- 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.
- A student decided to set up an experiment to see if cats prefered skim milk or 2%milk. She put out a cup of milk for 5 kittens and then measured how much the kittens drank over the course of a day. The same kittens were used and the milk was served at the same temperature. The student discovered that the cats liked the 2% more than the skim milk. What is wrong with the above experiment?
Repeated experimentation is needed.
The milk should be served at different temperatures.
There are no constants present.
There is no independent variable.
- What can be concluded by looking at the graphs above?
Euglena are photosynthetic organisms.
Paramecium are photosynthetic organisms.
Both organisms are photosynthetic.
Neither of these protists are photosynthetic.
- 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 ____________.
- According to the graph, enzymes are substances that:
speed up the rate of chemical reactions
work best at specific temperatures
cease to work at certain high temperatures
all of the above
- A scientist plants two rows of corn for experimentation. She puts fertilizer on row 1 but does not put fertilizer on row 2. Both rows receive the same amount of water and light intensity. She checks the growth of the corn over the course of 5 months. What is a constant in this experiment?
Corn without fertilizer
Corn with fertilizer
Amount of water
- 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
- The measurable factor in an experiment is known as the:
- 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.
- A scientific study showed that the depth at which algae were found in a lake varied from day to day. On clear days, the algae were found as much as 6 meters below the surface of the water but were only 1 meter below the surface on cloudy days. Which hypothesis best explains these observations?
Nitrogen concentration affects the growth of algae.
Precipitation affects the growth of algae.
Light intensity affects the growth of algae.
Wind currents affect the growth of algae.