Exchange Surfaces Flashcards
Compare the surface area to volume ratio of different sized objects.
Objects with a larger surface area have a small surface area to volume ratio.
Objects with a small surface area have a large surface area to volume ratio.
Describe the surface area to volume ratio of small organisms and how this affects their exchange surface.
They have a large surface are to volume ratio therefore the body of cell surface is enough for the exchange surfaces.
Explain the surface area to volume ratio of large animals and how this affects their exchange surfaces.
Low surface area to volume ratio so they can’t rely on diffusion to survive because the diffusion pathway and exchange distances are too great.
Because of this large animals must have specialised exchange systems to meet high activity and efficient transport systems to deliver materials to and from exchange surfaces.
What are the main features of exchange surfaces ?
Large surface area Short diffusion pathway Movement of environmental medium Internal transport system Permeable membrane
Why must exchange surfaces have a large surface area ?
It increases the rate of exchange often by folding the exchange surface.
Why do exchange surfaces need a short diffusion pathway ?
Diffusion distance must be short so materials can cross rapidly.
Why must exchange systems allow movement of environmental medium ?
Maintains a diffusion gradient.
What must exchange surfaces have an internal transport system ?
Ensures movement of internal medium.
Why must exchange surfaces have a permeable membrane ?
Allows liquids and gases to pass through.
What issues arrive with the gas exchange of land organisms ?
Cells need to be exposed to air to gas exchange
Terrestrial bodies are made of a high water percentage.
When living cells are exposed to air,water molecules evaporated and the cells dehydrate.
What factors limit water loss in land animals ?
Skin is impermeable
Exchange surfaces located inside the body
How do insects conserve water ?
They have a waterproof cuticle with a rigid exoskeleton covered by a waterproof covering.
Small surface area to volume ratio.
What affect does the small surface area to volume ratio of insects have on their gas exchange.
Means they cannot use their body to gas exchange so need to have gas exchange systems.
Describe the gas exchange systems in insects.
Openings in the body surface called spiracles. Spiracles lead the trachea which are supported by strengthened rings called chitin.
Tracheae lead to smaller tracheloes.
Tracheloes extent through body tissue to supply oxygen.
What are openings in the insect body called ?
Spiracles
What are spiracles.
Openings in the insect body go gas exchange.
What are chitin
Strengthen the trachea - small rings.
What are the strengthened rings that support the trachea called ?
Chitin
How do gases move in and out of the tracheloes ?
Across a diffusiongradient - oxygen in, carbon dioxide out.
Ventilation - contraction muscles of insects move air in and out of the tracheae.
What is ventilation interms of insects ?
Contacting muscles move air in and out of the trachaea.
How do spiracles affect water content in insects.
Spiracles are tiny pores where gases enter and leave the tracheae. Spiracles are owned and closed by valves. When the valves are open water evaporates.
What happens to partial pressure of oxygen when spiracles are closed.
When the valves are closed, oxygen within the tissue is being used for respiration(aerobic) so potential pressure of oxygen in the tracheae decreases.
When happens to carbon dioxide partial pressure when the spiracles are closed.
When the spiracles are closed, carbon dioxide cannot escape so partial pressure of carbon dioxide increases.
What stimulates the opening of spiracles ?
An increase in partial pressure of carbon dioxide.
Explain what causes the oxygen concentration in the tracheae to fall when the spiracles are closed.
Oxygen is used in aerobic respiration therefore diffuses into the tissues until oxygen is able to enter the organism again.
For insects that live in dry conditions, suggest an advantage of having a specific spiracle movement pattern.
If the spiracles infrequently open, less water is lost via evaporation.
What are terrestrial animals ?
Live predominantly on land.
What is the structure of bony fish ?
Small surface area to volume ration.
Impermeable skin which doesn’t allow gas exchange.
What is the specialised exchange surface of fish ?
Gills.
Describe the process of gill irrigation and how this works.
- Fish opens mouth to lower buffalo cavity so the volume of the buccal cavity increases.
- Opercula are closed.
- Pressure in the buccal cavity decreases so water is drawn in through the mouth, down a pressure gradient, into the buccal cavity.
- Mouth closes, opercula open, floor of buccal cavity raises.
- Pressure in buccal cavity increases.
- WAter flows from the buccal cavity, across the gills, out through the opercula.
Give adaptations of the gills and how they help gas exchange.
Lamellae are folds in the gill filament. They increase diffusion surface area, have a permeable membrane. Lots of capillaries to increase blood flow and maintain diffusion gradient. Thin flattened cells give a short distance for diffusion.
What are the features of the lamellae that help gas exchange.
They increase diffusion surface area, have a permeable membrane. Lots of capillaries to increase blood flow and maintain diffusion gradient. Thin flattened cells give a short distance for diffusion.
What are lamellae.
Folds in the gill filament.
What is counter current flow and how does it help gas exchange in fish ?
Water and blood flow in opposite directions. This means the diffusion gradient is maintained along the whole length of the lamellae. Equilibrium can never be reached and so gas exchange is constant.
What is parallel flow and why is it not used in fish ?
The water and blood would flow in the same direction meaning that equilibrium would eventually be reached and gas exchange would stop part way across the lamellae.
Explain the adaptations of gills for gas exchange (6 marks).
Foldings known as lamellae are foldings which increase surface area for diffusion and have many capillaries which maintain a diffusion gradient.
Permeable membrane.
Counter current flow enables concentration for gas exchange to be maintained across whole lamellae.
Flattened cells shorten the diffusion pathway.
What are cartilaginous fish ?
Fish with a skeleton of cartilage rather than bone such as sharks and rays.