What is the broadest category in the Linnaean system?

Which of the following is a reason why early living organisms on earth could not have survived on the surface? 1. the lack of an ozone layer 2. the lack of oxygen in the atmosphere 3. the fact that these organisms were single-celled

Abeaker of water was heated and then placed on a bench in the laboratory. the water cooled until it was the same temperature as the air in the laboratory. which of these explains the mechanism by which the water cooled? a. heat energy was transferred from the water to the air. b. water molecules from the water formed warm water currents. c. the water molecules absorbed energy from the molecules in the air. d. the water released radiation until it contained no heat energy.

Which of the following is the best definition of a eukaryota? a. a one-celled organism that does not have a membrane-bound nucleus b. a one-celled organism that does not have a cell wall c. an organism whose cells each contain a membrane-bound nucleus d. an organism whose cells each have a cell wall