A black hole begins to form as an aging star abruptly collapses when it ceases . *(options: gaining mass by collecting gas and dust; increases its gravitational force; emitting radiation from fusion reactions; generating heavy metals)* This occurs after the star has consumed its in this order: *(options: carbon, iron, then helium through hydrogen; iron, carbon, and helium; hydrogen, helium, then through iron; silicon, helium, hydrogen)*

Explanation:

A black hole begins to form as an aging star abruptly collapses when it ceases

. *(options: gaining mass by collecting gas and dust; increases its gravitational force; emitting radiation from fusion reactions; generating heavy metals)* This occurs after the star has consumed its in this order: *(options: carbon, iron, then helium through hydrogen; iron, carbon, and helium; hydrogen, helium, then through iron; silicon, helium, hydrogen)*

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.