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GCSE Edexcel Biology > Topic 1- key concepts in biology > Flashcards

Topic 1- key concepts in biology Flashcards

1
Q

What is osmosis?

A

Osmosis is net movement of water molecules across a partially permeable membrane from region of higher water concentration to region of lower water concentration

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2
Q

What is a partially permeable membrane?

A

it’s a membrane with small holes in it, tiny molecules (water) can pass through and bigger (sucrose) can’t

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3
Q

Which way do the water molecules pass through the membrane and why do they do this?
(osmosis step 1)

A

The water molecules pass both ways through the membrane during osmosis
(because water molecules move randomly all time)

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4
Q

What happens to the water molecules when there is more water molecules on one side? state which region the water molecules move to?

(osmosis step 2)

A

when there are more water molecules on one side of the membrane than the other there’s a net flow of water into the region with fewer water molecules

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5
Q

what happens to the solution in osmosis? And what happens to the water itself on what?

(osmosis step 3)

A

the solute solution gets more dilute, the water acts like it’s trying to equalize the concentration on either side of the membrane.

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6
Q

How do you calculate the percentage change in mass?

A

percentage change = final mass - initial mass/ initial mass x 100

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7
Q

What happens when the water concentration of the sucrose solutions is higher than in the potato bit?

A

The potato bit gains mass as water is drawn in by osmosis (hypertonic)

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8
Q

What happens when there is no change in mass?

A

The fluid inside the cylinders and the sucrose solution are isotonic (same water concentration)

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9
Q

What happens when the water concentration of the sucrose solutions is lower than the potato bit?

A

This causes the potato bit to lose water so their mass decreases (hypotonic)

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10
Q

What is Diffusion?

A

Diffusion is the net (overall) movement of particles from an area of higher concentration to an area of lower concentration

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11
Q

What states of matter does diffusion happen in?
Why?

A

Diffusion happens in both liquids & gases
because these substances are free to move about randomly

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12
Q

What types of molecules can diffuse in diffusion?
What types of molecules can and can’t go fit through the cell membrane?

A

Only very small molecules can diffuse through cell membranes
CAN-glucose, amino acids, water & oxygen
CAN’T- Starch and proteins

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13
Q

What is active transport? What is used in active transport?

A

Active transport is the movement of particles across a membrane against a concentration gradient from a area of lower concentration to an area of higher concentration using energy transferred during respiration

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14
Q

How is the movement particles different in active transport compared to diffusion? What does this process require?

A

Particles are moved up a concentration gradient rather than down
the process requires energy (diffusion = passive process)

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15
Q

What is calorimetry?

A

Food that can be burnt to see how much energy it contains

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16
Q

How do you calculate the energy in food? And the energy per gram of food?

A

energy in food (in J) = Mass of water (in g) x temp change of water (in C) x 4.2

energy per gram of food (in J/g) = energy in food (in J) / mass of food (in g)

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17
Q

How do you test for reducing sugars? What is a coloured precipitate?

A

1) Add benedict’s reagent to a sample (blue)
2) Heat it in a water bath (75 C)
3) If it’s positive–> coloured precipitate (solid particles suspended in solution)

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18
Q

What’s the order of precipitate concentration from low to high when benedict’s reagent is used in a sample?

A

blue —-> green —> yellow —-> orange —-> brick red

( low to high sugar concentration)

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19
Q

How does the biruet test work?
Why do you add the first solution? To make it what?
What colours does it turn if it contains & doesn’t contain proteins?

A

1) add potassium hydroxide to make the solution alkaline
2) then add copper (2) sulphate solution (bright blue)
3) no protein —> blue
2) protein (present) —> purple

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20
Q

What is biuret test is used for?

A

To find out if a substance contains proteins

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21
Q

How does the emulsion test work?

A

1) shake the substance with ethanol until it dissolves then pour it into water
2) any lipids present –> precipitates as a milky emulsion
3) more lipid –> more noticeable milky colour

22
Q

What is emulsion test used for?

A

tests for any lipids in sample

23
Q

How is starch tested for in a sample?

A

using an iodine solution

24
Q

what colours does the iodine solution turn if starch is and isn’t present?

A

1) starch present
browny orange –> dark, blue-black colour
2) no starch
stays browny-orange

25
Q

Why is it important that organisms need to break down big molecules into smaller components?

A

To use them from growth and other life processes

26
Q

What are carbohydrases and what do they do?

A

Carbohydrases are any enzymes that convert carbohydrates into simple sugars

27
Q

Give an example of a carbohydrase converting a carbohydrate into a sugar

A

starch ——–> maltose (and other sugars e.g dextrins)
(amylase enzyme)

28
Q

What are Proteases and what do they do?

A

Proteases are enzymes that convert proteins into amino acids

29
Q

What are Lipases and what do they do?

A

Lipases are enzymes that convert lipids into glycerol and fatty acids

30
Q

What do organisms need to be able do to carbohydrates, proteins and lipids and what are used in this process?

A

synthesis carbohydrates, proteins and lipids from their smaller components
enzymes are used

31
Q

How are carbohydrates synthesised?

A

by joining together simple sugars

32
Q

What is glycogen synthase?

A

an enzyme used that joins chains of glucose molecules to make glycogen (molecule used to store energy in animals)

33
Q

How are proteins synthesised?
What do enzymes do to reactions?

A

by joining amino acids together
They catalyse reactions

34
Q

What are enzymes?

A

a protein that acts as a biological catalyst produced by living organisms that catalyse reactions

35
Q

Why do living things produce enzymes?

A

reduces the need for high temperatures (high temperatures = quicker reactions)

only speed up the useful chemical reactions (wont speed up unwanted ones)

36
Q

what is a catalyst?

A

a substance which increases the speed of reaction without being changed/used up in the reaction

37
Q

what is the substrate?

A

the molecule changed in the reaction

38
Q

What is the active site & what does every enzyme have?

A

part where it joins on to its substrate to catalyse reactions
an active site

39
Q

what do enzymes only work with one of? What is this called?

A

only works with one substrate
high specificity for their substrate

40
Q

What has to happen to make sure the enzyme catalyses the reaction?

A

substrate has to fit into the active site

41
Q

what happens when the substrate’s shape doesn’t match the active site’s shape?

A

the reaction won’t be catalysed

42
Q

what is the lock and key mechanism?

A

when the substrate fits into the enzyme (like a key into a lock)

43
Q

where is amylase found?

A

saliva & small intestine

44
Q

what reaction does amylase catalyse?

A

breaks down starch —–>small sugars (e.g maltose)

45
Q

Where is catalase found?

A

most cells
but especially, liver cells

46
Q

What reaction does catalase catalyse?

A

break down hydrogen peroxide (made in cell reactions) –> water & oxygen

47
Q

Where is starch synthase found?

A

plant

48
Q

what reaction does starch synthase catalyse?

A

synthesis of starch <—-glucose

49
Q

Where is DNA polymerase found?

A

nucleus

50
Q

What reaction does DNA polymerase catalyse?

A

synthesis of DNA <—-monomers

51
Q

What is amylase, catalase, starch synthase, DNA polymerase?

A

enzymes

GCSE Edexcel Biology (1 decks)

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