The circulatory system transports substances such as glucose and oxygen around the body.
(a) name two other substances that the circulatory system transports around the body.

What is the answer for the complicated molecules that make up living things usually contain carbon. why is carbon so important in these molecules?

18. which statement about cancer is true?

Which of the following types of pollution is most responsible for large numbers of deaths worldwide because of unsafe drinking water? (a) nutrient pollution (b) thermal pollution (c) pathogen pollution (d) sediment pollution