Do you think that there were plants and animals in the past that we will never know existed?

When should a bar graph be used? a. when there is no independent variable. b. when the independent variable is continuous and does not show a relationship to the dependent variable. c. when the independent variable is continuous and shows a causal link to the dependent variable. d. when the independent variable is composed of categories and does not show a relationship.

The study of interaction between living organisms and their enviroment is called (a) phytogeography (b) ecology (c) phytosociology (d) ecosystem

Which of the following statements about archaea and bacteria is true? a. neither is single-celled. b. they both have nuclear membranes. c. neither reproduces by binary fission. d. they both lack a nuclear membrane.