lesson 17 required practical 3 effects of osmosis on plant tissue Flashcards

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1
Q

which plant can we use to investigate the effects of osmosis on plant tissue

A

potato (usually used)
beetroot
parsnip

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2
Q

first we do what with the potato

and why

A

peel it

because the potato skin can affect osmosis

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3
Q

then what do we do after peeling the potato

A

use a cork borer to produce three cylinders of potato

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4
Q

using a cork borer does what to the cylinders

A

makes them all the same diameter

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5
Q

after using the cork borer what do we do

A

use a scalpel to trim the cylinders to the same length

(around 3cm)

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6
Q

after using the scalpel, what do we do

A

measure the length of each cylinder using a ruler and the mass of each cylinder using a balance

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7
Q

one measuring the length of mass of the cylinders, what do we do

A

place each cylinder into a test tube

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8
Q

what do we add into the first test tube

A

add 10cm^3 of a 0.5 molar sugar solution

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9
Q

what do we add into the second test tube

A

add 10cm^3 of 0.25 molar sugar solution

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10
Q

what do we add to the third test tube

A

10cm^3 of distilled water

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11
Q

why do we use distilled water on the third test tube rather than tap water

A

because distilled water contains no dissolved substances and dissolved substances could affect the rate of osmosis

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12
Q

once the test tubes are finished what do we do

A

leave the potato cylinders overnight to allow osmosis to take place

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13
Q

once we have left the potato cylinders to allow osmosis to take place overnight then what occurs

A

we remove the potato cylinders and gently roll them on paper towel to remove any surface moisture

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14
Q

why do we not press on the cylinders to remove surface moisture

A

as we want to remove surface water, not forced water out of the cells

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15
Q

after we have allowed surface moisture to remove out of the cylinders, then what

A

measure the length and the mass of the cylinders again

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16
Q

how do we calculate percentage change

A

%change= change in value/original value x 100

17
Q

in water, the potato cylinder gains mass as what

(graph)

A

water moves into it via osmosis

18
Q

in concentrated sugar solution, the cylinder loses mass as what

(graph)

A

water moves out by osmosis

19
Q

where the line crosses the x axis, the is no change in what

(graph)

A

no change in the mass

20
Q

why is there no change in the mass

(graph)

A

because the concentration outside of the cell is the same as the concentration inside so no overall osmosis takes place

21
Q

the concentration when the line crosses the x axis is what

A

the approximate concentration inside the cel