Which of the following is a necessary reactant for cellular respiration to occur?

carbon dioxide

nitrogen

oxygen

water

How many trophic levels are there in the following food chain? phytoplankton - shrimp - perch - pike - osprey

Describe the response the kidneys have to dehydration and excessive water intake. what happens to the concentration of urine in each case ?

Asolution of an enzyme and a substrate was placed in a water bath and the temperature of the reaction was raised gradually. the graph shown was plotted at the end of the experiment. what can be concluded from the graph? a) temperature has no effect on the activity of the enzyme. b) the effect of temperature on the enzyme is unpredictable. c) the enzyme shows increased activity up to a certain temperature. d) the activity of the enzyme is inversely proportional to the temperature.