"The scheme below represents a hypothetical metabolic pathway for the synthesis of compound X starting with compound S, with enzymes E1-E5 carrying out the successive biochemical steps in the pathway. The pathway is regulated by feedback inhibition. Which enzyme is most likely to be inhibited and which compound is the likely inhibitor?"

volcanoes (an event in the geosphere) release a large amount of particulate matter into the atmosphere. these particles serve as nuclei for the formation of water droplets (hydrosphere). rainfall (hydrosphere) often increases following an eruption, stimulating plant growth (biosphere).

gold i'm pretty sure i might be wrong

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms

i believe your answer would be phagocytosis