An example of a grad-school level question?
Which property of an element is determined by adding the number of protons and number of neutrons?

An example of a grad-school level question?
Which of the following is a harmful waste material that leaves the blood and travels through the lungs before leaving the body?

An example of a grad-school level question?
Photosynthesis is the process that converts carbon dioxide and water into

An example of a grad-school level question?
Which of these is the best definition of heredity?