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Flashcards in Exchanging of substances/Processes Deck (23):

What are the 3 ways of transferring substances

Active Transport


What does Osmosis transport and which way does it go?

It transports water only through a partially permeable membrane
from a high region of water to a region of low concentration of water


What does Diffusion transport and which way does it go?

Transports substances/particles from an area of high concentration to an area of low concentration


What does Active Transport transport which way does it go?

It moves substances such as minerals and vitamins from a low concentration to a high concentration (requires energy)


How can you make diffusion happen faster?

By having a larger difference in concentration
or having a higher temperature will have give particles more energy so they move around faster
or by having a larger surface area of the membrane


Define diffusion

It is the spreading out of particles from an area of high concentration to an area of low concentration, through a cell membrane


What types of molecules can diffuse in and out of a cell?

small molecules like oxygen, glucose, amino acids and water, unlike larger particles such as starch and proteins


Define Osmosis

Osmosis is the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration


if there is a strong sugar solution on one side of membrane and pure water on the other describe what will happen

The strong sugar solution will become more dilute and there will be less water molecules on the pure water side but no sugar would've moved into the pure water side as the sugar molecules are too big


What experiment can you do to show osmosis working?

cut up potato into identical cylinders, get some beakers with different sugar solution concentrations in them. One very concentrated sugar solution the other pure water. you may have others inbetween

measure the mass of the cylinders, then leave one cylinder in each beaker of solution for 24 hours

take them out dry with a paper towel and weigh again

the potato with pure water shouldve not changed mass by very much as the water levels inside potato and outside are very similar, while in the concentrated sugar solution water shouldve been drawn out of the potato so the potato shouldve lost mass


What is the definition for active transport?

the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.


Where and when do we use active transport?

for example in plants there is often more water and mineral ions in the root hairs of the plant than in the soil so we need to use active transport to move those molecules across the cell membrane

we would use it in root hair cells in plants
and in the gut as there is less nutrients in the gut than in the blood. But diffusion is then used if this is not the case


Why are root hair cells adapted to absorbing nutrients and water

They are covered in many small hairs that help give it a larger surface area so the rate of exchange can happen faster


What small organs are in the lungs to help them with rapid gas exchange?

they have lots of small air sacs called alveoli to transfer oxygen into the blood stream and remove waste carbon dioxide


How are alveoli specialised for their job in the lungs?

The diffusion rate is maximised by the:
large surface area
moist lining for dissolving gases
very thin walls
a good blood supply


What is inside the small intestine that help speed up that rate of absorption for digested food?



How do Villi speed up the rate of absorption in the small intestine?

They increase the surface area so faster absorbtion into the blood
They have a thin layer (1 cell thick) so substances can travel between the blood and the intestine faster
They also have a very good blood supply so absorption happens faster


Why do cell use diffusion?

To get rid of waste products in the cell (CO2) and to take in substances they need (O2)


How do you work out surface area to volume ratio?

work out the volume of the animal or thing by representing as a block
add the area of the surface (top and bottom)
add the area of the surface on the sides (all 4 sides)
Then get the volume by multiplying length width and height
put the surface area on one side and volume on the other and try to cancel down if you can


What are exchange surfaces and why do we need them in multi-cellular organisms?

As multi-cellular organisms tend to have a smaller surface area to volume ratio. So not enough substances can diffuse from their outside surface to supply their entire volume. As a result we have exchange surfaces so we can have enough substances pass in and out

An exchange surface is apart of an organ or surface that has been adapted to allow maximum transport of substances


How are exchange surfaces adapted to maximise their effectiveness

They have thin membranes-substances only have to travel a short way to diffuse

They have large surface area-lots or substances can diffuse at once

They have rich blood supply (animals only)-so substances can get in and out of blood quickly

Gas exchange surfaces are also usually ventilated-so air moves in and out


How are leaves adapted to allow gases diffuse in and out?

CO2 diffuses into air spaces in the leaves

Under neath the leaf there is an exchange surface called stomata and the CO2 goes through the stomata

Oxygen and water vapour also diffuse out through the stomata

Size of the stomata is controlled by the guard cells, they close if the plant is losing too much water

The leaf is flat so the leaf increases in the area or the exchange surface.

The walls of the cells inside the leaf act as another exchange surface. The air spaces inside the leaf increase the area of this surface so there's more chance for CO2 to get into the cells

The water vapour evaporates from the cells inside the leaf. Then it escapes by diffusion there's a lot of it inside the leaf and less of it outside


How do gills work and what allows them to do this?

Gills have a large surface area for gas exchange

Water enters the mouth and passes out through the gills. Oxygen diffuses as this happens from the water into the blood in the gills and CO2 diffuses from the blood into the water

Each gill is made of lots of thin plates called gill filaments, which give a big surface area for exchange of gases

Gill filaments are covered in lots of tiny structures called lamellae, which increase the surface area even more

lamellae have lots of blood capillaries to speed up rate of diffusion

The have a thin surface layer of cells to minimise the distance that the gases have to diffuse

Blood flows through the lamellae in one direction and water flows over in the opposite direction. This maintains a large concentration gradient between the water and the blood

The concentration of oxygen in the water is always higher than that in the blood, so as much oxygen as possible diffuses from the water into the blood