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Flashcards in B3 - Exchange Of Materials Deck (52)
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1

What is osmosis?

The diffusion of water.

2

Explain osmosis.

Water moves from a dilute to a more concentrated solution through a partially permeable membrane that allows water to pass through.

3

What is a partially permeable membrane?

A membrane which only lets some types of particles through.


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4

How does osmosis restore water balance in the cells?

-If a cell uses water for a chemical reaction, the cytoplasm becomes more concentrated so water moves in by osmosis.
-If water is made from a chemical reaction, the cytoplasm becomes too dilute so the water moves out.

5

How can osmosis damage cells?

-If the solution outside a cell is more dilute than the cell contents, the water moves into the cell which can cause the cell to swell and burst.
-If the solution outside the cell has a high concentration, the water moves out of the cell causing the cell to shrivel so it can no longer survive.


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6

How does osmosis support plant structure?

Water moves into the cell causing the vacuole to swell and push the cytoplasm against the cell wall making the cell hard and rigid.

7

What is active transport?

Moving substances against a concentration gradient.

8

Why is active transport necessary?

To allow cells to absorb ions from dilute solutions and move them through cells.


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9

What is needed for active transport?

Energy from respiration.

10

What types of cells carry out a lot of active transport?

Root hair cells and cells in the gut, both of which have lots of mitochondria.

11

Give two examples of how active transport is important.

-Mineral ions in soil are usually in dilute solutions. Plants are only able to to absorb the ions by active transport.
-Sugar such as glucose is actively absorbed out of the gut.

12

What do sports drinks contain and why?

-Sugars to replace sugars used in energy release.
-Water and mineral ions to replace those lost during sweating.


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13

What causes dehydration?

-Exercise causes the loss of water and mineral ions.
-Body fluids become more concentrated.
-Water leaves the cells by osmosis.

14

What happens if water and mineral ions aren't replaced?

Cells don't work as efficiently.


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15

Give four adaptations that make an organ efficient at gas or solute exchange.

-Large surface area
-Being thin
-Efficient blood flow
-Ventilated for gaseous exchange

16

Why is does being thin make an organ more efficient for diffusion?

There is a shorter diffusion path.

17

Why does having an efficient blood supply make an organ more efficient for diffusion?

The diffusing substances are moved away, maintaining the concentration gradient.


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18

What is the purpose of alveoli?

They give the lungs a greater surface area.

19

What distinct adaptations do the lungs have?

-Alveoli
-Rich supplies of capillaries
-Ventilation

20

What separates the lungs from the abdomen?

The diaphragm.


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21

What is the process for breathing in?

-As the ribs move up and out, the diaphragm flattens increasing the volume of the chest.
-The increased volume lowers the pressure in the lungs.
-Atmospheric pressure is higher meaning air is drawn into the lungs.

22

Describe the process for breathing out.

-The ribs fall and the diaphragm moves up decreasing the volume of the chest.
-The decreased volume increases pressure in the chest.
-The pressure in the chest is higher than outside forcing air out of the lungs.


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23

What does breathing in do?

Supplies oxygen rich air into the lungs, maintaining a steep concentration gradient.

24

What does breathing out do?

Removes carbon dioxide from the lungs maintaining a steep concentration gradient.

25

Which muscles move when breathing in?

Intercostal muscles


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26

How do intercostal muscles move when breathing in?

They contract.

27

Give three reasons why people may struggle to breathe.

-The tubes to their lungs may be very narrow.
-The structure of the alveoli may break down.
-Some people are paralysed.

28

What method of pressure does the "iron lung" use?

Negative pressure.


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29

How does the "iron lung" work?

-The patient lays in a metal cylinder with a tight seal around their neck.
-Air is pumped out creating a vacuum.
-The lower pressure causes the chest to rise and air to be drawn into the lungs.
-The vacuum then turns off and air is forced out of the lungs.

30

How does a positive pressure ventilator work?

-A measured volume of air is forced into the lungs.
-The lungs then deflate as the ribs move down.