1.2 Transport Across Cell Membranes Flashcards
What is the function of the cell membrane?
The cell membrane controls what enters and exits the cell
What happens when a red blood cell is placed in a solution with a lower water concentration than inside the cell?
The red blood cell would shrink as the water leaves the cell
What substances can be moved by Active Transport?
Sodium and Potassium
Name two substances that move by diffusion?
Carbon Dioxide and Glucose
What does the term Osmosis mean?
The movement of water from an area of higher water concentration to lower water concentration
What happens to a leaf cell when placed in a solution with a higher water concentration than inside the cell?
The leaf cell becomes turgid as the cell swells with water (swells up!)
Why can glucose sugar move across the cell membrane and not starch?
Glucose is small enough to get through the ‘selectively permeable’ membrane, whereas starch molecules are too big. (The membrane is holey!!!)
What does selectively permeable mean?
That some substances can pass through whereas others can’t (to do with the size of the holes)
Give the definition of diffusion?
Diffusion is the movement of molecules from a higher concentration to a lower concentration down the concentration gradient
What does the term Plasmolysed mean?
When the cell shrinks and pulls away from the cell wall
What is Active Transport (across cell membranes)?
Active Transport is the movement of molecules from a lower concentration to a higher concentration, against the concentration gradient. (Concentration meaning a ‘greater or lesser number of molecules’)
What is a Concentration Gradient?
When there is a difference in concentration between two different areas (when there are more or less molecules in one area than the other)
