Osmosis and gas exchange

Question 1

What is osmosis?

Answer 1

It’s the movement of water molecules across a partially permeable membrane from a region where there is lots of water to where there is little

Question 2

What is a partially permeable membrane?

Answer 2

A membrane with very small holes in it. Only tiny molecules can pass through and bigger molecules can’t

Question 3

Which way do water molecules pass through the membrane during osmosis?
Why?

Answer 3

Both ways because they move about randomly at all times

Question 4

What happens if there are more water molecules on one side of the membrane?
What happens to the solution receiving more water?

Answer 4

There is a steady net flow of water into the region with fewer molecules
It becomes more dilute.

Question 5

Osmosis is a type of…. as the ….. movement of…… molecules from an area where there is …. of …. to an area where there is …..

Answer 5

Diffusion
passive 
water 
a lot
water 
little

Question 6

Where does osmosis happen?

Answer 6

in and out of cells

Question 7

Where is tissue fluid?
What is it made of?
Where does it come from And to do what?

Answer 7

Surrounding the cells in the body
water oxygen glucose is dissolved in it
Squeezed out of the blood capillaries
to supply cells with everything they need

Question 8

The tissue fluid will usually have a …… to the fluid inside the cell.
This means water will either have to …. from the tissue fluid or. … by …..

Answer 8

Different concentration
move into the cell
Out of the cell
osmosis

Question 9

If a cell is short of water what will will become concentrated inside it?
What will happen to the outside solution?
How does the inside get more concentrated?

Answer 9

The solution
It will become more dilute
Osmosis

Question 10

If a cell has lots of water what will the solution be like?

What will happen to the water inside the cell?

Answer 10

the solution inside it will be more dilute

it will be draw out through osmosis into the tissue fluid.

Question 11

How do show what osmosis does in an experiment in 4 steps?
Prep
In the beakers
Begin by.... then...
You can see that if...

What is the dependent variable? Independent?
What should happen to all the other variables?

Answer 11

Cut up potato into identical cylinders and get some beakers with varying sugar concentration solutions in them
One should be pure water, one very strongly concentrated, then the others in between.
Measure the length of the cylinders then place them into the beaker and leave for half an hour. Then take them out and measure their length.
If they have gotten longer they have drawn in water by osmosis. If the water has been drawn out they’ll be shorter.
Chip length. Concentration of the sugar solution. They should be kept the same.

Question 12

In what three ways do substances move?

What happens to waste substances?

Answer 12

Diffusion, osmosis, active transport

They need to move out of the cell by these processes to be removed by the organism.

Question 13

What do life processes need before they can happen? Give two examples…

Answer 13

Gases or other dissolved substances,
Photosynthesis requires CO2 and water to get into its plant cells.
Respiration needs glucose and oxygen inside the cells.

Question 14

What is diffusion?

Answer 14

When particles move from an area of high concentration to an area of low concentration.

Question 15

What is the difference (to do with concentration) between osmosis and diffusion, and active transport?

Answer 15

Osmosis and diffusion involve the movement of particles form an are a HC to an area of LConcentration when sometimes substances need to move towards the high concentration so this is what active transport does.

Question 16

What is the point of an exchange surface?
What are these adapted to do?
In what ways?
T
LSA
BV
V

Answer 16

To allow enough of the necessary substances to pass through for the processes.
Maximise effectiveness.
Thin: substances have a short distance to diffuse over.
Large surface area: lots of a substance can diffuse at once
Lots of blood vessels: in mammals to get substances in and out of the blood quickly
Ventilated: gas exchange surfaces in animals are often ventilated so air moves in and out

Question 17

Exchanging …. gets more …. in …. and more complex …. because the place where the …… are needed are very far ….. form the ……. .

Answer 17

substances…. more difficult…. bigger….organisms… substances… away.. exchange surfaces.

Question 18

The … of leaves lets gases ….. in and out of …..

What diffuses into the air spaces between leaves?

Answer 18

structure… diffuse.. cells

CO2

Question 19

Leaves structures are adapted so CO2 can diffuse into the air spaces easily.
How is the leaf adapted for diffusion? (5)

Underneath of the leaf...
Also....
The stomata...
Shape
Walls

Answer 19

Is an exchange surface covered in little holes called stomata, which the CO2 diffuses through.
O2 and water vapour can also diffuse through the stomata.
The size of the stomata are controlled by the guard cells that close the stomata if the plant is losing water faster than it is being replaced by the roots, without these the plant would wilt.
The area of the leaf’s exchange surface is large as it is a flattened shape so exchange is more effective.
The walls of the cells inside the leaf forms further exchange surfaces. There are airspaces inside the leaf so the cells have a larger surface area for CO2 to get into the cells

Question 20

Why does evaporation happen in a leaf and where?

Answer 20

Water evaporates from inside the leaf because there is a lot of water inside the leaf compared to outside, so it diffuses out.

Question 21

Where are the lungs?
What is this?
How is is separated from the abdomen?
What are your lungs like and how are these protected?

Answer 21

In the thorax.
The top part of your body.
By the diaphragm
Big pink sponges, by the ribcage.

Question 22

Where does the air you breath in go through?
What does this split into and where do these go?
What do these then progressively split into?
Where do these end up?

Answer 22

The trachea.
Bronchi, two tubes, bronchus, singular, one going to each lung.
Bronchioles.
In small bags called alveoli where the gas exchange takes place.

Question 23

Ventilation is ….
What are the 3 stages?
Now describe the movements of stage 1.

Answer 23

Breathing in and breathing out.
Intercostal muscles and the diaphragm contract
The thorax volume increases
This decreases pressure drawing air in.
The intercostal muscles pull the ribcage and sternum up and out. The diaphragm flattens out.

Question 24

Describe breathing out in 3 stages…

Now describe the movements of stage 1.

Answer 24

Intercostal muscles and diaphragm relax.
Thorax volume decreases.
This increases pressure so the air is forced out.
The ribcage and sternum drop in and down. The diaphragm moves up.

Question 25

What do active ventilators do?
What are ventilators and who do they help?
What do modern ventilators do and how does it work?
What is a possible problem?

Answer 25

Help people who can’t breathe.
Machines that move air (often with extra oxygen) into or out of the lungs. Whoever can’t breathe themselves, people under general anaesthetic or have a lung injury or disease.
Pump air into the lungs, expanding the ribcage. The pumping stops and the ribcage relaxes and pushes the air back out, not interfering with blood flow but it can burst alveoli if the lungs can’t cope with the artificial airflow.

Question 26

What were ventilators like?
How did they work?
What was a possible problem?

Answer 26

Giant cases that went from the next to the abdomen with on the patients head poking out (an iron lung).
Air was pumped out of the case so the pressure was dropped, the lungs expanded and the air was drawn into the lungs. Air pumped into the case had the opposite effect, forcing air out of the lungs, however this could interfere with the blood flow of the lower body.