exchanging materials Flashcards
for many single celled organisms like plankton, amoeba and bacteria, diffusion,osmosis and active transport are all that is needed to exchange materials with their environment … why?
because they have a relatively large surface area compared to the volume of the cell. (this allows sufficient transport of molecules into and out of the cell to meet the needs of the organism).
S. A. to volume ration very important. It makes a big difference to the way animals can exchange substances with their ..
environment.
S A is also important when you consider …
- how energy is transferred by living organisms, and
2. how water evaporates from the surface of plants and animals.
the ratio of SA to volume falls as objects get bigger. Bigger organisms (smaller SA to volume ratio) have to transport molecules …
further.
In a small object, the surface area to volume ratio is relatively large. this means that …
diffusion distances are short and that simple diffusion is sufficient for the exchange of materials.
As organisms get bigger the surface area to volume ratio falls. The distances between the center of the organism and the surface get …
bigger.
When the distances between the center of the organism and the surface get bigger happens simple diffusion is no longer enough to …
exchange materials between the cells and the environment.
what substances can no longer reach every cell inside the organism by simple diffusion?
Gases and food molecules
what cannot be removed fast enough to avoid poisoning the cells?
metabolic waste
In many larger organisms there are …
special surfaces where the exchange of materials take place. The surfaces are adapted to be as effective as possible.
These special surfaces can be found where?
In humans, in other animals and in plants.
To make the process of exchange more efficient ..
there are various adaptations.
Name four ways in which the effectiveness of an exchange surface can be increased. (Adaptations)
- having a large surface area over which exchange can take place.
2 having a thin membrane or epithelium or being thin to provide a short diffusion path (reduces the travel distance) - Exchange surfaces will have an efficient blood supply. this moves the diffusing substances away from the exchange surfaces and maintains a steep concentration (diffusion) gradient.
- being ventilated makes gas exchange more efficient by maintaining steep concentration gradients.
Exchange surfaces usually have a …
large Surface area and thin walls which provide short diffusion pathways.
Different organisms have different …
adaptations for the exchange of materials.
How does the Australian Fitzroy river turtle ‘breathe’ underwater.
Inside the rear opening are two large sacs lined with finger like folds which provide a large surface area and rich blood supply for gas exchange. Water is pumped in and out, ventilating the folds and maintaining a steep concentration gradient for gas exchange.
the human SA to volume ratio is very ..
low
The cells inside a human cannot get the ..
food and oxygen the need, or get rid of the waste they produce by simple diffusion.
air is moved into and out of your lungs when you breathe. What does this do?
Ventilates the millions of tiny air sacs called alveoli.
The alveoli have … (2 things)
- an enormous SA and 2.a very rich blood supply, for effective gas exchange.
The villi of the small intestine also provides …
a large SA, short diffusion paths and a rich blood supply to make exchange of materials more effective.
What do fish need to do?
Exchange oxygen and carbon dioxide between their blood and the water in which they swim.
How does this happen?
Across the gills.
What are the gills made up of?
Stacks of thin filaments, each with a rich blood supply.
