Bio Scientific Method Review

To study whether chocolate helped students perform well on their tests, Mrs. Rodriguez gave Amaya a piece of chocolate before every test during summer school.  At the end of the summer she analyzed Amaya’s test scores and concluded that chocolate does help students perform well on their tests.  What is a source of error in this experimental design?

• She should have given Amaya a different brand of chocolate before each successive test.
• She should have also given Amaya apples before each test
• She should have conducted this experiment on more than one student.
• She should have given Amaya two versions of each test to measure how she performed on each one.

Scientists use observations and data to form and test

• Constants
• Hypotheses
• Theories
• Conclusions

During a controlled experiment, a scientist isolates and tests

• A conclusion
• A mass of information
• A control group
• A single variable

A student hypothesized that lettuce seeds would not sprout (germinate) unless they were exposed to darkness.  The student planted 10 lettuce seeds under a layer of soil and scattered 10 lettuce seeds on top of the soil. The data collected are shown in the table above. One way to improve the validity of these results would be to

• Conclude that darkness is necessary for lettuce seed germination
• Conclude that light is necessary for lettuce seed germination
• Revise the hypothesis
• Repeat the experiment

A scientist noticed that the number of salamanders in ponds in the Rocky Mountains was decreasing. This is an example of

• A hypothesis
• An observation
• A theory
• A control

To study whether the average house cat prefers a chicken-based food or a vegetable-based food, Arianna provided her cat with access to each kind of food throughout the day. What is a source of error in this experimental design?

• She should have provided a third kind of food
• She should have conducted this experiment on more than one cat
• She should have provided a third kind of food
• She should have provided more of one kind of food than the other

A piece of refrigerated, cooked meat will remain safe to eat for a longer period of time than a refrigerated piece of raw meat of a similar size. Which statement is a valid inference based on this information?

• Cooking meat kills many bacteria and fungi
• Cool temperatures stimulate the growth of microbes on raw meat
• Raw meat cannot be preserved
• Cooked meat contains antibodies that destroy decomposers

A marine biologist noticed that a sea otter and her pup were using bottle tops to crack open sea urchin shells. Which of the following would be an appropriate hypothesis to study this observation?

• Is tool-use a learned behavior?
• Tool-use is a learned behavior among sea otters
• How do female sea otters teach their pups to use tools?
• If a female sea otter knows how to use a tool, then so will her pups.

Harvester ants often strip a bush of all of its leaves. Some people believe this helps the plant grow thicker healthier stems. In an experiment, a student stripped off all the leaves from a set of plants. In a second set of identical plants, the student allowed ants to strip off the plants’ leaves. In order to improve this experimental design, it is most important to add a set of plants – 

• Of a different species
• With its leaves left intact
• Exposed to a different ant species
• That are dormant

 A student performed an experiment to see if water temperature affects the level of activity in aquatic snails. The student set up four tanks with five snails in each tank. All four of the setups were identical in every way, except for the temperature of the water. In order to make the conclusions more valid, the student could

• alter the pH of the water
• change the size of the tank
• carry out the experiment for a shorter period of time
• use a larger number of snails