Osmosis and diffusion Flashcards
Red blood cells : Carry oxygen to the body's tissues, and are adapted by having a concave sn
Define Osmosis.
The net movement of free water molecules from an area of high water potential to an area of low water potential, across a partially-permeable membrane.
What is the process of diffusion called?
A passive process, meaning they do not require energy to get in and out of the cell, it just happens.
Explain the terms affecting the rate of diffusion.
. Temperature : As the temp. increases, the particles get more kinetic energy leading to faster movement for out to inside the cell. They are directly proportional.
. Distance : As the distance increases, the rate of diffusion decreases, as there’s more room for the particles to travel through. They are inversely related.
. Surface area : As the SA increases, so does the rate of diffusion, as there’s more space inside the cell for the particles to move to.
.Concentration gradient : The steeper the C.G, the faster the rate of diffusion is, meaning there’s more space in the concentration.
Towards what solution does the free water molecules always flow?
The free water molecules always move towards the hypertonic solution.
Name:
. The animal cell which shrinks.
. The animal cell that has become swelled.
.Crenate
. Cytolysis
What do you call a plant cell which has swollen? And shrank?
The swelling of plant cell is called becoming turgid, and the shrinking is called plasmolysis.
What is the name of solution where there isn’t any movement of particles/free water molecules?
Isotonic solution.
How is a plant cell supported by the vacuole?
The water within the vacuole creates pressure which pushes the cell membrane against the wall, and cell wall and the vacuole both support the plant cell.
When and why does active transport occur?
Active transport occurs when the organs of the organisms can absorb as many nutrients as possible.
Why can bacteria rely on diffusion? Give numerous explained reasons. (3)
Bacterium is an unicellular organism, meaning its whole body is in contact with the environment where it can exchange substances from its surrounding.
By being unicellular, they have a large surface area and smaller volume, meaning the diffused particles have a bigger place to go into.
The bacterium has less demands for diffusion as it is relatively tiny, and for having no body parts at all unlike humans.
Why is it impossible for the multicellular organisms to rely on diffusion?
The multi-cellular organisms have a lot of demands for exchanging particles, as there’re billions of cells who need to be fed to be able to work, and a lot of tissues.
Also, diffusion is slow, and a passive process meaning by the time it gets diffused into our lungs, our brain cells may die, because it takes too long.
Why is diffusion important for living beings?
Because it helps organisms to exchange substances by releasing waste products out and taking useful products in, in order to obtain energy.
How does the multi-cellular organisms take in the food and nutrients?
The multi-cellular and larger organisms have exchange systems e.g. in the lungs, and transport systems e.g. circulatory system.
What is meant by ‘more concentrated’ and ‘more dilute’ ?
‘More concentrated’ means the solution has more solute per unit volume. ‘More dilute’ means there’s less solute per unit volume.
What is the surface area in biology? And its volume?
Volume is the inside part of a cell whereas the surface area is the area of the outside of the cell, mainly plasma membrane.
