrong.

Only snails changed; the clarity index is just appearance and cannot be used as evidence about the ecosystem.

After fertilizer runoff begins, water clarity decreases (more algae) and snail numbers also decrease over the next years, showing evidence of population change after an ecosystem change.

Explanation

The core skill is analyzing data to understand how ecosystem changes affect populations over time. Ecosystems can change due to nutrient inputs like fertilizer runoff into a lake. Data, such as algae clarity index and snail counts, show population responses with algae increases leading to snail declines. To check, link abiotic measures like water clarity to biotic trends post-change. A common misconception is that data must show immediate effects or be invalid, but gradual changes are common. By examining such data, we can explain how eutrophication alters habitats and species. Ultimately, this helps us understand ecosystem dynamics and prevent nutrient pollution.

Page 1 of 5