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📝 Predictions in scientific experiments (7 MCQs)

📖 From Campbell Biology • 1. Evolution and the theme of Biology and Scientific Inquiry • 7 questions available

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What is Predictions in scientific experiments?

Definition:
Predictions in scientific experiments are specific, measurable statements about the expected outcomes of an experiment, deduced from a hypothesis using if-then" logic and they specify what the researcher will observe if the hypothesis is correct and they are crucial because they allow the hypothesis to be tested empirically providing a clear criterion for determining whether the hypothesis is supported.

Working:
Predictions work by stating a concrete result that is expected under certain conditions often in the form "If the hypothesis is true then we will observe [specific measurable outcome] in the experiment"; for example if a hypothesis states that light intensity affects photosynthesis the prediction could be "If light intensity is increased then the rate of oxygen production will increase and the experiment is then designed to measure oxygen production under different light intensities, and the data are compared to the prediction.

Example:
A simple example is predicting that plants grown with more water will be taller; if the hypothesis is Water increases plant height the prediction is If plants receive 100 mL of water per day they will be taller than plants receiving 50 mL per day and measuring the heights after two weeks tests this prediction.

Reason:
Predictions are vital because they translate abstract hypotheses into concrete, testable outcomes, making the scientific method operational and enabling objective evaluation, and they guide the design of experiments and the interpretation of results, ensuring that data can be meaningfully linked to hypotheses.

Easy

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Hard

📝 All Predictions in scientific experiments MCQs

Q1. A researcher predicts that if a plant receives less water, its average growth rate will decrease. Which feature makes this a useful scientific prediction?

A.It is guaranteed to occur under every environmental condition

B.It can be compared with observations collected after changing water availability ✅

C.It describes why all plants need water

D.It is based only on the researcher's personal expectation

💡 Difficulty: easy | ✅ Correct: B

📖 Explanation: A useful scientific prediction produces an expected observable outcome that can be compared with evidence. Here, growth rate can be measured after changing water availability, allowing the prediction to be supported or challenged by data.

Q2. Two competing explanations predict different outcomes when temperature increases. Explanation X predicts faster growth, while Explanation Y predicts slower growth. Which experiment would best distinguish between them?

A.Measure growth only before changing temperature

B.Measure growth at several temperatures while keeping other major conditions controlled ✅

C.Allow temperature and nutrient concentration to change simultaneously

D.Choose the explanation that seems more biologically reasonable before collecting data

💡 Difficulty: medium | ✅ Correct: B

📖 Explanation: The strongest test changes the relevant variable while controlling other important factors and measures the response. Testing several temperatures provides evidence that can distinguish the opposing predictions rather than relying on assumptions.

Q3. A biologist observes that insects are more abundant near flowering plants and predicts that removing flowers will reduce insect abundance. After flowers are removed, insect numbers remain unchanged. What is the best interpretation?

A.The original prediction is supported because insects were previously observed near flowers

B.The prediction failed under the tested conditions, so the proposed explanation should be reconsidered ✅

C.The observation proves that flowers have no relationship with insects

D.The experiment automatically proves a different explanation is correct

💡 Difficulty: medium | ✅ Correct: B

📖 Explanation: The unchanged insect abundance does not match the predicted outcome, so the prediction was not supported in this test. This result does not prove the explanation impossible, but it provides evidence requiring reconsideration or further testing.

Q4. A student predicts that fertilizer will increase plant height. The fertilizer group grows taller, but it also receives more sunlight than the control group. The student concludes that fertilizer caused the difference. What is the main error?

A.The prediction was too specific to test

B.The measured outcome was qualitative rather than quantitative

C.A second variable changed, preventing a clear attribution of the effect to fertilizer ✅

D.Plant height can never be used to test predictions

💡 Difficulty: hard | ✅ Correct: C

📖 Explanation: The conclusion is weakened because fertilizer and sunlight were changed together. Since both factors could influence growth, the experiment cannot isolate fertilizer as the cause. A controlled comparison should keep sunlight equivalent between groups.

Q5. A model predicts that population size will increase when food availability rises. The observed results are shown below: Food level = 1, 2, 3, 4; Observed population = 20, 29, 39, 38. Which conclusion is most justified?

A.The prediction is perfectly confirmed because population increased initially

B.The prediction is completely disproved because the final value decreased slightly

C.The data support the predicted trend at lower food levels but suggest that another factor may limit population growth at higher food availability ✅

D.The population must have increased continuously because food availability increased continuously

💡 Difficulty: hard | ✅ Correct: C

📖 Explanation: The population rises as food availability increases from levels 1 through 3, matching the predicted direction, but then declines slightly at level 4. This suggests food may influence population size while another limiting factor becomes important.

Q6. A researcher predicts that increasing exercise duration will increase heart rate. In one trial, heart rate rises from 90 to 120 beats per minute as exercise increases from 5 to 15 minutes, but in another trial it rises only from 90 to 105. Which approach gives the strongest evaluation of the prediction?

A.Use only the first trial because it shows the expected pattern

B.Use only the second trial because it is more conservative

C.Repeat controlled trials and examine the overall pattern and variability before deciding whether the prediction is supported ✅

D.Average the starting heart rates and assume the prediction is correct

💡 Difficulty: medium | ✅ Correct: C

📖 Explanation: Predictions should be evaluated using repeated evidence rather than a single favorable or unfavorable result. Replication helps determine whether the observed relationship is consistent and whether variation between trials affects confidence in the predicted pattern.

Q7. Two researchers predict the effect of light intensity on photosynthesis. Researcher A predicts a steady increase at all intensities, while Researcher B predicts an increase followed by a plateau. If measured photosynthesis rises rapidly at low intensity and then changes very little at high intensity, which prediction is better supported?

A.Researcher A, because photosynthesis increases at some intensities

B.Researcher B, because the observed pattern includes an increase followed by little further change ✅

C.Both predictions equally, because both mention increasing light

D.Neither prediction, because biological predictions cannot describe patterns

💡 Difficulty: easy | ✅ Correct: B

📖 Explanation: The observed pattern contains two phases: photosynthesis increases at lower light intensities and then approaches a plateau. This closely matches Researcher B's predicted pattern, whereas Researcher A incorrectly expects continued increases at every intensity.

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