transport across cells test Flashcards
What is an ion?
An atom that carries a positive or negative charge.
Which part of the cell membrane can allow charged molecules or ions through it?
Channel proteins.
What is meant by a ‘diffusion gradient’?
A situation where there are more molecules in one area and fewer molecules or ions in another area, there may or may not be a membrane between.
Define the term ‘diffusion’.
The movement of substances from a region of high concentration to low concentration.
Is diffusion an active or passive process?
Passive.
Name 3 ‘substances’ that can cross a cell membrane by simple diffusion.
0xygen, Carbon dioxide, H2O, Ethanol.
Which part of the cell membrane is involved in simple diffusion?
Phospholipid bilayer.
Name 3 ‘substances’ that can cross a cell membrane by facilitated diffusion.
Insulin, Glucose, Water, Na+
Which part of the cell membrane is involved in facilitated diffusion?
Channel proteins.
What is the difference between channel proteins and carrier proteins?
- Channel proteins are always open and carrier proteins open and close.
- Carrier proteins bind to molecules to allow them to pass through the membrane and channel proteins form pores to allow molecules to pass through.
Is facilitated diffusion a passive or active process?
Passive.
Define the term ‘osmosis’.
It’s the movement of water molecules from a region of high water potential to a region of lower water potential, across a partially permeable membrane.
Does a ‘salty’ solution have high water potential or low water potential?
Low.
What are the two ways water molecules can cross a membrane?
Simple and facilitated diffusion.
Name one ‘substance’ that can cross a cell membrane by exocytosis?
Hormones, Enzymes, Antibodies.
