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a_GCSE Biology > B3 - Exchange Of Materials > Flashcards

B3 - Exchange Of Materials Flashcards

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1
Q

What is osmosis?

A

The diffusion of water.

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2
Q

Explain osmosis.

A

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

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3
Q

What is a partially permeable membrane?

A

A membrane which only lets some types of particles through.

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4
Q

How does osmosis restore water balance in the cells?

A
  • 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.
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5
Q

How can osmosis damage cells?

A
  • 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
Q

How does osmosis support plant structure?

A

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

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7
Q

What is active transport?

A

Moving substances against a concentration gradient.

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8
Q

Why is active transport necessary?

A

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

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9
Q

What is needed for active transport?

A

Energy from respiration.

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10
Q

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

A

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

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11
Q

Give two examples of how active transport is important.

A
  • 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.
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12
Q

What do sports drinks contain and why?

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

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13
Q

What causes dehydration?

A
  • Exercise causes the loss of water and mineral ions.
  • Body fluids become more concentrated.
  • Water leaves the cells by osmosis.
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14
Q

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

A

Cells don’t work as efficiently.

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15
Q

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

A
  • Large surface area
  • Being thin
  • Efficient blood flow
  • Ventilated for gaseous exchange
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16
Q

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

A

There is a shorter diffusion path.

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17
Q

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

A

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

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18
Q

What is the purpose of alveoli?

A

They give the lungs a greater surface area.

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19
Q

What distinct adaptations do the lungs have?

A
  • Alveoli
  • Rich supplies of capillaries
  • Ventilation
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20
Q

What separates the lungs from the abdomen?

A

The diaphragm.

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21
Q

What is the process for breathing in?

A
  • 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
Q

Describe the process for breathing out.

A
  • 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
Q

What does breathing in do?

A

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

24
Q

What does breathing out do?

A

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

25
Q

Which muscles move when breathing in?

A

Intercostal muscles

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26
Q

How do intercostal muscles move when breathing in?

A

They contract.

27
Q

Give three reasons why people may struggle to breathe.

A
  • The tubes to their lungs may be very narrow.
  • The structure of the alveoli may break down.
  • Some people are paralysed.
28
Q

What method of pressure does the “iron lung” use?

A

Negative pressure.

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29
Q

How does the “iron lung” work?

A
  • 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
Q

How does a positive pressure ventilator work?

A
  • A measured volume of air is forced into the lungs.

- The lungs then deflate as the ribs move down.

31
Q

Which two ways can a ventilator be used?

A
  • As a face mask.
  • A tube that inserted into the trachea.

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32
Q

Give three advantages of positive pressure ventilation.

A
  • There is no need to place the patient inside a machine.
  • The patient can use it at home and about.
  • Patients can have control over the system.
33
Q

What are villi?

A

Finger like projections in the small intestine.

34
Q

Why do food molecules move into the blood from the small intestine?

A

There is a higher concentration in the small intestine than in the blood so the molecules diffuse.

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35
Q

What is the purpose of villi?

A

To increase the surface area of the small intestine allowing for greater net diffusion.

36
Q

What are villi covered in?

A

Microvilli

37
Q

How is glucose moved into the blood?

A

Active transport

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38
Q

Why is some food moved by active transport?

A

Sometimes the concentration gradient isn’t right but glucose cannot be wasted.

39
Q

How does carbon dioxide enter the leaf of a plant?

A

Through the stomata by diffusion.

40
Q

How are leaves adapted for gaseous exchange?

A

They have a flat, thin shape and internal air spaces.

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41
Q

Why can’t gases flow freely through a leaf?

A

-Too much water vapour would be lost by evaporation.

42
Q

What are stomata?

A

Small openings in a leaf to allow for gas exchange.

43
Q

What controls the opening and closing of stomata?

A

Guard cells.

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44
Q

How are root hair cells adapted?

A
  • They have projections which can push between the soil particles.
  • They have a partially permeable membrane which allows water to diffuse in.
  • There is then only a short distance to the xylem.
  • They can carry out active transport and have many mitochondria to carry out the process.
45
Q

What is transpiration?

A

The loss of water vapour from the surface of plant leaves.

46
Q

When is transpiration fastest?

A

Hot, dry, windy or bright conditions.

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47
Q

What is the transpiration stream?

A

The constant movement of water from the roots to the leaves.

48
Q

Why do some conditions increase the rate of transpiration?

A
  • These conditions also increase the rate of photosynthesis which means stomata need to be open to let in carbon dioxide.
  • Hot conditions increases the rate of evaporation.
49
Q

Why are the stomata on the bottom of the leaf?

A

They are protected from direct sunlight.

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50
Q

What is wilting?

A

A protection mechanism to prevent water loss.

51
Q

How does wilting prevent water loss?

A

It reduces the surface area for water loss by evaporation.

52
Q

Since you’ve been using these flashcards for free, please consider making a small donation for the hundreds of hours it took to make them.

A

http://bit.ly/21T6H3W

Thank you and good luck!

a_GCSE Biology (23 decks)

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