Year after year, Xavier raises a vegetable garden in the same plot of soil. He observes that the plants grow less abundantly from one year to the next, and they produce fewer vegetables. Which of these processes could help explain Xavier's observations?

A. the rate at which soil bacteria perform photosynthesis
B. the rate at which soil bacteria perform denitrification
C. the rate at which soil bacteria perform nitrogen fixation
D. the rate at which soil bacteria perform chemosythesis

Which muscle is responsible for inhalation ?

Which member of the following food chain will be least affected by ddt, a pesticide water pollutant, if bio-magnification is occurring? algae> zooplankton> crayfish> leopard frog> large mouth bass

Scientists are conducting a study on the effectiveness of a new drug on memory loss. they are giving some of the test subjects the new drug to find out if it improves their long-term memory. which are possible limitations of this study? check all that apply. a) test subjects may want to participate in additional experiments. b) test subjects may think they should be paid more. c) test subjects may get bored and want to quit early. d) test subjects may have to travel during the experiment. e) test subjects may have full-time jobs. this is multiple choice. you for the !