AS edexcel biology Unit 1
Spec point 20 - explain why people's 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)
1) people don't understand risk and so underestimate it 2) don;t unerstand risk fully and overestimate it
spec 10 and 11 - describe the clotting process (the thromboplastin release, conversion of prothrombin to thrombin and fibrinogen to fibrin) and its role in cardiovascular disease (CVD) explain the course of events that leades to atherosclerosis (endothelial dammage, inflammatory response, plaque formation, raised blood pressure)
Atherosclerosis is a disease which causes the wall of arteries to bemuse furred up with fatty deposits called plaques or thermos 1) endothelial layer on the inside of the artery is damaged 2)inflammation of the artery wall occurs 3) white blood cells move into the artery walls (ca2+ ions cause it to garden) 4) cholesterol begins to accumalate on site 5) atheroma forms, lumen narrows, pressure increases as hypertension speeds atheroma formation, cycle ensures. atherosclerosis can lead to a blood clot forming Clot formation 1) platelets are activated by substances released by the damaged artery wall 2)platelets become sticky and form a platelet plug on the surface of the atheroma 3)platelet plus releases chemic, thromboplastin initiates prothrombin to be converted to thrombin, triggering fibrinogen to convert to fibrin( a thread like insoluble fibrous protein which creates a net trapping blood) The blood clot can become dislodged and deposited elsewhere brain - stroke coronary arteries, CHD, or infarcation ischaemia
Spec point 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 obesity
BMI = mass/ height2 energy consumed > energy lost -> mass gain energy consumed< energy lost -> mass lost BMI <18.5 - underweight between 18.5 and 25 - normal between 25 and 30 - overweight >40 - obese
spec point 14 - analyse and interpret date on the possible significance for health of blood cholesterol levels and levels of high-density lipoproteins and low-density lipoproteins. Describe evidence for a causal relationship between blood and cholesterol levels and CVD
High cholesterol is bad because it can contribute to atheromas - sources are diet and made in the liver lipoproteins - made in liver, ferry cholesterol in the blood high density lipoproteins (HDLs) take cholesterol out of circulation to the liver where it excreted into bile salts. HDL lowers cholesterol levels Low density lipoproteins - take cholesterol from the liver and put into circulation to the liver, LDLS increase cholesterol
Spec point 2 - explain the importance of the water as a solvent in transport including its dipole nature
Water molecules are polar with the hydrogen being positive and the oxygen being negative. This allows hydrogen bonds to form with other water molecules Properties: -less dense as a solid - ice insulates water beneath arctic ecosystems -High specific heat capacity - cells don't heat up easily, thus stable temp. -present in all three states -transparent -cohesion - generates surface tension, capillary uptake, transpiration -Good solvent - essential role in transport in systems -immiscible with hydrophobic molecules -evaporation of water has a cooling effect, little water required to lose heat -water can accept and donate protons (buffer)
spec point 12 - describe the factors that increase the risk of CVD (genetic, diet, age, gender, high blood pressure smoking and inactivity)
age atherosclerosis occurs naturally as arteries become less elastic with ages. Less elastic = higher pressure during systole; hypertension; atherosclerosis Gender women have less atherosclerosis - oestrogen is protective against atherosclerosis Hypertension speeds up atheroma formation and causes endothelial damage (cause in atherosclerosis) Smoking Nicotine damages endothelium (carbon monoxide) Inactivity lower BMI = less hypertension fitter heart = less hypertension exerciuse decreases LDL levels exercise increases metabolic rate, lowering BMI Genes some alleles may give you less protection from/ greater risk of developing atherosclerosis, To an extent, a higher chance of getting atherosclerosis does run in families Diet High salt intake causes hypertension. eating saturated fats decreases HDL levels, eating more calories than you need causes BMI to increase. High BMI is associated with atherosclerosis, Alcohol causes Hypertension directly
Spec point 13 - describe the benefits and risks of treatments for CVD (antihypertensives, plant statins, anticoagulants and platelet inhibitory drugs)
antihypertensives diuretics work by blocking proteins that actively transports Na+ Ions in the blood, so reducing water in blood side effects - blood viscosity, dehydration, treats symptom not problem B - Blockers, blocks adrenaline receptor in the heart, reduces hypertension in times of stress side effects - bradycardia, sleep disturbance, vasoconstriction Ca2+ channel blockers - stop the heart from contracting too hard side effect - arrhythmia, fibrillation and infarcation ACE inhibitors - side effects - kidney failure vasodilators - dilate blood vessels, reducing blood pressure. side effects - hypotension, which can cause heart attacks statins - block an enzyme in the liver that makes cholesterol, removes LDL from circulation side effect - liver failure Anticoagulants block the clotting process (thrombosis) in atherosclerosis side effect - blood clots slowly platelet inhibitory drugs - these work in the same way as anticoagulants but target platelets which are required to activate the clotting process - similar side effects
spec point 8 - explain how the structure of blood vessels (capillaries, arteries and veins) relate to their functions
artery - thick muscle layer to withstand high blood pressure, elastic recoil - allows stretch when blood is forced into it. Protective collagen layer, round shape, small lumen Vein - thin muscle layer, valve to stop blackflow, protective collagen layer, not round shape (wall not thick enough to hold shape), large lumen - decrease effect of friction) capillary - smalle holes in epithelial wall, no muscle layer, lumen is same size as one red blood cell thick
spec point 7 - describe the cardiac cycle and relate the structure and operation of the mammalian heart to its function, including the major blood vessels.
atrial systole - the atria contract, atrial pressure rises and blood is pushed from atria into ventricles ventricular systole - ventricular pressure rises above atrial pressure and the cuspid valves shut. Ventricular pressure rises, but no blood leaves the heart - when ventricular pressure rises above pressure in the arteries the semi-lunar valves open, blood leaves the heart diastole - the ventricles relax, ventricular pressure fall and when pressure in the arteries >ventricular pressure and the semi-lunar valves shut diastole - the entire heart is relaxed, the cuspid valves open and both atria and ventricles fill with blood
spec point 5 - describe the synthesis of a triglyceride by the formation of ester bonds during condensation reactions between glycerol and three fatty acids and recognise difference between saturated and unsaturated lipids.
fats or oils made of C, H, O only used for: long term energy store, insulation, protection, bouyancy, synthesis of hormones triglycerides are formed via condensation reaction between 1 glycerol molecule and 3 fatty acids saturated - triglycerides have no c=c bonds in them (form fats) Unsaturated fats = triglycerides that have C=C bonds, form oils C=C bonds forms kinks in the chain, that push chains away from each other, lowering the intermolecular forces, lowers boiling and melting temp
spec point 4 - describe how monosaccharides join to form disaccharides and polysaccharides through condensation reactions forming glycosidic bonds, how these can be split through hydrolysis reactions
glucose/ saccharides can join together in condensation reaction to release a water molecules. glycosidic bond forms hydrolysis is the addition of a water molecule iodine turns from brown to blue in presence of starch
spec point 18 and 19 analyse and interpret quantitative date on illness and mortality rates to determine health risks (including distinguishing between correlation and causation and recognising conflicting evidence) 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)
if two sets of data follow the same pattern they are correlated if two sets of data follow the same pattern because one factor directly affects the other they are causal look for these flaws in experiments 1) people selected were not representative of the population 2) only few people were involved in the experiment (not very reliable) 3) not all variables were controlled systematic error in the experiment (smokers included with non-smokers) where has the data come from?
spec point 6 - explain why animals have a heart and circulation (mass transport to overcome limitations of diffusion in the meeting requirements of the organism)
rate of diffusion = surface area x conc gradientx distance mass transport system is needed when there is a small SA: Vol ratio because diffusion is too slow
spec point 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 (B-glucose and cellulose are not required in this topic)
saccharides are made from C,H,O only Saccharides are used for fuel in respiration, energy storage molecules, structural molecules Glucose + glucose = maltose Glucose + fructose = sucrose Glucose + Galactose = lactose Glycogen Made from poly a-glucose, found in muscle and liver for energy storage, insoluble, lots of branches, compact shape starch amylose and amylopectin, poly a-glucose, found in amyloplasts, inside plant for energy storage, insoluble, amylose- no branches (1,4 glycosidic bonds), amylopectin has some branches (1-4 and 1-6 glycosidic link) cellulose made from poly B-glucose, main component of cell walls, insoluble, no branches, 1,4 glycosidic bonds, hydrogen bonds form between adjacent chains, creating very strong cellulose fibrils
