2. STRUCTURE & FUNCTION IN LIVING ORGANISMS Flashcards
2.2 cells are separated from their surrounding environment by
a cell membrane
2.2 within the cell membrane is the
cytoplasm
2.2 eukaryotic cells have … contained within their cytoplasm
organelles
2.2 organelles are
where specific processes take place within the cell
2.2 what is in the cytoplasm of a eukaryotic cell
nucleus, mitochondria & ribosomes
2.2 plant cells contain the following additional structures
cell wall, chloroplasts & a vacuole
2.3 function of the nucleus
contains genetic material in chromosomes
controls cell division
2.3 function of the cytoplasm
supports cell structure
site of many chemical reactions
contains water and many solutes
jelly-like substance
2.3 function of the cell membrane
holds the cell together
controls substances entering and leaving the cell
2.3 function of the cell wall
gives the cell extra support and defines its shape
2.3 function of the mitochondria
site of aerobic respiration providing energy for the cell
2.3 function of the chloroplasts
site of photosynthesis - provides food for plants
chlorophyll pigment absorbs light energy
2.3 function of the ribosomes
the site of protein synthesis
2.3 function of the vacuole
contains cell sap
used for storage
helps support the shape of the cell
2.4 how many structures does a plant cell have
8
2.4 how many structures does an animal cell have
5
2.4 in addition to the structures an animal cell has, a plant cell also has
chloroplasts, a (cellulose) cell wall and a vacuole
2.4 what does an animal cell have
a nucleus, cell membrane, mitochondria, ribosomes and a cytoplasm
2.4 what does a plant cell have
a nucleus, cell membrane, mitochondria, ribosomes, cytoplasm, chloroplasts, cell wall and a vacuole
2.7 the chemical elements present in carbohydrates
carbon, hydrogen and oxygen
(C,H,O)
2.7 the chemical elements present in proteins
carbon, hydrogen, oxygen and nitrogen
(C,H,O,N)
2.7 the chemical elements present in lipids (fats&oils)
carbon, hydrogen and oxygen
(C,H,O)
2.8 starch and glycogen is from
simple sugars
2.8 protein is from
amino acids
2.8 lipids are from
fatty acids and glycerol
2.8 a monosaccharide is a …
simple sugar like glucose
2.8 a disaccharide is made when
two monosaccharides join together e.g. maltose = glucose & glucose
sucrose = glucose & fructose
2.8 a polysaccharide is formed when
lots of monosaccharides join together
2.8 polysaccharides starch, glycogen or cellulose are all formed when
lots of glucose molecules join together
2.8 most fats (lipids) in the body are made up of
triglycerides
2.8 lipids basic unit is
one glycerol molecule chemically bonded to three fatty acid chains
2.8 proteins are formed from
long chains of amino acids
2.8 when amino acids are joined together
a protein is formed
2.9 what is the test for starch?
iodine solution
2.9 explain the test for starch
- place food sample on a spotting tile
- add a few drops of iodine solution to the sample
- blue - black colour indicates starch
2.9 what is the test for glucose / reducing sugars?
benedicts solution
2.9 explain the test for glucose / reducing sugars?
- place food sample in a boiling tube
- add benedict’s solution to the sample of food in solution
- place in a water bath at 80*c for 5 minutes
- a change from blue to brick red if present
(if green, yellow or orange means less sugar present)
2.9 what is the test for protein?
biuret test
2.9 explain the test for protein
- place food sample in a boiling tube
- add enough biuret solution for colour to be pale blue
- if protein is present colour will change to mauve / purple
2.9 what is the test for lipids?
emulsion test
2.9 explain the test for lipids?
- place food sample in a test tube
- add small amount of ethanol and shake to dissolve any lipid in the alcohol.
- add equal volume of water
- cloudy white colour (emulsion will form) indication presence of lipid
2.9 benedicts solution is used to test for
reducing sugars (glucose)
2.9 benedicts solution colour change
blue to brick red
2.9 how do I remember benedicts solution
christmas sugar
2.9 iodine is used to test for
starch
2.9 iodine solution colour change
orange to blue-black
2.9 how do I remember iodine
bumblebee
2.9 biuret is used to test for
protein
2.9 biuret solution colour change
(light)blue to pale purple
2.9 how do I remember biuret
snowflakes
(et) proTEin biurET
2.9 emulsion is used to test for
lipids
2.9 emulsion colour change
colourless to a cloudy white emulsion
2.9 how do I remember emulsion
snowing
2.10 enzymes are biological
catalysts
2.10 a catalyst is a ……..
chemical which increases the rate of a reaction without being used up itself in the reaction
2.10 the theory for understanding how enzymes work is the
lock and key theory
2.10 what is the lock and key theory
the substrate and enzyme collide,
the substrate binds to the active site of the enzyme,
(the reaction occurs by an alternative pathway with a lower activation energy)
once the reaction occurs, the products don’t fit - so they are released,
the enzyme is free to catalyse the next reaction
2.10 the active site has a particular shape which is … to the shape of the substrates
complementary
2.10 because the shape of the active site is complementary to that of the substrates, this means
each enzyme can only catalyse one reaction
2.11 as temperature increases the enzyme & substrate have more
kinetic energy
so they move faster and there are more successful collisions
2.11 high temperatures and changes of pH cause the shape
to change
2.11 when the shape changes we say this is
the protein being denatured
2.11 when the active site changes shape it is no longer
complementary to the substrate
2.12 practical for investigating effect of temperature on enzymes
mix
10cm3 of 10% starch suspension
+ 5cm3 of 5% amylase
in a boiling tube
heat in water bath
every minute take 1 drop of the mix
add to 1 drop of iodine solution
in spotting tile
when digestion is complete
iodine solution will stay orange
(no starch)
repeat using water baths at different temperatures
2.15 definition of diffusion
the random movement of particles from an area of higher concentration to an area of lower concentration
2.15 definition of osmosis
the net diffusion of free water molecules from an area of high water concentration to an area of low water concentration across a partially permeable membrane
2.15 osmosis in cell:
what is: solution outside cell has same water potential as inside cell - no net movement
isotonic solution
(animal = normal)
(plant = flaccid)
2.15 osmosis in cell:
what is: solution outside cell has higher water potential then inside cell - net movement of free water molecules into cell
hypotonic solution
(animal = lysed)
(plant = turgid)
2.15 osmosis in cell:
what is: solution outside cell has lower water potential then inside cell - net movement of free water molecules out of cell
hypertonic solution
(animal = shrivelled)
(plant = plasmolysed)
2.15 definition of active transport
movement of molecules from an area of low concentration to an area of high concentration using ATP
2.16 the four main factors that affect the rate of movement
surface area to volume ratio, distance, temperature and concentration gradient
2.16 why is a larger surface area a good thing
it quickens the rate at which substances can move across its surface
2.16 example of large surface area
highly folded surface of the small intestine increases its surface area
2.16 why is a shorter distance a good thing
the smaller the distance molecules have to travel, the faster the transport will occur
2.16 example of short diffusion distance
alveoli walls are one cell thick - rate of diffusion across them is as fast as possible
2.16 why is higher temperature a good thing
the higher the temperature, the faster molecules move as they have more energy
2.16 how is higher temp a good thing
because there are more collisions against the cell membrane and therefore a faster rate of movement across them
2.16 why is a greater difference in a concentration gradient a good thing
the greater the difference in concentration on either side of the membrane, the faster movement across it will occur
2.16 how is a greater difference in a concentration gradient a good thing
because the on the side with the higher concentration, more random collisions against the membrane will occur
2.17 practical: investigating diffusion
coloured agar is made from indicators
coloured agar is cut into required dimensions
calculate the surface area, SA:V R and volume and record it
cubes placed in boiling tubes of different solutions (same volume of it)
^^^ e.g. dilute hydrochloric acid
measurements taken of time for cube to completely change colour of indicator
can draw a graph of rate of diffusion (rate of colour change) changes with surface area : volume ratio of agar cubes
2.17 practical: investigating osmosis
prepare a range of sucrose (sugar) solutions ranging from 0 Mol/dm3 (distilled water) to 1 mol/dm3
set up 6 labelled test tubes with 10cm3 of each of the sucrose solutions
using the knife, cork borer and ruler, cut 6 equally-sized cylinders of potato
blot each one with a paper towel and weigh on the balance
put 1 piece into each concentration of sucrose solution
after 4 hours, remove them, blot with paper towels and reweigh them
2.18 process of photosynthesis
energy from sunlight is absorbed by chlorophyll, a green pigment found inside chloroplasts
green plants use this energy to make the carbohydrate glucose from the raw materials carbon dioxide and water
at the same time, oxygen is made and released as a waste product
2.19 word and balanced chemical equations for photosynthesis
carbon dioxide + water -> glucose + oxygen
6CO2 + 6H2O -> C6H12O6 + 6O2
2.20 how does varying temperature affect the rate of photosynthesis
it affects how much kinetic energy the particles have so affects the speed at which carbon dioxide and water move
more successful collisions
(too high temp can denature enzymes that control the process of photosynthesis)
2.20 how does varying light intensity affect the rate of photosynthesis
the intensity of the light available to the plant will affect the amount of energy that it has to carry out photosynthesis
the more light a plant receives, the faster the rate of photosynthesis
2.20 how does varying carbon dioxide concentration affect the rate of photosynthesis
carbon dioxide is one of the raw materials required for photosynthesis
this means the more carbon dioxide that is present, the faster the reaction can occur
2.21 structure of waxy cuticle
protective layer on top of the leaf prevents water from evaporating
2.21 structure of upper epidermis
thin and transparent to allow light to enter palisade mesophyll layer underneath
2.21 structure of palisade mesophyll
column shaped cells tightly packed with chloroplasts to absorb more light maximising photosynthesis
2.21 structure of spongy mesophyll
internal air spaces which increase surface area to volume ratio for the diffusion of gases (mainly carbon dioxide)
2.21 structure of lower epidermis
contains guard cells and stomata
2.21 structure of guard cell
absorbs and loses water to open and close stomata to allow
carbon dioxide to diffuse in
oxygen to diffuse out
2.21 structure of stomata
where gas exchange takes place
opens during day closes during night
evaporation of water takes place here
found in much greater concentration on underside of leaf to reduce water loss (in most plants)
2.21 structure of vascular bundle
contains xylem and phloem to transport substances to and from the leaf
2.21 structure of xylem
transports water into leaf for mesophyll cells to use in photosynthesis and for transpiration from stomata
2.21 structure of phloem
transports sucrose and amino acids around the plant
2.21 what are all the 10 leaf structures
waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis, guard cell, stomata, vascular bundle, xylem and phloem
2.21 adaptation of large surface area (leaf)
increases surface area for the diffusion of carbon dioxide and absorption of light for photosynthesis
2.21 adaptation of being thin
allows carbon dioxide to diffuse to palisade mesophyll cells quickly
2.21 adaptation of chlorophyll
absorbs light energy so that photosynthesis can take place
2.21 adaptation of network of veins
allows the transport of water to the cells of the leaf and carbohydrates from the leaf for photosynthesis
(water for photosynthesis)
(carbohydrates - product of photosynthesis)
2.21 adaptation of stomata
allows carbon dioxide to diffuse into the leaf and oxygen to diffuse out
2.21 adaptation of epidermis being thin and transparent
allows more light to reach the palisade cells
2.21 adaptation of thin cuticle made of wax
to protect the leaf without blocking sunlight
2.21 adaptation of palisade cell layer at top of leaf
maximises the absorption of light as it will hit chloroplasts in the cells directly
2.21 adaptation of spongy layer
air spaces allow carbon dioxide to diffuse through the leaf increasing surface area
2.21 adaptation of vascular bundles
thick cell walls of the tissue in the bundles help to support the stem and leaf
2.21 specialised leaf for photosynthesis: large surface area and thin
to maximise absorption of sunlight and increases number of stomata so carbon dioxide can diffuse faster
2.21 specialised leaf for photosynthesis: upper epidermis
transparent allowing light to penetrate to the mesophyll
2.21 specialised leaf for photosynthesis: palisade cells
long thin and tightly packed w large numbers of chloroplasts
main site of photosynthesis
2.21 specialised leaf for photosynthesis: stomata
allows gases to diffuse into air spaces of the leaf - short diffusion distance for carbon dioxide
2.21 specialised leaf for photosynthesis: xylem transporting water
water that’s absorbed in the roots into the leaves so short distance for water to diffuse into cells
2.21 specialised leaf for photosynthesis: phloem vessels
phloem vessels transport sugars made in photosynthesis to other parts of plant
2.22 plants requires what for growth
mineral ions
2.22 chlorophyll requires what to be made
magnesium ions
2.22 amino acids require what to be made
(so proteins & nucleic acids - DNA & RNA)
nitrate ions
2.23 practical: investigate photosynthesis
take a bundle of shoots of a water plant
submerge them in a beaker of water underneath an upturned funnel
fill a boiling tube with water and place it over the end of the funnel
as oxygen is produced, the bubbles of gas will collect in the boiling tube and displace the water
show that the gas collected is oxygen by relighting a glowing splint
2.23 practical: investigating production of starch & photosynthesis&light
de-starch the plant by placing it in a dark cupboard for 24 hours
(this ensures that any starch already present in the leaves will be used up)
partially cover a leaf of the plant with aluminium foil and place the plant in sunlight for a day
remove the covered leaf and test for starch using iodine:
drop the leaf in boiling water
(kills the tissue and breaks down the cell walls)
transfer the leaf into hot ethanol in a boiling tube for 5-10 minutes
(removes the chlorophyll so colour changes from iodine are more clear)
rinse the leaf in cold water
to soften the leaf tissue
spread the leaf out on a white tile and cover it with iodine solution
the entire leaf will turn blue-black as photosynthesis is occurring in all areas of the leaf
proving light is necessary for photosynthesis and production of starch
2.23 practical: CORMS evaluation on light & photosynthesis
C - We are changing whether there is light or no light
O - The leaves will be taken from the same plant or same species, age and size of the plant
R - We will repeat the investigation several times to ensure our results are reliable
M1 - We will observe the colour change of the leaf when iodine is applied
M2 - …after 1 day
S - We will control the temperature of the room
2.23 practical: carbon dioxide & photosynthesis
de-starch the plant by placing it in a dark cupboard for 24 hours
following destarching, enclose 1 leaf with a conical flask containing potassium hydroxide
potassium hydroxide will absorb carbon dioxide from the surrounding air
enclose another leaf with a conical flask containing no potassium hydroxide (control experiment)
place the plant in bright light for several hours
test both leaves for starch using iodine solution
drop the leaf in boiling water
transfer the leaf into hot ethanol in a boiling tube for 5-10 minutes
rinse the leaf in cold water
spread the leaf out on a white tile and cover it with iodine solution
the leaf from the conical flask containing potassium hydroxide will remain orange-brown - couldn’t photosynthesise due to lack of carbon dioxide
the leaf from the conical flask not containing potassium hydroxide should turn blue-black as it had all necessary requirements for photosynthesis
2.23 practical: CORMS evaluation carbondioxide & photosynthesis
C - We are changing whether there is carbon dioxide or no carbon dioxide
O - The leaves will be taken from the same plant or same species, age and size of plant
R - We will repeat the investigation several times to ensure our results are reliable
M1 - We will observe the colour change of the leaf when iodine is applied
M2 - …after 1 day
S - We will control the temperature of the room and the light intensity
2.23 practical: investigating chlorophyll & photosynthesis
drop the leaf in boiling water
This kills the tissue and breaks down the cell walls
transfer the leaf into hot ethanol in a boiling tube for 5-10 minutes
this removes the chlorophyll so colour changes from iodine can be seen more clearly
rinse the leaf in cold water
this is done to soften the leaf tissue after being in ethanol
spread the leaf out on a white tile and cover it with iodine solution
the white areas of the leaf contain no chlorophyll and when the leaf is tested only the areas that contain chlorophyll stain blue-black
the areas that had no chlorophyll remain orange-brown as no photosynthesis is occurring here and so no starch is stored
2.23 practical: CORMS evaluation for chlorophyll and photosynthesis
C - We are changing whether there is chlorophyll or no chlorophyll
O - The leaves will be taken from the same plant or same species, age and size of the plant
R - We will repeat the investigation several times to ensure our results are reliable
M1 - We will observe the colour change of the leaf when iodine is applied
M2 - …after 1 day
S - We will control the temperature of the room and the light intensity
2.24 what are the key food groups are for a balanced diet
carbohydrates
proteins
lipids
dietary fibre
vitamins
minerals (mineral ions)
water
2.25 carbohydrates
what food source
what function
bread, potatoes, rice, cereals & fruit
fuel for respiration
source of energy
2.25 proteins
what food source
what function
meat, eggs, fish, quinoa & quorn
growth and repair of cells and tissues
fuel for respiration
2.25 lipids (fats)
what food source
what function
butter, oil, nuts, cream & avocados
store of energy
thermal (and electrical) insulation
fuel for respiration
2.25 dietary fibre
what food source
what function
vegetables, whole grains
provides bulk for the intestine to push food through it
2.25 vitamins
what food source
what function
fruits and vegetables
needed in small quantities to maintain health
2.25 minerals
what food source
what function
fruits and vegetables, meats, dairy products
needed in small quantities to maintain health
2.25 water
what food source
what function
water, juice, milk, fruits & vegetables
needed for chemical reactions to take place in cells
2.25 calcium
what food source
what function
milk, cheese, eggs
for strong teeth and bones (involved in the clotting of blood)
deficiency leads to osteoporosis later in life
2.25 vitamin D
what food source
what function
oily fish, dairy products
(also made naturally by body in sunlight)
helps body to absorb calcium & required for strong bones and teeth
2.25 vitamin C
what food source
what function
citrus fruits, strawberries, green vegetables
forms an essential part of collagen protein - makes up skin, hair, gums & bones
deficiency causes scurvy
2.25 vitamin A
what food source
what function
meat, liver, dairy, leafygreen vegetables (spinach), eggs
needed to make the pigment in the retina for vision
2.25 iron
what food source
what function
red meat, liver, leafygreen vegetables (spinach)
needed to make haemoglobin
^ pigment in redbloodcells that transports oxygen
2.26 energy requirements for age
the amount needed in young people increases towards adulthood - energy is needed for growth
children need a higher proportion of protein than adults for growth
energy for adults decrease as they age
2.26 energy requirements for activity levels
the more active, the more energy required for movement as muscles are contracting more and respiring faster
2.26 energy requirements for pregnancy
requirements increase as energy is needed to support the growth of the developing foetus
extra calcium & iron are needed to help build the bones, teeth and blood of the foetus
2.27 function of the mouth
where mechanical digestion takes place
teeth chew food - smaller pieces
amylase enzymes in saliva digest starch into maltose
shaped into bolus so it can be swallowed
2.27 function of the oesophagus
connects mouth to the stomach
contractions take place to push bolus down
2.27 function of the stomach
food’s mechanically digested by churning
protease enzymes chemically digest proteins
hydrochloric acid kills bacteria & optimum pH for protease enzymes to work
2.27 function of the small intestine
(duodenum)
food coming out stomach finishes being ^ - digested by enzymes produced here & also secreted from the pancreas
! slightly alkaline pH 8-9
2.27 function of the small intestine
(ileum)
where absorption of digested food
- molecules takes place
long & lined with villi - increasing surface
- area where absorption can take place
! slightly alkaline pH 8-9
2.27 function of the large intestine
(colon & rectum)
water is absorbed from remaining material in the COLON to produce faeces
faeces is stored in the rectum and removed through the anus
2.27 function of the pancreas
produces amylase, protease & lipase
secretes enzymes is an alkaline fluid into the duodenum(LARGEint) to raise pH of fluid coming out of the stomach
2.27 what are the 6 structures in the alimentary canal
mouth, oesophagus, stomach, small intestine, large intestine & pancreas
2.27 the stages of food breakdown
ingestion - taking in substances,
mechanical digestion - breaking food into smaller pieces
chemical digestion - large, insoluble molecules broken down into small, soluble molecules
absorption - movement of small food molecules and ions through the wall of the intestine into the blood
assimilation - movement of digested food molecules into body where they are used, becoming part of the cells
egestion - passing out undigested or unabsorbed food (as faeces) through the anus
2.28 how is food moved through the gut by peristalsis
muscles in the walls of the oesophagus create waves of contractions - forcing the bolus along
once the bolus has reached the stomach, it turns into chyme - continues on to the small intestine
peristalsis is controlled by circular & longitudinal muscles
mucus is produced to continually lubricate the food mass and reduce friction
dietary fibre provides the roughage required for the muscles to push against during peristalsis
2.28 what mechanism pushes food through the gut
peristalsis
2.29 protein ——>
protein —(pepsin)—>
[peptides] —(trypsin)—> amino acids
2.29 (carbohydrates?) starch ——>
(carbohydrates?) starch —(amylase)—> [maltose] —(maltase)—> glucose
2.29 lipids ——>
lipids —(lipase)—> glycerol & fatty acids
2.29 what enzyme breaks down protein into peptides
what enzyme breaks down peptides amino acids
protease: pepsin
pepsin is made in the stomach
protease: trypsin
trypsin is made in the pancreas & small intestine
2.29 what enzyme breaks down carbohydrates into maltose
what enzyme breaks down maltose into glucose
carbohydrase: amylase
amylase is made in pancreas and salivary glands
carbohydrase: maltase
maltase is made in pancreas
2.29 what enzyme breaks down lipids into fatty acids and glycerol
lipase: lipase enzymes
lipase enzymes are produced in the pancreas
2.30 where is bile produced
in the liver
2.30 where is bile stored
in the gall bladder
2.31 what does bile do to stomach acid
it neutralises the hydrochloric stomach acid
2.31 what does bile do to lipids
it emulsifying lipids
2.31 how does bile neutralise stomach acid
the alkaline properties in it allow it to neutralise the hydrochloric acid
the neutralisation is essential as enzymes in small intestine have higher optimum pH
2.31 how does bile emulsify lipids
it breaks apart large drops of fat into smaller ones (increasing their surface area)
2.32 how is the small intestine adapted for absorption
it is very long and has a highly folded surface with millions of villi
which increase the surface area allowing absorption to take place faster and more efficiently
peristalsis helps by mixing food and enzymes and keeping things moving
2.32 how is the structure of a villus adapted for absorption
a large surface area:
microvilli on the surface
short diffusion distance:
one cell thick walls
steep concentration gradient:
- surrounded by a network of blood
capillaries - transport
glucose&amino acids away
- a lacteal to transport fatty acids and glycerol away
2.33B practical: energy content of a food sample practical:
measure 25cm3 of water
pour into boiling tube
record starting temp
food is lit over bunsen burner
hold food under boiling tube to heat it
(if food stops burning relight it)
relight until food no longer burns
measure finishing temp of water
calculate the temp change
2.34 how does the process of respiration produce ATP
energy is released from glucose either in the presence of oxygen (aerobic) or no oxygen (anaerobic)
resulting in the production of carbon dioxide and water as waste products
energy is transferred in the form of ATP
2.35 what does ATP provide for cells
ATP provides energy for cells
(muscle contractions & keeping warm - painting a constant temperature)
2.36 differences between aerobic & anaerobic respiration with oxygen
aerobic needs oxygen
anaerobic doesn’t need oxygen
2.36 differences between aerobic & anaerobic respiration with the breakdown of glucose
breakdown is complete in aerobic
breakdown is incomplete in anaerobic
2.36 differences between aerobic & anaerobic respiration with the products
aerobic = carbon dioxide & water
anaerobic =
anima cells: lactic acid
yeast: carbon dioxide & ethanol
2.36 differences between aerobic & anaerobic respiration with the energy released
aerobic releases a lot of energy
anaerobic releases a little
2.37 word equation for aerobic respiration
glucose + oxygen → carbon dioxide + water
2.37 the balanced chemical symbol equation for aerobic respiration
C6H12O6 + 6O2 → 6CO2 + 6H20
2.38 the word equation for anaerobic respiration in animals
glucose —> lactic acid
2.38 the word equation for anaerobic respiration in plants
glucose —> ethanol + carbon dioxide
2.39 practical: evolution of carbon dioxide from respiring seeds
measure out 10 cm3 of hydrogencarbonate indicator into 3 boiling tubes
put in a layer of cotton wool
place 10 germinating seeds in tube A
place 10 boiled/dead seeds in tube B
place 10 glass beads in tubeC
seal each tube with a rubber bung
after 3 hours, observe the colour of the indicator
high CO2 = yellow
atmospheric CO2 = orange
low CO2 = purple
2.39 practical: demonstrating the production of heat from respiring seeds
flask A with the dead seeds
flask B with the germinating seeds
make sure the cotton wool is plugging the top of each flask
hold the thermometer in place with the cotton wool
invert the flask
record the initial temperature
after 4 days, record the final temperature
2.39 practical: analysis
the thermometer in the flask with the germinating seeds (Flask B) should show an increase in temperature
- the seeds in flask B are respiring and producing heat energy in the process
flask A should remain at room temperature
the seeds in flask A are not respiring because they are dead, so the temperature remains the same
this shows that respiration is an exothermic reaction
2.39 practical: CORMS evaluation evolution of carbon dioxide
change - we will change the content of the boiling tube (germinating seeds, dead seeds or glass beads)
organisms - the seeds used should all be of the same age, size and species
repeat - we will repeat the investigation several times to ensure our results are reliable
measurement 1 - we will observe the change in the hydrogen carbonate indicator
measurement 2 - …after 3 hours
same - we will control the volume of hydrogen carbonate indicator, the number of seeds/beads, the temperature of the environment
2.39 practical: CORMS evaluation evolution of heat
change - we will change the content of the flasks (germinating seeds or dead seeds)
organisms - the seeds used should all be of the same age, size and species
repeat - repeat the investigation several times to ensure our results are reliable
measurement 1 - change in the temperature on the thermometer
measurement 2 - …after 4 days
same - control the number of seeds, the starting temperature of the flasks, the material and size of the flasks
2.49 smoking can cause … and several types of caner including …
coronary heart disease and lung cancer
2.49 what does nicotine do
it narrows blood vessels - increased blood pressure
increased heart rate
2.49 what does carbon monoxide do
binds irreversibly to haemoglobin
breathing frequency has to increase
increases risk of coronary heart disease & strokes
2.49 emphysema does what
makes the alveoli less elastic & cannot stretch
the breakdown of alveoli reduces the surface area for gas exchange
2.49 smoking increases the risk of cancer which is
the rapid uncontrolled cell growth
2.49 tobacco smoke contains ______ ________ which permanently binds to the haemoglobin forming __________________ reducing the amount of oxygen being transported by the blood
carbon monoxide
carboxyhaemoglobim
2.49 in healthy lungs the linings of the trachea and bronchi are
specialised to prevent dirt and bacteria entering the lungs
2.49 the cilia of the lining cells move transporting the mucus
up the airways where it is then swallowed
2.49 chemicals in tobacco smoke destroy _____ reducing their number, at the same time mucus production will increase. the mucus cannot be moved out of the airways quickly so it ______ __ causing _______ _____ and increases the risk of infection
cilia
builds up
smokers cough
2.49 __________ is a disease resulting from the build up of in refuted mucus in the bronchi and bronchioles
bronchitis
2.49 smoke can also reach the alveoli damaging them: the alveoli walls break down in places and fuse together forming larger irregular air spaces this ___ the surface area for gas exchange so ____ oxygen diffuses into the blood, this disease is called _________ and kills around 20k people in Britain per year
decreases
less
emphysema
2.49 chemicals in cigarettes include:
tar - a carcinogen (a substance that causes cancer)
nicotine - an addictive substance which also narrows blood vessels
carbon monoxide - reduces the oxygen-carrying capacity of the blood
2.50 practical: the effect of expertise on breathing method
work out student A’s breathing rate at rest
count their number breaths for 15 seconds and multiply by 4
repeat to calculate an average
student A should then exercise for a set time (at least 4 minutes)
count the breaths taken in 15 seconds and multiply by 4 to obtain the breathing rate per minute
compare the result to the breathing rate at rest in order to work out the change in breathing rate as a result of exercise
repeat this last step every minute after exercise for 5 minutes
repeat the process for student B
finally, repeat the whole investigation for each student after a period of rest
2.50 practical: the effect of exercise on breathing results
frequency of breathing increases when exercising
this is because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand
if they cannot meet the energy demand they will also respire anaerobically, producing lactic acid
2.50 practical: the effect of exercise on breathing analysis
after exercise has finished, the breathing rate remained elevated for a period of time
this is because the lactic acid that has built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions
it can only be removed by combining it with oxygen - this is known as ‘repaying the oxygen debt’
this can be tested by seeing how long it takes after exercise for the breathing rate to return to normal
the longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid
2.50 practical: what might an unfit individual have
higher breathing rate while resting
more rapid increase in breathing rate during exercise
longer recovery period for their breathing rate to return back to a normal resting rate
2.50 practical: how do you control all variables
ensure students are similar size, general fitness, age, gender and provide each with the same meal before exercise
2.50 practical: CORMS evaluation
change - We will change whether the student has exercised or not
organisms - The students should be of the same age, gender, size and general fitness
repeat - We will repeat the investigation several times to ensure our results are reliable
measurement 1 - We will measure the change in breathing rate
measurement 2 - …immediately after exercise and each minute for the subsequent 5 minutes
same - We will control the type of exercise carried out, the temperature of the environment, the food intake of the students prior to the investigation
2.50 practical: exercise causes the frequency
exercise causes the frequency of breathing to increase in order to provide more oxygen for respiration and to pay off any subsequent oxygen debt
2.50 practical: apparatus needed for the effect of exercise
a stop watch
2 students
2.55B plants take in water from the soil through
their root hairs
2.55B root hairs are thinwalled
for a short distance
2.55B root hairs have hair-like extensions to
increase the surface area
2.55B the function of a root hair is to
absorb water and minerals from the soil
2.55B mineral ions are
actively transported into the root hair cells
2.55B water will enter the root hair cell by
osmosis
2.55B the soil water has a … concentration of water molecules
higher
2.55B osmosis is
the net diffusion of water molecules from an area of high water concentration to an area of low water concentration across a partially permeable membrane
2.56B the loss of water vapour from the leaves is called
transpiration
2.56B examiners definition of transpiration
the evaporation of water from the surface of a plant
2.57B how does temperature affect the rate of transpiration
water will evaporate quickly as the water molecules have more kinetic energy
2.57B how does humidity affect the rate of transpiration
humid air - water vapour = smaller conc gradient so transpiration slows down
2.57B how does wind speed affect the rate of transpiration
moving air - water vapour blown away from leaf - speeds up transpiration
2.57B transpiration .. as wind speed ..
transpiration increases as wind speed increases
2.57B transpiration .. as humidity ..
transpiration increases as humidity decreases
2.57B transpiration .. as temperature ..
transpiration increase as temp increases
2.57B light intensity does NOT affect
evaporation
2.57B how does light intensity affect the rate of transpiration
in daylight stomata leaves are open to supply CO2 for photosynthesis
allows more water to diffuse out leaves into atmosphere
2.58B practical: how to set up a potometer
set up underwater
cut the stem
shoot stem in bung
grease joint w jelly (no air entry/water loss)
bung in potometer
tap closed full of water
lift potometer out of water
leave end of capillary tube out of water until air bubble forms & then put in beaker of water
measure rate as distance bubble travelled in 5 mins
2.58B practical: a potometer is to measure
measure the rate of water uptake from a leafy shoot
2.58B practical: we can use potometer to collect readings in normal air or windy conditions by
using a hairdryer on cold
2.58B practical: we can use potometer to collect readings in temperature
increases and decreases
2.58B practical: we can use potometer to collect readings in increased humidity by
using a clear plastic bag
2.58B practical: we can use potometer to collect readings by changing the l & d
lightness and darkness
2.58B practical: changing the environmental factors stimulates
all the different conditions which affect the rate of transpiration
2.71 what are the excretory products of the lungs
carbon dioxide
(via blood plasma)
2.71 what are the excretory products of the kidneys
urea
2.71 what are the excretory products of the skin
urea
2.71 water is lost from the body in the following ways:
via the lungs during exhalation (breathing out)
lost from the skin as sweat (along side mineral ions and urea)
2.72B what does the kidney do
it filters the blood and removes any excess materials and passes them to the bladder to be excreted
2.72B the kidney contains millions of tiny structures called
nephrons
2.72B nephrons are structures which
filter the blood
2.72B what are the 3 main regions of the kidney
cortex, medulla and renal pelvis
2.74B what are the 3 stages that occur in the nephron
ultrafiltration, selective reabsorption and water reabsorption
2.74B the main sections in a nephron
bowman’s capsule
proximal convoluted tubule
loop of henle
distal convoluted tubule
collecting duct
2.74B surrounding the tubule is a network of
capillaries with a knotted section which sits inside the bowman’s capsule
2.74B where does the glomerulus sit
inside the bowmans capsule
2.74B what shape is the bowmans capsule
cup shaped
2.74B the glomerulus is a knot of
capillaries
2.74B where is glucose reabsorbed
in the proximal first convoluted tubule
2.74B the gates that facilitate the active transport of glucose are
only found in the proximal convoluted tubule
2.74B the cells lining in the PCT have many mitochondria to
provide ATP (energy) for active transport
2.74B the cells lining in the PCT have a folded membrane
to increase surface area
2.74B where is water reabsorbed
loop of henle and collecting duct
2.74B where are salts reabsorbed
loop of henle
2.75B step1. the diameter of the efferent arteriole at the exit of the glomerulus is
smaller than the diameter of the afferent arteriole at the entrance causing a build up of pressure
2.75B step1. the build up of pressure in the capillaries forms the
glomerulus
2.75B step2. the pressure causes the smaller molecules being carried in the blood to be forced out of the capillaries and into
the bowman’s capsule
where they form the glomerular filtrate
2.75B step2. small molecules like urea, glucose, amino acids, water and salts are forced
out the glomerulus into the bowmans capsule
2.75B step3. larger molecules like proteins or red blood cells are
too big to fit across the capillary wall so they stay in the blood
2.75B where is water reabsorbed
loop of henle & collecting duct
2.75B where are salts reabsorbed
loop of henle
2.75B where is glucose reabsorbed
proximal first convoluted
2.75B where is urea reabsorbed
it is NOT reabsorbed
2.75B what small molecules are pushed through
urea, glucose, amino acids, water and salts
2.75B what large molecules are too big to go through so stay in the blood
proteins and red blood cells
2.75B what makes up the glomerular filtrate
urea, glucose, amino acids, water and salts
2.77B after the glomerular filtrate enters the bowman’s capsule what’s the first thing to be reabsorbed
glucose is the first substance to be reabsorbed at the proximal (first) convoluted tubule
2.77B selective reabsorption takes place by
active transport
2.77B the cells lining in the PCT have a folded membrane for
an increased surface area
2.77B the cells lining in the PCT have many mitochondria to
provide ATP (energy) for active transport
2.77B reabsorption of glucose cannot take place anywhere else in the nephron as
the gates that facilitate the active transport of glucose are only found in the proximal convoluted tubule
2.79B urine contains
water, urea and ions
2.79B if someone is diabetic their urine may contain
glucose
2.79B urine produced by the kidneys contains a mixture of
urea
excess mineral ions
excess water
2.79B small quantities of urine are usually darker yellow / orange in colour because
it contains little water and so the urea is more concentrated
2.79B large quantities of urine are usually pale yellow in colour
because it contains a lot of water and so the urea is less concentrated
2.77B where does selective reabsorption of glucose occur
in the proximal convoluted tubule
2.79B what produces urine
the kidneys
2.77B what’s special about the reabsorption of glucose
its selectively reabsorped
