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.
What is the term for the swelling of a plant cell when water enters by osmosis?
Turgid
What happens to a red blood cell in a high water concentration solution?
It swells or may burst.
True or False: Diffusion requires energy.
False
True or False: Active transport involves moving substances against a concentration gradient.
True
What is osmosis?
Movement of water molecules from a higher water concentration to a lower water concentration through a selectively permeable membrane.
Define plasmolysed.
A condition where a cell has lost water and the cell membrane pulls away from the cell wall.
Define turgid.
A condition where a cell is swollen due to water intake, pressing the cell membrane against the cell wall.
What are the two components of a plasma (cell) membrane?
- Proteins
- Phospholipids
What is the function of proteins in the cell membrane?
To act as channels or receptors.
What feature allows the movement of only some substances into the cell?
Selectively permeable.
Describe the process of diffusion.
Movement of molecules from an area of higher concentration to an area of lower concentration, down a concentration gradient.
Name three substances that can enter a cell by diffusion.
- Glucose
- Oxygen
- Amino acids
Name two substances that leave a cell by diffusion.
- Carbon dioxide
- Waste products (e.g., Urea)
True or False: In osmosis, water molecules move down a concentration gradient.
True.
What does ‘passive’ mean in the context of diffusion?
Does not require energy.
What happens to glucose when tested with Benedict’s solution?
Changes from blue to orange.
What happens to starch when tested with iodine solution?
Changes from brown to blue/black.
Fill in the blank: Diffusion is the movement of molecules from a _______ concentration to a _______ concentration.
[higher] [lower]
What allows dissolved substances to pass through the cell membrane?
Tiny pores in the cell membrane.
True or False: Large substances like starch can easily pass through the pores of the cell membrane.
False.
