2: Organisation

Question 1

definition of a cell

Answer 1

basic functional & structural units in a living organism

Question 2

definition of a tissue

Answer 2

a group of cells of similar structure working together to perform a particular function

Question 3

definition of an organ

Answer 3

made from a group of different tissues working together to perform a particular function

Question 4

definition of an organ system

Answer 4

made from a group of organs with related functions, working together to perform body functions within the organism

Question 5

what is digestion?

Answer 5

the process where large, insoluble molecules in food are broken down into smaller, soluble molecules that can be absorbed into the bloodstream & delivered to cells in the body

Question 6

what is the function of the mouth/salivary glands?

Answer 6

mechanical digestion occurs here - teeth break food down to increase it s.a. to v ratio; amylase enzymes in saliva start to digest starch into maltose

Question 7

what is the function of the oesophagus?

Answer 7

tube that connects mouth to stomach

Question 8

what is the function of the stomach

Answer 8

food is mechanically digested by churning actions; protease enzymes start to chemically digest proteins; HCl is present to allow for optimum pH of enzymes and to kill bacteria

Question 9

what is the function of the small intestine?

Answer 9

enzymes are produced here; slightly alkaline pH; digested molecules are absorbed through walls, lined w villi to increase s.a.

Question 10

what is the function of the large intestine?

Answer 10

water is absorbed from remaining material in the colon to produce faeces (this is then stored in the rectum and removed through the anus)

Question 11

what is the function of the pancreas?

Answer 11

produces all three types of digestive enzyme, amylase, protease, lipase; secretes enzymes in alkaline fluid to raise pH of fluid coming out of stomach

Question 12

what is the function of the liver?

Answer 12

produces bile to emulsify fat, amino acids not used are broken down here to produce urea

Question 13

what is the function of the gall bladder?

Answer 13

stores bile

Question 14

why is bacteria important for digestion?

Answer 14

they form a microbial ecosystem; break down substances we can’t digest e.g. cellulose; supply essential nutrients; synthesise vitamin K; provide competition with any harmful bacteria to restrict their growth

Question 15

what is metabolism? what is metabolic rate?

Answer 15

sum of all the reactions happening in a cell or organism; m.r. is the rate at which this happens

Question 16

what do enzymes do?

Answer 16

speed up chemical reactions in cells, allowing reactions to occur at much faster speeds than they would without enzymes at relatively low temps.

Question 17

how do enzymes work?

Answer 17

enzymes and substrates randomly move about in solution; when an enzyme and its complementary substrate randomly collide – with the substrate fitting into the active site of the enzyme – an enzyme-substrate complex forms, and the reaction occurs; product/s forms from substrate/s, are then released from the active site; enzyme is unchanged and will go on to catalyse further reactions

Question 18

what is the induced-fit model?

Answer 18

when a substrate(s) binds to the active site of the enzyme, the active site and substrate change shape slightly to fit more perfectly together - makes it easier for bonds within the substrate to break and new bonds to form, producing product(s)

Question 19

what is the effect of temp on enzymes?

Answer 19

they work fastest at their ‘optimum temperature’ – in the human body, it’s around 37⁰C; heating beyond the optimum will start to break the bonds that hold the enzyme together, enzyme will start to lose its shape -this reduces the effectiveness of substrate binding to the active site reducing the activity; eventually, the shape of the active site is lost completely, it is ‘denatured’ - substrates cannot fit as specific shape of their active site has been lost
low temperatures do not denature enzymes, enzymes and their substrates collide at a lower rate - less ke

Question 20

what is the effect of pH on enzymes?

Answer 20

If pH is too high or too low, bonds that hold the amino acid chain together can be destroyed; this changes the shape of the active site, so substrate can no longer fit into it, reducing the rate of activity, until enzyme is denatured

Question 21

describe the practical to investigate the effect of pH on the rate of reaction of amylase enzyme

Answer 21

1. place single drops of iodine solution in rows on tile
2. use the syringe to place 2cm3 of amylase in a test tube
3. add 1cm3 buffer solution to test tube using syringe
4. add 2cm3 starch solution to amylase & buffer solution, start the stopwatch whilst mixing using a pipette
5. after 10 seconds, use pipette to place one drop of mixture on first drop of iodine, should turn blue-black
6. wait another 10 seconds and place another drop of the mixture on the second drop of iodine
7. repeat every 10 seconds until iodine solution remains orange-brown
8. repeat experiment at different pH values – the less time the iodine solution takes to remain orange-brown, the quicker all the starch has been digested and so the better the enzyme works at that pH

Question 22

how can the practical to investigate the effect of pH on the rate of reaction of amylase enzyme be improved?

Answer 22

temperature could be controlled by using a water bath at 35℃; all solutions that need to be used (starch etc.) should be placed in a water bath and allowed to reach the temperature (using a thermometer to check) before being used; a colorimeter can be used to measure the progress of the reaction more accurately; makes colour change more prominent

Question 23

what enzyme breaks down starch? what is the product? where is the enzyme made?

Answer 23

amylase; produces glucose; made in salivary glands, pancreas and small intestine

Question 24

what enzyme breaks down proteins? what is the product? where is the enzyme made?

Answer 24

protease; produces amino acid; made in stomach, pancreas and small intestine

Question 25

what enzyme breaks down lipids/fats? what is the product? where is the enzyme made?

Answer 25

lipase; produces fatty acids and glycerol; made in pancreas and small intestine

Question 26

where is bile produced, what does it do?

Answer 26

produced in the liver, stored in gall bladder; it is alkaline to neutralise HCl from stomach, and enzymes in the small intestine have a higher optimum pH than those in the stomach; also breaks down large drops of fat into smaller ones, increasing surface area - aka emulsification; alkaline conditions and larger surface area allows lipase to chemically break down fat (lipids) into glycerol and fatty acids faster (the rate of fat breakdown is increased)

Question 27

what are the products of digestion used for?

Answer 27

used to build new carbohydrates, lipids and proteins required for function and growth; some glucose is used in respiration to release energy; amino acids are used to build proteins like enzymes and antibodies; products of lipid digestion can be used to build new cell membranes and hormones

Question 28

what is the food test for starch? what is the colour change for a positive test?

Answer 28

iodine test; will change from orange/brown to blue/black

Question 29

what is the food test for sugar? what is the colour change for a positive test?

Answer 29

benedict’s solution and heat (water bath); change from blue to brick red (any colour change away from blue)

Question 30

what is the food test for protein? what is the colour change for a positive test?

Answer 30

biuret solution; change from blue to purple/lilac

Question 31

what is the food test for fat? what is the colour change for a positive test?

Answer 31

first add ethanol and shake, then add water and shake, it will change from clear/colourless to cloudy (white emulsion formed)

Question 32

what is coronary heart disease?

Answer 32

when layers of fatty material build up inside the coronary arteries, preventing oxygen getting to heart

Question 33

how can different diseases interact?

Answer 33

defects in the immune system mean that one is more likely to suffer from infectious diseases; viruses living in cells can trigger cancers; immune reactions initially caused by a pathogen can trigger allergies e.g. skin rashes and asthma; severe physical ill health can lead to depression and other mental illness

Question 34

how does poor diet increase the risk of what non-communicable diseases?

Answer 34

poor diet = obesity = type 2 diabetes

excess sugar consumption leads to a reduction in the body’s sensitivity to insulin

Question 35

how does smoking increase the risk of what non-communicable diseases?

Answer 35

lung disease, lung cancer, cardiovascular disease
chemicals in cigarettes damage the bronchioles, destroy many of the alveoli in the lungs; damage the lining of the arteries, including the coronary arteries - encourages the build-up of fatty material in the arteries, CO in smoke reduces the amount of oxygen carried by the blood, nicotine in smoke increases heart rate, putting strain on heart

Question 36

how does alcohol consumption increase the risk of what non-communicable diseases?

Answer 36

liver disease, impaired brain function
causes lipids to build up in the liver which is called fatty liver disease; neurones of brain can be damaged can e.g. slow reaction time, impair memory; cause brain shrinkage; lead to memory problems

Question 37

how does exposure to carcinogens increase the risk of what non-communicable diseases?

Answer 37

cancer

exposure to ionising radiation can damage DNA of cells

Question 38

how can the incidence of non-communicable disease impact all levels in society (from the individual to national and globally)?

Answer 38

non-communicable disease = treatment, hospitalisation and access to the right medication =
costs time and money at both a local and national level (and a personal level if healthcare is self-funded) = while receiving treatment, one may not be able to work = reduction their income and loss of work, can also have a profound effect on mental health = effects of the national economy (less people can work)