Question

1. a researcher studies if caffeine increases reaction time. the dependent variable is:

a) amount of caffeine
b) brand of coffee
c) reaction time measured
d) number of participants

1. if you run an experiment and get different results than expected, the best step is to:

a) ignore the results
b) change the data to match the hypothesis
c) repeat the experiment
d) stop the study

1. which of these scenarios has a poorly designed hypothesis?

a) if plants get more sunlight, then they will grow taller.
b) if sugar is added to water, then it will dissolve faster in hot water.
c) if vinegar is added to baking soda, then gas will form.
d) if soda tastes better, then students will like it more.

1. a student is testing different paper towel brands for absorbency. the dependent variable is:

a) type of paper towel
b) amount of water absorbed
c) size of towel
d) cost of towel

1. a student designs an experiment with two independent variables. why is this a problem?

a) it makes the experiment more accurate
b) it makes it harder to know what caused the results
c) it proves the hypothesis faster
d) it eliminates the need for constants

1. after many tests, the same results are observed. the data is considered:

a) unreliable
b) inconclusive
c) replicable
d) invalid

1. an experiment tests if plants grow faster in blue or red light. the control group should be:

a) plants in no light
b) plants in sunlight
c) plants in green light
d) plants in both red and blue light

1. a graph shows a direct upward line between fertilizer amount and plant height. this means:

a) more fertilizer has no effect
b) more fertilizer decreases plant growth
c) more fertilizer increases plant growth
d) the fertilizer was constant

Explanation:

1. In an experiment, the dependent variable is what is being measured. Here, reaction - time is being measured while caffeine amount is manipulated. So reaction time measured is the dependent variable.
2. When results are different from expected, the scientific approach is to repeat the experiment to check for errors or confirm the new results.
3. A good hypothesis should be testable. "If soda tastes better, then students will like it more" is subjective as "tastes better" is not objectively defined.
4. For an experiment on paper - towel absorbency, the amount of water absorbed is what is being measured (dependent variable), while paper - towel type is the independent variable.
5. Having two independent variables makes it difficult to determine which variable caused the observed results.
6. Consistent results across many tests mean the data is replicable.
7. In an experiment testing plant growth in blue or red light, plants in sunlight are the control group as sunlight is the natural light source for plants.
8. A direct upward line on a graph between fertilizer amount and plant height indicates that as fertilizer amount increases, plant height also increases.

Answer:

1. C. Reaction time measured
2. C. Repeat the experiment
3. D. If soda tastes better, then students will like it more.
4. B. Amount of water absorbed
5. B. It makes it harder to know what caused the results
6. C. Replicable
7. B. Plants in sunlight
8. C. More fertilizer increases plant growth