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.
How do cartilaginous fish regulate water content.
They don’t have opercula so cannot actively pump water across their gills. So they must continullary move forward to allow the flow of water across their gills.
AGD causes the lamellae to become thicker and fuse together. Give 2 reasons which it reduces the efficiency of gas exchange in fish.
Surface area for diffusion decreases.
Thickening of cells increases the diffusion pathway meaning it takes longer for oxygen to diffuse and reach the blood.
What is the equation and numerical formula for respiration ?
Glucose + oxygen - carbon dioxide + water
C6H12O6 + 6O2 - 6CO2 + 6H2O
What is the equation and numerical formula for photosynthesis?
Carbon dioxide + water + sunlight - glucose + oxygen
6CO2 + 6H2O + sunlight - C6H12O6 + 6O2
State the adaptations of leaves for photosynthesis.
Thin Air spaces in the spongy mesophyll Cuticle and upper epidermis are transparent Chloroplasts move Palisade cells form a continuous layer Guard cells open and close.
How does leaves being thin aid photosynthesis ?
Gives a short diffusion pathway.
How do air spaces in the spongy mesophyll of leaves aid photosynthesis ?
Creates a large surface area for diffusion of gases into cells.
Allows molecules to diffuse as gases and gases diffuse quicker than liquids.
What colour are the waxy cuticle and upper epidermis of leaves and how does this help photosynthesis.
Transparent to let light through.
Why do the chloroplasts move to help photosynthesis in leaves. ?
To maximise light absorption
How is it helpful to have a continuous layer of palisade cells in leaves ?
It maximises light trapping for photosynthesis.
Why are guard cells helpful to leaves in photosynthesis ?
They open and close stomata pores to enable gas exchange.
Give features of the spongy mesophyll.
Sure spaces so molecules can diffuse as gases.
Irregular shape.
Thin film of moisture for carbon dioxide to diffuse across.
Transport tissue present- xylem and phloem.
Very few / no chloroplasts.
Describe the features of palisade mesophyll.
Continuous layer to trap light. Vertical orientation. No intercellular spacing. Numerous chloroplasts No transport tissue. No layer of moisture.
Compare the intercellular spacing in spongy and palisade mesophyll.
Spongy mesophyll has intermolcular air spacing so gases can diffuse.
Palisade mesophyll are in a continuous layer to trap light.
Compare the shape and orientation of the spongy and palisade mesophyll.
Spongy mesophyll have irregular shape and orientation.
Palisade mesophyll is in a continuous layer with vertical orientation.
Why does the spongy mesophyll have a thin film of moisture ?
To allow carbon dioxide to diffuse through the tissue.
Compare the transport tissue preset in the spongy mesophyll and palisade mesophyll.
The spongy mesophyll has transport tissue such as the xylem and phloem tissue present.
The palisade mesophyll has no transport tissue present.
Compare the quantity of chloroplasts in the spongy and palisade mesophyll b
Spongy mesophyll has few to no chloroplasts
The palisade mesophyll has many chloroplasts
Describe how carbon dioxide moves through a leaf.
Diffuses in via the stomata did to the diffusion gradient present.
Diffuses into the spongy mesophyll tissue.diffuses into palisade mesophyll cells for photosynthesis.
Describe how oxygen moves through the leaf.
Diffuses our of the palisade leaf cells into the spongy mesophyll.
Diffuses out of mesophyll into air spaces carried by diffusion gradient.
Diffuses out of stomata.
Describe the concentration of carbon dioxide in palisade cells within leaves.
There is always a low concentration of carbon dioxide as the gas is being used for photosynthesis. This allows the diffusion gradient to be maintained.
Describe the concentration of oxygen in palisade cells within leaves.
High concentration as oyxygen is constantly being synthesised by aerobic respiration.
Explain how the stomata react in sunlight.
Guard cells take in water via osmosis and become turgid. This turgidity pulls the stomata open.
Explain how the stomata react in darkness
Guard cells loose water and become flaccid causing the stomata to close.
What are xerophytes ?
Plant which needs very little water.
How are xerophytes adapted to their conditions ?
Rolled up leaves Thick waxy cuticle Hairy leaves Stomata pitted and grooved Reduced surface area to volume ratio.
Why do xerophytes has rolled leaves and why does this help.
Stomata end up on the lower epidermis. Moist air is trapped and this means water potential between the lower epidermis and environmental medium is reduced. This also reduces transpiration.
Why do xerophytes have a thick cuticle ?
Prevents water loss
Why do xerophytes have hairy leaves ?
Reduces water potential gradient and traps moisture of air on the surface.
Why do xerophytes have grooves and pitted stomata ?
Traps most air near the lead surface causing the water potential gradient to decrease and reduces water loss by transpiration
Why do xerophytes have a reduced surface area to volume ratio ?
Less water diffuses out - slower diffusion rate
Why do we need to breathe ?
To supply oxygen to respiring tissue.
To remove carbon dioxide from the blood stream which is a waste product kf respiration.
What happens if there is too much carbon dioxide in the blood.
Ph is lowered.
What are the adaptations of the trachea for gas exchange ?
Rings of cartilage to support and keep trachea open.
Muscle and elastic tissue keep it elastic.
Cilliated epithelial cells waft mucus up the mouth for swallowing.
Goblet cells secrete protein mucus.
What are the adaptations of the bronchus for gas exchange ?
Rings of cartilage to support and keep bronchus open.
What are the adaptations of the bronchioles for gas exchange.
Muscle and elastic fibres allow them to easily contract and relax during ventilation.
What are the adaptations of the alveoli for gas exchange ?
There are numerous alveoli which give a large surface area for gas exchange.
Thin, permeable walls for diffusion.
Extensive capillary bed to maintain diffusion gradient and ensure movement of internal medium which is the blood.
Surrounded by collagen and elastic fibres to allow stretching and sprinting back to force air out.
What is the definition of respiration ?
Process by which energy is released from molecules of glucose and ATP is synthesised. In the mitochondria.
What is the definition for ventilation ?
A sequence of breathing movements which moves air in and out of the lungs to exchange surfaces.
What is the definition for gas exchange.
Oxygen passes from the atmosphere into the blood and carbon dioxide passes out entirely by diffusion.
Outline the movement of air into the lungs.
Mouth: nasal cavity Trachea Bronchus Bronchus Alveoli
Outline the movement of air out of the lungs.
Alveoli Broncheloes Bronchus Trachea Mouth/ nasal cavity
Outline what occurs to the body when breathing in.
The diaphragm contracts meaning it lowers and flattens. This moves the rib cage up and out and increases volume of the thoracic cavity. Air pressure in the thoracic cavity is then reduced.
Atmospheric pressure outside the body is greater than that in the lunges and so air is forced in.
Outline what occurs to the body when breathing out.
The diaphragm relaxes into a raised dome shape. The ribs move down and onwards therefore decreases thoracic cavity volume.
This causes an increase in thoracic cavity pressure.
Atmospheric pressure outside the body is lower than inside the lungs so air is forced out.
What happens to the diaphragm when breathing in.
It contracts therefore lowering and flattening.
What happens to the external intercostal muscles when breathing in.
They contract moving the rib cage up and increasing thoracic cavity.
What happens to thoracic cavity volume during breathing in.
Increases as the rib cage moves up and out.
What happens to the internal intercostal muscles upon breathing in ?
They relax
What happens to thoracic cavity pressure when breathing in.
Reduced.
What happens to the diaphragm muscles when breathing our ?
They relax and raise to a dome shape.
What happens to thoracic cavity volume when breathing out.
Thoracic cavity volume decreases as the diaphragm relaxes into a dome shape.
What happens to thoracic cavity pressure when breathing out.
Increases thoracic cavity pressure.
What are COPDs and give risk factors.
Smoking
Living in areas of high air pollution
Genetics
Infection.
Outline Asthma : symptoms , causes, what is medically happening and treatment
Symptoms: Deep breathing, wheezing, tight chest, coughing. Not infectious.
Causes:
Smoke, air pollution, pollen, airway infections.
What is happening: inclination is triggered and the bronchioles contract meaning the airways and narrowed and bronchodonstriction occurs meaning that air flow in the lungs is slowed. Epithelial cells also secrete more mucus which blocks airways.
Treatment:
Inhaling bronchodilators which relax and smooth muscles so bronchioles expand and ventilation increases.
Outline Pulmonay Tuberculosis : symptoms , causes, what is medically happening and treatment
Symptoms:
Persistent coughing, chest pains, tiredness, weight loss and coughing blood.
Causes: Transmitted by aerosol drips of coughs and sneezes of those who are infected.
What is medically happening:
Bacterial multiply in the epithelial cells of the Alveoli and bronchioles and create tubercle lumps which block the airway.
What are the risk factors of lung disease ?
Smoking
Air pollution - especially in areas of heavy industry which have pollution particles and gases.
Genetic makeup - some are more likely to get COPDs.
Infections- people who frequently have chest infections are more likely to get COPDs.
Occupation- people working with harmful chemicals, gases and dusts.
