Ascientist is trying to determine whether the use of cell phone contributes to brain cancer. for his study, he compares the medical records of subjects who have been diagnosed with brain cancer to the records of healthy subjects. what is the most significant weakness in this type of study?

What is called the "building block" of life?

After getting the slide and microscope ready, stella is eager to see the microscopic pond water specimen! she crouches around her microscope and aligns her eye with the microscope’s eyepiece. but she's only able to see a bright white light. at this point, no specimens or cells are visible on stella's pond water slide. after taking a moment to collect her thoughts, stella realizes she can't see any lifeforms because .

Which part of cellular respiration must occur before any of the other steps can occur