Which of the following is the scientific research question that is being tested in the following investigation?

  1. Use the graduated cylinder to add 100 mL of tap water to a 250 mL beaker.
  2. Use a balance to measure out 75 grams of salt.
  3. Pour the salt into tap water.
  4. Start the stopwatch and begin stirring the salt and water solution.
  5. Record the time (seconds) it takes the salt to completely dissolve.
  6. Repeat two more times and average.
  7. Repeat steps 1-6 using ice water and water that has been heated to 90°C.

A. How does the amount of salt affect the dissolving rate?
Incorrect. According to the procedure, the same amount of salt is being used in each trial.

B. How does the type of water affect the dissolving rate of salt?
Incorrect. According to the procedure, tap water is being used in each trial.

C. How does temperature affect the dissolving rate of salt?
Correct!

D. Which substance, salt or sugar, has a faster dissolving rate?
Incorrect. According to the procedure, the dissolving rate of sugar and salt are not being compared.

Which of the following is the scientific research question that is being tested in the following investigation?

A scientist was working with bacteria and placed samples of the same type of bacteria in four petri dishes and supplied them with equal amounts of nutrients, oxygen, and light. The petri dishes were placed in areas with controlled temperatures. The temperature was maintained at 20°C, 22°C, 24°C, and 26°C. After three weeks of observations, the scientist counted the number of bacterial colonies that were grown.

A. How does temperature affect the growth of bacteria?
Correct!

B. How does the amount of oxygen affect the growth of bacteria?
Incorrect. According to the description, the amount of oxygen is held constant.

C. How does the amount of light affect the growth of bacteria?
Incorrect. According to the description, the amount of light is held constant.

D. How does the amount of nutrients affect the growth of bacteria?
Incorrect. According to the description, the amount of nutrients is held constant.

What is the purpose of the following investigation?

In science class, Michalea was studying the vascular system of plants. She cut the bottom off a stalk of celery and then placed the celery in colored water. She left the celery in the cup for 24 hours. When she observed the celery, she noticed that there were colored tubes in the celery stalk, which she knew was the xylem tissue. She cut off a piece of the celery and observed it under a dissecting microscope and drew her observations.

A. To determine how the color of water affects to rate of transpiration
Incorrect. The rate of transpiration is not being studied in this lab.

B. To observe the xylem of plants
Correct! The colored water was absorbed by the xylem and that is what Michalea observed.

C. To determine how much water is absorbed by celery in 24 hours
Incorrect. The amount of water that was absorbed was not measured.

D. To determine how the color of water affects photosynthesis
Incorrect. Photosynthesis is not being studied in this lab.

What is the purpose of the following investigation?

During a laboratory investigation, Cole had three unknown food samples. He placed 1 gram of each food sample into separate test tubes. He then added 2 drops of iodine to the test tube. The food samples that contained starch turned black when the iodine was added.

A. To determine which food sample had the most calories
Incorrect. The number of calories is not being determined in this experiment.

B. To determine which food samples contained protein
Incorrect. The food samples were not being tested to see if they contained proteins.

C. To determine which food samples contained lipids
Incorrect. The food samples were not being tested to see if they contained lipids.

D. To determine which food samples contained starch
Correct! The food samples were being tested to see if they contained starch.