Norman thinks that the brain function of students suffers when they receive less sleep. He predicts that students who get less sleep before an exam will receive lower test grades. To investigate his idea, he tests two groups of chemistry students. Group 1 receives four hours of sleep, while Group 2 receives the recommended eight hours of sleep the night before the exam. Both groups consume the same foods before testing. They then take the same exam in the same room. What experimental factors could have been a possible source of error in Norman's investigation? A. the food students consumed before the exam
B. the amount of sleep students received before the exam
C. the grades students earned on their exam
D. the temperature and light of the testing room

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.

There are multiple lines of evidence that provide support for common ancestry and evolution. write 3-4 paragraphs describing at least three of them in detail. provide at least one example for each line of evidence.

What is point source pollution of an aquatic ecosystem? a) pollution of freshwater sources b) pollution from many sources that combine into one c) pollution that occurs over a wide area; water that runs off from fields, parking lots, and other land surfaces d) pollution that can easily be identified with a single discharge source, such as an open pipe which drains into a body of water