Blood usually passes through one network of capillaries from the time it leaves the heart until the time it returns, but there are exceptions, notably the .

When does the circulatory system work with the respiratory system? a. during blood cell formation b. during cellular respiration c. during intestinal digestion d. during a viral infection

Why do some dna fragments move farther than others during gel electrophoresis? a. because their shapes are different b. because they are different types of molecules c. because the samples are different colors d. because their masses are different

Everything in the universe originated from a single point. how was it possible for everything in the universe to have occupied a single point in space?