Acid precipitation lowered the pH of soil in a terrestrial e…

Acid precipitation lowered the pH of soil in a terrestrial ecosystem that supported a diverse community of plants and animals. The decrease in pH eliminated all nitrogen-fixing bacteria populations in the area. Which prediction most accurately reflects the impact this will have on the community?

Elephants are not the most abundant species in African grass…

Elephants are not the most abundant species in African grasslands, yet they influence community structure. The grasslands contain scattered woody plants, but they are kept in check by the uprooting activities of the elephants. Take away the elephants, and the grasslands are converted to forests or to shrublands. The newly growing forests support fewer species than the previous grasslands. Which of the following statements describes why elephants are the keystone species in this scenario?

A practical voltage source has an internal series resistance…

A practical voltage source has an internal series resistance RS. The practical voltage source is connected to a load resistor RL. Assume VS = {VS} V , RS = {RS} kΩ A maximum power transfer, from source to load, happens when RL = __________ kΩ (The unit of the answer is . Do NOT type the unit when you type your answer)