3.3 Organisms exchange substances with their environment Flashcards
what is meant by surface are: volume
how far the internal parts are from the surface.
what happens to the surface are:volume when an organism increases
the surface area:volume ratio decreases
why can smaller organisms rely on diffusion for gas exchange but animals cant?
large SA:V and short diffusion pathway allowing for gas exchange to occur.
why do animals need a specialised transport system?
smaller SA:V and also a longer diffusion pathway.
how do multicellular organisms get O2?
specialised systems and exchange systems: circulatory + respiratory
what do organisms exchange?
-urea
-O2
-CO2
-blood
-nutrients
explain why oxygen uptake is a measure of metabolic rate in organisms?
oxygen is used during respiration.
the greater the O2 uptake the larger the metabolic rate increases.
larger and multicellular.
what is the metabolic rate?
amount of energy expanded by an organism within a given amount of time.
explain how larger organisms are able to adapt to cold climates?
less heat is lost because:
small surface area to volume ratio
large diffusion pathway
how is the exoskeleton used to prevent water loss
a lipid layer
also fibrous material for protection.
how do the spiracles prevent water loss?
the open and close to reduce water loss
what enters and leaves the spiracles?
gases enter
water evaporates.
how do gases enter the tracheoles via diffusion?
-cells respire aerobically and O2 is used up.
-concentration decreases in tracheoles.
-diffusion gradient established between atmosphere and tracheoles.
-O2 diffuses in.
in what direction does O2 move when a diffusion gradient is established?
spiracles-trachea-tracheoles-cell
how do gases move out thee spiracle via mass transport?
muscle cells contract
causes the mass movement of O2 and CO2
how do gases move into tracheoles when its filled with water
after major activity
cells respire anaerobically
produces lactate + lowers WP
water from tracheoles move via osmosis into cells.
volume and pressure decreases draws air in
what happens when lactate is produced during anaerobic respiration in the spiracles
lowers water potential
what is an adaptation of the large no of tracheoles
larger surface area
how are tracheoles useful adaptations
thin walls
short diffusion pathway + distance between tracheoles and spiracles
what is the helpfulness of CO2+O2 in a fish
creates a steep diffusion grradient.
what is found on the surface of the gill filaments?
lamellae
what is Fick’s Law?
Diffusion dp surface area*diff in conc
divide by length of diffusion pathway
why do fish have special addaptations?
30x less O2 inwater than atmosphere
what do the lamelle provide?
larger surface area
how is the concentration gradient maintained in a fish?
countercurrent flow
how is a short diffusion pathway formed in a fish?
a capillary network in every lamelle
thin gill lamelle
Where is the large SA:V ratio created in a fish?
many gill fillaments covered by many gill lamelle
what is the countercurrent flow?
blood flows in the opposite direction of water
so equilibrium is not reached
ensures a concentrtion gradient is established across entire length of lamelle.
what flows in opposite direction in the countercurrent flow?
blood and water
why does blood and water flow in opposite direcctions?
so equilibrium is not reached
why should the equilibrium not be reached?
so a concentration gradient is estblished across the ENTIRE length of LAMELLE.
what diffuses into the leaf?
CO2
what diffuses out a plant cell?
O2
what does the stomata do to reduce water loss in dictolydenous plants?
stomata closes at night
what are xerophytes?
plants found in extreme temps
how dos a smaller SA:V reduce water loss in xerophytes?
reduces rate of diffusion
why do xerophytes have waxy cuticles?
waterproof
less water escapes as its THICK
what is the SA:V in xerophytes and how does this help with water loss?
reduces rate of diffuusion
what happens when the leaves are rolled in xerophytes?
lower epidermis is isolated
traps region of air
water evaporates and air becomes saturated.
WP increase in the region
WP M in leaf and air decreases no evaporation
what happens when the H2O evaporates within region of air
WP increase
WP M decreases no evaporation
what happens to the water potential gradient of a rolled leave?
it decreases
WP increases in the air
what is a useful adaptation of hairy xerophyes that prevents water loss?
hair traps moist layer of air
WP M from leaf to trapped air decreases
less water evaporates own WP M
what is ventilation?
to breathe in
where does the antagonistic interaction occur?
between the external and internal intercostal muscles
what is inspiration
to breathe in
what happens to the external intercostal muscles during inspiration?
it contracts (rib is pulled upwards)
what happens to the internal intercostal muscles during inspiration?
it relaxes
what happens to the diagraphm during inspiration?
contracts [n–>u]
what happens to the air pressure in the lungs during inspiration?
it decreases
what happens to the volume of the lungs during inspiration?
it increases
how does air move during inspiration?
high pressure in the atmosphere compared to inside the lungs.
what is expiration?
breathing out
what happens to the external intercostal muscles during expiration?
they relax
what happens to the internal intercostal muscles during expiration?
they contract
what happens to the diaphragm during expiration?
it relaxes (pops back up to dome)
[n->u->n]
what happens to the pressure in the lungs during expiration?
it increases
what happens to the volume of the lungs during expiration?
it decreases
how does air move in during expiration?
moves out cause higher pressure in lungs than atmosphere.
what variables can determine the BMR
CO2 production
Oxygen consumption
Heat generated
why do smaller organisms have a high BMR even though they are small.
-they have SA:V and therefore lose heat quickly
-will cool down if respiration stops
-so faster heart rate is needed to supply O2 for respiration
what is the function of a sunken stomata?
reduces air movement across stomata.
-moist air is trapped inside.
what is the function of a thick waxy cuticle?
reduces transpiration/evaporation
provides a larger diffusion distance
what is function of the hair on xerophytes?
traps air becoming damp/humid
What are large insoluble molecules broken down into
Small soluble molecules
what 2 enzymes break down carbohydrates?
amylase
membrane bound dissacharidases
where is amylase found?
salivary glands
pancreas
what are examples of the membrane bound dissacharidases?
maltase
lactase
sucrasse
what do membrane bound disaccharidases break things down to?
from disaccharides to monosaccharides
what is an example of the disaccharidases
lactase–>lactose–>glucose and galactose
what 3 enzymes break down proteins?
-endopeptidases
-exopeptidases
-membrane bound dipeptidases
how are proteins broken down
protein–>dipeptide–> amino acids
where are the protein enzymes found
stomach and pancreas
what is the role of exopeptidases?
enzymes that hydrolyse peptide bonds between the amino acids at the end of a polymer chain
what is the role of endopeptidases?
enzymes that hydrolyse the peptide bond between amino acids at the start of a polymer/ peptide chain.
where does the exopeptidase hydrolyse the peptide bond?
at the end of the polymer chain
(between amino acids)
where does the exopeptidase hydrolyse the peptide bond in the polymer
the end of the chain
where does the endopeptidases hydrolyse the peptide bonds in the polymer?
the middle of the chain
what is the role of a membrane bound dipeptidases?
hydrolyse the peptide bonds between dipeptides forming amino acids
what enzyme hydrolyses lipids?
lipase
where are bile salts produced?
liver
where are bile salts stored?
gall bladder
what is the role of bile salts?
emulsify triglycerides into monoglycerides and glycerol.
forming small droplets called micelles.
what is the role of lipase?
hydrolyse ester bonds in triglycerides
what is the usefullness of the small micelle droplets?
increases SA
faster hydrolyses action from lipase
what does the physical breakdown of lipids involve?
bile salts emulsifying triglyerides
what does the chemical breakdown of lipids invole
fast hydrolyses of lipase on micelle droplets
what is the alimentary canal?
the places where the food passes through
where is food absorbed?
small intestine (ileum)
what is the structure o the ileum?
-thin walls
-network of capillaries
-many microvilli
-villis
why are the thin walls a useful adaptation
shorter diffusion pathway
maintains the concentration gradient
why are the microvillis useful adaptations?
increase the surface area
what do long fatty acid chains and monoglycerides form?
triglycerides
what are triglycerides packaged into?
chylomicrons
where are the chylomicrons transported to?
lacteal
is the lacteal?
lymph vessel within villius
how does the chylomicrons leave the small intestine?
exocytosis
