The nutrient content and oxygen levels in streams and rivers often change from one part to another. Drag and drop the tiles to match the relative oxygen levels and zones of the river to its corresponding nutrient levels. Also, place the picture of an organism that would most likely inhabit each zone.

Which of these has happened to your food by the time it reaches your small intestine? a. all the macromolecules have been broken down completely. b. lipids and starches have been partially broken down. c. starches and proteins have been partially broken down. d. proteins and lipids have been broken down into subunits.

Describe how a non-resistant staphylococcus aureus bacterium can produce a bacterium that is resistant to methicillin

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