Flashcards in Diffusion&Osmosis Deck (22)
In realtion to structures such as cell membrane, explain the term selective permeability.
means that some substances are allowed to pass through while others are prevented
Suggest an advantage to the cell of having a selectively permeable membrane
Gives control to the cell over what passes into and out of the cell
Name two substances that enter a human muscle cell by diffusion.
Water, oxygen, glucose, water
Explain the term tugor.
Is the pressure of the cytoplasm and vacuole against the cell wall of a plant.
Give a feature of a plant cell that allows it to remain turgid for long periods.
Vacuole - holds water
Cuticle - prevents water loss
suggest a way in which turgor is value to plants.
it gives strenght
For what purpose did you use Visking tubing, potato tissue or some similat material?
To pretend to have a semi- permeable membrane
at the end of the demonstration, how did you conclude that osmosis had occured?
the mass and the fullness increased in the visking tubing
What is DIFFUSION?
Is the movement of molecules from a region of high concentration to a region of low concentration, until the two concentrations are the same
What is OSMOSIS?
Special type of Diffusion. It is the movement of water molecules from a region of high concentration to a region of low concentration across a semi- permeable membrane.
What means ACTIVE TRANSPORT?
means that energy is required to move molecules often against a concentration gradient.
State the precise location of the cell membrane in plant cells.
Just inside the cell wall surrounding the cytoplasm.
Whit what type of cell do you associate membrane- bound organelles?
What corresponding term is used to describe bacterial cells?
The cell membrane is described as being selectively permeable. What does this mean?
It allows some substances to pass trough but prevents others.
Why is diffusion alternatively known as passive transport?
It doesn't require any energy.
Osmosis may be described as a "special case of diffusion". Explain why
Diffusion is the movement of molecules from an area of high concentration to an area of lower concentration. Osmosis is a special case of diffusion as it relates only to water molecules and it also involves a semi- permeable membrane.
Describe, with the aid of a labelled diagram, how you demonstrate osmosis in the laboratory.
1) Place bags of visking tubing half filled with
Bag 1 - distilled water
Bag 2 - 80% sucrose solution
2) Tie a knot and record the mass
3) Place in beakers of distilled water and leave for 30 minutes
4) Remove bags, dry them and re-record mass
Result: Bag 1 - no change in mass or fullness
Bag 2 - gained mass and appears more full due to water entering tube as result of osmosis
Name the structure by which Amoeba gets rid of excess water that has entered by osmosis.
Contractile vacuole lets AMOEBA get rid of excess water that has entered by Osmosis.
Give two locations in a cell at which there is a selectively permeable membrane.
Nucleous and Vacuole and Chloroplast+ mitochondria
In the case of a named molecule, give a precise location at which it diffuses in the human body.
Oxygen diffusing from the blood into a cell.