Diffusion and Osmosis

Question 1

What is diffusion?

Answer 1

It’s the movement of a substance from a religion of its high concentration to a region of its low concentration

Question 2

What kind of a process is diffusion?

Answer 2

Passive - no energy required

Question 3

Examples of diffusion in humans and plants

Answer 3

Humans - 02 diffuses into the blood in the lungs [c02 diffuses out of]
Plants - Co2 diffuses into the leaf through stomata

Question 4

What are the membranes in a cell and what do they all have in common?

Answer 4

Cell membrane
Mitochondria membrane
Chloroplast membrane
Nuclear membrane
All semi permeable

Question 5

What is a semi permeable membrane?

Answer 5

It lets some substances in and out

Question 6

What is osmosis?

Answer 6

It’s the movement of water from a region of high water concentration to a region of low water concentration across a semi permeable membrane
It’s passive

Question 7

In a solution, if the concentration is high?

Answer 7

The water concentration is low

Question 8

What occurs in a solution that has a higher concentration?

Answer 8

High concentration = water is low

So water moves out of the cell by osmosis and the cell shrivels up and may die

Question 9

What occurs with animal cells in a low concentration solution

Answer 9

Low concentration = high water concentration
Water moves into the cell by osmosis
Cell swells up and may burst

Question 10

What is the problem that can occur in humans

Answer 10

Blood plasma has lower concentration than red blood cells, water moves into the cells from blood and causes cells to burst

Question 11

What controls the water level in blood plasma

Answer 11

The kidney

Question 12

Freshwater amoeba

Answer 12

Freshwater has low concentration than amoeba so water move into amoeba causing cells to swell and burst
So they have a contractile vacuole

Question 13

What is the function of the contractile vacuole?

Answer 13

Collects excess water and realises it

Question 14

Saltwater amoeba

Answer 14

Do not need contractile vacuole

The concentration of cytoplasm is same as external solution

Question 15

What is the concentration of amoeba’s cytoplasm

Answer 15

High concentration

Question 16

What kind of permeability does the cell wall have?

Answer 16

Fully permeable

Question 17

Plant cells in high concentration solution

Answer 17

Water moves out vacuole and cytoplasm by osmosis which results in cell membrane pulling away from cell wall, cell wall is intact but rest of cell shrivels up = plasmolysed
The plant wilts

Question 18

Plant cells in a solution with a low concentration

Answer 18

Water moves in to the vacuole and cytoplasm by osmosis.
The vacuole swells up and causing a cell to swell
It is turgid

Question 19

What is turgor pressure?

Answer 19

It’s the outward pressure of the vacuole and cytoplasm against the cell wall

Question 20

What is plasmolysis?

Answer 20

It’s the loss of water from the vacuole by osmosis and the pulling away of the cytoplasm from the cell wall

Question 21

Effects of turgor pressure?

Answer 21

Herbaceous plants reply on turgor pressure for mechanical support

Question 22

Why do sugary or salt solutions have a low water concentration?

Answer 22

Bacteria/fungi present will lose water by osmosis so the cells will die because they cannot survive without water

Question 23

Examples of food preservation

Answer 23

Jam is stored in a sugary solution

Question 24

What is active transport?

Answer 24

The movement of a substance from an area of its low concentration to an area of its high concentration
Requires energy

Question 25

Demonstrate osmosis

Answer 25

Soften visiking tubing
Knot
Control : one with distilled water
One : sucrose
Eliminate as much air as possible and tie other knot
Record mass using electronic balance
Submerge both in beaker of distilled water
15 mins
Remove and record mass
Mass of sucrose = go up bc water moved in

Question 26

What happens to a plant when it’s cells lose turgidity

Answer 26

Wilts

Question 27

If an animal cell were subjected to conditions that result in plant cell becoming turgid, what may happen and why

Answer 27

It would burst - no cell wall

Question 28

Name location and material involved in an active transport

Answer 28

Nephron

Glucose

Question 29

In the experiment for osmosis, how did you conclude it had occurred

Answer 29

Increase in mass

Question 30

From the graph, determine concentration [osmosis experiment]

Answer 30

Where it hits o on graph

Question 31

Explain how plant cells remain turgid

Answer 31

By being in a higher water solution - Water is taken into vacuole, causing pressure of vacuole and cytoplasm against cell wall. The cell wall prevents it from bursting

Question 32

Why is diffusion alternatively known as passive transport?

Answer 32

Requires no energy

Question 33

Osmosis may be described as “a special case of diffusion” explain why?

Answer 33

Movement of war

Requires semi permeable membrane

Question 34

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

Answer 34

Carbon dioxide

It diffuses out of blood in lungs

Question 35

Water enters the outmost cells of the root by osmosis, what does this tell you about the cell sap of these outermost cells

Answer 35

It has a high solute concentration