Living systems consist of organisms interacting with their environments. the carbon cycle is an example of a living system.

assuming the carbon cycle is a closed system, which of the following statements is true?

a. when all the fossil fuels are used up, there will be no more carbon.

b. as population sizes increase, more carbon is produced.

c. mass and energy are conserved in the carbon cycle.

d. the sun absorbs energy from the carbon cycle.

Scientists are conducting a study on the effectiveness of a new drug on memory loss. they are giving some of the test subjects the new drug to find out if it improves their long-term memory. which are possible limitations of this study? check all that apply. a) test subjects may want to participate in additional experiments. b) test subjects may think they should be paid more. c) test subjects may get bored and want to quit early. d) test subjects may have to travel during the experiment. e) test subjects may have full-time jobs. this is multiple choice. you for the !