Topic 1

2 Explain the importance of water as a solvent in transport, including its dipole nature. Water is a useful solvent transport as it is cohesive This means many water molecules can join together, which helps the water to flow This is because it is a dipolar molecule - it has a negative oxygen atom bonded to 2 positive hydrogen atoms Has an unevenly distributed electrical charge, so can form hydrogen bonds This means that many +ve or -ve ions from ionic reactions can be surrounded by water molecules by being bonded to either the positive hydrogen atom or the negative atom Therefore many substances can dissolve into water

3 Distinguish between monosaccharides, disaccharides and polysaccharides (glycogen and starch amylose and amylopectin) and relate their structures to their roles in providing and storing energy (-glucose and cellulose are notrequired in this topic). Monosaccharides which contain only 1 monomer of sugar (e.g. glucose, fructose, galactose) Disaccharides which contain 2 monomers of sugar (e.g. maltose, sucrose, lactose) Polysaccharides contain many monomers of sugars (e.g. glycogen, starch, cellulose) Glycogen contains 1,4 and 1,6 glycosidic bonds, large, compact (to store more energy in a little space) It is the energy storage for glucose in animals Starch is made up of amylose and amylopectin and is found in plants Amylose contain 1,4 glycosidic bonds with a long unbranched chain Amylopectin contains 1,4 and 1,6 glycosidic bonds. It contains side branches which can be rapidly hydrolysed by enzymes to release energy quickly Both glycogen and starch are insoluble in water so they cannot swell by osmosis Glycogen has more side branches

4 Describe how monosaccharides join to form disaccharides (sucrose, lactose and maltose) and polysaccharides (glycogen and amylose) through condensation reactions forming glycosidic bonds, and how these can be split through hydrolysis reactions. 2 glucose molecules = maltose Fructose and glucose = sucrose Galactose and glucose = lactose Monosaccharides can join together to form disaccharides and polysaccharides by condensation reaction (removal of water) This forms a (1,4 or 1,6) glycosidic bond The bond can be split by hydrolysis ( the addition of water)

5 Describe the synthesis of a triglyceride by the formation of ester bonds during condensation reactions between glycerol and three fatty acids and recognise differences between saturated and unsaturated lipids.

Triglycerides are a type of lipid A Triglyceride is made of 1 glycerol molecule with 3 fatty acids with hydrocarbon tails joined by ester bonds The long tails are made of hydrocarbons and are hydrophobic This makes lipids insoluble in water Triglycerides are formed by condensation reactions

Saturated Lipids Found in animal fats Do not have double bonds in their tails Saturated by hydrogen (2:1 Hydrogen to Carbon ratio)

Unsaturated Lipids Found in plants Have double bonds in tails - causing kinks in chain Melt at lower temperatures

6 Explain why many animals have a heart and circulation (mass transport to overcome limitations of diffusion in meeting the requirements of organisms). Animals have a circulatory system to overcome the limitations of diffusion All cells need energy (from aerobic respiration) Glucose and oxygen must be delivered to all these cells to obtain this (products of respiration) Because of the short diffusion distance these materials can diffuse directly into the cell across the cell membrane (large SA:V ratio) Therefore the diffusion rate is quick because of the short distance the materials need to travel Multicellular organisms have a small SA:V ratio because there is a larger distance for the substances to travel to reach the cells This means the rate of diffusion is too slow to deliver enough oxygen and glucose (energy) to cells Mass transport systems can carry substances around to different parts of the body and remove metabolic waste Blood can carry nutrients and oxygen and dispose of metabolic waste

7 Describe the cardiac cycle (atrial systole, ventricular systole and diastole) and relate the structure and operation of the mammalian heart to its function, including the major blood vessels.

1. Diastole/ Cardiac systole - All chambers are relaxed, which makes the blood flow into the hearts atria. The AV valves are open. Semilunar valves are closed2. Atrial systole - AV valves are open. Atria contracts. Ventricles in diastole, making the blood flow from atria to ventricles. Semilunar valves remain closed. 3. Ventricular systole - Ventricles contract, pushing the blood through the semilunar valves into the aorta and pulmonary artery.

How heart is adapted to its function Left ventricle is thicker -> needs to pump blood all around the body at a high pressure AV valves prevent backflow of blood into the atria when ventricles contract Ventricles have thicker walls than the atria -> have to push blood out of the heart Semilunar valves stop blood flowing back into the heart The cord attach the AV valves to the ventricles to stop them being forced up into the atria when the ventricles contract

8 Explain how the structures of blood vessels (capillaries, arteries and veins) relate to their functions.

Arteries Carry blood from the heart (oxygenated blood) Thick muscular wall - withstand blood flow under high blood pressure Narrow lumen - maintain high blood pressure Elastic fibres allow artery to stretch and recoil Tunica interna (endothelium) is folded, to allow artery to expand under high blood pressure

Veins Carry blood to the heart They have little elastic and muscular tissue (in the tunica media and externa) in their walls and a large lumen as blood flows at a low pressure Endothelium is folded to form valves, to prevent the backflow of blood Blood flow in veins is aided by muscle contraction around the vessels

Capillaries 1 cell thick - short diffusion distance of substances during metabolic exchange (quick) Capillary beds increase the surface area for exchange Tube of endothelial cells allow oxygen and CO2 and other soluble substances to diffuse across

9 Describe how the effect of caffeine on heart rate in Daphnia can be investigated practically, and discuss whether there are ethical issues in the use of invertebrates.

1. Make up a range of caffeine solutions of different concentrations and a control solution with no caffeine 2. Place Daphnia in cavity slide 3. Place the slide under a light microscope4. Count the number of heartbeats for 10 seconds. 5. Multiply this by 6 to get the number of beats per minute6. Repeat at different concentrations7. Keep other factors constant (e.g. temperature, vol of caffeine solution, size of Daphnia)

Ethics For: Small organisms, presumed to have a simple nervous system, will not undergo stress Against: There is no true informed consent from the organisms used

10 Describe the blood clotting process (thromboplastin release, conversion of prothrombin to thrombin and fibrinogen to fibrin) and its role in cardiovascular disease (CVD). Thromboplastin is released from the damaged tissue This triggers the conversion of prothrombin (soluble protein) into thrombin (enzyme) Thrombin catalyses the conversion of fibrinogen (a soluble protein) into fibrin (insoluble protein fibres) These tangle together and form a mesh, where platelets and RBCs are trapped. Forms a blood clot

Can lead to Cardiovascular disease:1. Formation of atheroma and fibrous cap in artery wall2. Repeated rupturing of fibrous cap and clotting3. Narrowing of artery lumen4. Partial reduction in blood and oxygen supply to the heart5. Development of angina6. Complete blockage of coronary artery7. Interruption of blood/oxygen supply to the heart8. Damage to heart tissue9. Myocardial infarction (heart attack)

11 Explain the course of events that leads to atherosclerosis (endothelial damage, inflammatory response, plaque formation, raised blood pressure).

Damage to the endothelial lining of the artery This triggers an inflammatory response and white blood cells release plasma in the damaged area This joins to the fatty deposits (cholesterol) on the artery wall forming a plaque This raises the blood pressure

12 Describe the factors that increase the risk of CVD (genetic, diet, age, gender, high blood pressure, smoking and inactivity).

Genetic Families that have a history of CVD are more likely to develop CVD. This could be due to the inheritance of alleles for the biochemistry of weak arteries, hypertension, high blood pressure etc. Diet A high salt content causes the kidney to retain water so LDLs cannot be broken down in the Liver. High saturated fat intake increases blood cholesterol levels which increases atheroma formation, and thrombosis. Lead to heart attack, stroke or Deep Vein Thrombosis. Age At an older age, the risk of CVD is higher because the blood vessels become less elastic, thus narrow and therefore blood can pass through vessels at a higher blood pressure which can lead to endothelial damage. Gender Men are at more risk than women. Women have more oestrogen which can reduce plaque buildup and reduce risk of the development of CVD, however after menopause (no oestrogen) the risk can be increased High Blood pressure A high blood pressure will damage the endothelial lining and form blood clots on the walls of the artery. This will block the artery and can prevent blood reaching different parts of the body. Can lead to a stroke. Smoking A cigarette contains Carbon Monoxide which prevents oxygen binding to haemoglobin and reduces the amount of oxygen being delivered to different tissues. Nicotine makes platelets sticky, increasing risk of atheroma formation. Inactivity Less exercise means level of cholesterol builds up in the arteries, thus raising the blood pressure.

13 Describe the benefits and risks of treatments for CVD (antihypertensives, plant statins, anticoagulants and platelet inhibitory drugs).

Antihypertensives Reduce blood pressure E.g. Diuretics, Beta Blockers, Sympathetic nerve inhibitors (inhibit constriction of arteries), ACE inhibitors (inhibit enzymes that constrict blood vessels) Benefits: Reduces risk of CVDs and damage to the kidneys and eyes. Risks: Blood pressure can become too low. Can lead to faintness, coughs, swelling of ankles, fatigue, constipation Plant Statins Lower blood cholesterol levels and block the enzyme in the liver that makes cholesterol Benefit: Very good at reducing the risk of CVD. Risk: Muscular inflammation (can be fatal) and liver problems Anticoagulants Interferes with the manufacture of prothrombin. It reduces blood clots. E.g. Warfarin1. Platelet Inhibitory Drugs (similar to anticoagulants). E.g. Aspirin. Make the platelets less sticky. Risk: Can cause stomach ulcers -> stomach bleeding

14 Analyse and interpret data on the possible significance for health of blood cholesterol levels and levels of high-density lipoproteins (HDLs) and low-density lipoproteins (LDLs). Describe the evidence for a causal relationship between bloodcholesterol levels (total cholesterol and LDL cholesterol) and CVD.

High Density Lipoproteins are gooda. Mainly proteinb. Transport cholesterol from body tissues to the liver where it is excreted or recycledc. Reduce blood cholesterol levels when levels are too high Low Density Lipoproteins are bada. Mainly lipidb. Transport cholesterol from the liver to the blood, where it is circulated until needed by cells.c. Increase blood cholesterol levels when levels are too low High total blood cholesterol level (LDL, HDL and other cholesterol) and high LDL levels have been linked to an increased risk of CVD

Correlation Relationship between 2 variables where one variable is reflects a change in the other Causation/Causal relationship Relationship between 2 variables where one variable is responsible for change in another

15 Discuss how people use scientific knowledge about the effects of diet (including obesity indicators), exercise and smoking to reduce their risk of coronary heart disease.

Risk - A measure of the probability that damage to health will occur at a result of a given hazard Involves the probability that a hazardous event will occur and the consequences of that event Calculating the risk of diseases: (no of people with disease)/(total people who could develop disease) x 100 Can also invert to give ratio Relative risk - comparing risk between 2 groups When risk is quantified, factors to consider: Time period (development of disease) Contribution and influence of stress levels/ alcohol consumption/occupation/gender Environment Weight and CVD -> high blood pressure -> increases risk Smoking and CVD -> damages endothelial lining -> atherosclerosis -> increases CVD Exercise and CVD -> Increases the strength of the cardiac muscle -> more blood pumped around the body -> reduces risk of CVD

Obesity indicator such as BMI can be used This is a measure of how healthy a patients weight is for their height Body Mass Index = Mass/(Height)^2

16 Describe how to investigate the vitamin C content of food and drink.1. Pipette 1cm3 blue DCPIP into test tube.2. Using burette (or accurate pipette) add 1% vitamin C solution drop by drop.3. Shake tube gently after each drop. Continue until the blue colour just disappears. 4. Record volume of solution needed to decolourise the DCPIP. 5. Repeat further 2 times and calculate mean result. 6. Repeat procedure with different fruit juices7. Control variables: Vol of DCPIP, vol of Vitamin C solution, concentration of Vitamin C

Calculations 1cm3 of 1% vitamin C solution contains 10 mg Vitamin C, therefore mass in 1cm3 = 10mg x volume of 1% vitamin C to decolourise 1cm3 of DCPIP Mass in sample = mass of vitamin C to decolourise 1cm3 DCPIP volume of sample required to decolourise 1cm3 DCPIP

Evaluation Difficulty in controlling temperature Amount of shaking (too much adds oxygen which will slightly restore the DCPIP to blue) Endpoint difficult to judge as needs to be just when blue colour disappears especially in highly coloured juices Some loss of solution when transferring from one beaker to another Accuracy of measuring equipment

17 Analyse data on energy budgets and diet so as to be able to discuss the consequences of energy imbalance, including weight loss, weight gain, and development of obesity. Energy budget balances the number of calories you require with those that you consume. Can be measured by Basal Metabolic rate Measures the temp change at rest Calculates the minimal rate of energy expenditure per unit time by endothermic animals at rest More energy consumed than expended = weight gain Excess carbohydrates converted to fat More energy expended than consumed = weight loss

18 Analyse and interpret quantitative data on illness and mortality rates to determine health risks (including distinguishing between correlation and causation and recognising conflicting evidence).

How to interpret data: Describe what you see Draw conclusions based on data Explain the link Evaluate method look at positives and negatives of the study design

General trendSub trend Manipulate

Correlation Relationship between 2 variables where one variable is reflects a change in the other Causation/Causal relationship Relationship between 2 variables where one variable is responsible for change in another19 Evaluate design of studies used to determine health risk factors (including sample selection and sample size used to collect data that is both valid and reliable).

Cohort- many people, long time period, categorised according to who has/ doesnt have condition- risk factors accessed Case-control studies- group with condition and control group- past history researched- important to match case/control groups in terms of age/ gender- independent variables are controlled Evaluation method: Size of group used - representative of population? Period of time taken for investigation - Days vs years? Other variables controlled- lifestyle of participants? age? No of sets of data Lack bias Standardised measurement

20 Explain why peoples perceptions of risks are often different from the actual risks (including underestimating and overestimating the risks due to diet and other lifestyle factors in the development of heart disease).

Underestimation - Do not understand the risk and thin the consequences is lower than their relative risk is lower than it is This is because people are not aware that risk factors tend to be associated with each other Overestimation - Do not understand the risk and think the consequences that their relative risk is higher than it is This is because people tend to predict the consequence of the potential hazard will be much harsher than expected

Describe and explain how the results of this experiment support this statement.

1. correct ref to diffusion (of substance B)occurring due to concentration difference /eq ;2. idea of rate of uptake decreases ;3. as the concentration gradient decreases / eq;4. (net) uptake stops / eq ;5. when concentration inside cell equals thatoutside the cell / eq ;

suggest the advantages that double circulatory system has compared with single circulatory.

1. blood flows {faster /at higher pressure / eq}(to the body) ;2. blood flows {slower /at lower pressure / eq}to the lung ;3. idea that this reduces risk of damage to lungs;4. correct ref to more efficient {exchange /transport} of gases / eq ;

Suggest why the insect does not need blood vessels to transport its blood aroundthe body.

1. correct ref to large surface area to volumeratios ;2. idea that (all) {cells / eq} are very close tothe {blood / heart} ;3. idea that diffusion is fast enough forexchange of {nutrients / gases / waste} ;4. idea of low metabolism ;5. idea that movement of blood back into theheart is fast enough (to return blood backinto the heart) ;

Describe the blood clotting process.

1. idea that there is a cascade of events(leading to blood clotting) ;2. ref to thromboplastin (starting the cascade) ;3. ref to conversion of prothrombin intothrombin ;4. idea that {thromboplastin /thrombin} is {anenzyme / a catalyst} ;5. ref to conversion of fibrinogen into fibrin ;6. ref to formation of mesh of {fibres / fibrin} ;7. ref to requirement of {calcium ions/ Ca2+ /vitamin K} ;8. ref to {platelets / blood cells} gettingtrapped (in the mesh) ;

Describe an experiment that the student could perform, using Daphnia.

1. idea of heart rate determined beforetreatment ;2. idea that daphnia need to be put into tea andallowed to acclimatise ;3. practical detail e.g. use of microscope ;4. details of determining heart rate described /eq ;5. ref to named controlled variable ;6. ref to {repeats /replicates} ;7. idea that heart rate of daphnia determined in{white tea (only) / known caffeineconcentration} ;

Reason for the use of invertebrates

1. Daphnia are very simple organisms / Daphniahave basic nervous system / eq ;

Reason against the use of invertebrates

1. use of (any) animal is wrong / how can we besure what the Daphnia can feel / ref. topossibility that the Daphnia could die / eq ;Describe two changes that this woman may be able to make to her lifestyle, to reduce her risk of dying from CVD. Explain how each change would reduce the risk. 1. idea that the woman could reduce her {energy / eq} intake ;2. {weight/BMI} decreases if her energy expenditure greater than intake / eq ;3. diet should have reduced cholesterol levels/eq;4. cholesterol has been associated with { high blood pressure / atherosclerosis / eq} ;5. diet should have reduced saturated fat/eq;6. reduces blood{cholesterol/LDL}/eq;7. idea that the woman could increase the amount of exercise she took;8. weight decreases if energy expenditure is greater than her intake / exercise helps maintain a healthy heart /reduces blood pressure / eq ;9. idea that if the woman smoked she should reduce it ;10. smoking {reduces oxygen uptake / increases stickiness of platelets / increases blood pressure / increases risk of atheroma / eq} ;11. idea that diet should have reduced salt ;12. high salt associated with high blood pressure13. idea of moderate alcohol intake ;14. high alcohol associated with high blood pressure

Describe the structure of glycogen and explain why it is a suitable molecule for storing energy

Any 3 of the following: 1. consists of () glucose ; 2. (joined by 1,4 / 1,6) glycosidic bonds ; 3. branched structure / eq ; 4. idea of compact structure ; Any 3 of the following: 5. idea that it is {easily / rapidly / eq} hydrolysed ; 6. (leading to) more {glucose / eq} in a smaller space (in a cell)/ eq ; 7. idea of low solubility ; 8. it does not diffuse out of cells /eq ; 9. it has no osmotic effect / eq ;

Discuss either one ethical issue or one social issue relating to the use of this method of prenatal genetic screening.

1. idea of right to life ; 2. abortion is murder / ref to risk of miscarriage / eq ; Or: 3. false positive / negative / eq ; 4. consequences of false result e.g. abortion of (healthy) fetus ; Or: 5. who has right to decide if tests should be performed / eq ; 6. {implications of medical costs / discrepancies over next step} / parents {have a right to know / can prepare / eq} ; Or: 7. issues relating to confidentiality of {parents / child} / eq ; 8. idea that {some other abnormality may be found / paternal DNA does NOT match / other family members have right to know results} ; Or: 9. if abnormality found / eq ; 10.consequence of abnormality found e.g. abortion, comment on possible problems with {future employment / insurance / what constitutes a serious condition} / eq ; Or: 11.damage to fetus / risk of miscarriage ; 12. loss of fetus / risk to mother / eq ; Or: 13.ref. to stress to parents /eq ; 14. consequences of stress e.g. increased risk of miscarriage ;

Explain why gene therapy has the potential to treat some genetic disorders.

1. reference to faulty {alleles / genes / DNA / eq} ; 2. idea that gene therapy uses {normal / functioning / healthy} {alleles / genes / eq} ; 3. so the normal {protein / gene product / RNA / eq } is produced (by the cells) / eq ;

Suggest how patients with cystic fibrosis could be treated using gene therapy.

1. reference to using {alleles / genes / eq} coding for the CFTR {protein / channel} ; 2. reference to introducing the {alleles / genes / eq} into the cells ; 3. of the {lungs / pancreas / reproductive tracts / eq} ; 4. that produce mucus / eq ; 5. using a {vector / named vector} ; 6. credit suitable delivery mechanism e.g. nebuliser, injection ; 7. idea that treatment needs to be repeated (due to cell replacement) ;

Describe how atherosclerosis develops.

1. {damage / eq} to {endothelial cells/ epithelial cells / lining / eq} of artery ; 2. ref to inflammatory response ; 3. ref to migration of white blood cells into area / eq ; 4. build up of cholesterol /eq ; 5. reference to formation of atheroma / plaque ; 6. reference to {calcium salts / fibrous tissue} ; 7. ref to {loss of elasticity (of artery) / narrowing of lumen} / eq ; 8. idea that this process is selfperpetuating ;

Describe the risks of using plant statins to treat CVD.

1. muscle {inflammation / pain / eq} ; 2. liver {damage / failure/ eq} ; 3. joint {aches / pains/ eq} ; 4. nausea/constipation/diarrhoea ; 5. kidney {damage / failure / eq} ; 6. cataracts ; 7. diabetes ; 8. allergies / skin inflammation / skin rash / eq ; 9. respiratory problems / persistent cough / eq ; 10.headaches / dizziness / depression ;

Why use statins

1. idea that statins seen as more effective / more aware of the benefits / eq ; 2. may be prescribed (more frequently) as a preventative measure to reduce risk of further CVD / eq ; 3. specific reference to cheaper / off-patent statins available / eq ; 4. perception of lower risks / more awareness of the risks / eq