Sarah designed an experiment to find out which mouthwash was most effective against some bacteria. She cut out four different circles from a paper towel and soaked each circle in a different mouthwash. She put the circles on a nutrient agar-coated petri dish that was covered with bacteria commonly found in the mouth. She then incubated the plate for 24 hours. The picture shows the results of this test. Which of the following should Sarah do to improve her experiment?

• Use different kinds of bacteria.
• Use the same type of mouthwash on each paper circle.
• Use the same size paper circles for all mouthwashes.
• Use a smaller petri dish.

An experiment for a new asthma medication was set up into two groups. Group one was given the new drug for asthma, while group 2 was given a sugar pill. The sugar pill serves as a ____________.

• control
• constant
• experimental variable
• dependent variable

Which sentence best states the importance of using control groups?

• Control groups eliminate the need for large sample sizes, reducing the number of measurements needed.
• Control groups eliminate the need for statistical tests and simplify calculations.
• Control groups provide a method by which statistical variability can be reduced.
• Control groups allow comparison between subjects receiving a treatment and those receiving no treatment.

A student decides to set up an experiment to see if detergent affects the growth of seeds. He sets up 10 seed pots. 5 of the seed pots will receive a small amount of detergent in the soil and will be placed in the sun. The other 5 seed pots will not receive detergent and will be placed in the shade. All 10 seed pots will receive the same amount of water, the same number of seeds, and the same type of seeds. He grows the seeds for two months and charts the growth every 2 days. What is wrong with his experiment?

• More than one variable is being tested.
• The student should have a larger number of pots.
• There is no way of measuring the outcome.
• There is no control set-up.

Express your answer to the nearest mL.

Express your answer to the nearest mL.

Express your answer to the nearest 0.1 mL.

Fuels that are renewable and produced from living things are referred to as _______fuels. What prefix would go in the blank. A definition for the prefix is shown in bold letters in the question. Just write the prefix and use all lowercase letters.

The creation of heat within the body is known as ___________genesis. What prefix would go in the blank. A definition for the prefix is shown in bold letters in the question. Just write the prefix and use all lowercase letters.

Two creatures that share the same or similar external structures may be described as ___________morphic. What prefix would go in the blank. A definition for the prefix is shown in bold letters in the question. Just write the prefix and use all lowercase letters.