Unit 1- Transport Across Cell Membranes Flashcards
What is active transport?
The movement of molecules and ions across the plasma membrane from a lower to a higher concentration against a concentration gradient.
What is required for active transport?
Energy
What are the two main components of the cell membrane?
Phospholipids and proteins
What does selectively permeable mean?
Only allows certain substances to pass through
Describe the process of osmosis.
The movement of water molecules from a higher water concentration to a lower water concentration through a selectively permeable membrane.
What happens to an animal cell placed in a higher water concentration outside than inside?
It bursts
What happens to an animal cell in a solution with a lower water concentration?
It shrinks
What happens to a plant cell placed in a solution with a lower water concentration?
It becomes plasmolysed
What happens to a plant cell in a solution with a higher water concentration?
It becomes turgid
Define diffusion.
Movement of ions or molecules from a higher to lower concentration.
What is the energy requirement for diffusion?
Passive
What is the energy requirement for osmosis?
Passive
What is the percentage change formula?
Percentage change = (Change in mass / Initial mass) x 100
What is the average final mass calculation for a group of potatoes?
Total mass of potatoes / Number of potatoes
Which direction do particles move in diffusion?
From higher concentration to lower concentration
What are examples of useful substances that enter cells by diffusion?
Oxygen and glucose
What are examples of waste substances that leave cells by diffusion?
Carbon dioxide and urea
What are the effects of osmosis on animal and plant cells?
- Animal cells may burst or shrink
- Plant cells may become turgid or plasmolysed
Fill in the blank: Water leaves the cell by osmosis and the membrane peels away from the cell wall, the cell is said to be _______.
plasmolysed
What stops a plant cell from bursting in a higher water concentration solution?
Cell wall
What happens to a plant cell in a solution with equal water concentration?
No change
What is the difference between diffusion and active transport?
Diffusion moves down a concentration gradient passively; active transport moves against a gradient and requires energy.
What is the function of proteins in the cell membrane?
To facilitate transport and communication across the membrane.
What is the outcome if the mass of a potato stays the same in an osmosis experiment?
The sucrose concentration is the same as the potato cell sap.