Chapter 1.2 Transport across cell membranes Flashcards
The cell membrane is composed of
lipid and protein
The cell membrane is
selectively permeable
The difference in concentration of a substance is a
concentration gradient
Passive transport of a substance does not
require additional energy
Passive transport is the movement of molecules
from a high concentration to a low concentration down a concentration gradient.
Diffusion and osmosis are examples of
passive transport processes
Diffusion is the movement of substances from a
high concentration gradient to a lower concentration down a concentration gradient.
Some substances that enter cells by diffusion are
oxygen, glucose and amino acids
Some substances that leave cells by diffusion are
carbon dioxide and urea
Diffusion is important to cells because it provides the cell with
raw materials and helps to remove waste products
Osmosis is the movement of water molecules from a region of
high water concentration to a region of lower water concentration through a selectively permeable membrane.
An animal cell placed in a solution with a water concentration higher than that inside the cell will
take up water by osmosis and could burst
An animal cell placed in a solution with a lower water concentration than that inside the cell will
lose water by osmosis and could shrink.
A plant cell placed in a solution with a higher water concentration than that inside the cell will
take up water by osmosis and become turgid
A plant cell placed in a solution with a lower water concentration than that inside the cell will
lose water by osmosis and become plasmolysed.
