Evaluating experiments (research summaries)

Question 1

Experiment 1: Seeds were kept at 10 °C, 20 °C and 30 °C, all watered daily, and the number that germinated was counted. Experiment 2: Seeds were kept at 20 °C and given 0, 5 or 10 mL of water a day. In Experiment 2, which variable was changed on purpose?

• A. the number of seeds that germinated
• B. the temperature
• C. the colour of the pots
• D. the volume of water

Question 2

A scientist tests a new fertiliser on 20 tomato plants. Another 20 plants get no fertiliser. What is the purpose of the second group?

• A. It is a control group to compare against.
• B. It is not needed.
• C. It makes the experiment faster.
• D. It increases the dependent variable.

Question 3

Experiment 1: A pendulum with a 0.5 kg bob was timed for 10 swings with string lengths of 0.25 m, 0.50 m and 1.00 m. Experiment 2: A 1.00 m pendulum was timed with bobs of 0.1 kg, 0.5 kg and 1.0 kg. Which variable was kept constant in Experiment 2 but changed in Experiment 1?

• A. the mass of the bob
• B. the temperature of the room
• C. the string length
• D. the time for 10 swings

Question 4

Experiment 1: Seeds were kept at 10 °C, 20 °C and 30 °C, all watered daily, and the number that germinated was counted. Experiment 2: Seeds were kept at 20 °C and given 0, 5 or 10 mL of water a day. In Experiment 2, which variable was changed on purpose?

• A. the number of seeds that germinated
• B. the temperature
• C. the colour of the pots
• D. the volume of water

Question 5

Hypothesis: "Plants grow faster in blue light than in red light." Which experiment tests it best?

• A. One plant in blue light outdoors and one in red light indoors
• B. Plants in blue light only
• C. Identical plants under blue or red lamps of equal brightness, same water and temperature
• D. Different species under the same lamp

Question 6

Experiment 1: A student dropped the same ball from heights of 0.5 m, 1.0 m and 1.5 m onto a wooden floor and measured the bounce height. Experiment 2: The student dropped the same ball from 1.0 m onto wood, carpet and concrete. Which variable was kept constant in Experiment 2 but changed in Experiment 1?

• A. the mass of the ball
• B. the floor surface
• C. the bounce height
• D. the drop height

Question 7

Experiment 1: Seeds were kept at 10 °C, 20 °C and 30 °C, all watered daily, and the number that germinated was counted. Experiment 2: Seeds were kept at 20 °C and given 0, 5 or 10 mL of water a day. In Experiment 2, which variable was changed on purpose?

• A. the temperature
• B. the volume of water
• C. the colour of the pots
• D. the number of seeds that germinated

Question 8

In a drug trial, neither the patients nor the doctors know who gets the real drug. Why?

• A. To save money
• B. To stop expectations from biasing the results
• C. Because the drug is secret
• D. To make the trial shorter

Question 9

Experiment 1: A student dropped the same ball from heights of 0.5 m, 1.0 m and 1.5 m onto a wooden floor and measured the bounce height. Experiment 2: The student dropped the same ball from 1.0 m onto wood, carpet and concrete. Which variable was kept constant in Experiment 2 but changed in Experiment 1?

• A. the bounce height
• B. the floor surface
• C. the mass of the ball
• D. the drop height

Question 10

Experiment 1: A student dropped the same ball from heights of 0.5 m, 1.0 m and 1.5 m onto a wooden floor and measured the bounce height. Experiment 2: The student dropped the same ball from 1.0 m onto wood, carpet and concrete. In Experiment 2, which variable was changed on purpose?

• A. the drop height
• B. the bounce height
• C. the floor surface
• D. the mass of the ball

Question 11

A scientist tests a new fertiliser on 20 tomato plants. Another 20 plants get no fertiliser. What is the purpose of the second group?

• A. It is not needed.
• B. It is a control group to compare against.
• C. It increases the dependent variable.
• D. It makes the experiment faster.

Question 12

Experiment 1: A student dropped the same ball from heights of 0.5 m, 1.0 m and 1.5 m onto a wooden floor and measured the bounce height. Experiment 2: The student dropped the same ball from 1.0 m onto wood, carpet and concrete. Which variable was kept constant in Experiment 2 but changed in Experiment 1?

• A. the mass of the ball
• B. the drop height
• C. the floor surface
• D. the bounce height

Question 13

Experiment 1: A student dropped the same ball from heights of 0.5 m, 1.0 m and 1.5 m onto a wooden floor and measured the bounce height. Experiment 2: The student dropped the same ball from 1.0 m onto wood, carpet and concrete. In Experiment 2, which variable was changed on purpose?

• A. the bounce height
• B. the mass of the ball
• C. the drop height
• D. the floor surface

Question 14

Hypothesis: "Plants grow faster in blue light than in red light." Which experiment tests it best?

• A. Plants in blue light only
• B. Identical plants under blue or red lamps of equal brightness, same water and temperature
• C. Different species under the same lamp
• D. One plant in blue light outdoors and one in red light indoors

Question 15

Experiment 1: Seeds were kept at 10 °C, 20 °C and 30 °C, all watered daily, and the number that germinated was counted. Experiment 2: Seeds were kept at 20 °C and given 0, 5 or 10 mL of water a day. Which variable was kept constant in Experiment 2 but changed in Experiment 1?

• A. the colour of the pots
• B. the volume of water
• C. the temperature
• D. the number of seeds that germinated

Question 16

Experiment 1: Magnesium ribbon was added to hydrochloric acid at concentrations of 0.5, 1.0 and 2.0 mol/dm³ at 25 °C, and the gas volume after 1 minute was measured. Experiment 2: The 1.0 mol/dm³ acid was used at 15 °C, 25 °C and 35 °C. In Experiment 2, which variable was changed on purpose?

• A. the colour of the magnesium
• B. the acid concentration
• C. the volume of gas after 1 minute
• D. the temperature