Exchange Flashcards
How do you workout the surface area of a cube?
Base x height x 6
How do you workout the volume of a cuboid?
Base x height x width
How do you workout the volume of a cylinder?
pir^2 x length
How do you workout the surface area to volume ratio?
divide surface area by volume, to :1
what does affective exchange of materials need?
A large surface area to volume ratio
what happens to the surface area to volume ratio as organisms get larger?
Launch of the organism, the smaller the ratio.
what do organisms need if they have a very small surface area to volume ratio (large organisms)?
specialised exchange surfaces. (E.g. lungs, intestines) these organisms, a multicellular and require these.
How do you work out rate of diffusion?
surface area x concentration gradient ➗ diffusion distance.
What key features do exchange surfaces need?
large surface area to volume ratio
To be very thin (diffusion path shorter)
Selectively permeable
Movement of environmental medium (maintains conc gradient)
Transport system (maintains conc gradient).
Where does exchange take place?
The surface of an organism
How is the waxy cuticle adapted for gas exchange?
This is the waxy layer of the top of the leaf, and it reduces water loss by evaporation.
How is the upper epidermis of a leaf adapted to gas exchange?
It’s a transparent layer on top of the leaf that allows light to pass through it (for photosynthesis).
how is the Palaside mesophyll of a leaf adapted to gas exchange?
It is a layer of long cylindrical walls where most photosynthesis happens.
It contains lots of chloroplasts.
how is the spongy mesophyll in a leaf adapted for gas exchange?
It is a layer of cells with air spaces between them, this is the site of gas exchange. It has a large surface area.
how is the xylem in a leaf adapted for exchange?
It transports water and mineral irons from Roots to leaves via transpiration.
how is the phloem in a leaf adapted for exchange?
It transports dissolved sugars in the plant from leaves elsewhere in the plant via translocation.
How is the lower epidermis of a leaf adapted for exchange?
it is the thin underside layer of cells, where the majority of the stomata (and guard cells) are located.
how are the stomata adapted for gas exchange?
they open and close due to changes in light intensity. There are also a large number of them.
Why are leaves being thin important for gas exchange?
Because it means there is a short diffusion distance, which makes it quicker.
how would potassium moving into guard cells cause the stomata to open?
Potassium ions, make water potential more negative than the guard cells, therefore water moves into them by osmosis.
what are xerophytes?
plants that have a restricted supply of water
name some ways that xerophytes are adapted to lack of water.
thick cuticle for less water loss
swollen stem for storing water for when water levels are low
Long and widespreading roots for water to be obtained from areas not close to the plant itself
What is the gas exchange surface in insects?
The tracheae
what is the tracheae of an insect?
an internal network of air filled tubes.
Why does the tracheae of an insect need chitin rings?
To strengthen them and prevent the car
what does the tracheae in an insect lead to?
Tracheoles, fluid filled tubes that extend to all body tissues.
What are spiracles in an insect?
pores on the body surface, valves open and close them and hairs filter out dust.
What does spiracles do?
They are the structure through which gases enter and leave the body of an insect. The valves close to prevent water loss and open to allow gas exchange.
What is the sequence of gas exchange in an insect?
oxygen in external air
Diffuse down a diffusion gradient through open spiracles
Into air filter tracheae
Into fluid filled tracheoles
Into cells by diffusion (down the diffusion gradient)
Why do insects need to be so small for gas exchange?
because the distance from external air to sells via tracheae to tracheoles needs to be short.
What does terrestrial mean?
On dry land
How do insects prevent water loss?
spiracles contain valves which can close to prevent water loss
They have waxy cuticles
Spiracles have hairs to help trap humid air reducing the concentration gradient of water vapour.
Small external surface area to volume ratio
what is the comparison of oxygen in water than air?
1% to 20%
Why could water not be able to move in and out of the lungs?
It’s too dense and too much energy is required to expel it
what are gills?
The gas exchange organ in fish
where are gills located?
The opercular cavity, which is covered by the operculum (Gill flap)
what is the operculum?
The gill flap located in the opercular cavity
how many gills do fish have?
Four pairs on each side of the head
what protects the gills of fish?
operculum
what does the inside of each gill consist of?
fleshy, threadlike, filaments
what are the filament of a gill closely spaced along?
A gill arch
what is the name of the tiny extensions on the filaments in a gill?
lamellae
What flows through the lamellae?
Blood
what gases are exchanged in the gills?
Oxygen in and CO2 out
where is the site of gas exchange in fish gills?
The lamellae
how are fish adapted to gas exchange through short diffusion distance?
The epithelial wall of the lamella is only one cell thick.
How are fish adapted for gas exchange through a large surface area to volume ratio?
each girl arch of thousands of Gill filaments. Gill filaments are covered in many lamellae.
how to fish gills maintain a concentration gradient?
The gills are constantly ventilated. This ensures freshwater is moving over the gills with a higher oxygen concentration in the blood. Counter current flow also plays a role in this.
What is the process of water moving into a fish?
mouth opens on the floor of the buccal (mouth) cavity is lowered.
Volume of buccal cavity increases.
Pressure in the buccal cavity decreases.
Water moves in.
After water has moved into the fish, what is the process of water being forced out the gills?
The mouth closes on the floor of the buccal cavity is raised. The operculum closes.
Volume of the cavity decreases.
Pressure in the cavity increases
Water is forced over the gills.
what is the mechanism fish need to be able to breathe in enough oxygen?
Counter current mechanism.
What is the counter current flow?
The mechanism fish need to be able to take in enough oxygen. It means that as water flows between the lamellae, it meets blood flowing in the opposite direction.
Why would a parallel flow not work in fish?
Because the diffusion gradient is not maintained. Equilibrium is reached by halfway. This means diffusion can only occur in half of the lamellae.
how does the counter current flow work?
The blood already has a high oxygen concentration, however water has a slightly higher concentration. this means equilibrium is never reached and the diffusion gradient is maintained. Diffusion occurs across the whole of the lamellae.
Where does gas exchange take place in humans?
The lungs
Where are the lungs found?
In the thorax, above the abdominal cavity
what is separates the thorax and abdomen?
The diaphragm
What are the lungs protected by?
Ribs
what is the only entrance to the thoracic cavity?
The trachea
what is the entrance to the trachea called?
The larynx
what are the bronchi?
The two divisions of the trachea that lead to bronchioles. They can produce mucus and have cilia. they are supported by rings of cartilage.
What are bronchioles?
branching subdivisions of the bronchi. The walls are made of muscle and are lined with ciliated epithelial what cells. They lead to the alveoli.
What are the alveoli?
Air sacs at the end of bronchioles. Between each air sack there are collagen and elastic fibres. They are the site of gas exchange.
What are the lungs?
A pair of lobed structures made of a series of highly branched tubules, the organ for gas exchange in humans.
What is the role of the cartilage in the trachea?
Provide support and flexibility, it stops it from collapsing.
Which cells in the lungs produce mucus?
Goblet cells
what is the function of mucus?
Traps pathogens, dust, or dirt
what is the role of ciliated epithelial cells?
wafts mucus or dirt out up the trachea.
what is the role of elastic fibres between the alveoli?
Allows alveoli to stretch and then recoil during pushing air out.
what is the role of collagen in the alveoli?
it supports the structure of the lungs, holds alveoli together and limits how much they can expand.
what is the role of muscles in the bronchioles?
they contract to make airways smaller, avoid things entering. Or larger to get as much air as possible.
what does passive mean?
This means something does not require energy.
is inspiration, an active or passive process?
An active process. It uses energy.
Is expiration an active or passive process?
Passive it does not require energy.
What is the process of inspiration in humans?
External intercostal muscles contract
Ribs are pulled upwards and outwards
Diaphragm muscle contracts and flattens
Volume of thorax increases
Pressure of thorax decreases
Atmospheric air pressure is higher than pulmonary pressure
Moves into the lungs
what is the process of expiration in humans?
External intercostal muscles relax
Ribs are pulled inwards and downwards
Diaphragm muscle relaxes and goes back to previous shape (dome)
Volume of thorax decreases
pressure of thorax increases
Atmospheric pressure is lower than that of the pulmonary pressure
Air moves out the lungs
Is forced exploration passive or active?
Active.
When is forced exploration necessary?
During times of exercise or activity
which intercostal muscles move during forced expiration?
internal intercostal muscles contract
what is different in the processes of expiration and forced expiration?
with forced expiration, as the external intercostal muscles relax, internal intercostal muscles contract, and the rest of the process is more rapid.
what is a spirometer?
Is a machine that can measure the volume of air breathed in and out of the lungs.
What graph do you get from a spirometer?
Spirogram
What is the tidal volume?
The name given to the volume of air, breathed in and out in a normal breath.
what is the inspiratory reserve volume?
The name given to the extra air breathed in during a deep breath
what is the expiratory reserve volume?
The name given to the extra air breathed out during a forced expiration
What is the residual volume?
The name given to the air left in the lungs after forced expiration
What is the inspiratory capacity?
tidal volume + inspiratory reserve volume
What is the vital capacity?
tidal volume + IRV + ERV
What factors affect rate of transpiration?
Windspeed, light intensity, humidity, temperature
Is the phloem a tissue or an organ?
Tissue
What is translocation?
The process of the phloem transporting sugar up and down the plant.
Does the phloem and the xylem have end walls?
The phloem does, but the xylem does not
What is the phloem made up of?
Sieve tubes, companion cells (to keep the sieve tubes alive, as they respire)
How does the sieve tubes connect to the companion cell?
Through pores in the side wall
Where is the source and the sink in translocation?
The source is typically the leaf (as these compounds are produced in photosynthesis)
And the sink is usually a growing shoot or tip or a storage organ.
Describe mass flow hypothesis for translocation?
Sugars is actively transported into phloem
By companion cells
Low water potential of sieve tube and water enters by osmosis
This increase in hydrostatic pressure causes mass movement
Sugars are then moved to route or shoot or storage for respiration.
