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

Option A and D

Explanation:

This experiment is about studying the effect caused on test grades of the student by the number of hours of sleep taken by them before the exams. Therefore, there is least chance of making a mistake in the variable "hour of sleep" as it is the main independent variable whose impact is to be studied on grades.  

Also grades earned are the dependent variable which is easily measurable hence chances of making mistakes in this variable are also less.  

However, the light and temperature of the room in which students were allowed to sleep may not be as per the requirement of all the students, therefore some kind of error may occur due to this variable.  

Likewise the food provided to the students may not be as per the requirement and likeliness of each and every student. Hence, it also becomes a source of error.

oak trees? ? what was listed

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."