17. The DDT story is an example of how scientists who work in one area (pesticides) caused harm in another (environment) without meaning to do so. How can this be avoided in the future?
A. Scientists must communicate their data publicly so that other scientists see them.
B.
Less experimentation must be done before
pesticides are released.
C. Scientists should not try to improve products due to potential harm.
D.
Only the government should develop potentially harmful pesticides.

18 Which of the following do viruses and living cells have in common?
A. the ability to adapt
B. the ability to create energy
C. the ability to respond to the environment
D. the ability to carry out complex metabolic activities with organelles

19 What does a virus need in order to reproduce?
A. a host cell
B. sunlight
C. extra protein
D. a vaccine

20 What products of photosynthesis are used in cellular respiration?
A. water and sugar
B. carbon dioxide and water
C. oxygen and sugar
D. oxygen and water