Exchange and Transport Systems (Topic 3) Flashcards
which has a bigger SA : volume ratio - smaller organisms or large organisms?
smaller
in single-celled organisms substances diffuse…
across the…
directly into the cell
cell surface membrane
in mammals ‘mass transport’ refers to
the circulatory system which uses blood to carry glucose, oxygen, hormones, antibodies and waste
mass transport in plants involves the transport of….
water and solutes in the xylem and phloem
heat exchange is influenced by..
body size
body shape
adaptions for heat exchange
gas exchange occurs over a…
gas exchange surface
what three factors increase the rate of diffusion?
- large surface area
- short diffusion distance
- steep concentration gradient
in fish the gas exchange surface is..
the gills
describe the structure of the gills
each gill is made out of gill filaments
gill filaments are covered in lamellae
gill filaments and lamellae in fish increase _____ so speed up the rate of ______
surface area
diffusion
how do the lamellae speed up diffusion?
they have a large SA
they have lots of capillaries and thin surface layer of cells
the counter current system in fish maintains a….
steep concentration gradient between the water and the blood
why is a steep concentration gradient between the water and blood and fish important?
so as much oxygen as possible diffuses from the water into the blood
in a counter current system water with a ____ concentration gradient flows next to ____ with a _____ concentration of oxygen
high
blood
lower
the main gas exchange surface in a plant is….
mesophyll cells
how are mesophyll cells adapted for gas exchange?
large surface area
in plants gases move in and out the leaf via the…
which opens to allow…
stomata
gas exchange
why would the stomata in a leaf close?
if the plant is losing too much water
what controls the opening and closing of the stomata?
guard cells
in insects air moves into the ____ through ______ . oxygen travels ___ the concentration gradient towards the _____ . tracheae branch off into ______ that go to ______ cells
trachea
spiracles
down
cells
tracheoles
individual
in insects how is CO2 removed from the organism?
- moves down its concentration gradient
- towards spiracles
- to be released
insects use ______ _______ ______ to move air in and out of the spiracles
rhythmic abdominal movements
if insects are losing too much water they will…
- close their spiracles using muscles
- the waxy cuticle and tiny hairs reduce evaporation
in plants the stomatal pore is opened by…
water moving into guard cells making them turgid
in plants the stomatal pore is closed by…
the plant becoming dehydrated so guard cells lose water and become flaccid, which closes the pore
plants that are adapted against water loss are called…
xerophytes
examples of xerophytic adaptions are:
- reduced no. of stomata
- thicker waxy waterproof cuticles
- curled leaves with stomata on the inside
what happens during inspiration?
- external intercostals and diaphragm contract
- causing the ribcage to move up and out and the diaphragm flattens
- increasing the volume of the thoracic cavity so pressure decreases
- air moved from high to low pressure down the pressure gradient into the lungs
is inspiration an active or passive process
active
what happens during expiration?
- external intercostals and diaphragm relax
- ribcage moves down and in
- decreasing the volume of the thoracic cavity so pressure increases
- air moves from high to low pressure down the pressure gradient so is forced out of lungs
is normal expiration active or passive?
passive
where does gas exchange occur in the lungs?
alveoli
what are the alveoli surrounded by?
a network of capillaries
the walls of alveoli contain _____ which….
elastin
helps them recoil to their normal shape after inhaling or exhaling air
describe gas exchange of oxygen at the alveoli
O2 diffuses out pf the alveoli across the alveolar epithelium and capillary epithelium into haemoglobin in the blood
describe gas exchange of carbon dioxide at the alveoli
CO2 diffuses out of the blood into the alveoli
what is the pathway of O2 when breathed in?
- trachea
- bronchi
- bronchioles
- alveoli
- alveolar epithelium
- capillary endothelium
- blood
how are alveoli adapted for fast diffusion?
- thin exchange surface
- large surface area
- steep conc gradient of O2 and CO2 between capillaries and alveoli
tidal volume is…
the volume of air inspired or expired per breath
ventilation rate is…
the no. of breaths per minute
forced expiratory volume is…
the maximum volume of air that can be breathed out in one second
forced vital capacity is…
the maximum volume of air possible to breathe out forcefully out of the lungs after a deep breath in
lung diseases reduce the rate of gas exchange in alveoli which means…
less O2 diffuses into the blood and body cells receive less O2 and rate of aerobic respiration is reduced
risk factors are…
factors that increase a persons chance of getting a disease
why do large biological molecules need to be broken down?
they are too large to be absorbed
what enzyme catalyses the breakdown of starch?
amylase
where is amylase produced?
salivary glands and pancreas
how do amylase work?
catalyses hydrolysis reactions that break the glycosidic bonds in starch to produce maltose
membrane bound disaccharides are..
enzymes that are attached to the cell membranes of epithelium cells lining the ileum
sucrose is broken down by…
to produce what two monosaccharides?
sucrase
glucose + fructose
maltose is broken down by….
to produce what two monosaccharides?
maltase
glucose + glucose
lactose is broken down by….
to produce what two monosacchrides?
lactase
glucose + galactose
what enzyme catalyses the breakdown of lipids?
lipase
when lipids are digested what bond is hydrolysed in the molecule?
ester bond
where are lipases produced?
then secreted to the….
pancreas
small intestine
where are bile salts produced?
liver
what do bile salts do and why is this useful for digestion?
emulsify lipids increasing the surface area for lipases to work on
once a lipid has been broken down,
the _______ and ____ ___ stick with the bile salts to form ______
monoglycerides
fatty acids
micelles
what do micelles do?
help the products of lipid digestion to be absorbed
what two peptidases are involved in digestion of proteins?
endopeptidases
exopeptidases
what do endopeptidases do?
hydrolyse peptide bonds within a protein
what do exopeptidases do?
hydrolyse peptide bonds at the end of proteins. they remove single amino acids from proteins
what are dipeptidases?
two exopeptidases that work specifically on dipeptides
how many molecules of oxygen can each haemoglobin molecule carry?
4
when there is a high pO2 oxygen…
loads onto haemoglobin to form oxyhaemoglobin
when there is a low pO2 oxygen…
unloads from oxyhaemoglobin
where pO2 is high does haemoglobin have high or low affinity for oxygen?
high
where pO2 is low does haemoglobin have high or low affinity for oxygen?
low
the pulmonary artery carries blood from the….
to the….
heart
lungs
the pulmonary vein carries blood from the….
to the…
lungs
heart
the aorta carries blood from the…
to the…..
heart
body
the vena cava carries blood from the…
to the….
body
heart
the renal artery carries blood from the….
to the…..
body
kidneys
the renal vein carries blood from the….
to the….
kidneys
body
does the aorta carry oxygenated or deoxygenated blood?
oxygenated
does the vena cava carry oxygenated or deoxygenated blood?
deoxygenated
does the pulmonary artery carry oxygenated or deoxygenated blood?
deoxygenated
does the pulmonary vein carry oxygenated or deoxygenated blood?
oxygenated
arteries carry blood from the….
to the….
heart
body
describe the structure of an artery and what this does?
- thick walls with elastic tissue
- inner lining is folded
which maintains a high pressure
arteries divide into….
arterioles
veins carry blood from the…
to the….
body or lungs
heart
in veins blood travels at a _____ pressure
low
describe the structure of a vein
- have valves to stop backflow of blood
- wider lumen than arteries
arterioles branch into….
capillaries
describe the structure of a capillary..
one cell thick
in a capillary bed, substances move out of the capillaries into the tissue fluid by….
pressure filtration
where is pressure highest in the capillary bed?
at the start
what has thicker walls atria or ventricles?
ventricles
what is the function of AV valves?
stop blood flowing back into the atria when the ventricles contract
what is the function of semi-lunar valves?
stop blood flowing back into the heart after the ventricles contract
what are the three stages of the cardiac cycle?
- ventricles relax and contract
- ventricles contract and atria relax
- ventricles relax and atria relax
cardiac output =
stroke volume x heart rate
how is an atheroma formed?
if the endothelium is damaged by high blood pressure, white blood cells and lipids clump together under the lining to form fatty streaks. more builds up and hardens to from atheroma
what is an aneurysm?
a balloon-like swelling of the artery
what is thrombosis?
the formation of a blood clot
what is the scientific term for heart attack?
myocardial infarction
what causes a heart attack?
when a coronary artery is completely blocked and an area of the hearts blood supply is completely cut off and receives no oxygen
what are the risk factors for cardiovascular disease?
high blood pressure
high blood cholesterol & poor diet
cigarette smoking
what tissues are involved in mass transport in plants?
xylem
phloem
what does xylem tissue transport?
water and mineral ions in solution
what does phloem tissue transport?
organic substances like sugars
describe the structure of the xylem
xylem vessels are long tube like structures formed from dead cells joined end to end
How does water move up a plant?
4 marks
- transpiration occurs at the leaf
- creating tension, pulling more water into the leaf
- water molecules stick together so the whole column of water in the xylem moves upwards
- water enters the stem through the roots
what is transpiration?
the evaporation of water from a plants surface
what 4 factors affect rate of transpiration?
- temperature
- humidity
- light intensity
- wind
what affect does light intensity have on transpiration?
the lighter it is the faster the rate of transpiration
what affect does temperature have on transpiration?
the higher the temperature the faster the rate of transpiration
what affect does humidity have on transpiration?
the lower the humidity the faster the rate of transpiration
what affect does wind have on transpiration?
the windier it is the faster the rate of transpiration
describe the structure of the phloem
formed from cells arranged in tubes and contains sieve tube elements and a companion cell for each sieve tube
what is the function of the sieve tube element of phloem?
they form the tube for transporting solutes
what is the function of the companion cell element of the phloem?
they carry out the living functions for sieve cells
translocation is….
the movement of solutes to where they are needed in the plant, from sources to sinks
what is the source in translocation?
where solutes are produced, so are at high concentration
what is the sink in translocation?
where solutes are used up, so are at a lower concentration
the concentration gradient in translocation is maintained by…
enzymes breaking down or converting solutes into something else at the sink
give evidence for the mass flow theory
- if a metabolic inhibitor is put into the phloem translocation stops - proving active transport is used
- a radioactive tracer can be used to track movement of organic substances in the plant
give evidence against the mass flow theory
- sugar travels to many different sinks not just the one with the highest water potential
- the sieve plates would create a barrier to mass flow
what is the mass flow hypothesis?
the theory for how dissolved substances (solutes) are transported from source to sink by translocation
Describe the mass flow hypothesis for the mechanism of translocation in plants
4 marks
- In source sugars are actively transported into phloem
- By companion cells
- Lowers water potential of sieve cell and water enters via osmosis
- Increase in pressure causes mass movement
Use your understanding of the mass flow hypothesis to explain how pressure is generated inside a phloem tube
3 marks
- sucrose actively transported into phloem
- lowering water potential
- water moves into phloem via osmosis
Describe how a high pressure is produced in the leaves
3 marks
- water potential becomes lower
- water enters phloem via osmosis
- increased volume of water causes increased pressure
Explain three ways in which an insects’s tracheal system is adapted for efficient gas exchange
3 marks
- tracheoles have thin walls so short diffusion distance to cells
- highly branched so short diffusion distance
- highly branched so large surface area
The concentration of oxygen in the surface water than it is in water close to the seabed. Explain why
3 marks
- mixing of air and water at surface
- air has a higher conc. of O2 than water
- oxygen diffuses in
Explain how the countercurrent system in fish ensures max volume of O2 passes into the blood
3 marks
- water and blood flow in opposite directions
- blood passing water with higher oxygen concentration
- diffusion gradient maintained throughout gill length
Explain how the gills of fish are adapted for efficient gas exchange
6 marks
- large SA provided by lamellae
- thin distance between blood and water
- water and blood flow in countercurrent
- which maintains high conc. gradient
- circulation replaces blood saturated with oxygen
- ventilation replaces water
