PLEASE HELP WILL MARK BRAINLIST WHEN I CAN. Why is it important that you keep two variables constant (such as light level and color) while you're testing how a third variable(CO2 level) affects photosynthesis

The circles, or orbits, for electrons are called energy levels. each level can hold only a certain number of electrons. add electrons to each level until you can't add any more. how many electrons can each level hold?

Some birds look for food near cattle and other livestock. the movement of the cattle churns up the ground, making insects available to the birds. the cattle appear to be unaffected by the presence of the birds. what kind of relationship exists between the birds and the cattle? o a. parasitism o b. commensalism o c. predation o d. mutualism

Which short-term environmental change is most likely to lead to ground shifting, landslides, and the collapse of buildings or roads? forest fires flooding earthquakes