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Question 1

water: characteristics

Answer 1

-water is a solvent
-water is cohesive
-the oxygen atoms attracts electrons a bit more strongly than the hydrogen atoms
-the unequal sharing of electrons gives the water molecule a slightly negative charge near its oxygen atom and a slight positive charge near its hydrogen atoms
-this causes water to have a permanent dipole- an uneven distribution of charge (one end more positive and another more negative) within the molecules, making water a polar molecule, also because the atoms are held by covalent bonds
-many substances, such as inorganic ions, can dissolve in water thanks to these positive and negative charges within the molecule
-when substances dissolve in water, they can move, allowing chemical reactions to occur

Question 2

carbohydrates: basic info.

Answer 2

-carbohydrates are molecules which consist only of carbon, hydrogen and oxygen and they are long chains of sugar units called saccharides
-there are 3 types of saccharides- monosaccharides, dissacharides and polysaccharides
-monosaccharides can join together to form dissacharides and polysaccharides by glycosidic bonds which are formed in condensation reactions

Question 3

monosaccharides:

Answer 3

-these are the monomers of carbohydrates
-they are soluble in water and small, simple molecules

Question 4

monosaccharides: glucose

Answer 4

-one of the most common monosaccharides is glucose, it contains six carbon atoms in each molecule, it is the main substrate for respiration therefore a very important biological molecule
-isomers of glucose -> a-glucose + b-glucose
-general formula -> (CH2O)n -carbon
-triose: 3 carbons
-pentose: 5 carbons
-hexose: 6 carbons

Question 5

disaccharides:

Answer 5

-> 2 monosaccharides join together in a condensation rxn to form a disaccharide
-maltose is a disaccharide formed by the condensation of two glucose molecules (a-glucose)
-surcrose is a disaccharide formed by condensation of b-glucose and fructose
-lactose is a disaccharide formed by the condensation of b-glucose and b-galactose

Question 6

what is a glycosidic bond?

Answer 6

-removal of hydrogen atom
-H from one monosaccharide and a hydroxyl group (-OH)

Question 7

polysaccharides: basic info.

Answer 7

-> these are formed from many monosaccharides of glucose joined together and are used as energy stores:
-they are a large molecule with a compact shape- there are many glucose molecules within a small space
-they can be easily hydrolysed to glucose-glucose can then be broken down in respiration to release energy
-they are insoluble-so they have no osmotic effect in cells

Question 8

polysaccharides: glycogen

Answer 8

-glycogen is the main energy storage molecule in animals and its formed from many molecules joined together by 1,4 and 1,6 glycosidic bonds
-it has a large number of side branches meaning that energy can be released quickly
-moreover, its relatively large but compact molecules thus maximising the amount of energy it can store

Question 9

polysaccharides: starch

Answer 9

-starch is the primary energy store in plants and it is a mixture of two polysaccharides called amylose and amylopectin:
-amylose -> amylose is an unbranched chain of glucose molecules joined by 1,4 glycosidic bonds, as a result of this amylose is coiled and this it is a very compact molecule meaning it can store a lot of energy
-amylopectin -> amylopectin is branched and is made up of glucose molecules joined by 1,4 and 1,6 glycosidic bonds, due to the presence of many side branches it is rapidly digested by enzymes therefore energy is released quickly
-also, they are large molecules so they have no effect on water potential

Question 10

joining monosaccharides to form disaccharides and polysaccharides:

Answer 10

-monosaccharide monomers such as glucose and galactose can join tog through condensation reactions-reactions that joins 2 molecules together through the release of a small molecule (often water)
-the bond formed between 2 monosaccharides is known as a glycosidic bond and contains a single oxygen atom
-to break apart polysaccharides these glycosidic bonds have to be broken, this through a hydrolysis reaction where are water molecule is added, splitting a polysaccharide into 2 smaller molecules, or a disaccharides into 2 monosaccharides

Question 11

lipids:

Answer 11

-> lipids are biological molecules that have many different functions within an organism such as energy storage, organ protection, thermal insulation and making cell membrames
-they are non-polar molecules so insoluble in water, but soluble in organic solvents
-lipids can be saturated or unsaturated

Question 12

saturated and unsaturated lipids:

Answer 12

-saturated lipids (such as those found in animal fats)- saturated lipids don’t obtain any carbon-carbon double bonds
-unsaturated lipids (these can be found in plants)- unsaturated lipids contain carbon-carbon double bonds and melt at lower temperatures than saturated fats
-mono -> 1 carbon carbon double bond
-poly -> many carbon = carbon double bonds

Question 13

fatty acids and glycerol:

Answer 13

-3 fatty acids: COOH carboxyl group
-1 glycerol molecule: -OH

Question 14

forming triglycerides:

Answer 14

-triglycerides are one of the most important lipids
-are made of one molecule of glycerol and three fatty acids joined by ester bonds formed in condensation reactions
-there are many different types of fatty acids, they vary in chain length, presence and number of double bonds
-also, some triglycerides contain a mix of different fatty acids
-triglycerides are used as long term energy reserves in plant and animal cells

Question 15

ester bonds:

Answer 15

-condensation reactions
-between carboxyl group (COOH) + hydroxyl group (-OH)
-this is called esterification condensation reaction
-(making esters) -> forms triglycerides

Question 16

proteins:

Answer 16

-amino acids are the monomers from which proteins are made
-amino acids contain:
-an amino group- NH2
-a carboxylic acid group
-a variable R group which is carbon-containing chain

Question 17

peptide bonds:

Answer 17

-there are 20 different amino acids with different R groups
-amino acids are joined by peptide bonds formed in condensation reactions
-a dipeptide contains two amino acids and polypeptides contain three or more amino acids

Question 18

protein structure: primary structure

Answer 18

-> indicated the order of the amino acids
-formed by many amino acid + peptide bonds

Question 19

protein structure: secondary structure

Answer 19

-> is the shape that the chain of amino acids fold into-either alpha helix or beta pleated sheet
-the shape is determined by the hydrogen bonding between the peptide bonds
-amino acids interact with eachother
-the H and NH group is attracted to the O on the CO group
-the H is slightly positive and the O is slightly negative
-a hydrogen bond forms between these two atoms

Question 20

alpha helices + beta pleated sheets:

Answer 20

-the H-bonds that keep alpha helices together are vulnerable to fluctuations in pH + temperature
-this is how proteins get denatured: their structure is discripted
-hydrogen bonds hold adjacent primary chains together

Question 21

protein structure: tertiary structure

Answer 21

-> is the 3D shape of the protein, it can be globular or fibrous
-globular proteins, such as enzymes, are compact
-fibrous proteins, such as keratin, are long and thus can be used to form fibre
-the shape of the protein is determined by hydrogen, ionic and disulphide bonds between the R groups of amino acids

Question 22

protein structure: tertiary structure- disulfide bonds

Answer 22

-the amino acid cysteine contains sulfur, where two cysteines are found close to each other a covalent bond can form

Question 23

protein structure: tertiary structure-ionic bonds

Answer 23

-R-groups sometimes carry a charge, either +ve or -ve, where oppositely charged amino acids are found close to each other than ionic bond forms

Question 24

protein structure: tertiary structure-hydrogen bonds

Answer 24

-as in secondary structure, wherever slightly positively charged groups ate found close to slightly negatively charged groups hydrogen bonds

Question 25

protein structure: tertiary structure- hydrophobic and hydrophilic bonds

Answer 25

-in a water-based environments, hydrophobic amino acids will be most stable if they are held together with water excluded -hydrophilic amino acids tend to be found on the outside in globular proteins with hydrophobic amino acids in the centre

Question 26

protein structure: quaternary structure

Answer 26

-> some proteins have a quaternary structure, this is when 2 or more polypeptide chains are joined together, sometimes with the addition of a non-protein prosthetic group

Question 27

collagen:

Answer 27

-> is a fibrous protein of great strength due to presence of both hydrogen and covalent bonds in its structure -collagen molecules wrap around each other and form fibrils which form strong collagen fibres -collagen forms the structure of bonds, cartilage and connective tissue and is a main component of tendons which connect muscles to bones

Question 28

haemoglobin:

Answer 28

-> is a water soluble globular protein which consists of two beta polypeptide chains,2 alpha polypeptide chains and 4 haem groups -it carries oxygen in the blood as oxygen can bind to the haem (Fe2+) group, and oxygen is then released when required -haemoglobin is made up of 4 polypeptide chains as well as 3 prosthetic groups, so it has a quaternary structure

Question 29

formula for area:

Answer 29

length x height x sides

Question 30

formula for volume:

Answer 30

length x width x height

Question 31

why we need a transport system:

Answer 31

-diffusion in single-celled organisms can occur directly between the external environment and the cell, this is known as simple diffusion as it occurs only through the cell membrane -exchange of substances, such as oxygen for these organisms occurs very quickly as they have a very large surface area: volume ratio -for larger organisms, like us humans, we have low surface area: volume ratio, meaning diffusion would be too slow to supply all cells with the nutrients they need and this is why larger organisms have mass transport systems that supply all cells with vital substances

Question 32

circulatory system:

Answer 32

-the mammalian circulatory system is comprised of the heart and three types of blood vessels: arteries, veins and capillaries -each blood vessel is adapted to its role in the circulation of the blood

Question 33

arteries:

Answer 33

-arteries carry oxygenated blood away from the heart -this vessel has thick walls containing muscles and elastic that expand and recoil with each heartbeat to withstand the high pressure of the blood -they have a relatively small lumen (hole in the centre through which the blood passes) -arteries contain no valves -its inner lining is folded to allow it to stretch -arteries split into smaller blood vessels called arterioles which split into capillaries -they are lined with smooth endothelium to reduce friction and ease flow of blood

Question 34

capillaries:

Answer 34

-arterioles branch into these to supply cells with substances from the blood -they are numerous and highly branched so have a large surface area -their walls are one cell thick to allow quick diffusion -very narrow diameter to reach close to every cell

Question 35

veins:

Answer 35

-capillaries join back up to form these, so veins carry deoxygenated blood back to the heart -carry blood a low pressure to have thin walls -have a wide lumen to maximise blood flow to the heart -have valves to prevent backflow (blood flowing in the wrong direction)

Question 36

structure of the heart:

Answer 36

-the heart is comprised of 4 chambers: the left and right atria and the left and right ventricles -the atria receive blood into the heart from the veins -the ventricles pump blood out of the heart via the arteries to the lungs or the body -between the ventricles and the atria are the atrioventricular valves which prevent blood flowing back from the ventricles and into the atria; between the ventricles and the arteries leaving the heart are the semilunar valves which prevent backflow of blood from the arteries into the ventricles

Question 37

a double circulatory system:

Answer 37

-mammals are described as having a ‘double circulatory system’, this is because the blood flows through the heart twice in each circulation -blood first enters the heart into the right atrium through the largest vein in the body- vena cava -the first time it leaves the heart it travels from the right ventricle via the pulmonary artery to the lungs where it becomes oxygenated, the blood then returns to the heart via the pulmonary vein into the left atrium -the second time the blood leaves the heart is from the left ventricle via the aorta, where blood now flows to the rest of the body

Question 38

the cardiac cycle:

Answer 38

-the movement of blood through the heart is carefully controlled by the contracting and relaxing of heart muscles, the cardiac cycle has three stages as follows: 1. Atrial systole 2. Ventricular systole 3. Cardiac diastole

Question 39

the cardiac cycle: atrial systole

Answer 39

-the atria contract and this forces the atrio-ventricular valves open and blood flows out of the atria and into the ventricles -pressure in the atria is greater than in the ventricles, so blood is forced out

Question 40

the cardiac cycle: ventricular systole

Answer 40

-the ventricles then contract, causing the atrio-ventricular valve to open and close and semi-lunar valves to open -thus allowing blood to leave the left ventricle through the aorta and right ventricle through the pulmonary artery

Question 41

the cardiac cycle: cardiac diastole

Answer 41

-the atria and ventricles relax, elastic recoil of the heart lowers the pressure inside the heart chambers and blood is drawn from the arteries and veins -thus causing semilunar valves in the aorta and pulmonary arteries to close, preventing backflow of blood

Question 42

transport of gases in the blood: haemoglobin

Answer 42

-haemoglobin is a water soluble globular proteins found in red blood cells, which consists of two beta polypeptide chains, 2 alpha polypeptide chains and 4 haem groups -each of the 4 polypeptide chains is bound to a haem group (Fe2+) to which 1 oxygen molecule can bind -this means each molecule of haemoglobin can carry 4 oxygen molecules -the oxygen binds with haemoglobin to form oxyhaemoglobin, and can unbind when needed in respiring cells and tissues

Question 43

transport of oxygen and carbon dioxide:

Answer 43

-the affinity of oxygen for haemoglobin (how easily oxygen loafs onto haemoglobin) varies depending on the partial pressure of oxygen, which is a measure of oxygen concentration -therefore, as partial pressure increases, the affinity of Hb for oxygen increases -this means that oxygen binds to Hb more readily -this occurs in the lungs in the process known as loading -during respiration, oxygen is used up therefore the partial pressure decreases, decreasing the affinity of oxygen for Hb -as a result of that, oxygen is released from Hb in respiring tissues where it is needed; this is known as unloading -as oxygen diffuses into respiring tissues for respiration, carbon dioxide diffuses out and into the capillaries -here, the low partial pressure of oxygen environment, carbon dioxide binds to Hb to form carboxyhaemoglobin -the deoxygenated blood returns to the lungs where carbon dioxide unloads from Hb, which binds to oxygen again

Question 44

dissociation curves:

Answer 44

-dissociation curves illustrate the change in haemoglobin saturation as partial pressure changes -the saturation of haemoglobin is affected by its affinity for oxygen, therefore in the case where partial pressure is high, Hb has high affinity for oxygen and is therefore highly saturated, and vice versa

Question 45

factors resulting in different affinities: saturation

Answer 45

-saturation can also have an effect on affinity, as after binding to the first oxygen molecule, the affinity of Hb for oxygen increases due to a change in shape, this making it easier for the other oxygen molecules to bind

Question 46

factors resulting in different affinities: fetal haemoglobin

Answer 46

-the haemoglobin present in foetuses has a different affinity for oxygen compared to adult haemoglobin, as it needs to be better at absorbing oxygen because by the time oxygen reaches the placenta, the oxygen saturation of the blood has decreased -therefore, fetal haemoglobin must have a higher affinity for oxygen in order for the foetus to survive at low partial pressure

Question 47

factors resulting in different affinities: the Bohr effect

Answer 47

-the affinity of Hb for oxygen is also affected by the partial pressure of carbon dioxide -carbon dioxide is released by respiring cells, which require oxygen for the process to occur -therefore, in the presence of carbon dioxide, the affinity of haemoglobin for oxygen decreases, thus causing it to be released

Question 48

astherosclerosis:

Answer 48

-astherosclerosis is the hardening of arteries cause by the build up of fibrous plaque called an atheroma -atheroma formation is the cause of many cardiovascular diseases and occurs as following: 1. The endothelium which lines the arteries is damaged, for instance by high cholesterol levels, smoking or high blood pressure 2. This increases the risk of blood clotting in the artery and leads to an inflammatory response causing white blood cells to move into the artery 3. Over time, white blood cell, cholesterol, calcium salts and fibres build up and harden leading to a plaque formation 4. The build up of fibrous plaque leads to narrowing of the artery and restricts blood flow thus increasing the blood pressure which in turn damages the endothelial lining and the process is repeated

Question 49

blood clotting:

Answer 49

-blood clots are formed to minimise blood loss from damaged vessels, and also to prevent pathogens entering the bloodstream -blood clots are important to preventing damage to the body, however when they form on the inside of blood vessels, they can restrict blood flow through the vessels and cause a blockade -this is known as thrombosis and can cause cardiovascular disease, blood clots are formed as follows: 1. Platelets come into contact with a damaged blood vessel wall and change shape from flattened discs to spherical shapes with thin outward projections which form a temporary plug by clumping together 2. The platelets and damaged tissues release clotting factors such as thromboplastin which causes prothrombin to change to thrombin 3. This enzyme catalyses the conversion of fibrinogen to insoluble fibrin, whose strands form a mesh, trapping bundles of blood cells, more platelets attach to this, forming the clot

Question 50

the effects of astherosclerosis on health: aneurysms

Answer 50

-weakened artery walls -bulging of artery wall (may rupture) -commonly occurs in the aorta -potentially life-threatening if ruptured

Question 51

the effects of astherosclerosis on health: raised blood pressure (hypertension)

Answer 51

-narrowed arteries restrict blood flow -increased resistance to blood flow -heart must work harder -risk factor for other cardiovascular events (heart attacks, strokes)

Question 52

the effects of astherosclerosis on health: heart disease

Answer 52

-Angina: -reduces blood flow to the heart -chest pain (especially during exertion) -temporary, typically relieved by rest -Myocardial infarction (heart attack): -complete blockage of coronary artery -heart muscle deprived of oxygen -permanent damage to heart tissue if not treated quickly -symptoms include sever chest pain, shortness of breath, sweating

Question 53

the effects of astherosclerosis on health: stroke

Answer 53

-blocked or ruptured arteries in the brain -ischemic stroke: blood clot obstructs blood flow to brain -hemorrhagic stroke: burst blood vessel in the brain -symptoms include sudden weakness, slurred speech, confusion, loss of coordination -can lead to permanent disability or death

Question 54

what is risk?

Answer 54

-> risk is the chance of something unfavourable occurring -genetics: certain genes can increase the risk, sometimes indirectly for instance by having genes for a higher blood pressure, family history of the disease also increases your risk -diets: diets high in cholesterol and certain fats increase the build-up of plaque on arteries -age: prevalence of CVD increases with age -high blood pressure: this can narrow and damage arteries or cause an aneurysm, both of which increase the risk of CVD -smoking: smoking damages the lining of arteries and cause the formation of atheroma -inactivity: has been linked with an increase in blood pressure

Question 55

dietary antioxidants:

Answer 55

-oxidative stress is an imbalance of antioxidants and free radicals of oxygen in the body -free radicals of oxygen are oxygen atoms with an uneven number of electrons, making it highly reactive and meaning it can cause damaging chains of chemical reactions in the body -antioxidants can donate electrons to make oxygen radical stable, without making itself unstable -it’s thought that this oxidative stress can contribute towards the cause of cardiovascular disease, so the intake of additional antioxidants in the diet should help prevent some cases of CVDs and at least lessen the risk

Question 56

Vitamin C:

Answer 56

-Vitamin C is water soluble and cannot be stored within the body -many mammals including dogs, can make Vitamin C in certain cells -humans cannot synthesis vitamin C and have to obtain it from their diet -however, if they consume more than needed, it will pass out from the urine -Vitamin C is also called Ascorbic Acid

Question 57

DCPIP:

Answer 57

-DCPIP is an indicator that can identify the concentration of Vitamin C in different foods and drinks -you can identify the concentration of Vitamin C by the colour change of DCPIP -in the presence of Vitamin C, DCPIP will turn colourless -during the reaction between DCPIP and ascorbic acid, DCPIP becomes reduced and ascorbic acid is oxidised

Question 58

DCPIP: experiment

Answer 58

-volume of fluid needed to decolourise the solution -6mg (example) divided by volume needed to turn colourless gives appoximate concentration of Vitamin C -which we can compare to toher results -need total colour change

Question 59

blood cholesterol levels and CVD:

Answer 59

-cholesterol is transported in your body in high-density lipoproteins (HDLs) or low-density proteins (LDLs), they each have different effect on cholesterol levels and are found in different types of food -there is a positive correlation between ingestion and saturated fats and an increase in cholesterol level -since increased cholesterol levels cause a build-up of plaque on artery walls, there is a casual relationship between saturated fats (LDLs) and cardiovascular disease

Question 60

high-density lipoproteins:

Answer 60

-transports cholesterol to the liver to be expelled -reduces cholesterol levels -the more of this you have in your body, the better -formed from unsaturated fats and proteins

Question 61

low-density lipoproteins:

Answer 61

-transports cholesterol to the arteries where it can build up and form plaque -increases cholesterol levels -the less you have of this in your body, the better -formed from saturated fats and proteins

Question 62

treatment of cardiovascular diseases: antihypertensives

Answer 62

-> these are drugs that are used to lower blood pressure -pros: generally effective on most patients and inexpensive -cons: different types of drugs have different side effects, although most aren’t severe and are irreversible

Question 63

treatment of cardiovascular diseases: statins

Answer 63

-> these are a class of drugs used to lower cholesterol levels and so reduce the build-up of plaques on artery walls -pros: mostly effective, also help relax blood vessels leading to a lower blood pressure, also helping to prevent CVD -cons: can cause nausea, vomiting and aches in muscles and joints, as well as more severe but less common side effects such as diabetes, the side effects often go away over time

Question 64

treatment of cardiovascular diseases: anticoagulants

Answer 64

-> these are drugs that help prevent blood clots -pros: reduce the risk of internal blood clots that can sometimes cause thrombosis and reduce blood flow in the artery -cons: can, like anticoagulants, also lead to excessive bleeding and haemorrhage due to slow clot formation

Question 65

obesity indicators:

Answer 65

-the public’s understanding of CVD disease and its causes has increased greatly over the years and a number of measurements can now be used to look at obesity, which is a cause of cardiovascular disease -being aware you are overweight or obese can help encourage a change in diet and increase in exercise to reduce the risk of CVDs

Question 66

body mass index (BMI):

Answer 66

BMI = body mass kg/ (body height (m))^2 -the value generated can be compared to a charge which classifies you under the following: -under 18.5 -> underweight -18.5-25 -> normal -25-30 -> overweight -over 30 -> obese

Question 67

waist to hip ratio (WHR):

Answer 67

-WHR is another way to view if someone is overweight and can also be used to view the risk of developing certain diseases -you are classified as obese if as a male you have a value greater than 0.8 and as a female a value greater than 0.85 Waist size (cm)/ hip size (cm)

Question 68

perceived risk:

Answer 68

-> risk is the chance of something unfavourable occurring -statistical chance of something occurring can be supported using data obtained by scientific research -whereas a perceived risk varies from person to person and is biased on factors, such as approvals of activity -therefore, as a result of that, the perceived risk can vary greatly from the actual risk, thus leading to underestimating or overestimating the probability of occurrence of an unwanted event or outcome

Question 69

lipoproteins:

Answer 69

-fats are not water soluble and cannot be transported in the blood -the liver creates lipoproteins to carry lipids -they are like vessels- a submarine- that transports triglyceride to the tissue where it can be oxidised for energy during respiration, or stored -once the fat has been ‘deposited’ lipopoteins return to the liver to be recycled -protein and cholesterol molecules on the membrane allow uptake of lipoproteins into tissue

Question 70

High fat diets and heart disease:

Answer 70

-the effect of diet in developing CVD isn’t just about becoming obese -epidemiological studies have shown a correlation between saturated fats and heart disease -this suggested that saturated fats in the diet may be a risk factor in the development of heart disease -however the correlation does not show a cause -further research has been carried out to identify increasing cholesterol levels in the blood and increasing astherosclerosis

Question 71

lipoprotein ratio and CVD:

Answer 71

-increasing cholesterol levels in the blood have a positive correlation towards CVD -however, recent research has shown that the links between diets high in saturated fats and astherosclerosis and CVD has been a correlation and nothing more -diets high in saturated fats did not appear to be linked directly with an increase in astherosclerosis and CVD

Question 72

LDL:HDL

Answer 72

-more recent research has pointed to the balance of these lipoproteins in the blood and the risk of developing astherosclerosis -genes have an influence on the ability to metabolise fats in a healthful way -lower LDL:HDL ratio is a better indicator for reduction in aestherosclerosis and CVD -higher LDL:HDL ratios are associated with an increased risk of CVD’s

Question 73

Obesity and CVDs:

Answer 73

-evidence has shown that positive energy balance leads to modern chronic disease -energy intake has increased while energy expenditure has decreased over the last century -more people are now overweight than those who are starving or do not have sufficient energy intake

Question 74

Fitness vs obesity and CVD:

Answer 74

-‘Fat and Fit’ model -aerobic fitness is an independent risk factor in the relative risk of CVDs -you can be obese and be `fit’ -being overweight is a risk factor identifies with all-cause mortality and CVD -BMI has been used to classify people into categories based off their weight and height -it does not account for type of tissue e.g. muscle or fat -muscle is more dense than fat

Question 75

prevention is better than a cure:

Answer 75

-drugs and surgery are often costly and lifestyle interventions can prevent costs associated with treatments -people are aware of the risk factors however people still smoke, and overeat

Question 76

salt:

Answer 76

-some populations eat less salt -they have lower blood pressure -this was used to draw a conclusion between salt and hypertension which has been supported with further research -consensus points to reducing salt to reduce prevalance of hypertension -however, salt is essential to human function, so restriction of salt needs to be treated with caution -what is appropiate for some might not be appropiate for all, all of the time