Movements In Cells

Question 1

What is the definition of water potential?

Answer 1

The ability of free water molecules to move in or out of the system

Question 2

What is the definition of osmosis?

Answer 2

The movement of water from an area of high water potential to an area of low water potential, down a water potential gradient through a partially permeable membrane

Question 3

What sort of process is osmosis?

Answer 3

It is a passive process

Question 4

What is water potential measured in

Answer 4

kPa- as a pressure

Question 5

Where does osmosis tend to occur?

Answer 5

Through an aquaporin and a small volume also through the phospholipid bilayer

Question 6

What molecules diffuse by osmosis?

Answer 6

Only water

Question 7

What is the highest water potential possible

Answer 7

0 kilopascals

Question 8

Does a dilute solution have a high or low water potential?

Answer 8

High

Question 9

What alternative unit can be used for or the concentration of a solution?

Answer 9

M for molar

Question 10

What does hypertonic mean in regards to a solution surrounding a cell

Answer 10

Water potential of the solution is lower than the cell. Water leave the cell down a water potential gradient by osmosis. There is more water in the cell relatively

Question 11

What are the rules for describing how a cell behaves in a solution?

Answer 11

Which area has a higher water potential? Say which way the water will move down a water potential gradient by osmosis. State the consequence of that on the cell and and whether the solution was hypotonic hypertonic or isotonic

Question 12

What is a hypotonic solution

Answer 12

Water potential of the solution is higher than the cell. Water enters by osmosis down a water potential gradient. there is less water relatively inside the cell

Question 13

What does isotonic mean in regards to a solution?

Answer 13

Water potential is equal between cell and solution. Therefore, water enters and exits the cell, but there is no net gain and the movement of water is at equilibrium.

Question 14

What is incipient plasmolysis in a plant tissue?

Answer 14

Where the solution is said to be isotonic according to the water potential at which the number of cells plasmolysed and turgid are equal. Incipient plasmolysis is the exact point at which the cell membrane is no longer forced against the cell wall. When [weird trident]p = 0kPa

Question 15

What happens to an animal cell that is in a hypotonic solution?

Answer 15

Water moves inside the cell and the cell membrane breaks allowing the nucleus to move out. The cell undergoes lysis and bursts. When this occurs with a red blood cell it is called haemolysis.

Question 16

What happens to an animal cell in a hypertonic solution?

Answer 16

It creates / shrinks

Question 17

What happens to an animal cell in a isotonic solution?

Answer 17

It is functional and normal

Question 18

What happens to a plant cell in a isotonic solution?

Answer 18

The vacuole and cytoplasm begin to shrink. The cell is said to be at incipient plasmolysis. The cell wall is freely permeable

Question 19

How is pressure potential created ?

Answer 19

Because the cell wall is rigid like a reaction force in contact forces

Question 20

What happens to a plant cell that is placed in a hypotonic solution ?

Answer 20

The cell is said to be turgid. As water enters by osmosis, the cytoplasm and vacuole swells. This creates an outward pressure called solute potential ([weird trident]s) exerted onto the cell wall. The cell will create an inward pressure to oppose it, pressure potential ([weird trident]p). Water constantly goes in as it is being used in photosynthesis. At full turgor ([weird trident]s) = ([weird trident]p)

Question 21

What happens when a plant cell is placed in a hypertonic solution?

Answer 21

The cell is said to be flaccid and plasmolysis having a occurred. The cytoplasm and the vacuole shrink due to lack of water and the cell membrane pulls away from the cell wall. This leaves crystals of solute between the cell membrane and cell wall. ([weird trident]p) = 0kPa

Question 22

What is ([weird trident]s)?

Answer 22

The solute potential which is the outward pressure exerted onto the cell by the cytoplasm when the cell is turgid. It is measured like water potential and is always negative

Question 23

What is ([weird trident]p)?

Answer 23

The pressure potential which is the inward pressure created by the cell wall to oppose the force of the solute potential. It acts when cell is turgid. It is the force of the cell wall on the cell. It is always positive or 0 but has the same units as water potential.

Question 24

([weird trident]cell) =

Answer 24

([weird trident]s) + ([weird trident]p)

Question 25

What is endocytosis?

Answer 25

The bulk movement of material into the cell that uses ATP. The the membrane invaginates to engulf the large molecule / microorganism. Then the member fuses back together to form of the circle surrounding its contents.

Question 26

Give an example of endocytosis

Answer 26

The phagocytosis of microorganisms

Question 27

What is exocytosis?

Answer 27

The bulk movement of material out of the cell (secretion) using ATP. The vesicle with it’s contents migrates to the cell plasma membrane. Then it combines with the plasma membrane and the contents are released from the cell.

Question 28

Give an example of exocytosis

Answer 28

Secretion of hormones.