Across the three experiments, the relationship between the independent and dependent variables is:
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30 questions
Across the three experiments, the relationship between the independent and dependent variables is:
Set 1 — Two scientists explain a decline in pond fish populations.
At Lake Marisol, populations of native fish have fallen by roughly over the past decade. Water samples and biological surveys are available.
Scientist 1. The decline is driven by rising water temperatures. Average summer surface temperatures have risen by over the same period. Most of the native species spawn within a narrow temperature window, and warmer water also reduces dissolved oxygen. Surveys show that during the hottest summers, native fish are concentrated near a cool deep-water spring rather than in their usual shallow-water habitat, consistent with thermal stress.
Scientist 2. The decline is driven by an invasive predator fish introduced from a connected stream around the same time. Stomach contents from sampled invasive individuals contain juvenile native fish in roughly of dissections, and the invasive population grew over the decade. The same native species that declined in Lake Marisol have remained stable in a nearby lake where the invasive species is not present, despite similar temperature trends.
According to Scientist 1, which observation most directly supports the claim that temperature drives the native fish decline?
Based on Set 1, what is the central observation Scientist 2 uses to argue AGAINST Scientist 1's temperature explanation?
Based on the data in Experiment 1, what additional conclusion is best supported by comparing trials 4 and 5?
Based on Experiment 3, suppose the team found that Method A reads about mg/dL HIGHER than Method B on every volunteer. What conclusion is best supported?
Experiment 1. A biology student measured the reaction rate of an enzyme at six different temperatures while keeping pH and substrate concentration constant. The data are shown below.
| Trial | Temperature (°C) | Reaction rate (μmol/min) |
|---|---|---|
| 1 | 10 | 1.2 |
| 2 | 20 | 2.8 |
| 3 | 30 | 5.1 |
| 4 | 40 | 8.2 |
| 5 | 50 | 6.5 |
| 6 | 60 | 2.3 |
According to the data, at what temperature was the reaction rate highest?
Experiment 2. An environmental scientist studied how tree-ring width varies with rainfall in the year the ring grew. She sampled trees from a single forest, measured ring widths for different years, and looked up that year's total rainfall.
| Year sampled | Total rainfall (cm) | Average ring width (mm) |
|---|---|---|
| 1991 | 38 | 2.1 |
| 1995 | 52 | 3.0 |
| 2003 | 71 | 4.4 |
| 2010 | 65 | 4.0 |
| 2018 | 45 | 2.5 |
Which of the following best characterizes Experiment 2's design?
Experiment 2. A physics class hung known masses from a vertical spring and measured the resulting extension. The setup was kept in a temperature-controlled room.
| Mass (g) | Extension (cm) |
|---|---|
| 100 | 2.0 |
| 200 | 4.0 |
| 300 | 6.0 |
| 400 | 8.0 |
| 500 | 10.0 |
According to the data in Experiment 2, what is the extension when a mass is hung?
Compare the results of Experiment 1 (enzyme rate vs. temperature) and Experiment 2 (extension vs. mass). Which statement best characterizes the difference?
Based on Set 1, both scientists could agree on which of the following?
Based on Experiment 2, what specific change would strengthen the design as a test of the causal effect of rainfall on ring width?
Based on Experiment 1, why was it important that all pots received the same volume of water?
Based on Experiment 2, in which year did the trees grow rings widest, and how does that year's rainfall compare?
Experiment 1. A botany student tested how soil pH affects the growth of tomato seedlings. She prepared four identical pots with sterile potting soil, watered each with the same volume of water buffered to a specific pH, and recorded the seedling height after days under identical light and temperature.
| Pot | Soil pH | Height after 14 days (cm) |
|---|---|---|
| 1 | 4.5 | 3.2 |
| 2 | 5.5 | 7.1 |
| 3 | 6.5 | 9.4 |
| 4 | 7.5 | 5.8 |
In Experiment 1, what is the independent variable?
Based on the data in Experiment 1, if the student had run an additional trial at , the reaction rate would most likely have been:
Based on Set 2, what observation would Researcher 2 expect that Researcher 1 would NOT necessarily expect?
Set 2 — Two researchers explain why a battery's voltage declines faster in cold weather.
Field technicians have noticed that car batteries lose voltage faster on cold mornings than on warm ones, especially when the temperature drops below .
Researcher 1. The decline is caused by reduced chemical reaction rates at low temperatures. Battery chemistry depends on ions moving through an electrolyte; at lower temperatures the ions move more slowly, so the rate at which the battery can deliver current is reduced. Lab measurements of identical batteries at temperatures from to show that the achievable peak current drops smoothly as temperature falls. This effect is fully reversible — when the battery warms up, it works normally again.
Researcher 2. The decline is caused by increased mechanical load on the engine in the cold. Engines are harder to crank in the cold because oil is more viscous and internal friction is higher, drawing far more current from the battery during a cold start than during a warm start. The battery is not failing chemically; it is being asked to deliver much more energy per start. As soon as engines start more easily (warmer weather, lighter oil), the same battery performs normally.
According to Researcher 1, what is the underlying cause of poor cold-weather battery performance?
Based on Experiment 3, what is the most likely salinity at km from the river mouth?
Among Experiments 1, 2, and 3, which best demonstrates a relationship that levels off as the independent variable increases?
Based on Set 2, what finding would MOST SUPPORT Researcher 2 over Researcher 1?
Based on Experiment 3, if the team had measured salinity at km, the value would most likely be:
Based on Set 1, which finding, if newly discovered, would MOST SUPPORT Scientist 2's hypothesis?
Across all three experiments, which one best supports a CAUSAL claim about the independent variable's effect on the dependent variable?
Based on the data in Experiment 1, what best describes the relationship between temperature and reaction rate from to ?
Based on Set 1, which finding, if newly discovered, would MOST WEAKEN Scientist 1's hypothesis?
Based on Experiment 1, what additional trial would most help refine the conclusion about the optimal pH for tomato seedling growth?
Experiment 3. A clinical team compared two methods for measuring blood glucose: a finger-stick monitor (Method A) and a continuous-glucose sensor patch (Method B). Both methods were used on the same volunteers, and each volunteer's measurement was repeated times by each method. Average readings (mg/dL) for each volunteer were compared.
Which of the following is the most important reason both methods were used on every volunteer?
Across Set 1 and Set 2, what common reasoning pattern do the scientists use to support their hypotheses?
Based on Experiment 1, what factor was held constant across all four pots?
Based on Set 2, what would both researchers likely AGREE on?