Edexcel Biology Unit 1 Common Markscheme Answers

Biology Unit 1 Common Markscheme Answers

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  • Created by: Henna
  • Created on: 04-01-13 19:53
Preview of Edexcel Biology Unit 1 Common Markscheme Answers

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Cell fragments called platelets stick to the wall of the damaged blood
vessel forming a plug.
A series of chemical changes occur in the blood, resulting in
prothrombin being converted into thrombin.
Thrombin is an enzyme that catalyses the conversion of fibrinogen into
long soluble strands of fibrin.
Calcium & Vitamin K is also used
These strands form a mesh that traps cells to form the clot.
Describe the structure of starch & why it is suitable for storing energy
Amylose and amylopectin
Compact structure
More glucose in a smaller space
It is insoluble
Easily hydrolysed
Leading to no osmotic effect
Describe the structure of glycogen & why it is suitable for storing energy
Consists of glucose
Joined by glycosidic bonds
Branched structure
Easily hydrolysed
More glucose in small spaces
No osmotic effect
Catalyse activity experiment
Measure volume of oxygen
Time taken to produce same amount of oxygen
Measure initial rate of reaction
Controlled variable
Risk of statins
Muscle pain
Liver damage
Kidney failure
Why phospholipid molecules form a bilayer
Tails are hydrophobic
So orientate themselves away from water
Heads are hydrophilic
So interact with water

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Structure of Artery Structure of Capillary Structure of Vein
Small Lumen making it Link the veins and Large Lumen
hard for flood flow arteries
Elastic fibres in wall to Thin walls with no Thin layer of smooth
allow stretching elastic fibres, muscle muscles with few
or collagen allowing elastic fibres +
rapid diffusion endothelial cells
Pressure is high but Wall made of one Blood pressure is
falls as blood goes endothelial cell relatively low
away from the heart allowing diffusion
Carries blood away Carries blood…read more

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When one variable changes, there is also a change in an
accompanying variable
Large surface area of capillary network
Faster/more exchange of gases
Increased diffusion
Occurs through the cell membrane
Membrane is thin ;
Oxygen enters cell through water
Carbon dioxide leaves cell (into water)
Conc.…read more

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Active transport
Against a conc. Gradient
Requires ATP
Proteins are involved
Protein carrier changes shape
Down a conc. Gradient
Doesn't require energy
Facilitated diffusion
Proteins act as channels
Channels open and close
Large polar molecule to pass through
Down a conc.…read more

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Narrow arteries
More likely to develop atherosclerosis
1 glycerol molecule and 3 fatty acid molecules
Joined by ester bonds
Bond is formed by condensation
Unsaturated lipids have double bonds between carbon atoms and
between carbon and oxygen atoms
Saturated lipids have more hydrogen atoms than unsaturated lipids
Amniotic fluid removed from mother
Embryonic cells present in amniotic fluid
DNA can be analysed
To detect defective gene in sample
Chronic villus sampling
Placental tissue removed from womb of mother
Foetal cells present in placental…read more

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White blood cells build up
Cholesterol build up
Prothrombin - thrombin
Thrombin is a catalyst
Fibrinogen - fibrin - platelets
Forms a mesh of fibres
Forms an atheroma
loss of elasticity
Vitamin C content experiment
Use different juices
Titrate juice with DC PIP
Colour change from blue to colourless
Repeat procedure with different juice
Controlled variable
Movement of water particles through a partially permeable
Heart & major blood vessels
The mammalian heart consists of four chamber called atrium
Two lower chambers…read more

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Blocks the ducts
In the pancreas
Enzymes cannot reach small intestines
Reduced digestion of food
Reduced absorption
Permeability experiment
Beetroot cell tissue
Wash thoroughly prior
Use a water bath to control temperature
At least 5 diff.…read more

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branched chain
1-4 & 1-6 bonds
Enzyme substrate experiment
Use a range of substrate concentrations
Mix the enzyme and substrate
Measure the pH using a pH indicator
Repeat without the enzyme
Control enzyme concentration
Controlled variable?
Drug used to treat high blood pressure
Prescribed to older people as they are more at risk of CVD…read more


Ricky Rozay

yaar plz write which exam board

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