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Biology > B1 Diffusion Osmosis Active Transport > Flashcards

B1 Diffusion Osmosis Active Transport Flashcards

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1
Q

Diffusion

A

The spreading out of particles from an area of higher concentration to an area of lower concentration

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2
Q

Why does diffusion only happen in solutions and gases

A

The particles in these substances are free to move randomely

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3
Q

Factors which affect rate of diffusion

A

Temperature

Concentration gradient

Surface area

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4
Q

How does temperature increase rate of diffusion

A

Particles have more energy

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5
Q

How does concentration gradient affect the rate of diffusion

A

The greater the concentration gradient, the quicker diffusion takes place

When there is large difference in concentration between 2 regions particles will move more quickly from area of high concentration to area of low concentration

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6
Q

How does surface area affect rate of diffusion

A

As the surface area of the membrane increases, the rate of diffusion also increases

As there is more space for molecules to diffuse across the membrane

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7
Q

How to predict which way substances will move across a cell membran

A

Molecules travel across the membrane in the direction determined by their concentration gradients

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8
Q

Osmosis

A

The movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration

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9
Q

Why is diffusion important

A

So particles can move from 1 side of the room to another

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10
Q

Why is it important for multicellular organisms to have exchange surfaces and transport systems

A

In order for substances to pass in and out of the cells

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11
Q

How are exchange surfaces adapted for sufficient molecules to be transported in and out of cells

A

Large surface area

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12
Q

Why is diffusion passive process

A

No energy is needed

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13
Q

Concentration gradient

A

A difference in concentration between 2 areas

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14
Q

What happens to surface area to volume ratio as object gets bigger

A

Decreases

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15
Q

How do root hairs take in water from soil

A

Osmosis

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16
Q

What happens to a plant cell when it is placed in a more DILUTE solution?

A

The cell gains water by osmosis but does not burst
This cell is now turgid

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17
Q

What happens to an plant cell when it is placed in a more CONCENTRATED solution

A

Cell loses water by osmosis

Cell membrane pulls away from the cell wall

This is is called plasmolysis.

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18
Q

What happens to an animal cell when it is placed in a more DILUTE solution

A

The cell gains water by osmosis and may burst. This is called lysis.

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19
Q

What happens to an animal cell when it is placed in a more CONCENTRATED solution

A

The cell loses water by osmosis shrivels. This is called crenation.

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20
Q

Why does a plant cell not burst when it is placed in a more dilute solution

A

The plant cell has a cell wall

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21
Q

Differences between osmosis and diffusion

A

Diffusion is movement of particles and osmosis is movement of water

Diffusion does not require a membrane osmosis does

Diffusion driven by concentration gradient of particles but osmosis driven by concentration gradient of water

When they reach equilibrium

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22
Q

Isotonic solution

A

A solution which has same concentration of solutes as the inside of a cell

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23
Q

What happens when a cell placed us isotonic solution

A

No net movement of water across cell membrane as concentration of solutes equal inside and outside the cell

Water moves in and out of cell at same rate so cell’s size remains stable

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24
Q

Hypotonic solution

A

Solution with a lower solute concentration compared to the inside of the cell

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25
Q

What happens when cell placed in hypotonic solution

A

Water will move into the cell as concentration of water is higher outside the cell and lower inside the cell

Cell could burst (lyse) if too much water enters

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26
Q

Hypertonic solution

A

Solution with a higher solute concentration compared to the inside of the cell

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27
Q

What happens when cell placed in hypertonic solution

A

Water will move out of cell as concentration of water is lower outside the cell and higher inside the cell

As water leaves cell shrinks (crenate in animals or plasmolyze plant cells) as loses water

28
Q

Movement of water isotonic, hypotonic and hypertonic solution

A

Isotonic - No net water movement, cell remains the same size

Hypotonic - Water enters the cell, causing it to swell

Hypertonic - Water leaves the cell, causing it to shrink

29
Q

What happens to animal cells when they lose or gain too much water

A

They stop working properly

30
Q

Why maintaining constant internal conditions in living organisms is important

A

Enzymes only function properly under a small range of certain conditions, such as preferred pH and temperature

If enzymes cannot function this could cause organism to die

31
Q

What happens if plant loses too much water

A

They become soft

32
Q

Use osmosis to explain the effect of placing plant tissue in salt or sugar solutions

A

The cells will shrink if placed in a solution of sugar or salt in water due to osmosis

33
Q

Explain the mechanisms that lead to turgid or flaccid plant cells and plasmolysis

A

The pressure created by the cell wall stops too much water entering and prevents cell lysis

Cells that are not turgid are flaccid (lacking in stiffness or strength)

34
Q

Explain how a model shows osmosis in a cell

A

As water moves in by osmosis the vacuole fills up and presses out against the cell wall

35
Q

Write a suitable plan to investigate into the effect of salt or sugar solutions on plant tissue

A

Prepare samples of potatoes (or other plant tissue)

Place in different concentrations of sugar or sodium chloride solution

Make measurements of mass and length of your samples before and after soaking them in solutions

Calculate the percentage change in mass of plant tissue

36
Q

Active transport

A

Movement of a substance against a concentration gradient using energy

37
Q

Why active transport is important for living organisms

A

Crucial for cell survival and rapid nutrient absorption by the cells

38
Q

Why can’t root hair cells use diffusion to take up minerals from soil

A

Concentration of minerals is usually higher in root hair cells than in the soil around them

39
Q

Why do plants need mineral ions

A

Healthy growth

40
Q

What does active transport need to work

A

Energy from respiration to make it work

41
Q

Example of how active transport happens in humans

A

Taking glucose from the gut

42
Q

When is active transport used in the gut

A

When there is lower concenration of nutrients in the gut but a higher concentration of nutrients in the blood

43
Q

What happens in there’s higher concentration of glucose and amino acids in the gut

A

They diffuse into the blood

44
Q

When would a concentration gradient be the wrong way

A

When there’s a lower concentration of nutrients in the gut than there is blood

45
Q

Urea

A

Waste product produced from breakdown of proteins

46
Q

Where does urea diffuse from

A

Liver

47
Q

What does how easy it is for an organism to exchange substances with its environment depend on

A

Organism’s surface area to volume ratio

48
Q

The larger an organism is…

A

The smaller its surface area is compared to its volume

49
Q

In single celled organisms how can gases and dissolved substances diffuse directly into (or out of) the cell across the cell membrane

A

They have large surface area compared to their volume

50
Q

Why do multicellular organisms need some sort of exchange surface for efficient diffusion

A

Substances can diffuse from their outside surface to supply their entire volume.

51
Q

Where does active transport take place

A

Root hair cells in plants

Small intestine

Kidneys

Nerve cells (neurons)

52
Q

Differences between diffusion, osmosis and active transport

A

Active transport and osmosis always require a membrane, diffusion occurs with or without a membrane

Active transport requires energy, osmosis and diffusion don’t

Diffusion is high to low gradient, active transport is low to high and osmosis is high water potential to low water potential

53
Q

How does active transport take place

A

Binding of molecules

ATP binding and release

Conformational change of transport protein

Release of molecule

Return to original shape

54
Q

How a cell that carries out active transport is adapted to this function

A

High number of mitochondria

Abundance of transport proteins in membrane

Increased surface area of cell membrane

Removal of metabolic waste

55
Q

Suggest improvements a representational model
that shows active transport

A

Show energy used

Direction of concentration gradients

56
Q

Suggest limitations a representational model
that shows active transport

A

Oversimplification

Lack of context

57
Q

Function of exchange surfaces

A

Allows water and other nutrients to enter the organism, and waste to be exchanged

58
Q

How the effectiveness of exchange surfaces is increased

A

Large surface area

Short diffusion distance

Good blood supply

59
Q

link ideas about diffusion to explain how the adaptations of exchange surfaces increases their effectiveness

A

Large surface area provides space for molecules to diffuse

Thin membranes reduces distance over which diffusion must occur

60
Q

What ratio does a single celled organism have

A

Relatively large surface area to volume ratio

61
Q

Use ideas about surface area to explain the shape of a leaf

A

Most leaves are broad and so have a large surface area

62
Q

What do cells use diffusion for

A

To take in substances they need and get rid of waste products

63
Q

When is oxygen and carbon dioxide transferred between cells and environment

A

During gas exchange

64
Q

Where does gas exchange take place in the lungs

A

Alveoli

65
Q

How are alveoli adapated for maximise diffusion

A

Enormous surface area

Thin walls

Moist lining

Biology (12 decks)

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