Active transport occurs when molecules are moved across a semi-permeable membrane and
a concentration gradient.

a)down
b)up

How do chloroplasts set plants apart from other living things

In general, characteristics that an organism survive and reproduce become more common over time. what mechanism of evolution causes this?

What would most likely happen if a person increased the amount of saturated fat in his or her diet? the person's risk of cardiovascular disease would increase. the person's risk of cardiovascular disease would decrease. the person's bad cholesterol would decrease. the person’s good cholesterol would increase.