AST Science Reasoning 1 — Questions and Answers
Question 1: In a controlled experiment, the variable that the researcher deliberately changes is called the:
- Independent variable (Correct answer)
- Dependent variable
- Constant variable
- Control group
Correct answer: Independent variable
The independent variable is intentionally manipulated by the researcher to observe its effect on the dependent variable.
Question 2: A student notices that plants near a window grow faster than those in a dark corner. What is the most reasonable hypothesis?
- Light exposure increases plant growth rate. (Correct answer)
- Temperature affects plant growth rate.
- Water intake determines plant growth rate.
- Soil type influences plant growth rate.
Correct answer: Light exposure increases plant growth rate.
Since the observed difference relates to proximity to a light source, the most direct hypothesis involves light exposure.
Question 3: A graph shows that as temperature increases, enzyme activity first rises then falls sharply. What can be concluded?
- Enzymes have an optimal temperature range beyond which they denature. (Correct answer)
- Higher temperatures always improve enzyme function.
- Enzymes are unaffected by temperature changes.
- Low temperatures destroy enzymes instantly.
Correct answer: Enzymes have an optimal temperature range beyond which they denature.
Enzymes function best within an optimal temperature range; excessive heat disrupts their structure (denaturation).
Question 4: Which of the following best describes a scientific theory?
- A well-substantiated explanation supported by extensive evidence (Correct answer)
- An educated guess about a phenomenon
- An absolute, unchangeable fact
- A hypothesis that has not yet been tested
Correct answer: A well-substantiated explanation supported by extensive evidence
A scientific theory is a rigorously tested explanation supported by a large body of evidence, not merely a guess.
Question 5: In an experiment, results that support the null hypothesis mean:
- No significant effect was found between variables. (Correct answer)
- The experiment proved the researcher's prediction.
- The data was unreliable and must be discarded.
- The experiment needs to be repeated immediately.
Correct answer: No significant effect was found between variables.
Supporting the null hypothesis means the data showed no statistically significant relationship between the variables tested.
Question 6: A researcher tests whether caffeine affects reaction time by giving one group coffee and another group water. The group given water is the:
- Control group (Correct answer)
- Experimental group
- Independent variable
- Dependent variable
Correct answer: Control group
The control group receives no treatment (or a placebo) to serve as a baseline comparison for the experimental group.
AST Science Reasoning 1
In a controlled experiment, the variable that the researcher deliberately changes is called the: