What is the main function of the krebs cycle?
A. to produce large amounts of ATP molecules
B. To provide molecules for the electron transport chain
C. To produce carbon dioxide for use in the thylakoid
D. two break glucose down into two pyruvate molecules

Nobody seems to be giving a straight forward answer, and if I'm being honest I'm not entirely sure which answer it is. But I'd have to go with A - To produce large amounts of ATP molecules. Sorry if it's wrong.

an adaptation is a change or process by which an organism takes to be better suited for its environment. for example; migration is a behavioral adaptation, this is needed because birds are not built to last extremely cold climates. there are different adaptations because there are different species needing to adjust to different things, bears don't migrate; they hibernate.

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs