Cell membrane exam
The maintenance of a constant internal environment within the organism is known as
Homeostasis
How does bulk transport across the plasma membrane occur?
occurs by phagocytosis and pinocytosis.
What happens when a cell loses water?
It shrinks
Which diagram best represents the fluid mosaic model of a cell membrane
^^
The membrane is permeable to
glucose, K+, Na+, water, iodine
One primary function of the cell membrane is
regulating the flow of materials into or out of the cell
The membrane is impermeable to
starch
Active transport
the movement of materials through a cell membrane using energy
Which molecule will most likely diffuse through a cell membrane?
water
What large molecules can not move throughout the cell?
1) starch 2) DNA 3) proteins 4) lipids 5) ions - atoms with a charge, either positive or negative.
What small molecules can move through the cell membrane?
1) water (H2O) 2) oxygen (O2) 3) carbon dioxide (CO2) 4) glucose (C6H12O6)
Which letter structure is responsible for the excretion of most cellular wastes? Carbon dioxide is considered a cellular waste. Excretion means "removal"
2nd outer layer on plant cell!
Which structure is responsible for the passage of materials in and out of a cell
A
Which substance may pass through a cell membrane by simple diffusion
Carbon dioxide and water
A selectively permeable lipid bilayer with proteins embedded within the bilayer is the
Cell membrane
Which structure is most directly responsible for maintaining homeostasis in all cells?
Cell membrane
What happens when a cell gains water?
It swells.
Which structure of the cell allows the passage of oxygen?
Second outer layer of plant cell!
If the concentration of water is equal on both sides of the membrane, water molecules are equal on both sides of the membrane
The cell is in homeostasis
Which is not true?
The cell membrane forms a barrier that keeps all substances that might harm the cell from entering.
When does water diffuse into cell?
When cells are surrounded by distilled water, pure water
When does water diffuse out of the cell?
When cells are surrounded by salt water
What colors will be seen?
When iodine and starch mix, a bluish/black color will be seen.
concetration gradient
a difference in the amount of a substance on one side of the membrane
The spontaneous movement of materials across the membrane from regions of higher concentration to regions of lower concentration until equilibrium is reached
diffusion
passive transport
the movement of substances across a cell membrane without the use of energy by the cell
