Biology unit 1

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  • Created on: 17-04-16 17:44
What is cardiovascular disease (CVD)?
Disease of the heart and circulation
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What are the main forms of CVD?
Coronary heart disease and stroke
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What is the primary purpose of the heart and circulation?
To move substances around the body
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What is moved around a small organisms body by diffusion?
Oxygen, carbon dioxide and digestive products
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What is diffusion?
The movement of molecules from a region of high concentration to low concentration down a concentration gradient
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What is an open circulatory system?
Blood circulates in an open space.Simple heart pumps blood out into cavities surrounding animal's organs.Substances diffuse between blood and cells.Heart muscle relaxes,blood drawn back into heart, through small valve opening along its length
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What is a closed circulatory system?
Blood is enclosed within tubes creating high b.p. as the blood is forced along narrow channels.This means blood travels faster and so blood system is more efficient at delivering substances around the body
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Describe the process within a closed circulatory system
Blood leaves heart under pressure along arteries and arterioles to capillaries.Substances are exchanged here between blood and cells.Blood returns to the heart by venules and then veins.Valves ensure that blood flows in one direction
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What are the two different types of closed circulatory systems?
Single circulation and double circulation
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Describe the process of the single circulatory system in fish
Heart pumps deoxygenated blood to the gills.Gaseous exchange takes place(diffusion of CO2 from blood into water surrounding gills and oxygen from water into blood).Blood then flows to rest of body and back to heart
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Describe the process of the double circulatory system in birds and mammals
The right ventricle pumps deoxygenated blood to the lungs where it receives oxygen.The oxygenated blood return to the heart to be pumped out to the rest of the body
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Why do only small animals have an open circulatory system?
Movement of O2,CO2 and other products carried by blood relies on diffusion in an open circulatory system;diffusion is only fast enough for small organisms
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What are the advantages of having a double circulatory system?
Blood can pass slowly through the region where gaseous exchange takes place;maximising transfer of O2 and CO2 and then pumped vigorously round to the rest of the body;enabling organism to be very active
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What is plasma mainly made up of?
Mainly water and contains dissolved substances such as food, oxygen and carbon dioxide
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Name some of the substances transported in the plasma
Proteins, amino acids, salts, enzymes,hormones,antibodies and urea
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What is the role of arteries?
Carries blood away from the heart
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What is the role of veins?
Carries blood towards the heart
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What is collagen?
A tough fibrous protein which makes vessels strong and durable
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What do both arteries and veins contain?
Collagen,elastic fibres and smooth muscle cells
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What is the role of elastic fibres in vessels?
Allows them to stretch and recoil
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What is the role of smooth muscle cells in the walls of vessels?
Allows them to constrict and dilate
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State the key physical features of arteries
1.Narrow lumen 2.Thicker walls 3.More collagen,elastic fibres and smooth muscle 4.No valves
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State the key physical features of veins
1.Wide lumen 2.Thinner walls 3.Less collagen,elastic fibres and smooth muscles 4.Valves
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What is the outer coat of veins and arteries made up of?
Connective tissue with collagen fibres
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State the physical features of capillaries
One cell thick
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What do capillaries join together?
Arterioles and venules
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What happens during systole?
Blood is forced into the arteries and their elastic walls stretch to accommodate the blood(cardiac muscle contracts and heart pumps blood out through aorta and pulmonary arteries)
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What happens during diastole?
The elasticity of the artery walls causes them to recoil behind the blood, pushing the blood forward out through the artery (cardiac muscles relax and the heart fills with blood)
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What is blood flow assisted by in the veins?
The contraction of skeletal muscles during movement of limbs and breathing.Low pressure in the thorax when breathing helps draw blood back into the heart from the veins.Valves prevent backflow. Blood is under low pressure in veins
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List the features that enable the artery to withstand high pressure and then recoil to maintain a steady flow of blood
Thick layer of mainly elastic fibres (to allow expansion and recoil of artery) surrounded by thick layer of mainly collagen fibres (tough and durable to withstand high pressure)
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How is heart muscle supplied with blood?
Through two muscles called the coronary arteries
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What is the cardiac cycle?
One complete sequence of filling and pumping blood
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What is atherosclerosis?
The disease process that leads to coronary heart disease and strokes. This is when fatty deposits either block an artery directly or increase its chance of being blocked by a blood clot (thrombosis)
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Describe what happens in atherosclerosis
1.Damage to endothelial cells 2.Inflammatory response 3.White blood cells move to damage site 4.Cholesterol accumulates 5.Atheroma forms 6.Plaque forms 7.Artery narrows 8.High blood pressure
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What is plaque made up of?
Calcium salts and fibrous tissue
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Describe the formation of a blood clot
1.Prothrombin is converted into thrombin 2.Thrombin is used to convert fibrinogen into fibrin 3. Fibrin forms a mesh with traps platelets and blood cells 4.Clot is formed
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Why do only arteries get atherosclerosis?
There is high blood pressure in the arteries due to the fast-flowing blood this means that there is a high chance that there will be damage to the wall. Veins on the other hand have low blood pressure so there is less risk of damage to the walls
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Why is angina experienced?
During exertion heart muscle lacks oxygen so is forced to respire anaerobically.This results in chemical changes which trigger pain
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What happens during myocarial infarction?
Fatty plaque in coronary arteries ruptures,cholesterol released leading to clot formation.Blood supply to heart blocked completely.Heart muscle supplied by arteries becomes ischaemic(without oxygen). If they are are ischaemic for long-perm damage
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What is the cause of a stroke?
When blood supply to the brain is blocked
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What factors contribute to health risks?
1.Heredity 2.Physical environment 3.Social environment 4.Lifestyle and behaviour choices
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Name two types of studies used to look for correlations between a disease and a specific risk factor?
1.Cohort:a group of people who are followed over time to see who develops the disease 2.Case-control:A group of people who have a disease that are compared with a group who do not have the disease
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What factors can lead to an increased risk of CVD?
1.High blood pressure 2.Obesity 3. Blood cholesterol and other dietary factors 4.Smoking 5.Genetic inheritance 6.Gender(males are more likely to get CVD than women) 7.Age
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What is hypertension?
Elevated blood pressure
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What is blood pressure?
A measure of the hydrostatic force of the blood against the walls of a blood vessel
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When is systolic pressure?
When the blood pressure is the highest during the phase of the cardiac cycle when the ventricles have contracted and forced blood into the arteries
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What is diastolic pressure?
Pressure is the lowest in the arteries when the ventricles are relaxed
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What are the units for pressure?
mmHG (millimetres of mercury)
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What is peripheral resistance?
Contact between blood and the walls of the blood vessels causes friction and this prevents the flow of blood
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What happens if the smooth muscles in the walls of an artery contract?
The vessels constrict, increasing resistance.In turn your blood pressure is raised
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What happens if the smooth muscles in the walls of an artery relax?
The lumen is dilates so peripheral resistance is reduced and blood pressure falls
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What factors can cause arteries to constrict increasing blood pressure?
1.Natural loss of elasticity with age 2.Release of hormones such as adrenaline 3.High salt diet
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How does tissue fluid form?
Blood is under pressure in the artery end of a capilary.This forces fluid and small molecules found in plasm out through capillary walls into the intercellular space
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What are the types of food which store energy?
1.Carbohydrates 2.Lipids 3.Proteins
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What is a calorie?
The quantity of heat energy required to raise the temperature of 1cm3 of water by 1 degree.
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What are monosaccharides?
A single sugar unit
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What are disaccharides?
Two sugar units that have combined in a condensation reaction
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What is a polysaccharide?
A long straight or branched chain of sugar units
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Why is glucose important?
Main sugar used by all cells in respiration
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How is glucose produced?
Starch and glycogen are polymers made up of glucose subunits joined together.When they are digested, glucose is produced. This can then be absorbed and transported in the blood stream to cells
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Where are glucose and fructose found naturally?
In fruit, vegetables and honey
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Name some monosaccharides
Glucose, galactose and fructose
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What is the name of the bond that forms between glucoses?
Glycosidic bond
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Name the three disaccharides
Sucrose,maltose and lactose
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What is sucrose formed from?
Glucose and fructose
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What is sucrose?
The usual form in which sugar is transported around the plant
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What is maltose formed from?
Two glucose molecules
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When is maltose produced?
When amylase breaks down starch
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Where is maltose found?
In germinating seeds as they break down their starch stored to use for food
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What is lactose formed from?
Glucose and galactose
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Where is lactose found?
In milk
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When does hydrolysis of carbohydrates take place?
When carbohydrates are digested in the gut and when carbohydrate stores in a cell are broken down to release sugars
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What do starch and glycogen act as?
Energy storage molecules within cells
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Why are starch and glycogen suitable for storage?
They are compact molecules with low solubility in water. This means that they don't affect the concentration of water in the cytoplasm so do not affect the movement of water into or out of the cell
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What is starch made up of?
Two polysaccharides of alpha-glucose-amylose and amylopectin. Starch is insoluble in water so it doesn't cause water to enter the cell by osmosis.This makes it good for storage
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Describe amylose
A long unbranched chain of glucose joined together by 1-4 glycosidic bonds. The angles of the glycosidic bonds give it a coiled structure. This makes it compact so it is good for storage as you can fit more into a small space
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Describe amylopectin
A long branched chain of glucose that contains 1-4 and 1-6 glycosidic bonds.Its side branches allow enzymes that break the molecule down to get to the glycosidic bond easily.This means that glucose can be released quickly
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Describe glycogen
Animals store excess glucose as glycogen a polysaccharide of a-glucose.Has 1-4 & 1-6 glycosidic bonds with many side chains.So that glucose can be released quickly.Is a compact molecule so good for storage & is insoluble.Large molecule-store energy
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Where does starch occur naturally?
Animals store excess glucose as glycogen a polysaccharide of a-glucose.Has 1-4 & 1-6 glycosidic bonds with many side chains.So that glucose can be released quickly.Is a compact molecule so good for storage & is insoluble.Large molecule-store energy
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Where does starch occur naturally?
In fruits, vegetables and cereals
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What stores glycogen?
Bacteria, fungi and animals
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Where is glycogen stored in humans?
Liver and muscles
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What is the function of cellulose?
As it is indigestible in the human gut it is used in the movement of material through the digestive tract
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What are lipids?
Organic molecules found in every type of cell; they are insoluble in water but soluble in organic solvents such as ethanol
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What are triglycerides?
Lipids that are used as energy stores in plants and animals
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Describe the structure of a triglyceride
A glycerol joined together with 3 fatty acids during a condensation reaction
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What is the name of the bond that forms between each fatty acid and glycerol in a triglyceride?
An ester bond
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What is a saturated fat?
When the fatty acid chains in a lipid contain the maximum number of hydrogen atoms..The hydrocarbon chain is long and straight allowing chains to pack closely together to form strong intermolecular bonds which make them solid at r.t
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What are major sources of saturated fats?
Fats from meats and dairy products
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What is an unsaturated fat
When the fatty acid chains in a lipid has double bonds which create kinks in the hydrocarbon chain.These kinks prevent the unsaturated hydrocarbons from packing closely together.So they form weak intermolecular bonds making them liquid at r.t.
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What contains monounsaturated fats?
Olive oil
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What are good sources of polyunsaturated fats?
Vegetable oils, nuts and fish
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What is cholesterol?
A short lipid molecule that is a vital component if cell membranes with roles in the organisation and functioning
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Name the types of hormones produced from cholesterol
Steroid sex hormones and some growth hormone
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Where is cholesterol made?
In the liver from unsaturated fats and also obtained in our diet
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Describe the structure of a phospholipid
Glycerol bonded to two fatty acid chains and one negatively charged phosphate group
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What are the risks as a result of obesity
Increased risk of coronary heart disease and stroke, type II diabetes, high blood pressure and high blood lipid levels
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How is cholesterol transported in the bloodstream?
Cholesterol is not soluble in water so it is combined with proteins to form soluble lipoproteins
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What are the two main transport lipoproteins?
Low-density lipoproteins (LDLs) and high-density lipoproteins (HDLs)
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Describe what LDLs are and how they work
Triglycerides from saturated fats combine with cholesterol and proteins to form LDLs.They circulate in the bloodstream and bind to receptor sites on cell membranes before being taken up by the cells
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Describe the effect of excess LDLs in the diet.
Can overload membrane receptors resulting in high blood cholesterol levels.Saturated fats may also reduce the activity of LDL receptors so LDLs are not removed from the blood thus further increasing the blood cholesterol levels.Formation of atheromas
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Describe what HDLs are and what role they have
Triglycerides from unsaturated fats combine with cholesterol and protein. HDLs transport cholesterol from the body tissues to the liver where it is broken down.This lowers blood cholesterol levels and helps remove the fatty plaques of atherosclerosis
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What affect does smoking have on the circulatory system?
Causes haemoglobin in r.b.c to carry CO from the smoke instead of O, reducing the supply of O to the cells, thus heart rate increases.Nicotine stimulates the production of hormone adrenaline which increases h.r which raises b.p.Can cause atherosclero
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What are the positive effects of moderate exercise?
Reduces blood pressure, increases levels of HDLs and reduces risk of developing type II diabetes
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Describe the affect of adrenaline
Causes arteries and arterioles to constrict, resulting in raised blood pressure
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How can the risk of CVD be reduced?
Stop smoking,increase physical activity,moderate or no use of alcohol, healthy BMI and maintaining low blood cholesterol level
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What are the three main types of drugs used to treat high blood pressure?
ACE inhibitors, calcium channel blockers and diuretics
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How do ACE inhibitors work?
Are antihypertensive drugs that reduce the synthesis of angiotensin II.This hormone causes vasoconstriction of blood vessels to help control b.p. ACE inhibitors prevent hormone from being produced from an inactive form angiotensin I,thus reducing b.p
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What are the negative side effects of ACE inhibitors?
Abnormal heart rhythm, dizziness and reduction in the function of the kidneys
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How do calcium channels blockers work?
Antihypertensive drugs that block the Ca2+ channels in the muscle cells in the lining of arteries. In order for a muscle to contract,calcium must pass through these channels into the muscle cells.Therefore contraction is prevented so b.p is lowered
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What are the negative side effects of calcium channel blockers?
Headaches, dizziness, abnormal heart rhythms and constipations
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How do diuretics work?
Increase the volume of urine produced by the kidneys and so get rid of excess fluids and salts.This leads to a decrease in blood plasma volume and cardiac output, which lowers blood pressure
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What do statins do and how do they work?
Lowers cholesterol by inhibiting the enzyme involved in the production of LDLs
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Name four types of drugs that can be used to treat CVD
Antihypertensives, plant statins, anticoagulants and platelet inhibitory drugs
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Describe how antihypertensives work
e.g. diuretics and beta blockers. Reduce blood pressure so there is less risk of damage occuring to the walls of the arteries. This reduces the risks of atheromas forming and blood clots developing
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State the advantages and disadvantages of antihypertensives
ADV:Different types work in different ways so can be giving in combination to reduce b.p, also b.p can be monitored at home so patient can see if working DIS:Palpatations.abnormal heart rhythm and headaches
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How do plant statins work?
Plants contain chemicals called stanols(saturated) and sterols.They reduce blood cholesterol by reducing the amount of cholesterol absorbed from the gut(compete with cholesterol). Lowering cholesterol reduces atheroma formation reducing CVD risk
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What are the advantages and disadvantages of plant statins?
ADV:Reduce the risk of developing CVD DIS:Reduce the absorption of some vitamins from the gut
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Describe how anticoagulants work
e.g. warfrin and heparin. Reduce blood clotting as it decreases the stickiness of platelets which means that blood clots are less likely to form at sites of damage in artery walls so less likely for blood vessel to become blocked by a blood clot
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What are the advantages and disadvantages of anticoagulants?
ADV:Can be used to treat people who already have blood clots or CVD, they prevent exsisting blood clots from getting larger and any new blood clots from forming DIS:Excessive bleeding, osteoporosis and can cause damage to fetus
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Describe how platelet inhibitory drugs work
e.g. Aspirin. It is a type of anticoagulant. They work by preventing platelets clumping together to form a blood clot so reduce the formations of blood clots
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What are the advantages and disadvantages of platelet inhibitory drugs
ADV:Can be used to treat people who already have blood clots or CVD DIS:Rashes,liver function problems and excessive bleeding0
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What does CF cause?
The build up of sticky mucus in tubes and ducts into the gas exchange, digestive and reproductive system
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How do the lungs allow rapid gas exchange between the atmosphere and the blood
Air drawn into the lungs via the trachea due to low pressure in the lungs.Trachea splits into two bronchi which carry air to the lungs.In lungs there are bronchioles with alveoli where gas-exchange takes place
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How does sticky mucus increase the chance of lung infection?
Mucus is too sticky so cilia is unable to move it.This creates a thick layer of mucus on the lungs. There are low levels of oxygen in the mucus as oxygen diffusion through it is slow. Harmful bacteria can thrive in anaeorbic conditions
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Why does swallowing the mucus reduce the risk of infection?
Acid in the stomach kills the microorganisms
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What are the key features of the gas exchange surface?
Large surface area of the alveoli, numerous capillaries around the alveoli and thin walls of the alveoli and capillaries so there is a short diffusion distance
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What three properties is the rate of diffusion dependent on?
Surface area(as surface area increases rate of diffusion increases), concentration gradient and thickness of gas exchange surface
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What ensures the rapid diffusion across the gas exchange surface in the alveoli?
Large surface area of alveoli, steep concentration gradient between the alveoli air and the blood(maintained by the ventilation of the alveoli) and the thin walls of the alveoli and capillaries
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How does sticky mucus affect gas exchange?
Blockage in bronchioles blocks narrow airways preventing ventilation below blockage .This reduces the number of alveoli providing surface area for gas exchange.Decrease in elasticity.Cannot undergo aerobic respiration
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What are the two main types of polysaccharides?
Starch and glycogen
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What are the structural properties of a globular protein?
Round and compact, hydrophilic on the outside and hydrophobic on the inside and is soluble so is easily transported. E.g. haemoglobin
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Describe the structural properties of a fibrous protein
Long, insoluble polypeptide chains, they are tightly coiled to form a rope shape. It has lots of very strong bonds e.g. hydrogen bonds. E.g. collagen
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Describe secondary structure of a protein
Can fold into an alpha helix or beta pleated sheet.H bonds form between C double bond O and amine group in a alpha helix and in a beta pleated sheet H bonds form with parallel chains
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Describe how a tertiary structure is maintained
Chemical bonds e.g. ionic, hydrogen and disulfide, and hydrophobic attractions between R groups
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Describe the structure of a phospholipid
Glycerol with two fatty acid chains and a negatively charged phosphate group bonded to it.Head is polar so it is attracted to water, tail non-polar so repelled by water`
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Describe the initial model of the membrane that was first proposed
Two layers of protein with a lipid bilayer in the middle
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Describe how proteins can be dissociated from the membrane
By increasing the ionic strength of the solution or by adding a detergent
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Describe evidence for the fluid mosaic model
Mouse & human cell fused together.Specific membrane protein in each cell marked with different coloured fluorescent tag.Light microscope used to follow proteins.After 40mins proteins were intermixed.This only happens if they had diffused through memb
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How does cholesterol reduce the fluidity of the membrane?
By preventing the movement of the phospholipids by bonding to them
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What is facilitated diffusion?
The diffusion of large hydrophilic molecules or ions from an area of high concentration to low concentration with the aid of proteins such as channel and carrier proteins (does not require ATP)
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What is a carrier protein and how does it work?
A protein that moves large molecules out of the cell down their concentration gradient (Molecule attaches to protein membrane, protein changes shape and releases molecule on opposite side)
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What is a channel protein and how does it work?
A protein that forms pores in the membrane for charged particles to pass through
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What is osmosis?
The movement of water molecules from an area of high concentration to low concentration through a partially permeable membrane.
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What is active transport and how does it work?
The movement of molecules across a membrane against a concentration gradient using ATP. (molecules bind to carrier protein, energy from ATP changes the shape of the carrier protein, releasing molecule on the other side of the membrane)
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Describe how endocytosis works
Cell surrounds the substance with a section of its cell membrane, the section of the membrane comes off to form a vesicle inside the cell containing the indigested substance
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Describe how exocytosis works
Vesicles containing substance comes off the sacs of the golgi apparatus and moves towards the cell membrane, vesicle fuses with the cell membrane and releases its contents outside the cell.
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Describe how water is moved out of the lungs
Sodium and chloride ions are transported across the epithelial cells.Water then follows the ions because of osmosis
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What happens if there is excess water in the mucus layer?
Detected by epithelial cells.Carriers in basal membrane,pump Na+ out of cell.Conc Na+ falls creating conc grad across mem facing airway.Na+ diffuses down using Na+ channels.Creates electrical grad between tissue fluid and mucus,Cl- goes in.H2O follow
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What happens to the movement of water in a person with CF?
CFTR channel is absent of or not functional, Na+ channel is permanently open causing Cl- and water to move out of the mucus into the cell
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Describe how CF effects the digestive system
Tube connecting pancreas to small intestines becomes blocked with mucus or cysts form on pancreas,preventing digestive enzymes from reaching the small intestines.Reduces their ability to digest food so fewer nutrients can be absorbed(malabsorption sy
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Describe the lock and key theory
A specific substrate or two specific substrates that join together fit into the active site of an enzyme forming temporary bonds with the amino acids in active site to form enzyme-substrate complex.Enzyme holds substrate so they can react more easily
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Describe the induced fit theory
Active site is flexible so when the substrate enters the active site the enzyme changes shape slightly fitting more closely around the substrate
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How do enzymes reduce the activation energy required to convert the substrate into a product?
Electrically charged groups on their surface interact. The attraction of oppositely charged groups distorts the shape of the substrate causing its bonds to break and new ones to form. Therefore less energy is required
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How does cystic fibrosis effect the reproductive systems?
Mucus plug develops in the cervix,this prevents sperm from reaching the egg.In some men the sperm duct is absent or is blocked by mucus so fewer sperm are present in each ejaculate
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What is the role of DNA?
It is a type of nucleic acid that is found in every cell nucleus it contains genetic code which dictates all the inherited characteristics of an organism by controlling the manufacture of proteins. This is unique to an individual
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What is a gene?
A sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chai
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What is a genome?
All the genes in an individual
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What is a mononucleotide made up of?
A deoxyribose sugar, a phosphate group and a nitrogenous base
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What is semi conservative replication?
When the two new DNA molecules produced from replication both contain one strand of DNA from original DNA molecule and one new strand
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Describe the Meselson and Stahl experiment
Two samples of Ecoli grown one in light nitrogen other in heavy.Bacteria from both taken and spun in a centrifugeW
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What is a mutation?
Changes to the base sequence of DNA that can be caused during DNA replication
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What are the different causes of mutation?
Substitution (1 base sub for another), deletion (1 base deleted), insertion (extra base added), duplication (one or more bases repeated) and inversion (a sequence of bases is reversed)
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What causes sickly cell anaemia?
Mutation in gene that codes for a polypeptide chain in haemoglobin. This causes a non-polar amino acid to be produced so the haemoglobin in less soluble
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Describe how mutations can affect the CFTR protein
1.ATP is unable to bind and open channel 2.Channel is open but changes in protein structure cause reduced movement of Cl- ions through channel 3.deletion of 3 nucleotides causing a change in folding of protein
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What is a mutation?
Changes to the DNA base sequence that can be caused by errors during DNA replication
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State how mutations can be caused
1.Substitution (1 base substituted with another) 2.Deletion (1 base is deleted) 3.Insertion (An extra base is added) 4.Duplication (1 or more bases are repeated) 5.Inversion (A sequence of bases is reversed)
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What is genotype?
The alleles a person has
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What is phenotype?
The physical characteristic caused by the genotype
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What is meant by the term dominant allele
An allele is a different version of a gene, if it is dominant the charecteristic will appear in the genotype even when there is only one coppy
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What is meant by the term recessive allele
An allele is a different version of a gene, if it is recessive the characteristic will only appear in the phenotype if two copies are present on the same locus
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What is meant is meant by the term homozygote?
An organism that carries two copies of the same allele
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What is meant by the term heterozygote?
An organism that has two different alleles
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What is monohybrid inheritance?
The inheritance of a single characteristic controlled by different alleles
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How is gene therapy carried out?
Normal alleles of gene are inserted into target cell using virus or liposome, normal gene transcribed and translated and functioning protein is produced in target cell
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How are genes inserted using viruses?
DNA sequence that allows virus to replicate is removed and is replaced with normal allele of desired gene with a promoter sequence which initiates transcription and translation of the gene.Viral DNA incorporated into our DNA
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How are genes inserted using liposomes?
Copy of normal allele is inserted into plasmid.Plasmids are then combined with liposomes(spherical phospholipid bilayer).+ve head groups of phospholipid combine with DNA to form a liposome-DNA complex.CF patient inhales using nebuliser.
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What are the main uses of genetic screening?
1.Identification of carriers 2.Testing of embryos (Preimplantation genetic diagnosis) 3.Prenatal testing
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What is identification of carriers and what are some of the issues raised by it?
Tests offered to individuals with a family history of genetic disorders to see whether they carry an allele for the disorder (False results, genetic discrimination and emotional stress)
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What is preimplantation genetic diagnosis (PGD)?
Test carried out on embryos produced by IVF which involves screening embryos for genetic disorders before they are implanted into the woman
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What are some of the advantages and disadvantages of preimplantation genetic diagnosis?
ADV:Reduces chances of having a baby with a genetic disorder, avoids issue of abortion DIS:Can find out other characteristics which could lead to designer babies and false posatives
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What is prenatal testing?
Screening of unborn babies for genetic disorders this can be done by amniocentesis or chorionic villus sampling
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Describe how amniocentesis is carried out
Carried out at 15-16 weeks of pregnancy. Sample of amniotic fluid is obtained using a fine needle.DNA extracted from fetal cells which can then be tested
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Describe how chorionic villius sampling is carried out
Carried out at 8-12 weeks of pregnancy.A sample of cells are taken from the chorionic villi using a catheter. The fetal DNA is then extracted and tested
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What are the advantages and disadvantages of prenatal testing?
ADV:Parents can make informed decisions, allows parents to prepare for future DIS:Increased risk of miscarriage, false positive and unethical to abort because it has a genetic disorder
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What are the main forms of CVD?


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What is the primary purpose of the heart and circulation?


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Card 4


What is moved around a small organisms body by diffusion?


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What is diffusion?


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