Unit 01 - the Body and Its Diseases Mark Scheme

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Mark Scheme – General Certificate of Education (A-level) Human Biology – Unit 1: The Body and its Diseases – January 2012 3
Question
Marking Guidance
Mark
Comments
1(a)
Phospholipid/lipid/bilayer;
1
1(b)(i)
Protein;
1
1(b)(ii)
2 possible functions;;
e.g. carrier;
channel;
2
Allow named examples, e.g. facilitated diffusion, active transport Accept transport of two substances of ion/molecular size
1(c)
Mitochondrion/mitochondria;
1
Mark Scheme – General Certificate of Education (A-level) Human Biology – Unit 1: The Body and its Diseases – January 2012 4
Question
Marking Guidance
Mark
Comments
2(a)
1. (Blood) vessel/artery/vein used (from other part of body); 2. By-passes blockage in (coronary) artery;
3. Restores blood supply to heart (muscle);
2 max
Accept restores oxygen/glucose to the heart
2(b)
1. Fit into receptors on heart muscle;
2. Block effect of adrenaline/noradrenaline;
3. Prevents rise in heart rate/lowers heart rate;
4. Reduces blood pressure;
5. Reduces likelihood of atheroma/MI/stroke/aneurysm;
2 max
Reject regulates heart rate
Reject artery bursting. Accept thrombus/blood clot
2(c)
1. (Angioplasty) opens blocked (coronary) artery;
2. Increases blood flow to heart muscle / in coronary artery; 3. Increases supply of oxygen / glucose to heart;
2 max
Do not credit incorrect artery
Ignore reduces pressure
Mark Scheme – General Certificate of Education (A-level) Human Biology – Unit 1: The Body and its Diseases – January 2012 5
Question
Marking Guidance
Mark
Comments
3(a)
1. Source of fibre;
2. Slows absorption of sugars/lowers GI/prevents constipation/promotes healthy gut flora/protects against colon cancer/promotes fullness; 3. High in vitamins;
4. High in minerals;
5. Specific effect of vitamin/mineral;
2 max
Reject Vitamin D
3(b)
Any four suitable reasons ;;;;
e.g. No
1. Does not give quantities/portion size;
2. So you don’t know how much energy;
3. Different people/sex/activity level;
4. Does not give information about processed foods/ how food is prepared; 5. Does not distinguish wholemeal/white bread;
6. Does not distinguish chicken/red meat;
7. Does not distinguish whole/skimmed milk;
e.g. Yes
8. Is of use because tells us which foods to eat more/less of; 9. Gives picture clues/examples of types of food;
4 max
Ignore references to water/drinks
Mark Scheme – General Certificate of Education (A-level) Human Biology – Unit 1: The Body and its Diseases – January 2012 6
Question
Marking Guidance
Mark
Comments
4(a)(i)
A;
1
4(a)(ii)
A;
1
4(b)
1. Movement of sodium ions from blood / into tissue fluid;
2. Lower water potential in tissue fluid;
3. Reduced water potential gradient (between tissue fluid and capillary); 4. Less water from tissue fluid enters capillaries;
5. By osmosis;
6. Builds up in tissues (causing oedema) / not drained by lymphatic system; 3 max
Mark Scheme – General Certificate of Education (A-level) Human Biology – Unit 1: The Body and its Diseases – January 2012 7
Question
Marking Guidance
Mark
Comments
5(a)
1. Net movement of water across a (selectively permeable) membrane; 2. Down a water potential gradient/from high water potential to lower water potential; 2
Reject along/across a water potential gradient
5(b)
1. Red caused by red blood cells/haemoglobin;
(Tube 2)
2. Has higher water potential than cells;
3. So water enters cells (by osmosis);
4. Cells burst/swell;
5. Haemoglobin released/cell contents in solution;
6. Small pellet in tube 2 because fewer cells;
(Tube 1)
7. Idea that cells are denser than solution;
8. Goes yellow because that is the colour of plasma;
4 max
Accept hypotonic
Mark Scheme – General Certificate of Education (A-level) Human Biology – Unit 1: The Body and its Diseases – January 2012 8
Question
Marking Guidance
Mark
Comments
6(a)
1. No/less/insufficient lactase produced;
2. Lactose not digested;
3. Lactose lowers water potential in gut;
4. Water absorbed...
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