Organisation Flashcards
How are muscle cells specialised x 2
they can contract and contain special protien fibres which change their length
full of mitochondria which provide energy for contraction
what are cells
Cells are the basic building blocks of all living organisms.
what are tissues
A tissue is a group of cells with a similar structure and function
what are organs
Organs are aggregations (groups) of tissues that work together performing specific functions
what are organs
Organs are aggregations (groups) of tissues that work together performing specific functions
example of an organ
stomach, contains muscle tissue and glandular tissue which release enzymes
what does the stomach have that helps it carry out its function
contains muscle tissue and glandular tissue which release enzymes
what is an organ system
Organs are organised into organ systems, which work together to form organisms.
what three main nutrients do food contain
carbohydrates eg starch
protiens
lipids eg fat
why do the three main nutrients in food have to be digested
they are large molecules, too large to be absorbed into the bloodstream
what happens during digestion
large food molecules are broken down into small molecules by enzymes. Small molecules absorbed into bloodstream.
what happens in the mouth during digestion
food is chewed. enzymes in the saliva begin to digest the starch into smaller sugar molecules.
where does food travel to from the mouth
oesophagous
food travels from the oesophagous to the stomach. what happens in the stomach
in the stomach, enzymes begin the digestion of protiens
what does the stomach contain that helps digestion and how
hydrochloric acid which helps the enzymes digest protiens
how is the food turned into a fluid. Why is this beneficial
the churning action of stomach muscles turns food into fluid
increases s.a for enzymes to digest
where does the fluid go from the stomach
stomach to small intestine
chemicals are released into the small intestine from……
liver and pancreas
what does the pancreas release
pancreas releases enzymes which continue digestion of starch and protiens
and start digestion of lipids
Bile is made in the …… and stored in the ……..
Bile is made in the liver and stored in the gall bladder.
what does bile do
bile neutralises hydrochloric acid from the stomach
what does bile do to fat
bile emulsifies fat
to form small droplets which increases the surface area.
how does the bile increase fat breakdown
The alkaline conditions and large surface area increase the rate of fat (lipid) breakdown by lipase
what do the walls of the small intestines release
walls of small intestine release enzymes to continue breakdown of protien and lipids
what happens in the small intestines
in small intestine, small food molecules produced by digestion are absorbed into the bloodstream
by diffusion or active transport
where does food go from small intestine
large intestine
what happens in large intestine
in large intestine, water is absorbed into the bloodstream
what happens after the large intestine
faeces released rom body
what happens in the digestive system
large food molecules are digested into smaller molecules and then the products of digestion are absorbed into the bloodstream
how are the products of digestion used
used to build new carbohydrates, lipids and protiens.
state the role of enzymes
Catalyse chemical reactions
what are enzymes and what do they have on their surface
large protien molecules. have a groove on the surface called an active site
what happens at the active site
substrate attaches at active site and is broken down into products
enzymes are …… , the subtrate must fit …….. into the active site, This is called the …. and……. theory
enzymes are specific, the subtrate must fit perfectly into the active site, This is called the LOCK and KEY theory
what enzyme breaks down protiens
proteases
what enzyme breaks down lipids
lipases
what enzyme breaks down starch
amalyse
amalyse breaks down …… into…..
amalyse breaks down starch into glucose
proteas breaks down ……. into……
proteas breaks down protiens into amino acids
lipase breaks down …… into …… & …….
lipase breaks down lipids into fatty acid and glycerol
3 places amalyse is found
salivary glands
pancreas
sm. intestine
3 places proteas is found
stomach
pancreas
sm.intestine
what enzyme is found in only two places, and where
lipase is found in:
pancreas
sm.intestine
what enzymes are found in the pancreas and sm. intestine
lipase
proteas
amalyse
protiens are long chains of……. called ……. ….
protiens are long chains of chemicals called amino acids
what does proteas do to protien
proteas convert the protien back into amino acids which are absorbed into bloodstream
how are human protiens made
amino acids are absorbed by body cells and joined togethe rin a different order
what is starch and what does it consist of
starch is a carbohydrate
consists of a chain of glucose molecules
what are carbohydrates broken down by
carbohydrases
Carbohydrases break down carbohydrates to ……
simple sugars
Amylase is a ………which breaks down starch
carbohydrase ( an enyme)
lipid molecule consists of
a ……. molecule attached to ….. molecules of …. …..
lipid molecule consists of
a glycerol molecule attached to three molecules of fatty acids
what does lipase do..
it splits apart the glycerol molecule and three molecules of fatty acids
what happens to enzymes as we increase the temperature
as temp increases, the activity of the enzyme increases (reaction gets faster)
why does an increase in temp cause a faster reaction
the enzyme and substrate move faster so there are MORE COLLISIONS per second btwn them
explain the optimum temp for an enzyme
when the enzyme is working at the fastest possible rate
maximum frequency of successful collisions between substrate and active site
what is optimum temp for most enzymes
37 degrees ( human body temp)
what will we see on a graph when temperature is increase past the optimum
the enzyme activity rapidly decreases to 0
why does an enzyme (active site) denature from too high temps. (3 points)
the enzyme molecule vibrates
the shape of the active site changes
substrate no longer fits into active site
what cant happen when enzyme denatures
enzyme can no longer catalyse the reaction
describe the graph for:
effect of temp on activity of enzymes
rises diagonally to a point, then curves and decreases rapidly to 0
a .
c . .
t . .
i . .
v . .
i . .
t . .
y . .
temperature
what happens to the enzyme activity when the ph is more acidic or alkaline then the optimum
enzyme activity drops to 0 when ph is more acidic or alkaline
the active site…….. if the conditions are too ….. or too …….
active site denatures if conditions are too acidic or too alkaline.
fill in the gaps
Each …… has a …….. optimum ..
each enzyme has a specific optimum ph
what PH does a protease enzyme work best at.
acidic ph
where are protease enzymes found
in the stomach
what ph does lipase work best at
alkaline ph
lipase is released from the ……….. into the …… …….
lipase is released from the pancreas into the small intestine
describe a graph for:
effect of ph on enzymes activity
a .
c . .
t . .
i . .
v . .
i . .
t . .
y . .
PH
what solution do you use to test for starch
and what colour does a positive test turn
Starchy Dina
bluey black
use iodine to test for starch
turns bluey black
what solution do you use to test for a reducing sugar, ( glucose )
and what colour does a positive test turn
Sweet Benedict
brick red -only reducing sugars
use Benedict’s solution to test for glucose
when testing for reducing sugars, what colour will a high/ low amount turn
green/yellow if the amount is low
red if it is high.
what solution do you use to test for protein
what colour does a positive test turn
Protien Biuret
purple
add protien solution to test for protien
turn purple/lilac if protien is present
what are the first 5 steps for food tests
1.grind food sample with distilled water
2.use mortar and pestle to make a paste
3.put paste in Beaker add more distilled
4.stir so chemicals in food dissolve
5.filter solution
Rhyme to remember first 5 steps of food tests
Water
mortar
paste in beaker
stir
filter
describe test for starch
add 2cm cubed of food solution into test tube
and orange iodine solution
turns blue-black starch present
stays orange starch not present
describe the test for sugars
add 2cm cubed of food solution into test tube
add benedict solution - blue (10 drops)
Heat for 2 mins in water bath
@boiling point
colour change if sugars are present
what do different colours tell us in the test for sugar
Green- small amount of sugar
Yellow- more sugar present
Brick red- alot of sugar present
benedict test only works for …….. sugars. it will not work for ….. ……. sugars eg ……
benedict test only works for reducing sugars
it will not work for non reducing sugars eg sucrose
describe test for protien
add 2 cm cubed of food solution
then add 2 cm cubed of biuret solution (blue)
protien present:
colour change from blue to purple/ lilac
describe the test for lipids fats
add 2 cm cubed of food solution (unfiltered) to test tube
add few drops of d.water and ethanol
shake shake shake (gently;)
turns cloudy milky if lipids are present
what is the emulsion test
the test for lipids
TRUE / FALSE
we filter the solution when testing for lipids.
why/why not
FALSE
we don’t filter the solution when testing for lipids
as lipid molecules can stick to filter paper
what do you use to test for lipids
what colour does a positive test turn
Fatty Ethanol
cloudy, milky
add ethanol ( and water )
cloudy milky emulsion formed if lipid present
why do you need to take caution with ethanol
Ethanol is highly flammable
Make sure no naked flames are present
describe RP effect of ph on enzymes
Step 1
Place one drop of iodine solution into each well of a spotting tile
Step 2
Take 3 test tubes - label each one
Step 3
1st test tube = add 2cm cubed of starch solution
2nd test tube = add 2cm cubed of amylase solution
3rd test tube = add 2cm cubed of PH5 buffer solution
Buffer solution - used to control PH
Step 4
Place all 3 test tubes in water bath at 30 degrees
Step 5
Leave them for 10 minutes - to allow solutions to reach right temperature
Step 6
Combine 3 solutions into one test tube
Mix with a stirring rod
Step 7
Return test tubes to water bath and start stop watch
Step 8
After 30 seconds use the stirring rod to transfer one drop of solution to a well in the spotting tile that contains iodine
Results
The iodine should turn blue - black if starch is present
Until result
Take a sample every 30 seconds and continue until iodine remains orange
What does it mean when iodine remains orange?
When iodine remains orange - tells us that starch is no longer present and the reaction has been completed
time taken
We record the time for this in our results
Repeat
Repeat the whole experiment several times using different PH Buffers
PH 6, PH 7, PH 8
how is sm. intestine adapted (length)
length of 5 m
large s.a for absorbtion of products of digestion
how is the interior of small intestine adapted
sm. intestine interior has millions of villi
increase s.a for absorbtion of molecules
where are microvilli found and what do they do
microvilli are found on the surface of villi
increase s.a even further
describe another way villi are adapted (blood)
very good blood supply.
blood stream removes products of digestion rapidly
increases concentration gradient
how do villi increase the concentration gradient
they have god blood supply which quickly removes the products of digestion
how are villi adapted ( membrane )
thin membrane,
short diffusion pathway
list all the adaptations of sm.intestine inc villi (5 points)
very long- large s.a for absorbtion
have villi- increase s.a
villi have microvilli
villi have good blood supply
villi have thin membrane
fish have a single circulatory system. describe this
blood pumped from heart to gills
collects o2 in gills(oxygenated)
blood passes straight to organs
oxygen diffuses OUT of blood into body CELLS
blood returns to heart
what is a problem with single circulatory system
blood loses pressure as it passes to gills before organs
blood travels to organs slowly, cant deliver alot of o2
double cirulatory system
heart to lungs
collects o2
o2 blood back to heart
o2 blood pumped to organs
o2 transferred to body cells
deoxygenated blood back to heart
benefit of double circulatory system
blood passes to heart twice,
travels rapidly to body cells
delivers o2 cells need
the heart is an ………. consisting mainly of …….. tissue
the heart is an organ consisting mainly of muscle tissue
name the 4 chambers of the heart
right atrium left atrium
right ventricle left ventricle
the heart and circulatory system
……. are separated from ….. by valves
atria separated from ventricle by valves
what does vena cava do
brings X O2 blood to heart
what does pulmonary artery do
PA takes X O2 blood to lunfs
what does Pulmonary Vein do
brings O2 blood from lungs to heart
what does aorta do
takes O2 blood from heart to body
describe pattern of blood flow through heart
blood enters right and left atrium
atria contract-
blood forced to ventricles
ventricles contract-
blood forced out of heart
what do valves do
valves stop back flow of blood
(in atria when ventricles contract)
The …… ventricle pumps blood to the lungs where
….. …. takes place
The right ventricle pumps blood to the lungs where
gas exchange takes place
The ….. ventricle pumps blood ………
The left ventricle pumps blood around the
rest of the body.
what does the left ventricle do
The left ventricle pumps blood around the
rest of the body.
what does the right ventricle do
The right ventricle pumps blood to the lungs where
gas exchange takes place.
the … side of the heart has a thicker…… …. than the … side
the left side of the heart has a thicker musculer wall then the right side
why does the left side of the heart have a thicker muscular wall then the right side
the left ventricle pumple blood around ENTIRE body.
needs to provide a GREATER force
where do coronary arteries branch out from
coronary arteries branch out from aorta
coronary arteries …… out of ….. and spread out into ….. ……
coronary arteries branch out of aorta and spread out into heart muscle
what is the purpose of the coronary arteries
purpose of coronary arteries is to provide oxygen to muscle cells of heart
coronary arteries provide oxygen to muscle cells of heart. how is the O2 used
used in respiration to provide energy for contraction
The ……. …… heart rate is controlled by a ….. … ….. located in the ….. …… that act as a pacemaker
The natural resting heart rate is controlled by a group of cells located
in the right atrium that act as a pacemaker
what is the natural resting heart rate controlled by
natural resting heart rate controlled by a group of cell called pacemaker
the group of cell that act as a pace maker are found in …..
the right atrium
what is an artificial pace maker
a small electric device that corrects irregularities in the heart rate
what do arteries do
carry high pressure blood from heart to organs
adaptation of arteries ( walls)
thick muscular walls,
withstand high pressure of blood
blood travel through the arteries in …… every time the heart …..
blood travels through the arteries in surges every time the heart beats
how do elastic fibres in arteries keep blood moving
the elastic fibres stretch when the surge of blood passes
they recoil in between surges
keeps blood moving
three adaptations of arteries
thick muscular elastic walls
walls stretch to withstand pressure
small lumen
what happens when blood passes through capillaries. 2 points
substances eg glucose and oxygen diffuse from blood into cells
co2 diffuses from cells into blood
adaptations of capillaries
once cell thick- short diffusion pathway
small lumen
what does the short diffusion pathway in capillaries allow
allows substances to diffuse rapidly between blood and cells
what do capillaries do
pumps blood to tissue/cells
connects arteries and veins
what do veins do
take deoxygenated blood from organs to heart (low pressure)
veins have a ….. wall as the blood is … pressure
veins have a thin wall as the blood is low pressure
what do veins contain and what do these do
valves in veins stop backflow of blood
three adaptations of veins
valves
thin wals
large lumen
blood has 4 important part which are …..
plasma the liquid part of the blood
white blood cells
red blood cells
platelets
Blood is a ……… consisting of …….., in which the ….. blood cells, …… blood cells and ……… are ……..
Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended.
what are platelets
tiny fragments of cells
three substances blood plasma transports
urea
carbon dioxide
soluble digestion products (eg glucos)
where does plasma transport soluble digestion products to
plasma transports soluble digestion products from sm.intestine to other organs
where does plasma transport co2 to
from organs to lungs to be breathed out
where does plasma transport urea to
from liver to kidneys to be excreted in urine
what do red blood cells do
transport o2 from lungs to body cells
red blood cells contain the o2 carrying molecule called……
haemaglobin
what does haemaglobin do
heamaglobin combines with O2 in the lungs, forming oxyhaemoglobin
haemglobin + ………….. = oxyhaemaglobin
haemglobin + oxygen = oxyhaemaglobin
combines with O2 in the lungs
red blood cells (containing the oxyheamoglobin) travel to the organs. what happens next
once red blood cells (containing the oxyheamoglobin) travel to the organs
the oxyheameglobin releases the oxygeon
equation for oxyheamaglobin releaseing o2
oxyhaemaglobin to organs = heamaglobin + oxygen
red blood cell adaptations x3
no nucleus (space for haemaglobin)
has red pigment, haemaglobin
bi-concave disc shape
what does biconcave disc shape do
give greater s.a so O2 diffuses in and out rapidly
white blood cells form part of the …… …… for example making ……..
white blood cells form part of the immune system for example making antibodies
white blood cells contain a nucleus. how is this helpful
nucleus contains DNA, which encodes the instructions that the wbc need to do their job
what is the job of platelets
platelets help blood to clot
3 uses of donated blood in medicine
replace blood loss due to injury
people given platelets extracted from blood to help clotting
proteins extracted from blood can be useful eg antibodies
what do you need to make sure of in a blood transfusion, why
make sure the donated blood is the same blood type as the patients
immune system could reject blood. patient could die
two problems with dontated blood
body could reject blood
diseases transmitted in blood
why is blood screened in the uk
blood screened for infections as lots of diseases can be transmitted via blood
what are cardiovascular diseases
disease of the heart and blood vessels, non communicable.
example of a cardiovascular disease
coronary heart disease
what happens in coronary heart disease . what does this cause
layers of fatty material build up in coronary arteries, causing coronary arteries to NARROW
what happens when coronary arteries are narrowed and how does this affect the heart
blood flow through the coronary arteries is reduced so there is a lack of O2 for the heart muscle
what happens in extreme cases of coronary heart disease
a heart attack as heart is starved of oxygen
2 common treatments for coronary heart disease
statins
stents
what are statins
drugs that lower cholestrol in blood
how do statins help coronary heart disease
statins slow down rate of fatty build up in arteries
advantage and disadvantage of statins
statins are effective
(they lower cholestrol + reduce fat build up)
unwanted side effects
(liver problems)
why are some people with chd treated using stent
as chd caused almost a total blockage of an artery
what is a stent
a tube inserted into coronary artery to keep it open
advantage and disadvantage of a stent
the blood can flow normally through artery
does not treat cause of disease/ wont stop other parts of coronary artery from narrowing
coronary heart disease to do with valves opening and what it causes
heart valves X fully open. heart pumps xtra hard to get blood through. causes heart to enlarge
leaky valve causes
patient to feel weak and tired
In coronary heart disease layers of ………….. ……. build up inside the
…………… ……….. narrowing them. This reduces the flow of blood
through the coronary arteries, resulting in a …. …. …… for the heart muscle. ………. are used to keep the coronary arteries open. ……….. are
widely used to reduce blood ………. levels which slows down the rate of ….. …….. deposit.
In coronary heart disease layers of fatty material build up inside the
coronary arteries, narrowing them. This reduces the flow of blood
through the coronary arteries, resulting in a lack of oxygen for the heart
muscle. Stents are used to keep the coronary arteries open. Statins are
widely used to reduce blood cholesterol levels which slows down the
rate of fatty material deposit.
In some people heart valves may become…….., preventing the valve
from …. ……, or the heart valve might develop a ……
In some people heart valves may become faulty, preventing the valve
from opening fully, or the heart valve might develop a leak
Faulty heart
valves can be replaced using …… ……. from a pig or …….. valves made of metal
Faulty heart
valves can be replaced using biological valves from a pig or mechanical valves made of metal
advantage and disadvantage of mechanical valves
mechanical valve last a lifetime
increase risk of bloodclot
solution for mechanical valve problem
anticlotting drugs
advantage and disadvantages of biological valves
need to be replaced
patient doesnt need to take any drugs
what is heart failure
the heart cannot pump enough blood around the body
what are patients with heart failure given
donated heart or donated heart and lungs
In the case of …. …. a donor heart, or
……….. and ……… can be
transplanted. ………….. hearts are occasionally used to keep patients alive
whilst waiting for a heart
……….., or to allow the heart to …….. as an
aid to ……………
In the case of heart failure a donor heart, or heart and lungs can be
transplanted. Artificial hearts are occasionally used to keep patients alive
whilst waiting for a heart transplant, or to allow the heart to rest as an
aid to recovery.
problems with donating hearts x2
not enough donated hearts
patient must take drugs to stop heart being rejected by immune system
why are artificial hearts not long term solutions to heart failure
artificial hearts increase the risk of blood clotting
how does air pass into the lungs
air passes to lungs through the trachea
one key feature of trachea
trachea contains rings of cartilage
what do the rings of cartilage in trachea do
prevent trachea collapsing during inhalation
trachea splits into two …….. tubes called …….. , with one passing to each …….
trachea splits into two smaller tubes called bronchi with one passing to each lung
what happens to the bronchi further into the lung
further into the lung the bronchi subdivides into many smaller tubes called bronchioles
what do bronchioles end in
bronchioles end in tiny air sacs called alveoli
what happens at alveoli
sites of gas exchange
oxygen diffuses out of air into blood
co2 diffuses out of bloodstream into air
how are alveoli adapted for efficient gas exchange
millions of alveoli mean lungs have large s.a
alveoli have thin walls, short diffusion pathway
alveoli have very good blood supply
how does alveoli blood supply affect concentration gradient
once o2 diffuses into blood, its rapidly removed
this ensures a steep concentration gradient
how does breathing increase rate of diffusion ( 3 points)
breathing brings fresh o2 into alveoli
takes away co2
makes concentration gradients high for these gases
increasing rate of diffusion
what is a benign tumour
growths of abnormal cells which are contained in
one area
what is a malignant tumour
cancerous tumours that invade neighbouring tissue and move into the bloodstream
what happens in mitosis
one cell is copied into two cells
when does cell division by mitosis usually happen
during growth and repair
mitosis is extremely tightly controlled. what does this mean
genes in the nucleus tell the cell when and when to stop dividing
how does uncontrolled growth and mitosis occur
when the genes
(which tell cells when to stop dividing )
are changed
when the genes
(which tell cells when to stop dividing )
are changed, what is produced
a tumour (growth)
where are benign tumours usually contained
within a membrane
do benign tumours invade other parts of the body
no, stay in one place
what do malignant tumour cells do
they invade neighbouring tissue
spread to different parts of the body
through the blood
and form secondary tumours
at are malignant tumour cells classed as
classed as a cancer
what are the two risk factors for cancer
lifetyle factors
genetic factors
what are three cancers linked to lifestyle
smoking - lung cancer
ultraviolet light- skin cancer
alcohol- mouth and throat cancer
what is a gas in the environment that increases chance of lung cancer
radon gas (radioactive)
what does radon gas do
releases ionising radiation
which damages dna in our cells
what do cells damaged by radon radiation end up doing
dividing uncontrollably, leading to cancer
what are non communicable diseases caused by
risk factors
what is epedimiology
studying the patterns of disease to determine the risk factors
what do scientists used to identify a correlations between potential risk factors and the disease
a scatter graph
what must you remember about scattergraphs being used in terms of risk factors
a correlation does not prove cause
just suggests that disease and the action may be linlked
what two graphs did scientists use for smoking and lung cancer
number of cigarettes daily
and
risk of developing lung cancer
number of years smoking
and
risk of lung cancer
the action and the risk
the time of doing the action and the risk
what two areas of risk factors are there
- aspects of a person’s lifestyle
- substances in the person’s body or environment.
what is a causal mechanism
a scientific explanation of how the supposed risk factor can cause the disease
why is smoking a risk factor for lung cancer
cigarrette smoke contains chemicals which damage dna and increase risk of cancer
what are carcinegens
chemicals which damage dna and increase risk of cancer
when can we accept that a factor is actually a true risk factor for a disease?
strong correlation between the factor and the disease
a causal mechanism
epedimiology is studying the pattern of disease to determine risk factors. What is an issue with this
to study the pattern of disease, a sample is needed.
ideally you’d study every person in a population, but that’s not possible.
so scientists study a group of people and draw conclusions about the whole population
however, the sample could be biased ( all people from one town may under exercise )
so that sample doesn’t represent the countries population.
we cant use those results to draw conclusions about the whole country.
how to tackle bias in a sample
large, random sample
what are risk factors for cardiovascular diseases
diet
smoking
exercise
how does diet increase risk of cardiovascular disease
high fat, low veg
increases cholestrol
increases rate of fatty material build up in arteries
high salt increases blood pressure
how does smoking increase risk of cardiovascular diseases
chemicals in cigarette cause blood to clot
nicotene increases heart rate, straining the heart
how does smoking cause lung cancer
chemicals in cigarrette trigger cancer (carcinagens)
smoking is a risk factor for…
cardiovascular disease
lung disease
lung cancer
miscarriage / premature birth/ lowbody mass
how does smoking affect an unborn child
miscarriage
premature birth
low body mass
what can drinking when pregnant cause in a child
fetal alcohol syndrome
learning difficulties
mental / physical problems
what diseases/ problems can excessive drinking cause
(not including pregnant women)
liver diseases (cirrhosis and cancer)
addiction
memory loss
what is obesity a risk factor for
type 2 diabetes
what happens with type 2 diabetes
struggle to control blood glucose levels
give an example of how risk factors can interact
alcohol increases risk of obesity
obesity increases risk of type 2 diabetes
what gas is a risk factor of cancer
radon gas
what does smoking increase the risk of
cardiovascular diseases
lung cancer
lung disease eg emphysema
what are leaves
a plant organ
what tissues are found in a leaf, in order of there placement, top to bottom
(waxy cuticle)
1.upper epidermis
xylem and phloem + palisade mesophyll
3. spongy mesophyll
lower epidermis + stomata + guard cells
name all the structures and tissues in a plant leaf
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upper epidermis
xylem and phloem
palisade mesophyll
spongy mesophyll
stomata and guard cells
meristem tissue
lower epidermis
what does the epidermis do
protects the surface of the leaf
adaptation of upper epidermis
transparent
why is the upper epidermis transparent
to allow light to pass through to the photosynthetic cells below
what is the upper epidermis covered by
the waxy cuticle- thin layer of oily material
what does the waxy cuticle do and why
reduces water evaporation from leaf surface
this prevents leaf from drying out
what are the u/L
upperdermis made of
very thin epidermal cells
what does the lower epidermis have
stomata and guard cells
what is the role of stomata
allow CO2 to enter and O2 to leave
control water vapour passing out
where is the palisade mesophyll found
top of leaf under epidermis
what does the palisade mesophyll contain
palisade cells
which contain
chlorplasts
which contain
chlorophyll
where are the chlorophyll found
in the palisade mesophyll
hat do the chlorphyll do
absorb light energy for photosynthesis
what is beneath the palisade mesophyll
spongy mesophyll
key feature of spongy mesophyll
full of air spaces
what do the air spaces in the spongy mesophyll allow
allow CO2 to diffuse from stomata
through the spongy mesophyll
to the palisade cells
Allow O2 to diffuse from palisade cells through spongy mesophyll to stomata
what do xylem cells form
long tubes
what do the xylem tubes do
transport water + minerals from the roots of the plant to the leaves
what do the xylem tubes do
transport water + minerals from the roots of the plant to the leaves
one feature of xylem cells (walls)
very thick walls containing lignin
xylem cells have very thick walls containing lignin- how does this help the plant
provides support to the plant
xylem cell walls are sealed with lignin, what does this cause
causes the xylem cells to die
another feature of xylem cells
(end walls)
the end wall between cells is completely broken down.
in xylem cells, the end walls btwn cells have completely broken down. What does this mean for the plant
the cells form a long tube,
water and dissolved minerals flow easily
2 adaptations of xylem cells that makes the flow of water / minerals easier
no internal structures
+
end walls broken down
what do phloem tubes do
carry dissolved sugars up and down the plant
phloem consists of two different types of cells. what are they
phloem vessel cells
companion cell
describe the internal structures of a phloem vessel cells
no nucleus
limited cytoplasm
what do the end walls of phloem vessel cells have
pores called sieve plates
what two features of a phloem vessel cell allow easy travel of sugars
pores called sieve plates
very few internal structures
why does a phloem vessel cell have a companion cell
phloem vessel cell doesn’t have many mitrochondria
companion cell does
how are the phloem vessel cell and companion cell connected
by pores
what is the role of a companion cell in the phloem
companion cell provides energy for phloem vessel cell
the xylem tissue transports water and minerals from roots to the stem and leaves. What is this water used for
some water used in photosynthesis
what mineral ion travels up the xylem is used to makechlorophyll
magnesium
what does the phloem tissue do
transports dissolved sugars
(from photosynthesis)
from leaves to rest of plant
when can the dissolved sugar from the phloem be used
immediately- eg glucose in respiration
stored- as starch
hat is translocation
movement of sugars and other molecules through the phloem tissue
where is the meristem tissue found
at growing tips
eg shoots and tips
what does meristem tissue contain
meristem tissue contains stem cells.
can differentiate into different types of plant tissue.water
define transpiration
evaporation of water from the leaves
When the plant opens its stomata to let in carbon dioxide, water on the surface of the cells of the spongy mesophyll and palisade mesophyll evaporates and diffuses out of the leaf
where does photosynthesis take place in a leaf
in the palisade mesophyll- (contains chlorophyll)
describe process of transpiration stream
4 steps
. water from palisade mesophyll cells evaporates
. water vapour diffuses through air spaces in spongy mesophyll
. then out of the leaf through the stomata
. water passes from xylem into leaf to replace lost water
. water and mineral ions drawn into root hair cells and up xylem vessels into the leaf
why is transpiration important
3 key points
brings water to the leaf
water is required for photosynthesis
transports dissolved mineral ions like magnesium which are important
evaporation of water cools leaf down
how does temp affect rate of transpiration
rate of transpiration is higher at higher temp
(as evaporation is faster)
how does humidity affect rate of transpiration
transpiration faster under dry conditions when its not humid-
evaporation takes place faster
how does wind affect rate of transpirations
rate of transpiration increases under windy conditions
wind removes water vapour, allowing water to evaporate
how does light intensity affect rate of transpiration
rate of transpiration increases as light intensity increases.
why does rate of transpiration increases as light intensity increases.
high light intensity increases rate of photosynthesis
stomata open for CO2 to enter
so water can pass out of the leaf
what are stomata surrounded by
guard cells
what happens to guard cells when light intensity is high
guard cells swell
change their shape
causing stomata to open
what happens when stomata open
CO2 diffuses in leaf
can be used in photosynthesis
what happens to stomata in hot conditions
what is a negative of this
stomata close to reduce water loss by transpiration
plant cannot photosynthesise
what is transpiration- 1 sentence
water constantly evaporating from surface of leaves
what is a positive correlation in terms of a graph for smoking and lung cancer
when doing one thing also increases chance of another
