Diffusion and Osmosis
True or False If you put 1 teaspoon of salt in a cup of water and 10 teaspoons of salt in a different cup of water, the first cup would have the lower water concentration.
False
A solution that is hypotonic to a cell has .....................
Fewer solutes than the cell
What is diffusion?
Movement of molecules from high to low concentration or down a concentration gradient
What is facilitated diffusion?
Movement of specific molecules across cell membranes through protein channels or the diffusion of molecules across a membrane through transport proteins.
What is Osmosis?
Osmosis is the diffusion of water across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration.
What molecules difusse easily across the membrane?
Small lipids and other nonpolar molecules, such as carbon dioxide and oxygen
What does iso mean?
equal, same
True or False Aquaporins allow all molecule types to pass it
False
True or False There is only one type of transport protiens
False
True or False osmosis alone can account for the rapid movement of water into and out of cells
False
The words isotonic, hypertonic, and hypotonic share the root word tonic, which means:
"pressure"
Explain What a concentration gradient is and what it means for a molecule to diffuse down its concentration gradient.
A concentration gradient means that there is a difference in the concentration of a given substance in two nearby regions (such as the two sides of a membrane). Diffusing down the gradient means that through the random motion of small molecules, some of the molecules in the high concentration region will end up in the formerly low concentration region.
What is a isotonic solution?
A solution that has a solute concentration equal to the solute concentration inside a cell. Equal amounts of water enter and exit the cell, so its size stays constant.
What is a hypertonic solution?
A solution that has a solute concentration higher than the solute concentration inside a cell. more water exits a cell in a hypertonic solution, causing the cell to shrivel or even die.
What is a hypotonic solution?
A solution that has a solute concentration lower than the solute concentration inside a cell.
What is a solute?
A substance that is dissolved in a solution.
Why does isotonic cells size stay constant?
Because equal amounts of water enter and exit the cell
What causes Hypotonic cells to burst or expand?
Because of more water entering the cell
What causes Hypertonic cells to shrivel or die?
Because of more water exiting the cell
Why does oxygen generally diffuse into a cell without the cell expending any energy?
Because the oxygen concentration is almost always higher outside a cell than it is inside a cell
Passive transport requires no ........................
Energy from cell
The word facilitate means "to make easier." ___________________ means that the transport protein makes it easier for a molecule that cannot directly cross the cell membrane to enter or exit a cell.
Facilated diffusion
Suppose you have three solutions with different concentrations of particles. Relative to the concentration of particles in a cell, one solution is isotonic, one is hypertonic, and one is hypotonic. Use this information to answer the question The ______________ solution has the highest concentration of particles.
Hpertonic
People with more energy than most other people are described as hyper. A solution with a higher level of solutes than the solvent that is being compared to is called ___________________.
Hypertonic
Suppose you have three solutions with different concentrations of particles. Relative to the concentration of particles in a cell, one solution is isotonic, one is hypertonic, and one is hypotonic. Use this information to answer the question The _______________ solution has the highest concentration of water molecules.
Hypotonic
Water enters a cell when the solution surrounding the cell is ........................
Hypotonic to the cell
A cell is bathed in fluid. However, you notice that water is flowing out of the cell in what kind of solution is this cell immersed : isotonic, hypotonic, or hypertonic?
If water is flowing out of the cell then the water outside the cell has more nutrients. Therefore the solution outside the cell is hypertonic to the cell; it is the solution with a higher concentration. The cell would be hypertonic
What does Facilitated diffusion do?
It enables molecules that cannot directly cross the phospholipid bilayer to diffuse through transport proteins in the membrane.
What is a concentration gradient?
It is the difference in the concentration of a substance from one location to another.
What is Passive transport?
It is the movement of molecules across the membrane from areas of higher concentration to areas of lower concentration. It does not require energy input from the cell.
What is Concentration?
It is the number of molecules of a substance in a given volume, and it can vary from one region to another.
What can Passive transport also be discribed as?
It may also be described as the diffusion of molecules across a membrane.
What does the word facilitate mean?
It means "to make easier."
What does pressure exerted on the cell wall by fluid inside the central vacuole do?
It provides structural support for each cell and for the plant as a whole.
What does Diffusion result from?
It results from the natural motion of particles, which causes molecules to collide and scatter.
Diffusion and osmosis are types of ........................... transport
Passive
When a person becomes dehydrated due to the loss of fluids and solutes, saline solution (water and salts) is infused into the bloodstream by medical personnel. Why is saline solution used instead of pure water?
Pure water would be hypotonic relative to the contents of blood cells and could cause the cells to burst. The saline solution is isotonic relative to the cell contents.
What is Osmosis?
The diffusion of water
What is Diffusion?
The movement of molecules in a fluid or gas from a region of higher concentration to a region of lower concentration.
Where does diffusion get energy from?
The natural motion of particles
What will happen to a houseplant if you water it with salt water (a hypertonic solution)?
The plant will shrivel up because the hypertonic solution will cause the water to move from an area of high concentration to an area of low concentration. So the water would move out of the cell.
Explain why facilitated diffusion does not require energy from a cell.
The solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane.
What is one example of Facilitated diffusion?
The transport of water by aquaporins
How does some animals and single-celled organisms survive in hypotonic environments?
Their cells have adaptations for removing excess water.
What do Aquaporin molecules do?
They form channels, or tunnels, through the cell membrane. The structure of these channels allows water molecules to pass through in a single file. However, no charged particles, not even hydrogen ions, can pass through.
What does molecules diffuse down their concentration gradient mean?
They go from a region of higher concentration to a region of lower concentration.
What does transport proteins do?
They make it easier for molecules to enter or exit a cell. But the process is still a form of passive transport. The molecules move down a concentration gradient, requiring no energy expenditure by the cell.
How do water molecules diffuse?
They move across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration. This process is called osmosis.
How are receptors and transport proteins similar?
They only work with specific molecules, and they change shape
Aquaporins are what type of protiens?
Transport protiens
True ir False If you put 1 teaspoon of salt in a cup of water and 10 teaspoons of salt in a different cup of water, the first cup would have the higher water concentration.
True
True or False Chaged particles cannot pass through Aquaporin molecules
True
What plays an important role in the transport of water into and out of cells other than Osmosis?
a group of membrane proteins called aquaporins
The terms isotonic, hypertonic, and hypotonic are comparisons; so they require:
a point of reference
dynamic equilibrium means:
balance
The difference in the concentration of a substance from one location to another is called a _______________________________.
concentration gradient
What are examples of passive transport?
diffusion and osmosis
What is osmosis and how does it work?
diffusion of water through a selectively permeable membrane. water will move from an area with more present to an area with less water present. takes place in the kidneys which reabsorb large amounts of water. FOR WATER
The higher the concentration of ................................. in a solution, the lower the concentration of .............................. in the same solution.
dissolved particles, water molecules
In facilitated diffusion, molecules move down a concentration gradient / against a concentration gradient
down the concentration gradient
Most of your cells continually consume oxygen, which means that the oxygen concentration is almost always ..................................
higher outside a cell than it is inside a cell
A molecule that diffuses down a concentration gradient goes from an area of ____________ concentration into an area of ____________ concentration.
higher, lower
What is the impotant role diffusion plays in cells?
in moving substances across the membrane.
A solution may be described as ............................................. relative to another solution.
isotonic, hypertonic, or hypotonic
The higher the concentration of dissolved particles in a solution, the _______________ the concentration of water molecules in that solution.
lower
Most transport protiens allow ........................................
only a certain type of molecule or ion to pass
What does hyper mean?
over, above
Simple / Facilitated diffusion occurs across the membrane, but simple / facilitated diffusion occurs through selective transport proteins.
simple , facilitated
What happens when a specific molecule binds with the transport protein?
the protein changes shape in a way that allows the molecule to travel the rest of the way into the cell.
What helps plant cells adapt to hypotonic environments?
the rigid cell wall prevents the membrane from expanding too much. more water enters a cell in a hypotonic solution, causing the cell to expand or even burst.
What is a solvent?
the substance in which the solute dissolves
What does hypo mean?
under, below
