Which pair of words represent the protein found in muscle cells

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

Apopulation of black bears depends on salmon from a stream for food. if a drought causes the stream to run dry one year, how will this likely impact the black bear population?

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?