Which of the following is the best definition of a pollutant?
a. a natural resource that humans overuse
b. a human activity that destroys habitats
c. a harmfal substance released into the environment
d. a species that humans introduce into an ecosystem

Students in biology are studying the macromolecules of life. they used a calorimeter to determine the calories in various types of food. once the lab was completed, the students ate the left over food samples. monica commented that in just 6 or 7 "chews" of the saltine, it was gone; nothing but a sticky paste in her mouth. elaborate on what happened chemically while chewing the saltine. include the macromolecules present.

Which of these statements is true about autotrophs, but not heterotrophs? a. they use sugar and oxygen to make carbon dioxide and water. b. they use chlorophyll and oxygen to make carbon dioxide and water. c. they use sunlight, water, and carbon dioxide to make sugars. d. they use sunlight, water, and oxygen to make chlorophyll.

The best instrument to use to separate the liquid portion from the solid portions in whole blood is a(an) a. compound light microscope. c. test tube. b. centrifuge. d. electron microscope.