Diffusion&Osmosis

Question 0

Suggest an advantage to the cell of having a selectively permeable membrane

Answer 0

Gives control to the cell over what passes into and out of the cell

Question 1

In realtion to structures such as cell membrane, explain the term selective permeability.

Answer 1

means that some substances are allowed to pass through while others are prevented

Question 2

Name two substances that enter a human muscle cell by diffusion.

Answer 2

Water, oxygen, glucose, water

Question 3

Explain the term tugor.

Answer 3

Is the pressure of the cytoplasm and vacuole against the cell wall of a plant.

Question 4

Give a feature of a plant cell that allows it to remain turgid for long periods.

Answer 4

Vacuole - holds water

Cuticle - prevents water loss

Question 5

suggest a way in which turgor is value to plants.

Answer 5

it gives strenght

Question 6

For what purpose did you use Visking tubing, potato tissue or some similat material?

Answer 6

To pretend to have a semi- permeable membrane

Question 7

at the end of the demonstration, how did you conclude that osmosis had occured?

Answer 7

the mass and the fullness increased in the visking tubing

Question 8

What is DIFFUSION?

Answer 8

Is the movement of molecules from a region of high concentration to a region of low concentration, until the two concentrations are the same

Question 9

What is OSMOSIS?

Answer 9

Special type of Diffusion. It is the movement of water molecules from a region of high concentration to a region of low concentration across a semi- permeable membrane.

Question 10

What means ACTIVE TRANSPORT?

Answer 10

means that energy is required to move molecules often against a concentration gradient.

Question 11

State the precise location of the cell membrane in plant cells.

Answer 11

Just inside the cell wall surrounding the cytoplasm.

Question 12

Whit what type of cell do you associate membrane- bound organelles?

Answer 12

Eukaryotic

Question 13

What corresponding term is used to describe bacterial cells?

Answer 13

Prokaryotic

Question 14

The cell membrane is described as being selectively permeable. What does this mean?

Answer 14

It allows some substances to pass trough but prevents others.

Question 15

Why is diffusion alternatively known as passive transport?

Answer 15

It doesn’t require any energy.

Question 16

Osmosis may be described as a “special case of diffusion”. Explain why

Answer 16

Diffusion is the movement of molecules from an area of high concentration to an area of lower concentration. Osmosis is a special case of diffusion as it relates only to water molecules and it also involves a semi- permeable membrane.

Question 17

Describe, with the aid of a labelled diagram, how you demonstrate osmosis in the laboratory.

Answer 17

1) Place bags of visking tubing half filled with
Bag 1 - distilled water
Bag 2 - 80% sucrose solution

2) Tie a knot and record the mass
3) Place in beakers of distilled water and leave for 30 minutes
4) Remove bags, dry them and re-record mass

Result: Bag 1 - no change in mass or fullness
Bag 2 - gained mass and appears more full due to water entering tube as result of osmosis

Question 18

Name the structure by which Amoeba gets rid of excess water that has entered by osmosis.

Answer 18

Contractile vacuole lets AMOEBA get rid of excess water that has entered by Osmosis.

Question 19

Give two locations in a cell at which there is a selectively permeable membrane.

Answer 19

Nucleous and Vacuole and Chloroplast+ mitochondria

Question 20

In the case of a named molecule, give a precise location at which it diffuses in the human body.

Answer 20

Oxygen diffusing from the blood into a cell.

Question 21

Explain the biological basis for the use of high sugar or high salt concentrations in the preservation of food.

Answer 21

The use of high sugar ot high salt concentrations in the preservations of food is used because any micro organisms in or on food will lose water and die due osmosis.