Gas Exchange Flashcards
What are the main adaptions of gas exchange surfaces shown by gas exchange?
1)Across the body surface of a single-called organism(e.g aemoba)
2)in the tracheal system of an insect (trachea,tracheoles and spiracles)
3)across the gills of fish(lamealle ,filaments and counter-current )
4)by the leaves of dicotyledonous (plant sprout into 2 leaves)(meosphyll and stomata)
Why do gills have to be efficient for gas exchange in fish ?
They extract oxygen from water and there is far less oxygen dissolved in water compared to the same volume in air.
-The water is pumped to avoid it from flowing backwards
How do gills ,filaments and lamealle link together?
Bony fish usually have 4 gills
1)Each gill is made up of two rows of filaments (folded ,thin structure)they come of the gill (large SA:V)
2)filaments are composed of lamellae (the gas exchange surface) and they contain blood flow through capillaries
How does the water in the fish gas exchange not flow in the wrong direction?
As the water moves across the lamealle is there a lot of Oxygen ?
When water enters the mouth it is forced to flow out through the gill(operculum)
No ,the water just passing the lamellae has more oxygen than water leaving at the end.
What is the counter-current mechanism?
Explain and describe the advantage of counter current flow?
Water flows across the gill plate in the opposite direction to the flow of blood.
- water has a HIGHER concentration of oxygen than the blood so concentration gradient maintained.
So diffusion can occur across THE FULL LENGTH OF THE GILL.
What are some extra adaptions of of gills for DIFFUSION?
-the distance between two lamellae is 50 micrometers (water stops it from collapsing)
-gills have extensive network of blood capillaries to maintain concentration gradient aiding diffusion.
-The distance between the water and blood cell is 5micrometer so short diffusion
Why would it have been bad if fish used concurrent flow instead of counter-current flow?
Initially, there would be a steep concentration gradient, so oxygen would diffuses from water (high O₂) into the blood (low O₂).
However, as both water and blood move in the same direction, their oxygen levels become similar, reducing diffusion.
Eventually, equilibrium is reached, meaning no further oxygen diffusion occurs
What are 3 features of leaves on dicotyledonous(plant that has two leaves) plants?
They are :
Flat -
Thin -so short diffusion distance
Wide-bigger surface area so more
stomata present so can absorb more gasses
What are the parts of a leave in cross-section view?
Waxy cuticle-made out of lipids so is waterproof so stops water loss
Upper epidermiss -makes the waxy cuticle
Palisade meosphyll -lots of chloroplast for photosynthesis
Spongey meosphyll-crates space for air so makes diffusion pathway clearer
Lower epidermis-stomata and guard cell are found there
Waxy cuticle
What parts of the leaf are actually adapted /gas exchange more efficient for photosynthesis?
Stomata -allows them to diffuse through
Spongey meosphyll-creates air gaps for gases to diffuse through
Air spaces -allows gases to move freely inside the leaf
How are organisms able to exchange gases with their external environment and what are the problems with it?
By their pores(spiracles,stomata,)
Problem with this gaseous exchange surfaces is :
Is the loss of water vapour
When do stomata’s close and in what conditions +why?
-water potential
Stomata’s are closed at night time and when it is dry.
As there is is lower water potential inside the cell than outside the cell so so water will move out due to the water potential gradient which the cell cannot afford as it could store the water instead for photosynthesis.
What is another thing plants need to account for ?
Stomata’s need to also open to allow transpiration to take place .
what are plants called that are adapted to grow in dry conditions and give an example?
Xerophytes e.g cacti
what adaptations do xerophytes(plants that grow in dry conditions) have and how do they affect water conservation ?
what are the adaptations in insects to minimise water loss?
thick waxy cuticle - so reduces evaporation and increases diffusion distance as it is thick
fewer stomata-fewer pores for water loss
sunken stomata-traps water vapour so reduces water potential gradient
fine hair on leaf surface-traps moist air so reduces water potential gradient.
stomata open at night=less water loss during the day
rolled leaves=traps water vapour so water potential gradient decrease
shallow extensive root system so condesation formed at night is absorbed.
insects
exoskeleton -impearmable so reduces water loss
round spiracles-so reduce water loss
what does structural and functional comprises between the opposing needs for effficent gas exchange mean?
for instance leaves have the same structural features e.g. hair ,stomata etc but some leaves need to use the stomatas in diffrent ways depending on their surroundings e.g. they might open their stomata during the night time becouse they live in a moist area e.g. rainforest as water potential would be the same inside and outside the organism.
unlike other plants they would open in the morning as CO2 needs to enter for photosynthsis.
Describe and explain how the lungs are adapted to allow rapid exchange of oxygen between air in the alveoli and blood in the capillaries around them?
1)Many alveoli WALLS folded /many capillaries provide large surface area so fast DIFFUSION
2)Sqamerous epithelial cells(walls of alveoli 1cell thick) /cappillary walls are so thin that RBC are compressed against the epithelial cell membrane of alveolus so shorter diffusion pathway so fast diffusion
3)moist surface (surfactant) so easier to absorb gases via diffusion
large SA:Vol ratio
Not important
What are some features of the trachea ,bronchi and bronchioles and how are they adapted to their function?
Trachea -c shape cartilage in their wall separated by muscle(keep air passage open during preassure change )and elastic tissue (allows trachea to be flexible and to stretch)
Bronchi-also has cartilage however it is thinner than the tracheas one
Bronchioles - only has muscle and elastic fibres so that they can contract and relax easily during ventilation
Describe and explain the mechanism that causes lungs to fill with air(inspiration)?
1)External intercostal muscle contract and innner intercostal muscle relax
2)rib cage moves up and out
3)diaphragm muscle contract and moves down
4)Volome of thoracic cavity increase
5)preassure in the lungs decreases and so there is more pressure in the atmosphere
6)air flows into the lungs down a preassure concentration gradient
Describe and explain the mechanism that causes lungs to do expiration/exhale?
-Inner intercostal muscle contracts ,external intercostal muscle relax
-Rib cage moves down and in
-diaphragm muscle relax and moves down(normal pose)
-Volume of thoracic cavitiy decreases
-so preassure in the lungs increases and becomes more than what is in the atmosphere
So air flows out the lungs down the preassure gradient
Explain why death of alveolar epithelium cells reduced gas exchange in human lungs?
Any damage to alveoli reduces alveolar surface area and increases diffusion distance.
