Exchange and Transport in Animals Flashcards
How does oxygen and carbon dioxide move between cells?
By diffusion.
How is water taken up by the cells?
By osmosis.
What organisms diffuse along with water?
Dissolved food molecules and Mineral ions.
What is Urea?
A waste product produced by animals from proteins which diffuses from cells to the blood plasma for removal from the body by the kidneys.
What is the surface area to volume ratio (SA : V)?
How big its surface area is compared to its volume.
The larger an organism is…
the smaller its surface area is compared to its volume.
How do you calculate surface area to volume ratio?
Calculate the surface area
Calculate the volume
Divide both the surface area and the volume by number of the volume to get N : 1.
What does it mean if an organism has a high surface area to volume ratio? (Single-celled organisms)
It is tiny, can rely on diffusion across their surface to exchange everything they need.
What does it mean if an organism has a low surface area to volume ratio? (Multicellular organisms)
It is big, can’t rely on diffusion. So they need Specialised exchange surfaces to increase their surface area to volume ratio.
What happens to the distance that molecules would have to diffuse to get from the outside of their body to the inside of their body?
Increases massively. Meaning diffusion will be slower
Exchange systems…
get substances in and out of their bodies.
Transport systems…
transport those substances to the parts of their bodies that need them.
What is the job of the lungs?
to transfer oxygen to the blood and to remove waste carbon dioxide from it.
How does the lungs do its job?
Contain millions of little air sacs called alveoli where gas exchange takes place.
What happens with blood arriving at the alveoli?
Just returned to the lungs from the rest of the body, so it contains a lot of CO2 and not much O2. Maximises the concentration gradient for diffusion in both gases.
What does concentration gradient mean?
Difference in concentration.
Substances diffuse faster if…
Theres a big difference in concentration between the area they are diffusing from and the area they are diffusing to.
Where does O2 diffuse out of and into?
Out of the air, in the alveoli and into the blood.
Where does CO2 diffuse?
In the opposite direction to O2 to be breathed out.
How are the Alveoli adapted for efficient gas exchange?
Moist lining - for dissolving gases.
A good blood supply - to maintain the concentration gradients of O2 and CO2.
Very thin walls - minimising the distance that gases have to move.
An enormous surface area.
What is the job of red blood cells?
To carry oxygen from the lungs to all the cells in the body.
Why do red blood cells have bio concave disc shape?
To give a large surface area for absorbing oxygen.
Why do red blood cells not have a nucleus?
To allow more space for more oxygen to be carried.
What is haemoglobin?
A red pigment, which contains iron. In the lungs haemoglobin binds with oxygen to become oxyhaemoglobin. In body tissues the opposite happens.