Transport across cell membranes Flashcards
What is the function of the cell membrane?
To control entry and exit points of molecules to cells.
Is the cell membrane selectively permeable?
Yes
Can starch move through the cell membrane? Explain why
Starch cannot move through the cell membrane because it is not selectively permeable which means the starch molecules cannot fit through the membrane
Describe the structure of the cell membrane
The cell membrane is composed of phospholipids (fat) bilateral with protein molecules spread amongst the phospholipids.
Explain one function of protein molecules in the membrane
Channel-forming proteins help diffusion of small molecules.
What is diffusion
Diffusion is the movement of molecules from a region of higher concentration of molecules to a region of lower concentration.
What does it mean by passive transport?
Passive transport means that it does not require energy.
What is a concentration gradient?
A concentration gradient is just the difference between two different concentrations.
If there are a higher concentration of molecules on the left than the right. Which direction would diffusion take place?
Left, (high concentration to right ( low concentration ).
Will diffusion take place if there are an equal concentration of molecules on both sides of the concentration gradient
No
What is the waste product cells produce during aerobic respiration .
Carbon dioxide.
Which way must carbon dioxide diffuse in a cell. Why is this important?
It must diffuse out of the cell so the cell can stay alive.
When does passive transport occur?
Down a concentration gradient and does not require energy.
Why does oxygen diffuse from an alveolus in the lungs to a blood capillary
The oxygen concentration is higher in the alveolus than in the blood.
Why does oxygen diffuse from the air into the water before reaching a fish?
Oxygen is more concentrated in the air than in the water.
