Cells - Transport across cell membrane - 3.2.3.3 - Osmosis Flashcards

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1
Q

The passive movement of water from an area of high water potential to an area of low water potential through a selectively permeable membrane is…

A

OSMOSIS

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2
Q

Osmosis involves the movement of

A

water ONLY

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3
Q

By adding more solute the a solution how does this affect the water potential

A

it lowers the WP - becomes more negative

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4
Q

Why does pure water have a higher water potential than a solution of sugar

A

there are more ‘free’ water particles in pure water

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5
Q

A potato has a WP of -200kPa was placed in pure water WP 0kPa, what happens?

A

Water ENTERS the potato by osmosis (water moved from a high WP to a lower WP)

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6
Q

water potential is represented by

A

psi (greek letter)

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7
Q

water potential is measured in units of pressure which are

A

kPa

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8
Q

Pure water has a WP of

A

0kPa

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9
Q

How can you determine the the WP of a potato

A

place potato in a series of solutions of different WP. Where there is no net gain of water by the potato is the WP of the potato.

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10
Q

What happens if a red blood cell is placed in pure water

A

it swells and bursts - water enters the cell

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11
Q

What happens if a red blood cell is placed in strong sugar solution

A

It shrinks - water leaves the cell

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12
Q

What happens if a plant cell is placed in pure water

A

It swells - water enters the cell - it becomes turgid

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13
Q

What happens if a plant cell is placed in strong salt solution

A

water leaves the cell - it shrinks - it plasmolysed

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14
Q

What is meant by selectively permeable

A

Membrane only allows certain molecules through; it is only permeable to water and other small molecules `

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15
Q

During an osmosis practical, how and why do you dry the potato chips?

A

with a paper towel. To remove surface water - This would add to the mass - which we do not want

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16
Q

You must control the temperature during your osmosis practical - HOW?

A

Using a water bath and check the temperature at regular intervals using a thermometer

17
Q

give 2 similarities in the movement of substances by diffusion and osmosis

A
  1. down a gradient (High to Low)

2. passive not active (does not use energy)