Topic 4- Cell Transport Mechanisms

Question 1

What is passive transport?

Answer 1

Is transport that takes place as a result of concentration, pressure or electrochemical gradients and involves no energy from a cell.

Question 2

What is active transport?

Answer 2

Is the movement of substances into and out of our cells using ATP produced during cellular respiration

Question 3

What is diffusion?

Answer 3

Is the movement of particles in a liquid or gas down a concentration gradient from an area of high concentration to an area of low concentration.

Question 4

What is facilitated diffusion?

Answer 4

Is diffusion that takes place through carrier proteins or protein channels

Question 5

What is osmosis?

Answer 5

Is a specialised form of diffusion that involves the movement of water down a concentration gradient.

Question 6

Endocytosis?

Answer 6

Movement of large molecules into cells through vesicles formation

Question 7

Exocytosis?

Answer 7

Is the movement of large molecules out of cells by the fusing of a vesicles containing the molecules with the cell surface membrane. Requires ATP

Question 8

What is the phospholipid bilayer made up of?

Answer 8

Polar lipids

Question 9

What are the characteristics of phospholipids?

Answer 9

Hydrophobic tails

Hydrophilic head

Question 10

What are the functions of integral protein in the phospholipid bilayer?

Answer 10

Some proteins form pores or gated channels, some permanent and some temporary. They can open and close depending on what the cell needs.

Question 11

What are glycoproteins and what is their function on the bilayer?

Answer 11

They act as antigens important for cell recognition or as receptors for hormones.

Question 12

What is facilitated diffusion?

Answer 12

It occurs with substances with a strong negative or positive charge and larger molecules which cannot pass through the bilayer.
It involves carrier proteins which only let a certain substance through.
The protein carrier picks up a molecule from an area of high concentration then changes shape to release the molecule into the area of low concentration passively.
This process only works when the concentration gradient is in the right direction

Question 13

What does osmotic concentration mean?

Answer 13

The osmotic concentration of a solution concerns only those solutes that have an osmotic affect. Therefore large insoluble molecules which have no effect on the movement of water are not considered

Question 14

Isotonic?

Answer 14

The osmotic concentration of the solutes in the solution is the same as that in the cells

Question 15

Hypotonic?

Answer 15

The osmotic concentration of solutes in the concentration of solutes is lower than that in the cytoplasm of the cells.

Question 16

Hypertonic?

Answer 16

The osmotic concentration of solutes in the solution is higher than that in the cytoplasm.

Question 17

Describe pressure potential in plant cells

Answer 17

In plant cells the water is mostly hypotonic to the cells water will enter the cells.
Due to the cell wall the cell doesn’t pop like it does in animals.
As the cytoplasm cells and presses on the cell wall it generates hydrostatic pressures.
The inward pressure increases until it cancels out the tendency for water molecules to move in.
The inward pressure is pressure potential.

Question 18

What does it mean for a cell to be turgor?

Answer 18

When the osmotic force moving water into the plant cell is balanced by the pressure potential forcing it out, the plant cell is rigid, most plant cells are turgid all the time.

Question 19

What is incipient plasmolysis?

Answer 19

If plant cells are put in a slightly hypertonic solution water moves out of the and the cell membrane pulls away from the cell wall. The protoplasm will shrink away and the acutely will change but the actual size and shape of the cell doesn’t change that much it is just the internals that change.

Question 20

What is water potential? (trident)

Answer 20

The measure of water to move out of a cell, pure water had a water potential of 0. It has the highest water potential because it will always move to an area of lower concentration.
All other liquids will have a lower water potential (negative numbers)

Question 21

What is turgor pressure?

Answer 21

As water enters the cell via osmosis it causes the protoplasm of the cell to expand but the cell wall stops it from expanding. Hydrostatic forces push against the cell wall, the cell wall pushes back on the protoplasm with turgor pressure. Turgor pressure will rise until both turgor pressure and osmotic potential are in equilibrium.

Question 22

What is osmotic potential?

Answer 22

It is the potential that water has to move across the partially permeable membrane depending on condpcentration. This takes into account hyper, iso and hypotonic potentials.

Question 23

What is the formula for water potential of a plant cell?

Answer 23

Turgor pressure + osmotic potential

Question 24

What is the formula for water potential in an animal cell?

Answer 24

Osmotic potential

Question 25

What is incident plasmolysis?

Answer 25

Where so much water has left the cell via osmosis that turgor is lost and the cell membrane begins to pull away from the cell wall.

Question 26

What is plasmolysis?

Answer 26

Is the situation where a plant cell is placed in a hypertonic solution where so much water leaves the vacuole is reduced and the protoplasm is concentrated and throngs away from the cell wall

Question 27

When does exocytosis and endocytosis take place?

Answer 27

Materials too big to move through the protein channels are taken in another way. Vesicles form around substances when they enter or leave. The formation and breakdown of the membrane surrounding the substance requires atp.