Organisation (2)
what are tissues made up of?
similar cells working together to carry out a particular function. This can include more than one type of cell
what are organs made up of?
a group of different tissues working together to perform a function
what is an organ system?
a group of organs working together to perform a particular function
what do muscular tissues do?
they contract to move whatever they are attached to
what does glandular tissue do?
make and secrete chemicals such as enzymes and hormones
what does epithelial tissue do?
covers parts of the body such as the inside of the gut
what does the digestive system do?
break down and absorb food
what are the organs in the digestive system?
Glands - pancreas & salivary glands
Stomach
Small intestine
Liver
Large intestine
gullet
gall bladder
rectum
name the glands and what they do
the salivary gland and pancreas produce digestive juices. Ghe salivary gland produces amylaze enzymes in the saliva, the pancreas produces protease, amylase and lipase and releases them into the small intestine
how does the stomach digest food?
- it pummels the food using its muscular walls
- it produces protease (pepsin)
- it produces hydrochloric acid to kill bacteria and give the right pH for protease to work (pH2- acidic)
what are the 2 functions of the small intestine?
producing enzymes to complete digestion and absorbing soluble food molecules into the blood
what does the liver do?
produce bile
what does the large intestine do?
absorb water from undigested food, leaving faeces
name a biological catalyst
enzymes
what is a catalyst?
a substance which increases the speed of a reaction without being changed or used up
what is the active site of an enzyme?
the side of the enzyme with a unique shape that can only be fit by the specific substance involved in the specific reaction that enzyme catalyses
whats the name for the substance an enzyme acts upon
substrate
what happens if the temperature becomes too high for an enzyme?
the bonds holding the enzyme together break, changing the shape of the active site, meaning the substrate will no longer fit, therefore the enzyme is denatured
what are the 2 tjings affecting the rate of enzymes?
temperature and pH
what happens if the pH is too high or low for an enzyme?
this interferes with the bonds holding the enzyme together, this changes the shape of the active site and denatures the enzyme
how do you calculate the rate of reaction?
rate = 1000 divided by time in seconds
OR
rate = change (eg. amount of product formed) divided by time
What do enzymes do?
break down big molecules into smaller ones so they can pass more easily through the walks of the digestive system, allowing them to be absorbed into the bloodstream
what does protease do?
convert proteins into amino acids
where is protease made? name 3
stomach
pancreas
small intestine
what do lipases do?
covert lipids into glycerol and fatty acids
what are lipids
fars and oils
where are lipases made? name 2
pancreas
small intestine
what do carbohydrases do?
convert carbohydrates into simple sugars
name a type of carbohydrase?
amylase
what does amylase break down?
starch into sugars such as maltose and dextrins
where is amylase produced? name 3
salivary glands
pancreas
small intestine
what does bile do?
neutralise stomach acids and emulsifies fats
what dies the rectum do?
where the faeces (indigestible food) is stored before being pood out
what is the function of the gall bladder?
where bile is stored before being released into the small intestine
how do you prepare a food sample?
-break it up using pestle and mortar
- transfer to beaker and add distilled water
- stir mixture to dissolve food
- filter the solution using a funnel lined with filter paper
how do you ise Benedicts test to test for sugars?
- prepare food sample and transfer 5cm3 to a test tube
- prepare a water bath to 75°C
- add 10 drops of benedicts solution using a pipette
- place test tube in water bath and leave it fir 5 min. ensure test tube is pointing away from you
- if food sample contains reducing sugar, the solution will turn from blue to green yellow or brick red depending how much sugar is in the food
how is iodine solution used to test for starch?
- transfer 5cm3 of your food sample to a test tube
- add a few drops of iodine solution and gently shake tube to mix contents
- if the sample contains starch the colour of the solution will change from browny orange to black or blue black
how is the biuret test used ti test for proteins?
- prepare a food sample and transfer 2cm3 of sample to test tube
- add 2cm3 of biuret solution to sample and mix cintents by gently shaking
- if the food samole contains protein the solution will change from blue to purple
how do you use the sudan III test to test for lipids?
- prepare a food sample without filtering
- transfer 5cm3 to test tube
- use a pipette to add 3 drops of sudan III stain solution to the test tube and gently shake the tube
- the sudan solution stains lipids.
- if any are present, the solution will separate out into 2 layers and the top layer (lipids) will turn bright red.
what happens to the rate of reaction when temperature is increased
the rate of reaction increases until the enzyme denatures . same is true for the pH getting too high or too low
enzyme practical
- mix amylase with starch and start a timer
- remive a few drops from the mixture every 10s and add to iodine
- record the time taken for no starch to be detected (iodine to remain orange)
- repeat at different temperatures or with different pH solutions
- plot on a graph time: temperature or pH and the optimum temp or pH is between the 2 lowest times
what are alveoli
air sacs with a large surface area to allow gas exchange to occur at a fast rate
how is oxygen transported through the body
oxygen diffuses into the bloodstream and binds to the haemoglobin in red blood cells and is transported around the body through the bloodstream
how is carbon dioxide made from respiration diffused out of the body
it dissolves into the plasma of the blood which diffuses into the lungs and is exhaled, some water is also excreted this way
what does it mean that the heart is a double circulatory system
blood enters the heart twice every time it is pumped around the body
how does deoxygenated blood enter the heart
through the vena cava it enters the right atrium of the heart
what do valves in the heart do?
prevent backflow of blood
the blood pumped out of the right atrium goes to?
the right ventricle
what does the pulmonary artery do
carries deoxygenated blood from the right ventricle to the lungs
what does the pulmonary vein do
carries oxygenated blood from the lungs back to the heart into the left atrium
why does the left side of the heart have thicker walls?
due to higher pressure needed to pump blood to the body
what does the aorta do?
carries the oxygenated blood from the left ventricle to the rest of the body
how do you know if something is a vein or artery?
veins carry deoxygenated blood to the heart whereas arteries carry oxygenated blood away from the heart - exception pulmonary artery carries deoxygenated blood to lungs and pulmonary vein carries oxygenated blood to heart
what causes the heart to contract
a group of cells in the walls of the right atrium create electrical pulses that cause the heart to contract. an artificial pacemaker can be used if its not working
adaptations of arteries
- thick walls to withstand high pressure pumping blood away from the heart
- thin lumen
what is the lumen
the hole in the middle of a blood vessel that the blood travels through
adaptations of veins
thin walls
wide lumen
valves to prevent backflow (can be replaced with artificial ones if faulty) as it carries blood back to the heart
adaptations of capillaries
one cell thick walls to allow diffusion between blood and cells
what does the coronary artery do
supplies oxygenated blood to the heart (an exception of the fact that arteries carry blood away from the heart, however it does carry oxygenated blood)
what is coronary heart disease?
when the artery carting blood to the heart (coronary artery) is blocked by a build up of fatty deposits
what is cardiovascular disease
when fat builds up inside arteries that restricts blood flow
what is a stent
a thing that can be inserted jnto an artery to open up the vessel
what are statins
drugs that reduce the fatty deposits in the arteries
what do platelets do
clump together to clot wounds and stop bleeding
what does blood carry
red blood cells
white blood cells
plasma
platelets
non-communicable disease
the cause comes from inside the body
communicable disease
caused by pathogen
examples of non communicable diseases
diabetes
heart disease
liver disease
lung disease
cancer
what are carcinogens
anything that increases the risk of developing cancer
what is cancer
a disease caused by a genetic mutation in cells causing them to multiply uncontrollably
what is the purpose of leaves
photosynthesis
gas exchange
water evaporates out
what is the xylem
continuous tubes that carry water & dissolved mineral ions upwards (unidirectional) for transpiration
what happens at the roots of a plant
water enters through osmosis
mineral ions enter by active transport
where are the reproductive organs of a plant
in the flower
where are stem cells produced in a plant
the meristem
what is transpiration
the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers
what increases the rate of transpiration
increased air movement and temperature or decreased humidity
what is the phloem
tubes of cells that carry sugars (eg.sucrose) and other nutrients to where needed. bidirectional for translocation
what does nitrate defficiency lead to?
nitrates are needed for protein synthesis a defficiency stunts growth
what is chlorosis?
the name for the yellowing of leaves caused by magnesium defficiency leading to less chlorophyll therefore yellow leaves and stunted growth
leaf structure (top to bottom)
waxy cuticle
upper epidermis
palisade mesophyll
spongy mesophyll including the:
vein/vascular bundle (xylem & phloem)
lower epidermis
stomata & guard cells
upper epidermis features
transparent to let light through to the palisade mesophyll layer
waxy cuticle feature
waterproof to stop water loss from top of the leaf so it doesnt dry out
palisade mesophyll
most photosynthesis takes place here as they are full of chloroplasts
spongy mesophyll features
gaps around cells to increase surface area through which gas exchange can occur carbon dioxide diffuses into yhe cells while water and oxygen diffuse out
where is the vascular bundle and what does it include
in the spongy mesophyll layer including the xylem and phloem
what are stomata
holes in the lower epidermis of the leaf to allow gases to enter and exit including water
what is the function of guard cells
to control the size of a stoma which controls the rate of gases entering and exiting through stomata