B2 ORGANISATION Flashcards
what is a cell?
the basic building block of a living organism
what is a tissue?
a group of cells with a similar structure and function working together.
what is an organ?
a collection of tissues with a similar structure and function working together.
what is an organ system?
a group of organs working together to perform a specific function.
what is the main function of the digestive system?
large food molecules are broken down into small molecules by enzymes.
small molecules can then be absorbed into the bloodstream.
what are the 3 nutrients that a food contains?
carbohydrates e.g starch
protein
lipids (fats)
what is the function of the mouth?
enzymes in the saliva begin to digest the starch into smaller sugar molecules.
what is the function of the stomach?
(enzymes begin the digestion of proteins)
the stomach contains hydrochloric acid which helps the enzyme to digest proteins.
churning action of the stomach muscles turns the food into a fluid increasing the surface area for enzymes to digest.
what is the function of the small intestine?
the walls of the small intestine release enzymes to continue the digestion of proteins and lipids.
small food molecules=absorbed into the blood stream by either diffusion or active transport
what is the function of the liver?
releases bile which helps speed up the digestion of lipids.
neutralises the acid released from the stomach
what is the function of the pancreas?
releases enzymes =digestion of starch and proteins= start the digestion of lipids.
what is the function of the large intestine?
fluid makes its way through the large intestine where water is absorbed into the blood stream.
faeces is released from the body
how are the products of digestion used?
used by the body to build new carbohydrates , lipids and proteins (some of the glucose produced is used in respiration)
what is an enzyme?
catalyse (speed up) chemical reactions
what are the features of an enzymes?
are large protein molecules
have a groove on their surface called active sites.
the active site is where the substrate attaches to
how does the shape of an enzyme affect its function?
enzymes have specific active site which is complementary to their substrate (lock and key theory)
explain how the enzymes work?
substrate fits perfectly into the active site , the enzyme now breaks down the substrate into the products
what are proteins broken down by?
proteases
where is proteases found?
stomach , pancreas , small intestine
what are proteins
long chains of amino acids
explain how proteases work?
protein=individual amino acids = absorbed into bloodstream=absorbed by body cells together in a different order to make human proteins
what is starch?
chain of glucose molecules
how are carbohydrates broken down?
carbohydrases (starch = amylase)
when starch is digested what do we produce
simple sugars
where is amylase found
saliva and pancreatic fluid
what does a lipid molecule consist of?
molecule of glycerol attached to three molecules of fatty acids
how are lipid molecules digested?
by the enzyme lipase , this produces glycerol and fatty acids
where is lipase found?
pancreatic fluid and small intestine
where is bile made and stored?
made = liver
stored = gallbladder
what is the point of bile?
speeds up the digestion of lipids (not an enzyme)
what does bile do?
bile emulsifies the lipid (converts large lipids into smaller droplets)
increases surface area of lipid droplets and increases the rate of lipid breakdown by lipase
what does bile also do?
its an alkaline which means it neutralises stomach acid , creating alkaline conditions in the small intestine.
increases the rate of lipid digestion by lipase.
how does temperature effect enzyme action?
as temp increases= enzymes and substrates are moving faster = more collisions per second between the substrate and the active site.
at a certain temp the enzyme is working at the fastest possible rate (optimum temperature) = maximum frequency of successful collisions between the substrate and active site.
increasing the temp after optimum temp = enzyme will rapidly decrease to 0 because= enzyme molecules vibrates and the shape of the active site changes (denatured)
enzyme can no longer catalyse the reaction
how does pH affect enzyme action
enzyme has an optimum pH where the activity is as its maximum , if we make the pH more acidic or more alkaline then the activity drops to zero (active site denatures if conditions are too alkaline or two acidic)
how long is the small intestine
around 5m
provides very large surface area for absorption of the products of digestion
what is the interior of small intestine covered with?
millions of villi
increases large surface area for the absorption of molecules
where is microvilli found?
villi
what does microvilli do?
increase surface area
adaptations of villi?
very good blood supply , so the bloodstream rapidly removes the product of digestion , this increases the surface concentration gradient.
thin membranes = short diffusion path
all of these features mean there is a rapid rate of diffusion , any molecules which cannot be absorbed by diffusion are absorbed by active transport
do humans double or single circulatory system?
double
what is the heart
an organ consisting of mainly muscle tissue
what is the job of the heart?
pumps blood around the body
how many chambers do the heart have and what are they called?
4
left atrium
right atrium
left ventricle
right ventricle
describe the process of blood flow through the heart?
vena cava brings in deoxygenated blood from the body
the blood passes from the heart to the lungs pulmonary artery (in the lungs blood collects oxygen)
oxygenated blood passes from the lungs to the heart in the pulmonary vein , then the oxygenated blood is pumped from the heart to the body in the aorta
what is the pattern of the blood flow through the heart?
first blood enters the left atrium and the right atrium , the atria now contract and the blood is forced into the ventricles , the ventricles now contract and force blood out of the heart.
what is the point of valves?
stop the blood from flowing backwards into the atria when the ventricle contracts
why does the left side of the heart have a thick muscular wall then the right?
pumps blood around the whole entire body
what is the purpose of the coronary artery?
provide oxygen to the muscle cells of the heart (the oxygen is used in respiration to provide the energy for contraction)
what is the heart rate controlled by?
pacemaker
what is a pacemaker
group of cells
what is an artificial pacemaker?
small electrical device and it corrects irregularities in the heart rate
what is the function of the arteries?
transport blood away from the heart (usually at high pressure)
adaptations of arteries?
very thick muscular walls - allows them to withstand high pressure of the blood
thick elastic layer - allows arteries to stretch and recoil in order to withstand higher pressure.
what is the function of the capillaries?
enable transfer of substances between the blood and tissues
adaptations of capillaries
very thin walls = diffusion paths is short = this allows substances to diffuse rapidly between the blood and body cells
what is the function of veins?
carry blood towards the heart
adaptations of veins?
thin wall = blood pressure is low so the walls don’t need to be thick.
valves = stop blood flowing backwards (when blood is flowing through right direction, then the valves open to allow the blood to flow through)(when the blood starts to flow backwards , the valves shut)
what is plasma?
a yellow liquid which transport substances from the body
what substances are transported by plasma?
soluble digestion
carbon dioxide
waste product urea
red blood cells
white blood cells
platelets
function of red blood cells?
transport oxygen from the lungs to the body cells
adaptations of red blood cells?
contain haemoglobin ( haemoglobin combines with oxygen in the lungs forming the molecules oxyhaemoglobin , then the red blood cells travel to the organs where oxyhaemoglobin releases the oxygen)
no nucleus = more room for haemoglobin
dimples (centre of the cell) = biconcave disc = greater surface area so that oxygen can diffuse in and out rapidly
function of white blood cells?
form part of the immune system
adaptations of white blood cells?
contains nucleus.= contains DNA= encodes instructions that the white blood cells need to do their job
what is a platelet?
tiny fragment of cells
function of platelet?
to help the blood clot
what are the uses of donated blood?
replace blood lost during injury
some people are given platelets extracted from blood to help in clotting
proteins are extracted from blood can also be useful e.g antibodies
problems with donated blood?
in a blood transfusion , we have to make sure the donated blood is the same blood type as the patients. otherwise the body’s immune system will reject the blood and the patient could die.
lots of different diseases can be transmitted (in the uk, blood is screened so the risk s extremely low)
what is a cardiovascular disease?
diseases of the heart and blood vessels (non communicable)
how does coronary heart disease occur?
layer of fatty material builds up inside the coronary arteries (this causes the coronary artery to narrow, the effect of this is to reduce the flow of blood through the coronary arteries), this leads to lack of oxygen for the heart muscle , in extreme cases, it can result in a heart attack.
what are the treatments for coronary heart disease?
statins
stent
what are statins?
drugs which reduce the level of cholesterol in the blood. (slows down the rate that fatty materials build up in the arteries)
adv of statins
proven to reduce the risk of the disease
increase the amount of good cholesterol in the body
disadv of statins
unwanted side effects
need to be taken over a long term regularly
what is a stent
tube which can be inserted into the coronary artery to keep it open
adv of stent
blood can flow normally through the artery
effective for a long time
disadv of stent
will not prevent other regions of the coronary arteries from narrowing.
it does not treat the underlying cause of the disease.
what happens if the heart valve cannot fully open?
the heart has to pump extra hard to get the blood through (this causes the heart to enlarge)
what happens if the valves are leaky?
can cause the patients to be tired and feel weak
what type of valves can replace leaky valves?
mechanical valve = metal
animal valve = pig
adv of mechanical valve
can last a lifetime
disadv of mechanical valve
increase the risk of bloodclots (patients have to take anticlotting drugs)
adv of animal valve
patients dont need to take drugs
disadv of animal valve
dont last long and may need to be replaced
what is heart failure?
when the heart cannot pump enough blood around the body
what are given to those who have heart failure?
donates heart or a donated heart and lungs
problem - there is not enough donated hearts , the patients must take drugs to stop the donated heart from being rejected by the body’s immune system
artificial heart = temporary = or to allow a damaged heart to rest
problems = increase the risk of blood clotting , not a long term solution for heart failure
what is the trachea
brings air into the lungs , has rings of cartilages to prevent it from collapsing during inhalation
what is a bronchus?
Branches off the trachea to bring air into the lungs. Also supported by rings of cartilage.
what is a bronchiole
Branches off the bronchi.
what is an alveoli
bronchiole that end in tiny air sacs.
how are alveoli adapted to gas exchange?
oxygen from the air diffuses into the bloodstream.
carbon dioxide diffuses out of the bloodstream.
what are the adaptations of alveoli?
huge surface area
very thin walls = diffusion path is short
very good blood supply (once the oxygen diffuses into the blood, it is rapidly removed, this ensures that the concentration gradient is as steep as possible)
how does breathing affect rate of diffusion
it can increase diffusion
breathing brings fresh oxygen into the alveoli and takes away the carbon dioxide
this makes the concentration gradients high for these gases, that increases the rate of diffusion
what is cancer?
when cell division goes wrong (produces tumour = growth)
2 types of tumour?
malignant
benign
benign tumour?
growth of abnormal cells which is found in one area.
usually contained within a membrane.
do not invade other parts of the body , they stay in one place.
maligant tumour?
malignant cells invade neighbouring tissues and move into the bloodstream.
classed as a cancer.
once in the bloodstream , malignant cells spread to different parts of the body and they form new tumours (secondary tumours)
risk factors of cancer?
genetics - breast cancer , prostate cancer , cancer of the large intestine.
lifestyle - smoking = lung cancer , ultraviolet light = skin cancer , alcohol = mouth and throat cancer
radon = radioactive gas which increases risk of lung cancer (because radon releases ionising radiation which damages DNA in cells, this can cause uncontrolled cell division = cancer)
communicable diseases?
pathogens which can be spread from person to person.
non - communicable disease?
disease which cannot be spread from person to person
health?
state of the physical and mental well-being
what is ill health caused by
communicable and non communicable diseases
it can also be caused by poor diet , high level of stress and other life situations
what is tb?
tuberculosis (communicable disease ,can be fatal, most people immune system can fight it off however some people have a defective immune system e.g people with HIV)
how can defective immune system effect a person?
much more likely going to suffer with an infectious diseases
what is hpv?
human papilloma virus (extremely common , is harmless to most people and can cause cervical cancer to some people)
how many women are diagnosed with cervical cancer every year?
3000
what is cervical cancer caused by?
hpv which infects the cells of the cervix
how can a disease be triggered?
by the immune system e.g allergies
how is an allergy created?
the body is infected with a pathogen which the immune system fights off but the person left with an allergy
how can physical illness impact a mental illness
mental illness can trigger a physical illness e.g arthritis
what is arthritis?
very painful joint condition
how can arthritis impact a person?
difficult to move , this can make them feel depressed or isolated
epidemiology?
studying the patterns of disease to determine the risk factors
what did scientists notice about lung cancer?
much more common among cigarettes smokers than among non-smokers
what does correlation mean
link
what is carcinogens
chemicals which damage DNA and increase the risk of cancer
how does sampling work?
scientists sample a group of people and then try to draw conclusions about the whole population. (if we select our sample from one town , it doesn’t represent the entire population of the country (baised))
to avoid bais we need to take as many samples as possible and it must be as random as possible.
we cannot draw conclusions from a small or non-random sample.
risk factors for cardiovascular disease?
diet high in fat and low in vegetables increases the levels of certain types of cholesterol in the blood (increases the rate that fatty materials build up in the arteries).
diet high in salt = increase blood pressure
people who smoke = massively increased (risk is decreased for whoever exercises)
risk factors for lung cancer?
smoking = increases the risk (because it contains carcinogens) and other lung diseases e.g emphysema (extremely unpresent and lead to a very poor quality of life)
effects of smoking on unborn baby?
pregnant = increases the risk of miscarriage and premature baby and low body mass
effect of drinking alcohol on unborn baby?
pregnant - causes fetal alcohol syndrome (children born with this can have learning difficulties and other mental/physical problems)
effects of drinking alcohol on adults?
increases the risk of liver cirrhosis and liver cancer , can also effect the brain (leading to addiction and memory loss)
what is type 2 diabetes?
condition that causes too much sugar in your blood.
people with type 2 diabetes struggle to control their glucose levels.
can lead to blindness or require the amputation of a limb.
obese people have much a higher risk of developing it.
how can risk factors interact?
drinking excess alcohol can lead to obesity and then that increases the risk of type 2 diabetes
what is radon?
radioactive gas which increases the risk of developing lung cancer
what is the leaf?
plant organ (contains different tissues)
how is epidermal tissue adapted to its function?
contain lots of chloroplast= allows photosynthesis to progress at a faster rate
describe the waxy cuticle
protective layer on top of the leaf , prevents water from evaporating.
describe the upper epidermis?
thin and transparent to allow light to enter palisade mesophyll layer underneath it
describe the palisade mesophyll?
column shaped cells tightly packed with chloroplasts = absorb more light = maximising photosynthesis.
describe the spongy mesophyll?
contains internal air spaces=increases the surface area to volume ratio=for the diffusion of gases (mainly carbon dioxide)
describe the lower epidermis?
contains guard cells and stomata
describe the guard cell?
absorbs and loses water to open and close the stomata to allow carbon dioxide to diffuse in, oxygen to diffuse out.
describe the stomata?
where the gas exchange takes place: open during the day closes during the night.
The evaporation of water also takes place from here. in most plants found found in much greater concentration on the underside of the leaf to reduce water loss
how is a large surface area adapted to a leaf?
increases surface area for the diffusion of carbon dioxide and absorption of light for photosynthesis
how is ‘thin’ adapted to a leaf?
allows carbon dioxide to diffuse to palisade mesophyll cells quickly.
how is chlorophyll adapted to a leaf?
absorbs light energy so that photosynthesis can take place
how is ‘network of veins’ adapted to a leaf?
allows the transport of water to the cells of the leaf and carbohydrates from the leaf of photosynthesis.
how is the stomata adapted to the leaf?
allows carbon dioxide to diffuse into the leaf and allows oxygen to diffuse out
how is the ‘epidermis is thin and transparent’ adapted to the leaf?
allows more light to reach the palisade cells.
how is the ‘thin cuticle made of wax’ adapted to the leaf?
stop the water vapour escaping through the epidermis.
how is the ‘palisade cell layer at top of the leaf’ adapted to the leaf?
maximises the absorption of light as it will hit chloroplasts in the cells directly.
how is the ‘spongy layer’ adapted to the leaf?
air spaces allow carbon dioxide to diffuse through the leaf , increasing the surface area
how is the ‘vascular bundle’ adapted to the leaf?
thick cell walls of the tissue in the bundles help to support the stem and leaf.
describe the ‘vascular bundle’
contains xylem and phloem to transport substances to or from the leaves.
describe the xylem
transports water into the leaf for mesophyll cells to use in photosynthesis and for transpiration from stomata
describe the phloem
transports sucrose and amino acids around the plant
what is translocation?
movement of sugar through and other molecules through the phloem
explain meristem tissue?
find them at growing tips.
contains stem cells which mean they can differentiate into different types of plant tissue
what is transpiration?
when water is constantly evaporating from the surface of the leaves
explain the transpiration stream?
starts with evaporation of water from cells inside the leaf
water vapour then diffuses through the air spaces in the spongy mesophyll and out of the leaf through the stomata.
water passes from the xylem into the leaf to replace the water that has been lost.
water is drawn into the root hair cells and up the xylem vessels to the leaf.
why is transpiration important?
brings water to the leaf (water is required for photosynthesis)
transports dissolved mineral ions (e.g magnesium which play an important role in the plant)
the evaporation of water from the leaf cools down, esp in warm weather
factors affecting transpiration?
temperature - transpiration is greater if temp is higher (because evaporation faster = when temp higher)
under dry conditions - is faster (when air is not humid) (because evaporation takes place more quickly under dry conditions).
windy conditions - (because wind removes any water vapour)
light intensity - it increases when light intensity increases (because high light intensity increases rate of photosynthesis) the stomata now open to allow carbon dioxide to enter, once the stomata has opened water vapour can now pass out of the leaf
how does the stomata work?
- surrounded by two guard cells
- light intensity = high = guard cells swell and change shape
- causes it to open , carbon dioxide can diffuse into the leaf and be used in photosynthesis
- under hot conditions = closes its stomata = to reduce water loss by transpiration (cannot photosynthesis)
REQUIRED PRACTICAL : FOOD TESTS
-take the food sample and grind this with distilled water using a mortar and pestle (we want to make a paste)
-transfer the paste to a beaker and add more distilled water. stir so the chemicals in the food dissolve in the water.
-filter the solution to remove any suspended food particles
REQUIRED PRACTICAL: TEST FOR STARCH
- place 2cm cubed of food solution into the tube
- add a few drops of iodine solution (orange)
- starch present = blue/black
- no starch = no change (orange)
REQUIRED PRACTICAL:TEST FOR GLUCOSE/SUGAR
- place 2cm cubed of food solution into a test tube
- add 10 drops of benedict’s solution (blue colour)
- place the test tube containing our solution into a beaker half fill the beaker with hot water from a kettle
- leave this around for 5 mins
- green= small amount of sugar
- yellow = more sugar
- brick red = lot of sugar
only works on glucose (reducing sugar)
benedict’s wont work on sugars that are non-reducing e.g sucrose
REQUIRED PRACTICAL: TESTING FOR PROTEIN
- take 2cm cubed of food solution
- add 2cm cubed of biuret solution (blue colour)
- protein present = purple/lilac
REQUIRED PRACTICAL: TESTING FOR LIPIDS
- grind food with distilled water
- transfer 2cm cubed of food solution to a test tube
- add a few drops of distilled water and ethanol
- ## lipid present = white cloudy emulsion forms
HAZARDS : TESTING FOR LIPIDS
Wear safety goggles.
Ethanol is flammable.
Avoid contact with skin and eyes
HAZARDS : TESTING FOR SUGAR
Wear safety goggles.
Benedict’s solution is an irritant.
Avoid contact with skin and eyes.
HAZARDS: TESTING FOR STARCH
Wear safety goggles.
Iodine’s solution is an irritant.
Avoid contact with skin and eyes.
HAZARDS: TESTING FOR PROTEIN
Wear safety goggles.
Biuret solution A is corrosive.
Biuret solution B is an irritant.
Avoid contact with skin and eyes
REQUIRED PRACTICAL: EFFECT ON pH ON AMYLASE
- place one drop of iodine solution into each well of a spotting tile.
- place 2cm cubed starch , amylase , pH 5 buffer solution into a water bath for 30 degrees celcius , leave them for 10 mins to allow the solutions to reach the correct temp
- combine 3 solution into a test tube and mix with stirring rod , return to the water bath and start a stopwatch
- after 30 secs use the stirring rod to transfer one drop of solution to a well in the spotting tile which contains iodine
- starch present = iodine turns blue/black
- continue the same process until the iodine remains orange ( starch is no longer present when it remains orange)
- repeat the whole experiment using different pH buffers
HAZARDS:EFFECT ON pH ON AMYLASE
Iodine solution is an irritant. If it touches skin it should be washed off.
Goggles should be worn at all times.
