Lab One 1A And 1C

Front 1

What is the purpose of lab 1A?

Back 1

To investigate the processes of diffusion and osmosis in a dialysis tubing and investigate the effect of solute concentration on water potential as it relates to living plant tissues

Front 2

What does Diffusion mean?

Back 2

The random movement of molecules from an area of higher concentration of those molecules to an area of lower concentration

Front 3

What does Osmosis mean?

Back 3

The diffusion of water throgh a selectively permeable membrane from a region of higher water potential to a region of lower water potential

Front 4

What is water potential?

Back 4

The measure of free energy of water in a solution

Front 5

What is active transport?

Back 5

It moves substances against a concentration gradient, from regions of low concentration of that substance into regions of higher concentrations

Front 6

What will you do in 1a?

Back 6

You will measure diffusion of small molecules through dialysis tubing

Front 7

What is dialysis?

Back 7

The movement of a solute through a selectively permeable membrane

Front 8

What will you do in 1C?

Back 8

You will use potato cores placed in different molar concentrations of sucrose in order to determine the water potential of potato cells

Front 9

Water Potential?

Back 9

The movement of water into or out of plant cells

Front 10

Where does water move to?

Back 10

Water always move from an area of higher water potential to an area of lower water potential

Front 11

What are the two physical factors water potential is affected by?

Back 11

One factor is the addition of solute which lowers the water potential

The other factor is pressure potential where an increase in pressure raises the water potential

Front 12

What is the movement of water into and out of a cell influenced by?

Back 12

Solute Potential

Front 13

What happens when water moves out of a cell?

Back 13

The cell will shrink

Front 14

What happens when water moves into an animal cell?

Back 14

It will swell and maybe burst

Front 15

What happens when water moves into a plant cell?

Back 15

The presence of a cell wall prevents cells from bursting as water enters the cell

Front 16

What happens when water enters a dialysis bag or a cell with a cell water?

Back 16

Pressure will develop inside the bag or cell as water pushes against the bag or cell wall.
The pressure would cause the water to rise in an osmometer tube or increase the pressure on a cell wall.

Front 17

What is the solute potential?

Back 17

It is the effect that solutes have on a solution's overall water potential

Front 18

What is pressure potential?

Back 18

Pressure potential is usually positive in living cells; in dead xylem elements it is often negative.

Front 19

What is the value of water potential?

Back 19

The water potential value can be positive, zero or negative

Front 20

What is the value of solute potential?

Back 20

Solute potential is always negative

Front 21

When in a solution and the inside of a potato cell is separated from pure water by a permeable cell membrane, what happens?

Back 21

The water will move (by osmosis) from the surrounding water where water potential is higher into the cell where water potential is lower

Front 22

What happens when water potential of the cell equals the water potential of the pure water outside the cell?

Back 22

A dynamic equilibrium is reached and there will be no net water movement

Front 23

what happens when you add solute to the water outside the potato cells?

Back 23

the water potential of the solution surrounding the cells would decrease

Front 24

What happens when enough solute is added to the water outside the cells?

Back 24

Water will leave the cells, moving from an area of higher water potential to an area of lower water potential. The loss of the water from the cells will cause the cells to lose turgor. A continued loss of water will eventually cause the cell membrane to shrink away from the cell wall (plasmolysis)