1.during diffusion, when the concentration of molecules on both sides of a membrane is the same, the molecules will a) move across the membrane to the outside of the cell.
b) stop moving across the membrane.
c) continue to move across the membrane in both directions.
d) move across the membrane to the inside of the cell.
2.an animal cell that is surrounded by fresh water will burst because the osmotic pressure causes (1 point)
a) water to move into the cell.
b) water to move out of the cell.
c) solutes to move into the cell.
d) solutes to move out of the cell. 3.which of the following statements is true? (1 point)
a) during active transport, a material may be moved from an area of low concentration to an area of high concentration.
b) during passive transport, energy is used to move material against a concentration gradient.
c) during active transport, water is pumped across a membrane to equalize the concentration of salts on both sides.
d) during passive transport, osmosis allows salts to move from one side of the membrane to the other to equalize concentrations on both sides.

1. During diffusion, when the concentration of molecules on both sides of the membrane is the same, the molecules will C) continue to move across the membrane in both directions.

2. An animal cell that is surrounded by fresh water will burst because the osmotic pressure causes A) water to move into the cell.

3.  A) During active transport, a material may be moved from an area of low concentration to an area of high concentration.

Further Explanation:

1. Diffusion is the movement of solutes from an area of high concentration to an area of low concentration until equilibrium is reached. At equilibrium,  when there is no concentration gradient (i.e. the concentrations on both sides are equal), the molecules move in both directions, thereby ensuring the the concentration in both sides are maintained.

A) move across the membrane to the outside of the cell is FALSE because the  concentration of molecules inside and outside the cell is the same, therefore, equilibrium will be disturbed if molecules move outward.

B) stop moving across the membrane is FALSE because equilibrium is not a static state but a dynamic state. Solutes are constantly moving in both directions to maintain the balance in concentration.

D) move across membrane to the inside of the cell is FALSE because there is no concentration gradient, therefore, movement will be on both directions to maintain equilibrium.

2. Osmosis is the movement of water from an area of high water potential (high solvent concentration, low solute concentration) to an area of low water potential (low solvent concentration, high solute concentration). Since fresh water has lower solute concentration than the inside of the cell, the cell will have low water potential while outside it has high water potential.

B) water to move out of the cell is FALSE because the direction of movement of water has to be from high water potential to low water potential. High water potential is outside the cell so water moves from the outside to inside of the cell causing it to burst.

C) solutes move into the cell is FALSE because osmosis involves the movement of water not solutes.

D) solutes move out of the cell is FALSE because osmosis involves the movement of water due to a difference in water potential.

3. Active transport is the movement of solutes from an area of low concentration to high concentration. Since this is going against the concentration gradient, energy is needed to cause the movement.

Passive transport is the movement of solute across a concentration gradient. No energy is needed for this as it is a spontaneous occurrence.

B) During passive transport, energy is used to move material against a concentration gradient is FALSE because energy is not required during passive transport.

C) During active transport, water is pumped across a membrane to equalize the concentration of salts on both sides is FALSE because solutes are moved across a membrane not water during active transport. Movement of water is called osmosis.

D) During passive transport, osmosis allows salts to move from one side of the membrane to the other to equalize is FALSE. Osmosis is a specific type of passive transport of water, not of salts.

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Keywords: Osmosis, Active Transport, Diffusion