Topic 1b Transport In Cells Flashcards
What is diffusion
Diffusion is the movement of particles from an area of high concentration to an area of low concentration
Name the 4 particles that can diffuse through a cell membrane and explain why this is
Small molecules can diffuse through cell membranes
- oxeygen
- glucose
- amino acids
- water
Give an example of molecules that cannot diffuse through cell embranes and explain why
Starch and protein
They are to large to permiate the cell membrane
What three things can affect the rate of diffusion in a cell and why
(The concentration gradient)
- this is the difference in concentration of particles between the inside of the cell and outside of the cell. The bigger the visible difference between the amount of molecules inside and outside the cell the faster the rate of diffusion will be
(The temperature)
- higher the temp the faster the rate of diffusion due to the particles having more energy so they move around faster
(The surface area)
- the larger the surface area the more area particles have to pass through at one given time
What is osmosis
Osmosis is the movement of water across a partially permiable membrane from a high water concentration to a region of lower water concentration
If a cell is short of water where will the net movement occur
If the cell is short of water the solution inside the cell will be quit concentrated therefore the solution outside of the cell will be more dilute.
- the net movement of water in this case will be into the cell as the cell is short of water
What is active transport
Active transport is the movement of particles against a concentration gradient from an area of lower concentration to an area of higher concentration using energy transfered during respiration
It can be used to move substances in and out of cells
True or false active transport allows cells to absorb ions from very dilute substances
True
Explain why root hair cells use active transport to take minerals up from the soil
Because there is usually a higher concentration of minerals in the root hair cells than the soil. Therefore active transport is used to take up the minerals against the concentration gradient
Why do plants need to take up minerals and ions
Essential for plant health and growth
Name one molecule that is taken up by active transport in the gut
Glucose
Explain how active transport works in the gut
Active transport allows glucose and amino acids to be taken from the gut into the blood even though there is a higher concentration of glucose in the blood than the gut (the movement of nutrients is against the concentration gradient).
Glucose can then be to cells where it is used for respiration.
What is the concentration gradient
The difference in concentration of particles between the inside of a cell and the outside of a cell.
The bigger the difference in particles the faster the rate of diffusion will be
What is a solute
A solute is a dissolved substance
Name the three ways in which substances move in and out of a cell
Diffusion - oxeygen and carbon dioxide are transfered between cells and the environment using diffusion during gas exchange
Active transport
Osmosis
Give 2 ways in which dissolved substances can move into and out of a cell
Diffusion and active transport
Give three ways in which exchange surfaces in animals may be adapted for effective exchange
- They have a short diffusion pathway/thin membrane so substances only have to travel a short distance in order to diffuse
- They have a large surface area so lots of substances can diffuse at once
- Exchange surfaces in animals have lots of blood vessels to get substances into and out of the blood quickly
- Gas exchange surfaces in animals are often ventilated too so air moves in and out
Suggest and explain two features that an earthworm’s skin may have to make it effective as a gas exchange surface
Any of the adaptations
- So the worm may have lots of blood vessels in its skin to get gases in and out quickly
- It may have a large surface area so a lot of substance can be diffused at once
- It may have thin membrane so substances have a shorter distance to travel in order to diffuse
Explain why some animals like elephants need a specialised organ system for gas exchange while earthworm’s don’t
Multicellular organisms (elephant) have a smaller surface area compared to their overall volume so not enough substances can be diffused from their outside surface to supply their entire volume. Single cell organism (earthworm) have a large surface area in comparison to the volume so substances can exchange directly in and out across the cell membrane without a specialised gas exchange
What are the Alveoli
The Alveoli are air sacs contained within the lungs that increase the surface area of the lungs where gas exchange takes place
How are the Alveoli adapted to maximise gas exchange within the lungs
- An enourmous surface area 75m2 in humans so they are able to diffuse a lot of oxeygen at one time
- They have thin walls so the diffusion distance is short
- The lining of the alveoli are moist so the gases are able to dissolve easier
- They have a good blood supply as the capillaries are close by so there is a steep concentration gradient
What are villi and how do they aid absorbtion of nutrients in the small intestine?
Villi are tiny little projections which cover the inside of the small intestine and aid the absorption nutrients e.g. glucose, amino acids
- This is done through the increasing of the surface area of the small intestine so that nutrients can be absorbed quicker
What adaptations do villi have to increase absorption of nutrients in the small intestine?
large surface area
good blood supply to assist absorption quickly
What are Stomata and what is their role in gas exchange in leaves?
Stomato are little holes on the leafs of plants. They allow gas exchange to take place with carbon dioxide into the leaf.
Oxygen (produced in photosynthesis) and water vapour out of the leaves through the stomata
