Sorry this is biology, i need asap !

1). in what direction do particles naturally diffuse?

a). up concentration gradients
b). down concentration gradients
c). across concentration gradients
d). thought concentration gradients

2). what is the main difference between active and passive transport?

a). active transport involves molecules of gases: passive transport involves the molecule of lipuids

b). active transport takes place in plant cells: passive transport takes place in animal cells

c). active transport takes place in the bloodstream: passive transport takes place in cells

d). active transport requires a cell to use energy: passive transport does not

3). the cell membrane is important for because it controls what enters and leaves the cell.

a). shape
b). pressure
c). homeostasis
d). temperature