Membrane Basics
What is the outer boundary of a cell called?
What is the plasma membrane.
Does diffusion require energy?
No
Does facilitated diffusion require energy?
Does active transport require energy?
Yes
What substance moves during osmosis?
Water
What are the two main parts of a phospholipid?
A phosphate head and fatty acid tails.
In diffusion, do molecules move from high to low concentration or low to high?
From high to low concentration
What helps substances cross the membrane during facilitated diffusion?
Membrane proteins.
Does active transport move substances from high to low concentration or low to high?
From low to high concentration.
Is osmosis passive or active transport?
Passive transport.
What does selectively permeable mean?
The membrane allows some substances to pass through but not others.
What is the name for molecules spreading from an area of high concentration to low concentration?
Diffusion
Do substances move with or against the concentration gradient during facilitated diffusion?
With the gradient, from high to low concentration.
What does a cell need to provide for active transport?
Energy
What type of barrier does water cross during osmosis?
A selectively permeable membrane.
What is the name of the double layer of phospholipids?
The phospholipid bilayer.
A substance spreads from a crowded area to a less crowded area without energy. What process is this?
Diffusion
Why might a substance need a protein to cross the membrane?
It may not be able to pass directly through the phospholipid bilayer.
A cell moves a substance against its concentration gradient. Which transport process is used?
Active transport.
A water molecule moves across the cell membrane. What process is this?
Osmosis