Exchange And Transpor Flashcards
What surface area to volume ratio do single cell organisms have?
a high SA:V ratio which allows for the exchange of substances to occur via simple diffusion
The large surface area allows for maximum absorption of nutrients and gases and secretion of waste products
The small volume means the diffusion distance to all organelles is short
As organisms increase in size, what happens to their surface area to volume ratio?
their SA:V ratio decreases
There is less surface area for the absorption of nutrients and gases and secretion of waste products
The greater volume results in a longer diffusion distance to the cells and tissues of the organism
Why is oxygen required for specialised systems for gas exchange?
Supply of Oxygen:
Organisms require ATP in order to carry out the biochemical processes required for survival. The majority of ATP is produced through aerobic respiration which requires oxygen
Why is the removal of carbon dioxide needed for specialised systems gas exchange
Removal of Carbon Dioxide:
Carbon dioxide is a toxic waste product of aerobic respiration
If it accumulates in cells/tissues it alters the pH
Why is diffusion a viable transport mechanism for single-celled organisms but not for larger multicellular organisms
The time taken for oxygen to diffuse from the cell-surface membrane to the tissues would be too long
Body mass affecting metabolic rate
Experiments conducted by scientists have shown that the greater the mass of an organism, the higher the metabolic rate
Therefore, a single rhino consumes more oxygen within a given period of time compared to a single mouse
SA:V Ratio affecting metabolism
Although metabolic rate increases with body mass the BMR per unit of body mass is higher in smaller animals than in larger animals
Smaller animals have a greater SA:V ratio so they lose more heat, meaning they have to use up more energy to maintain their body temperature
What is metabolic rate
The metabolic rate of an organism is the amount of energy expended by that organism within a given period of time
What is the basal metabolic rate
The basal metabolic rate (BMR) is the metabolic rate of an organism when at rest. The BMR is significantly lower than when an organism is actively moving
How can the metabolic rate of an organism be measured
The metabolic rate of an organism can be measured/estimate using different methods:
Oxygen consumption
Carbon dioxide production
Heat production
What features that organism surfaces have that make them effective exchange surfaces have
A large surface area
Short diffusion distance
Concentration gradient (maintained)
What does all trachael insect systems contain
All insects possess a rigid exoskeleton with a waxy coating that is impermeable to gases
Insects have evolved a breathing system that delivers oxygen directly to all the organs and tissues of their bodies
What is a spiracle
A spiracle is an round valve like openings in the exoskeleton running along length of abdomen
It allows air to enter the insect and flow into the system of tracheae. The trachea attatch to these openings.
Most of the time, the spiracle is closed to reduce water loss
What are the trachea
Tracheae are a network of internal tubes within the insect breathing system which lead to tracheoles (narrower tubes)
The walls of trachaea are reinforced with spirals of chitin. This prevents the trachaea from collapsing when the insect moves.
The tracheae walls have reinforcement that keeps them open as the air pressure inside them fluctuates
Where do the tracheoles go?
A large number of tracheoles run between cells and into the muscle fibres - the site of gas exchange
For smaller insects, this system provides sufficient oxygen via diffusion
How is a concentration gradient created in insects?
A concentration gradient is created as oxygen is used by respiring tissues allowing more to move in through the spiracles by diffusion
Carbon dioxide produced by the respiring tissues moves out through the spiracles down a concentration gradient
How do insects create a mass flow of air into the tracheal system
flying insects need a more rapid supply/intake of oxygen.
They create a mass flow of air into the tracheal system by:
Closing the spiracles
Using muscles to create a pumping movement for ventilation
What happens during flight in an insect
During flight, the production of lactate in the respiring muscles, lowers the water potential of muscle cells
water found at the narrow ends of the tracheoles is then drawn into the respiring muscle by osmosis
This allows gases to diffuse across more quickly
Structure of fish gills in bony fish
Series of gills on each side of the head
Each gill arch is attached to two stacks of filaments
On the surface of each filament, there are rows of lamellae
The lamellae surface consists of a single layer of flattened cells that cover a vast network of capillaries
Explain the mechanism of the structure of bony fish
The capillary system within the lamellae ensures that the blood flow is in the opposite direction to the flow of water - it is a counter-current system
The counter-current system ensures the concentration gradient is maintained along the whole length of the capillary
The water with the lowest oxygen concentration is found adjacent to the most deoxygenated blood
Structure of a leaf:
Waterproof cuticle
Upper epidermis - layer of tightly packed cells
Palisade mesophyll layer - layer of elongated cells containing chloroplasts
Spongy mesophyll layer - layer of cells that contains an extensive network of air spaces
Stomata - pores (usually) on the underside of the leaf which allow air to enter
Guard cells - pairs of cells that control the opening and closing of the stomata
Lower epidermis - layer of tightly packed cells
Mechanism of the structure of the leaf
When the guard cells are turgid (full of water) the stoma remains open allowing air to enter the leaf
The air spaces within the spongy mesophyll layer allows carbon dioxide to rapidly diffuse into cells
The carbon dioxide is quickly used up in photosynthesis by cells containing chloroplasts - maintaining the concentration gradient
No active ventilation is required as the thinness of the plant tissues and the presence of stomata helps to create a short diffusion pathway
Why is the exchange of gases from the atmosphere essential for the survival of organisms
Oxygen is required for respiration
Carbon dioxide is required for photosynthesis
What range of vital functions within organisms does water have
It is a solvent that facilitates the transport of essential nutrients
Extreme water loss can lead to death
It is a solvent that facilitates the transport of essential nutrients
Extreme water loss can lead to death
What do terrestrial insects have that prevents water loss
The waterproof waxy coating of the exoskeleton makes gas exchange by diffusion very difficult (lipid layer)
Spiracle are openings in the exoskeleton of insects that are connected to the tracheal system can open and close to reduce water loss.
Insects have a small surface area to volume ratio where water can evaporate from.
Why are xerophytic plants vulnerable to water loss
Plants that live in conditions with a plentiful supply of freshwater have leaves with a short diffusion distance through the stomata and a large surface area provided by the air spaces in the spongy mesophyll
What adaptations do xerophytic plants have
adaptations to conserve water:
Very few stomata
Sunken stomata
Hairs surrounding stomata
Needle-shaped or small leaves
Waxy cuticle
Characteristics of cacti
Their leaves have become spines that can no longer photosynthesise
Photosynthesis occurs in the green stem which possesses chloroplasts
The stem has a thick cuticle and is very large in diameter which allows it to store water
There are both shallow and deep penetrating roots which allow it to access all available water
Marram Grass sand dune grass adaptions
Leaves can roll up to reduce the exposure of surfaces to the wind
The rolling of the leaf provides deep grooves which protect the stomata
The exposed surface has no stomata and a thick cuticle
The inner surface of the leaf possesses a large number of hairs
What is the exoskeleton
Insects are covered with a protective exoskeleton that is made of the polysaccharide chitin.
It is made of hard fibrous material for protection and a lipid layer to prevent water loss.
Gasses such as oxygen and carbon dioxide cannot easily pass through the exoskeleton.
How do trachaeoles help diffusion
The narrow diameter allow the tubes to be extremely close to cells.
there is a very short diffusion distance for gases moving between the cells and the tracheoles.
This oxygen is needed for aerobic respiration which produces carbon dioxide. The short diffusion distance also allows the carbon dioxide to rapidly diffuse back into the air in the tracheoles.
The huge number of tracheoles provides a very large surface area for gas exchange this allows insects to maintain a very rapid rate of aerobic respiration
What does trachael fluid do
During activity, cells around tracheoles undergo anaroboic respiration. This produces lactic acid which lowers the water potential of the cells. This causes tracheal fluid to move into cells. This reduces the volume of tracheal fluid drawing air down into the tracheoles.
This also means that more tracheole surface is available for diffusion of oxygen and carbon dioxide.
What are the trachaeols
Extending from the tracheae are very fine tubes called tracheoles. They have a diameter of 1micrometer or less. Each tracheole is a single cell that has extended to form a hollow tube. A huge number of tracheoles extend between the cells of the insects body. They are not supported by chitin.
How is gas exchange a passive process in insects
Oxygen diffuses down its concentration gradient from the high concentration in external air to the low concentration in the tracheoles.
Carbon dioxide diffuses down. Its concentration gradient from high concentration in the tracheoles to a low concentration in external air.
How is water loss reduced in insects
The walls of the tracheoles are moist an the ends of the tracheoles contain trachael fluid.
This means that water vapour can diffuse out of the insect via the spiracles. But each spiracle is surrounded by a muscular sphincter. This means that insects can reduce water loss by closing their spiracles.
What is the structure of the fish gills
They consist of several bony gill arches
Extending from each gill are a large number of gill filaments. Many gill filamets extend from each gill arch.
Gill filaments are also covered with numerous gill lamellae —> this is where gas exchange takes place.
Water flows between the gill lamellae, oxygen diffuses from the water into the bloodstream.
They have many adaptations for efficient diffusion of gases.
What are the adaptions of gill lamellae
They have a large surface area to volume ratio for gasses to diffuse over.
They have a very short diffusion distance through the walls of the lamellae
They also have an extensive network of blood capillaries.
Once oxygen diffuses into the blood it is carried away, meaning a steep concentration gradient is maintained for oxygen.
Counter current flow
Blood with a low concentration of oxygen passes into the capillaries of the gill lamellae
Oxygen diffuses into the blood. This oxygen rich blood now passes out of the gill lamellae abd leaves the gills.
The flow of blood is in the OPPOSITE direction to the flow of water.
This is an advantage because it maintains a steep concentration throughout entire length of lamellae gradient for oxygen
Paralell flow vs opposite
Paralell flow —> initially there is a high rate of diffusion of oxygen from the water into the bloodstream. However after a short distance, the concentrations hit equilibrium. At this point diffusion stops. Meaning no more than 50% of the available oxygen in the water can diffuse into the blood.
Opposite flow —> there is always a concentration gradient for oxygen meaning equilibrium is never reached. Meaning diffusion of oxygen takes place right across the length of the lamellae . Therefore up to 80% of the oxygen in the water can diffuse into the bloodstream.
What are the two methords of moving gases in the tracheal system
- Gas can exchange by diffusion as when cells respire they use up oxygen and produce carbon dioxide creating a concentration gradient from the tracheoles to the atmosphere.
- Mass transport.-an insect contracts and relaxes their abdominal muscles to move gases on mass.
How is anaerobic respiration a method of moving gases in the tracheal system?
When the insect is in the muscle cells start to respire anaerobically to produce lactate. This lowers the water potential of cells and therefore water moves from the tracks into the cells by osmosis. This decreases the volume of the tracks and more air from the atmosphere is drawn in.
Why do fish require a gas exchange surface
Fish are waterproof
They have a small surface area to volume ratio.
Fish gill anatomy
- four layers of gills
- gills are made up of stacks of gill filament
- each filament is covered in gill lamellae (which creates a large surface area)
How are fish gills adapted for efficient gas exchange
- large surface area to volume ratio - created by many gill filaments covered in many gill lamellae
- short diffusion distance - due to a capillary network in every lamellae and very thin gill lamellae
- maintaining conc gradient - countercurrent flow mechanism
How do humans ventilate
By using their
Diaphragm
And antagonistic interaction between the external and internal intercostal muscles
(One muscle relaxing while the other one is contracting)
What happens during inspiration in human gas exchange system
Thoracic cavity expands and rib cage
External intercostal muscles contract
Diaphragm contracts
Thoracic cavity volume increases causing air in lungs to decrease
Expiration
Thoracic cavity reduces
Rib cage moves down and in
External intercostal muscles relax
The diaphragm relaxes
Thoracic cavity volume decreases causing air pressure to increase
Air forced out the lungs
The alveolar epithelium
Once gas is in alveoli, it exchanges between epithelium and the blood
Alvioli are tiny air sacks that create a large surface area for gas exchange
The alveoli epithelium cells are very thin to minimise diffusion distance.
Each alveolus is surrounded by a network of capilaries to remove exchanged gases and therefore maintains a concentration gradient
Structure and Adaptations of capilaries
The lining of the alveolus is composed of fkattened epithelial cells
- surrounded by collagen and elastic tissure which allows stretching for breathing
- surrounded by a dense capilary network
- thin walls of one cell thick containing elastic and collagen
- has a very rich blood supply
What is the trachea
A tube which is supported by C shape rings of cartilege which prevents kinking
It contains smooth muscle and elastic tissue which allows for reconstriction and recoiling
What are the two types of cells lining the trachea
Goblet cells - which secrete mucus
Epithelial cells - which waft the mucus containing dust and bacteria up to the trachea
Comparing bronchi to bronchioles
Bronchi have a similar structure to the trachea
Whereas
Bronchiols have no cartilege pr ciliated epithelial cells.
But they do contract to controll air movement because they contain a ring of muscle
Structure of lungs
Each lung is surrounded by a double membrane called the plueral membrane
The space between the membrane is called the plueral cavity
What is the plueral fluid
The fluid lubricates the lungs. It also adheres to the outer walls of lungs to theoratic chest cavity by water cohesion
So lungs expand with the chest while breathing.
Gas exchange in the stomata
Oxygen diffuses out of the stomata
Carbon dioxide diffuses in through the stomata
To reduce water loss by evapouration,
Stoma opening = guard cells swollen
What are xerophytic plants
Plants that are adapted to survive in environments with limiting water
How does the adaptation - small surface areal- in xerophytes work
Less area for evapouration fewer gaps in leaves
Eg conifer needles, cactus spines
How does the adaptation - sunken stomata and stomatal hairs - in xerophytes work
Both maintain humid air around the stomata
How does the adaptation - low stomata density and stomata on lower surface of the leaf only - in xerophytes work
- Fewer gaps in leaves
- More humid air on lower surface so less evapouration
How does the adaptation - thick cuticle and sheddin leaves in dry cold season - in xerophytes work
- Stops uncontrolled evapouration
- Reduce water loss at certain times of year
How does the adaptation - folded leaves, succulent leaves and extensive roots- in xerophytes work
- Maintains humid air around stomata
- Stores water
- Maximise water uptake
How is gas exchange similar in leaf and insects?
- Short difusion distance
- both stomata and spiricles are external
- both are responsible for water loss and controll it
How is gas exchange different between leaves and insects
- insects create mass air flow to assist gas exchnage
- plants have a larger sa to vol
- plants interchange gases for respiration and photosynthesis
What are dicotylendonus plants
Plant exchange gas through surface of mesophyll cells in their leaves
Adaptations of dicotyledonus plants
-large surface area to ensure maximum diffusion of gases
Smart which are special pauses in the epidermis which can open and closed due to exchange of gases
Guard sells control opening and closing of the stomata
What happoens when carbon dioxide levels in plants get low.
Guard cells gain water and become turgid. They curve out opening stomata and allowing gas in and out
What happoens when carbon dioxide levels in plants get high.
Guard cells lose water becoming flacid and closing stomatal pore preventing water loss
Adaptation of mesophytes
Plants adapted to habitats with adequate water
What are halophytes
Salty water plants
Hydrophytes
Fresh water plant
What is an epithelial cell
- refer to any type of animal cells that cover the surfaces or line a cavity performing secreting, transporting or regulatory functions
- line both internal and external surface of the body
- either single or several cell layers
What is an endothelial cell
- a type of epithelial cell that like the cavities of the circulatory system
- line the internal surface of the components of the circulatory system
- consist of single squamous epithelial cells.
- provides slipery nonsticky surfaces for the flow of fluids is the main function
Describe pathway taken by oxygen from alveoli into blood
Across the alveolar epithelium
To the endo/epithelium of capilary
What is the pulmonary ventilation rate?
Total volume of air that is moved in the lungs during one minute
What is the tidal volume?
The volume of air taken in at each breath at rest
What is the ventilation rate?
The number of breaths taken in one minute
What is the inspiratory capacity?
Maximum possible volume inhaled after a relaxed exhalatiom
Expiratory capacity
Maximum possible volume exhaled after a relaxed inhalation
Total lung volume
Total volume of air the lungs holds after a maximum inhalation
Vital capacity
The maximum volume of air that can be exiled after a maximum inhalation
Describe and explain one feature of the alveoli that makes it a well adapted surface for gas exchange
- one cell thick
- reduces diffusion pathway
- permeable
- allows diffusion of o2 and co2
Suggest and explain how a reduced tidal volume affects the exchange of carbon dioxide between the blood and the alveoli
More carbon dioxide remains (in lung);
(So) reduced diffusion/concentration gradient (between blood and
alveoli);
More carbon dioxide stays in blood;
Explain how the counter current principle allows efficient oxygen uptake in the fish gas exchange system
Blood and water flow in opposite directions
Diffusion gradient mainatined along length of lamella/filament
Describe and explain the mechanism that causes lunsg to fill with air
Diaphragm muscle contracts and external intercostal muscles contract
Causes volume to increase and pressure to decrease
The air moves down a pressure gradient
Explain why death of alveolar cells reduce gas exchange in human lungs
Reduced surface area
Increased distance for diffusion
Reduced rate of gas exchange
Describe and explain the advantage of the counter current principle in gas exchanged
Flow in opposite directions
Equilibrium never reached
Maintained a conc gradient
Gas exchange is constant
Why do plants that grow in soil with very little water grow only slowly
The stomata close
Less carbon dioxide uptake for less photosynthesis/glucose production
Describe the pathway taken by an oxygen olecule from an alveolus to the blood
Across alveolar epithelium;
Endothelium / epithelium of capillary;
Explain how one feature of an alveolus allows efficient gas exchange to occur
The alveolar epithelium is one cell thick
Creating a short diffusion pathway taken/ reduces the diffusion distance
Describe structure of human gas exchange system and how we breathe in and out
Trachea, bronchi, bronchioles, alveoli
Breathing in - diaphragm contracts and intercostal muscles contract
Thoratic cavity volume decreases
Breathing out - diaphragm relaxes and intercostal mucles too
Increased pressure in thoratic cavity causes air to move out
Explain 3 wways an insects tracheal system is adapted for efficient gas exchange
- tracheoles have thin walls so short diffusion distance to cells
- large number of tracheoles so large sa for gas exchaneg
-tracheal fluid moves out into tissues during excercise so fasteer and larger surface area for gas exchange
- muscles pump like a ventilator tomaintain diffusion gradient.
Explain two ways in which the structure of fish gills is adapted for effiecient gas exchange
Many lamellae so large surface area
Thin surface so short diffusion pathway
Explain advantage for larger animals of having specialised systems that faciliattes oxygen uptake
Larger organisisms have a smaller surface area to vol ratio
So overcomes a long diffusion pathway
For faster diffusion
Why is metabolic rate faster in a mouse thsn it is in a horse
Mouse
Smaller so larger surface areas of volume ratio
Faster heat loss
Faster rate of respiration/metabolism releases heat
Describe relationship between size and surface area to volume ratio
A size increases surface area to volume decreases
Explain why oxygen uptake is a measure of metabolic rate
Oxygen used in respiration which provides energy ATP
Which is a metabolic process chemical reaction
