Answer:
1 = A
2 = B
3 = B
Explanation:
1) Black holes occur when really big stars collapse on themselves. And, in order to get big, the star has to be an old one.
2) A black hole is something huge that swallows up everything, while a protostar is just the very beginning of a star.
3) Scientist can't truly know for sure, but they can infer about them due to the effects of the surrounding areas.
Answer:
D
Explanation:
Cancer cells exhibit uncontrolled and disorganized growth. Formation of new blood vessels is required to bring nutrients and oxygen to cancerous tumors. Cancer cells cannot enter the cell cycle and therefore are mortal. cancer cells enter the cell cycle repeatedly, and in this way they are immortal.
