Cells - Transport Across Cell membranes Flashcards
Which two words describe the cell membrane?
The cell membrane is selectively permeable
What is a concentration gradient?
A concentration gradient is the difference in concentration of a substance
What is passive transport?
Passive transport of a substance does not require additional energy and describes the movement of its molecules down the concentration gradient from a high to a low concentratoon
What are two examples of passive transport?
Two examples of passive transport are diffusion and osmosis
What is diffusion?
Diffusion is the movement of substances from a high concentration to a lower concentration down a concentration gradient.
Name 3 examples of substances that enter most cells by diffusion
Oxygen
Glucose
Amino acids
Name 2 examples of substances that leave most cells by diffusion
Carbon dioxide
Urea
Why is diffusion important to cells?
It helps provide the cell with raw materials and helps to remove waste products
What is osmosis?
Osmosis is the movement of water from a region of high water concentration to a region of lower water concentration through a selectively permeable membrane
What would happen to an animal cell placed in a solution with a water concentration higher than that inside the cell?
It would take up water by osmosis and could burst
What would happen to a plant cell placed in placed inside a solution with a water concentration higher than that inside the cell?
It would take up water by osmosis and become turgid
What is the cell membrane composed of?
Lipid and protein
What would happen to a plant cell placed in a solution with a lower water concentration than that inside the cell?
It would lose water by osmosis and become plasmolysed
What does plasmolysed mean?
Plasmolysed is the term used to describe a cell in which the vacuole has shrunk due to water loss, causing the cell membrane to pull away from the cell wall.
What does turgid mean?
Turgid is the term used to describe a cell or tissue in which the vacuole has swollen due to water gain and presses the cytoplasm and cell membrane against the cell wall.
