Biology Topic 1

  • Created by: Qazwsxed
  • Created on: 27-06-18 18:14
Why do mammals and other large organisms need a circulation system?
Because they are too large for diffusion to be an effective way of supplying needs and removing waste
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In large organisms what special organs are needed?
Heart and lungs
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What does the sa/vol ratio affect?
The ratio of the sa of an organism to its volume affects how substances enter the organism and how co2 leaves
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Explain small organisms sa
Small organism have a large sa/vol ratio. Substances and water can enter and leave by diffusion or osmosis
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LArge organisms have a ......... sa/vol
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What is a perfect solvent for transporting substances and co2 around the body?
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Explain why water is the perfect solvent in terms of water being a polar molecule
Polar molecules have uneven distractions. 1 end of water molecule is slightly positive and other slightly negative. Water is said to be dipolar
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Explain why water is the perfect solvent in terms of water being liquid at room temperature
3 water molecules are joined to each other by H bonds formed by electrostatic attraction between polar molecules
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Explain why water is the perfect solvent in terms of water easily dissolving molecules held together by ionic bonds
Sodium and chloride ions in common salt are pulled apart by water molecules and then surrounded by them. Water also dissolves polar molecules such as sugars and amino acids
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Structure of artery
Relatively thick wall, smooth muscle, elastic fibres, lined with smooth layer of endothelial cells and narrow lumen
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Functional significance of a relatively thick cell wall in artery
withstands high blood pressure
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Functional significance of smooth muscle in artery
alters diameter of lumen to vary blood flow
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Functional significance of elastic fibres
allows walls to stretch when blood is pumped into the artery and then recoil, smoothing blood flow
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Functional significance of an artery being lined with a smooth layer of endothelial cells
low friction surface to ease blood flow
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Functional significance of narrow lumen in artery
to maintain high blood pressure
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Structure of capillaries
very thin cell wall-only 1 cell thick and 1 red blood cell thick lumen
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Functional significance of a very thin cell wall in capillaries
Allows rapid exchange between blood and tissues
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Structure of veins
Relatively thin wall, very little smooth muscle or elastic fibres, wide lumen, valves
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Functional significance of a relatively thin wall in vein
blood is under low pressure so wall doesn't need to be strong
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Functional significance of a veinhaving very little smooth muscle or elastic fibres
no pulse of blood so no stretching and recoiling
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Functional significance of a wide lumen in vein
large volume acts as blood reservoir
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Functional significance of valves in veins
stock back flow of blood
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How do you work out the magnification of photographs?
image size/actual size
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How many chambers does the heart consist of?
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What are the top chambers called
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What are the lower chambers called
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Very simple description of the 4-chambered heart
deoxygenated blood enters the right atrium from body, its then pushed by muscles in right ventricle to lungs where its oxygenated. The oxygenated blood returns from lungs to the left atrium its then pushed into left ventricle and out along aorta
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What is the bottom point of heart called?
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Which ventricle of cardiac muscle is thicker and why?
Left-as theres higher pressure when pumping blood to body
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Purpose of septum
to separate the 2 sides of heart
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Why has the mammalian heart got 2 sides?
allow oxygenated and deoxygenated blood to be kept separate, allowing as much oxygen as possible to be carried to the cells. both sides have different amounts of muscle so that there can be higher pressure on the side pumping to the body
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The cardiac cycle in the left side of the heart
Blood drains into left atrium from lungs along pulmonary vein*raising of BP in left atrium forces left av valve open*contraction of left atrial muscle(left atrial systole)forces more blood through valve
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The cardiac cycle in the left side of the heart
as soon as left atrial systole (muscle contraction) is over, left av muscle starts to contract. This is left ventricular systole*This forces left av valve to close and opens valve in mouth of aorta (semilunar valve) blood then leaves left ventricle a
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The cardiac cycle in the left side of the heart
This forces left av valve to close and opens valve in mouth of aorta (semilunar valve) blood then leaves left ventricle along the aorta
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what are the hearts blood vessels called?
Coronary arteries and veins
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Where can coronary be seen?
Branched over the surface of the heart
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What do av valves do?
Stop blood flow from ventricles to atria and semilunar valves from arteries back into the heart
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what is attached to the av valves?
Tendons (heart strings)
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What do tendons do?
Stop valves from tuning inside out
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In an ECG of heart beat what does it mean when graph line starts to rise?
Ventricles start to contract, ventricular pressure is greater than atrial pressure so av valve closes
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In an ECG of heart what happens on graph when semilunar valve opens?
Pressure in ventricles is now greater than that in the aorta so the semilunar valve opens
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Atherosclerosis definition
Atherosclerosis is the disease process that leads to coronary disease and strokes (cv disease)
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What can block an artery?
fatty deposits (atheroma) can either block an artery directly or increase its chance of being blocked by a blood clot (thrombosis)
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Describe the process of atherosclerosis developing
*Endothelial lining of artery is slightly damaged(endothelial dysfunction) which causes an inflammatory response and white blood cells move into artery wall. Cholesterol builds up leading to formation of atheroma. Build-up of calcium salts and fibres
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Describe the process of atherosclerosis developing
Leads to plaque formation. The artery narrows and loses elasticity which raises blood pressure which damages endothelial lining more which increases risk of blood clotting in the artery
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what are the 5 health effects of an atheroma?
Increased BP*aneurysm*angina*Heart attack*Stroke
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Describe increased blood pressure as a health effect of an atheroma
Increased blood pressure can damage kidneys and retina and cause strokes
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Describe aneurysm as a health effect of an atheroma
Aneurysm is where the increased pressure of blood caused by blockage can lead to the bursting of an artery and internal bleeding
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Describe Angina as a health effect of an atheroma
Angina, is a chest pain often felt during exercise, Caused by reduced blood flow to heart due to narrowing of coronary arteries
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Describe a heart attach as a health effect of an atheroma
Heart attack is when a coronary artery becomes totally blocked, usually by a clot, and part of the heart becomes starved of oxygen and dies
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Describe a stroke as a health effect of an atheroma
Stroke is an interruption to the blood supply of the brain which can cause paralysis or even death
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Where is it crucial that a blood clot does not form?
Blood vessels
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Explain a very simple version of the sequence of thrombosis
platelets stick to damaged tissue, a protein thromboplastin turns into soluble prothrombin in plasma. calcium and vitamin K build up turning it into soluble thrombin the fibrinogen into fibrin to blood clot
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What does thromboplastin do?
Trigger blood clotting
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What will more fibrinogen result in?
Larger blood clot
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What is more likely to happen if blood flow is slow?
Blood clot is more likely to form
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Definition of risk
Risk is the probability of the occurrence of an unwanted event or outcome
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When do people often overestimate the risk of something?
*When its involuntary e.g.being a passenger in an airplane *when its dreaded e.g.natural disaster *not natural (nuclear power) *unfamiliar *Unfair *very small
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What are risks for CVD?
Poor diet, lack of exercise, smoking
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When is risk poorly judged?
*own experience which will carry more weight than statistics *inability to assess risks well * peer pressure * idea that is something is destined to happen then it will and there is not much that can be done about it *
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What are the 7 factors that increase risk of CVD?
high BP *genetics *inactivity *age *gender *smoking *diet
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Info about BP and the maximum mmHg
Should not be above 140mmHg/90mmHg
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Why is age a factor that increases risk of CVD?
Because with age elasticity and width of arteries decrease
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why is genetics a risk factor of CVD
People can inherit tendencies to gift BP, poor cholesterol metabolism, arteries that are more easily damaged, relative hHDL : LDL levels in blood
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Why is inactivity a risk factor of CVD
Regular vigorous exercise reduces the risk of CVD by reducing blood pressure and raising HDL (good cholesterol) levels
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Why is gender a risk factor of CVD
Oestrogen gives women some protection from CVD before the menopause
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Why is smoking a risk factor of CVD
Correlation and causation shown because chemicals in smoke physically damage artery linings and could also cause them to constrict
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Why is diet a risk factor of CVD
Many correlations between dietary habits and levels of CVD e.g. lipoproteins and salt levels; some might be casual particularly for blood cholesterol levels
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2 variables can be ..................when a change in 1 is accompanied by a change in the other
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What does it mean to be casually linked
when the change in 1 variable os the cause of the change in the other
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Give an example of correlation causation with smoking?
smoking causes lung cancer
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What do epidemiologists do?
Scientists who carry out research on patterns of diseases or health risks in population to try to determine the risk factors of health
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what are the 2 main kinds of studies
cohort studies*case-control studies
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explain cohort studies
follow a large number of people over an extended period. subjects are monitored to see if they develop the condition, cohort then divided into groups those with and those without the condition. Subjects are interviewed to assess their risk factors.
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explain cohort studies
correlation between risk factors and development of the condition is looked for
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explain case-control studies
A group with the condition (cases) is compared with a group without it (control). Past histories of the 2 groups are investigated. The study will only have validity if the 2 groups are matched for other factors such as age and gender
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Name 4 factors that make a good study
*variables should be controlled when selecting cohort or control groups to ensure validity and reliability. This is difficult because human beings are so variable *Measurement techniques or the questions on a questionnaire must be standardised
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Name 4 factors that make a good study
*sample size is very important. For many diseases, only a low % of the population has the condition so an apparently large sample size might only contain a small number of individuals with the condition
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Name 4 factors that make a good study
*The studied sample should be representative of the whole population to avoid bias
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What are energy budgets
energy budgets is the balance between the amount of energy a person requires compared to the energy they take in through their diet
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What does the energy you need in a day depend on?
your basal metabolic rate and level of activity
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what is BMR
basal metabolic rate
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what is BMR usually quoted as
the basic energy requirement for the day
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What does energy budgets depend on?
gender, age, body mass
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When will you weight stay the same?
If the energy transferred from food you eat is the same as your BMR
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What will put you at risk of weight gain/loss
an energy imbalance
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How do you work out body mass index
body mass(kg ). / (height m) squared
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explain BMI values
Below 20=underweight. 20-25=correct weight 25.1-30=overweight over 30=obese
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What should the waist:hip ratio not be greater than in males and females?
males:0.9 Females:0.85
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What does carbohydrate mean?
carbo=carbon Hydrate=water
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what is the general formula of carbohydrates
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what is the main energy source in the diet
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What are saccharides
saccharides are sugar units that make up carbohydrates
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How many units does a disaccharide have
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How many units does a monosaccharide have
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how many units does a polysaccharide have
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what is the general formula for glucose
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what sugar is Glucose
Hexose sugar
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What different forms of glucose are there
alpha and beta
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What is glucose the source of?
Glucose is the source of the most readily available energy from respiration in living things
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Is glucose soluble?
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How does its solubility help
helps it fulfil role of energy as it can easily be carried to where ut is need
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Why is glucose being a relatively small molecule helpful?
because its important for its movement into cells
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When are disaccharides made
disaccharides are made when 2 monosaccharides join by losing water in a condensation reaction
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When do 1,4 glycosidic links form
When disaccharides join at C atoms 1 and 4
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When do disaccharides split
disaccharides are split by adding water
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What is the reaction called where water is added
hydrolysis reaction
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what is needed to break glycosidic bonds
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what is maltose made of
a 2 alpha glucose molecule
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what is sucrose made of
alpha glucose and fructose molecule
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What is lactose
sugar milk
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what is lactose made with
lactose is glucose and galactose joined with a bet a1,4 bond as glucose is in beta form
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what does amylopectin mean
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what does amylose mean
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are polysaccharides amylose or amylopectin
can be both
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what is glycogen
animal starch
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What joins to make amylose
alpha glucose monomers join with 1,4 glycosidic bonds to make amylose
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what is amylose
a component of starch
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what joins to make amylose and amylopectin
alpha glucose monomers join with alpha 1,4 and alpha 1,6 glycosidic bonds to make amylopectin and amylose
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what has glycogen got more of that amylopectin in terms of bonds
glycogen has more alpha 1,6 and is more branched
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What is starch a mixture of
amylose and amylopectin
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What happens when starch is broken down in digestion
the enzymes catalyse a hydrolysis reaction and monosaccharides are produced again
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Is amylose straight or coiled
amylose is a straight chain
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why is amylose a straight chain
due to the H Bonding
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What bonds does amylopectin have to not allow much coiling, is it branched and what do the bonds not allow so much of?
In amylopectin, the branches (1,6 glycosidic bonds) do not allow so much coiling
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What is glycogen like
amylopectin but more branched
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Explain starch and its coiled shape
the coiled shape makes it more compact so it can store lots of glucose and therefore energy in a small space
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Is starch soluble or insoluble
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Starch is insoluble so does not............
exert a problematic osmotic effect
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............... Is more easily broken down than amylose
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Why is amylopectin more easily broken down than amylose
due to more branches, which creates more terminal ends where breakdowns occur and gives a mixture of rapid and slower glucose and energy release
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explain glycogen and its branches
glycogen has even more branches so can release glucose even faster, which is needed in animals
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what bonds does amylose have
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what bonds does amylopectin have
1,4 and 1,6
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what are lipids
fats and oils
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are lipids hydrophobic or hydrophilic
all lipids are hydrophobic molecules
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what is hydrophobic
water hating/repelling
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what are lipids used for
lipids are used to store energy and act as waterproofing and insulating agents
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what bond joins a triglyceride
ester bond
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What are triglycerides made of
3 fatty acids and a glycerol joined by an ester bond
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by what reaction are ester bonds made
condensation reaction
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explain hydrophobic/hydrophilic tails and heads in a triglyceride
hydrophobic tail, hydrophilic head
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how do fatty acids vary
*fatty acids are of different lengths *in mixed triglycerides the 3 fatty acids are different from each other *fatty acids may be saturated or unsaturated with hydrogen
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Explain a saturated fatty acid
no double bond between carbons
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explain an unsaturated fatty acid
double bonds between some carbon atoms
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explain the properties of unsaturated fatty acids
the kink in an unsaturated fatty acid makes the membrane more fluid than 1 with saturated lipids
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Where is the kink in unsaturated fats
unsaturated fatty acids have a kink at each double bond
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name an example of a saturated fatty acid
palmitic acid
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name an example of an unsaturated fatty acid
oleic acid
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what is cholesterol
cholesterol is an essential component of cell membranes where it affects their fluidity
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Explain cholesterol in terms of solubility
Cholesterol is a water-insoluble lipid which has to be carried by proteins in complexes called lipoproteins
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How many different types of lipids are there
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What are the 2 types
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Explain what LDL's are made from
LDL's are made from saturated fats, proteins and cholesterol
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Explain what HDL's are made from
HDL's are made from unsaturated fats, proteins and cholesterol
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Purpose of HDL
Transport cholesterol from body tissues to liver where it is broken down
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Purpose of LDL
Bind to cell surface receptors which can become saturated leaving LDL's in blood
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What is LDL associated with
Associated with formation of atherosclerosis
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What does HDL discourage
Discourages atherosclerosis as reduces blood cholesterol levels
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At what level should HDL's be maintained at
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At what level should LDL's be maintained at
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what does cholesterol help form
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Explain the casual link between the 2 variables using rats
rats fed on a high cholesterol diet formed more plaques in the endothelium of arteries than the other control groups
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what are the most important factors that reduce the risks of CVD
*stop smoking *maintain resting blood pressure below 140/90 mmHg *maintain a low blood cholesterol level *maintain a normal BMI/low waist to hip ratio *take regular physical exercise *moderate/no use of alcohol *reduce stress
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What dietary strategies reduce the risk of CVD
*reduce saturated fats *more polyunsaturated fats *reduce salts (lower fluid levels in turn reduces blood pressure) *more fruit and veg (antioxidants and non-starch cabs lower blood cholesterol)
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What dietary strategies reduce the risk of CVD
*more oily fish (linked to slight reduction in BP and risk of blood clotting) *more non-starch polysaccharides
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What is vitamin C and what is it common in
Vitamin C is an antioxidant common in many foods such as citrus fruits
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what are antioxidants important for
neutralising free radicals which can damage cells
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What are antioxidants destroyed by
heat treatments
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Why are antioxidants reducing agents
because they lose electrons
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What will many substances do when they are reduced
change colour
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What are these substances that change colour when reduced called
redox dyes (reduction-oxidation dyes)
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What is DCPIP and explain its colour changes
a blue dye in its non-reduced form; goes colourless when in presence of vitamin C as it gains electrons
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What may be done if lifestyle and diet may not be enough to prevent CVD and why
drugs may be given to control blood pressure and/or lower blood cholesterol
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Name the 6 drugs that reduce the risk of CVD
*diuretics *calcium channel blockers *ACE inhibitors (angiotensin converting enzyme) *statins *warfarin *aspirin
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What is aspirin an example of
platelet inhibitory drugs
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What is warfarin an example of
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name 3 antihypertensive drugs
*diuretics *calcium channel blockers *ACE
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What does ACE stand for
angiotensin converting enzyme
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What do diuretics do
increase volume of urine, lowers blood volume and blood pressure
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What is the risk/side effect of diuretics
very occasional dizziness *nausea *muscle cramps
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What do calcium channel blockers do
disrupts calcium ion movement through calcium channels in the cell membrane, reducing muscle contractions so increases diameter of arteries reduces force of heart beat and frequency, lowering BP
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What is the risk/side effect of calcium channel blockers
headaches *dizziness *swollen ankles *constipation *lushing in face
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What does ACE inhibitors do
blocks the production of ACE, reducing arterial constriction and lowering BP
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WHta is ten risk/side effect of ACE inhibitors
*cough *dizziness *abnormal heart rhythm *impaired kidney function
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What do statins do
inhibit an enzyme in the liver that produces LDL cholesterol
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What are the risk/side effects of statins
*tiredness *disturbed sleep *nausea *diarrhoea *headache *muscle weakness
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What do anticoagulants do
reduce risk of clot formation
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What are the risk/side effects of anticoagulants
Risk of uncontrollable bleeding, dosage control is essential
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What do platelet inhibitory drugs do
Make platelets less sticky
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rosk/side effects of platelet inhibitory drugs
aspirin irritates stomach lining ands can cause stomach bleeding *clopidogrel with aspirin increases risk
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compare the ethical issues of using daphnia and humans in the daphnia heart rate experiment
daphnia= have simple nervous system humans=complex nervous system *daphnia=no need for dissection as transparent and can see heart beating human=needs dissection *D=abundant in nature H=cannot kill for *D=bred for fish food H=experiment
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compare the ethical issues of using daphnia and humans in the daphnia heart rate experiment
*D=no loss of genetic variation *D=cannot give consent H=can give consent
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Why is daphnia used for this experiment
*abundant *easily obtained *transparent-so heart can be seen *simple nervous system so ethically less of an issue that a mammal
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what are some limitations of this daphnia experiment
*they are not human
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Explain the step in the experiment and method
*immobilise the daphnia-use strands of cotton wool in a small dish of the experimental solution to trap the daphnia
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Explain the step in the experiment and method
*control other variables e.g.water temperature, daphnia size-difficult to maintain constant temperature but should be monitored with thermometer in water, daphnia of similar size etc. should all be used for all experiments
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Explain the step in the experiment and method
*accurate measurement of HR-dots are put on piece of paper in S shape to avoid putting dot on top of another or repeatedly press a button on a calculator *repeatability-ensure that variables other than caffeine conc are controlled
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What are the variables considered to be in the daphnia experiment
*temperature *age, size, sex of daphnia *aspects of pretreatment such as type of water, length of time out of natural habitat
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What are the safety measures that should be taken during the experiment
*do not mix water an electricity *don't forget to wash your hands after handling daphnia
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Card 2


In large organisms what special organs are needed?


Heart and lungs

Card 3


What does the sa/vol ratio affect?


Preview of the front of card 3

Card 4


Explain small organisms sa


Preview of the front of card 4

Card 5


LArge organisms have a ......... sa/vol


Preview of the front of card 5
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