Name______
Period-Teacher______
Due Date______
Biology I Cell Transport HW 1
Chapter 3
section 3.3 cell membrane
Key Concept
The cell membrane is a barrier that separates a cell from the external environment.
VOCABULARY
cell membrane / selective permeabilityphospholipid / Receptor protein
fluid mosaic model / Marker protein
Channel/carrier transport protein
MAIN IDEA: Cell membranes are composed of two phospholipid layers.
- Draw a phospholipid bilayer in the box below. Label the hydrophilic (polar) heads and hydrophobic (nonpolar) tails.
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© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology1Cell Structure and Function
A cell membrane has other types of molecules embedded in the phospholipid bilayer. Fill in the type of protein that performs each function indicated in the sentences below:
Use transport, marker, and receptor.
2.______protein functions in communication by sending and receiving chemical messages.
3.______proteins help materials cross the membrane.
4.______proteins help identify cell types.
Choose whether the statement is true or false.
5.true / false A selectively permeable membrane allows all molecules to cross.
Section 3.4 Diffusion & Osmosis
KEY CONCEPT
Materials move across membranes because of concentration differences.
VOCABULARY
passive transport / osmosis / hypotonicdiffusion / isotonic / facilitated diffusion
concentration gradient / hypertonic
MAIN IDEA: Diffusion and osmosis are types of passive transport.
1.The difference in the concentration of a substance from one location to another is called a ______.
2.A molecule that diffuses down a concentration gradient goes from an area of ______concentration into an area of ______concentration.
3. Osmosis is the diffusion of ______molecules.
MAIN IDEA: Some molecules diffuse through transport proteins.
Circle the word or phrase that best completes the statement.
4.Simple / Facilitated diffusion occurs across the membrane, but simple / facilitated diffusion occurs through selective transport proteins.
Vocabulary Check
Fill in the blank with the word or phrase that best completes the sentence.
5. People with more energy than most other people are described as hyper. A solution with a higher level of solutes than the solution it is being compared to is called ______.
6. 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.
Complete the table by checking the correct column(s) for each description
Description of solution surrounding the cell / Isotonic Solution / Hypotonic Solution / Hypertonic Solution7. A solution that has the same osmotic concentration as the cell’s cytoplasm.
8. A solution that causes a cell to shrivel/shrink
9. A solution that causes a cell to swell
10. A solution that neither shrinks nor swells a cell
11. A solution in which there is more water outside the cell than inside the cell
12. A solution that causes water to move out of a cell
For each of the following problems, do these things.
- Determine the solute and solvent for the solution outside the cell (environment) and for the inside of the cell and write the numbers in the blanks given.
- Answer A, B, and C according to the instructions below.
- Tell whether the solution outside the cell is hypotonic, hypertonic, or isotonic.
- Give the direction of the net movement of water (into cell, out of cell, or into & out of cell at equal rates).
- Tell what will happen to the cell (shrink, swell, or stay the same).
The first one has been done for you.
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14.
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Name______
Period-Teacher______
Due Date______
Biology I Cell Transport HW 2
Section 3.4 Passive Transport: Diffusion & Osmosis
Read the following experiment scenario and answer the questions that follow.
The cell membrane of red blood cells is permeable to water but not to sodium chloride, NaCl (salt).
Suppose that you have three beakers:
- Beaker X contains a solution that is 0.5% NaCl (solute)
- Beaker Y contains a solution that is 0.9% NaCl (solute)
- Beaker Z contains a solution that is 1.5% NaCl (solute)
To each beaker you add red blood cells, which have an internal concentration of 0.9% NaCl (solute).
Beaker X Beaker YBeaker Z
For the diagrams above, label the percentages as solute for each beaker and cells.
Then, calculate and label the solvent (water) for each.
Finally, draw an arrow to represent the way the solvent (water) moves for each.
Answer the three questions below.
1. Predict what will happen to the red blood cells in Beaker X:(shrink / swell / stay the same).
(circle one in each section)
The solution in the beaker is ( hypertonic / hypotonic / isotonic ) (circle one in each section)
2. Predict what will happen to the red blood cells in Beaker Y: (shrink / swell / stay the same ).
The solution in the beaker is ( hypertonic / hypotonic / isotonic )
3. Predict what will happen to the red blood cells in Beaker Z:(shrink / swell / stay the same).
The solution in the beaker is ( hypertonic / hypotonic / isotonic )
4. Look at the U-tube above. The semi-permeable membrane is permeable to only water.
Label the side that has a HIGH solvent and the side with the LOW solvent.
Which way will the water move? ______
Why?______
______
What will the U-tube look like in a few hours? (circle the correct diagram)
Section 3.5Active Transport
KEY CONCEPT
Cells use energy to transport materials that cannot diffuse across a membrane.
VOCABULARY
active transport endocytosis exocytosis / phagocytosis pinocytosisMAIN IDEA: Proteins can transport materials against a concentration gradient.
For each of the following statements, place a check mark in the appropriate box if it is true for simple diffusion, facilitated diffusion, or active transport.
Statement / Simple Diffusion / Facilitated Diffusion / Active Transport1. The movement of molecules against a concentration gradient (Low to High)
2. The movement of molecules down a concentration gradient (High to Low)
3. The movement of molecules through selective membrane proteins either down or against the concentration gradient.
4.Active transport proteins have one key distinguishing feature, which is that they use ______to move a substance against its concentration gradient.
5.Most active transport proteins use energy in the form of ______which is made by the breaking down of glucose in cellular respiration.
6. The sodium-potassium pump, is a form of active transport where the protein pumps ______ions out and ______ions in against the gradient.
MAIN IDEA: Endocytosis and exocytosis transport materials across the membrane in vesicles.
Circle the word or phrase that best completes the statement.
7.A cell may transport a substance in lysosomes / vesicles if the substance is too large to cross the membrane.
8.Complete the table below to compare and contrast the processes of endocytosis and exocytosis.
Characteristic / Endocytosis / Exocytosis / BothUses energy
Takes substances into a cell
Releases substances outside a cell
Moves substances in vesicles
Vocabulary Check
Circle the word or phrase that best completes the statement.
9.Pinocytosis / Phagocytosis is a term that means “cell eating.” It describes a type of endocytosis.
10.The prefix exo- means “out of,” and the prefix endo- means “taking in.” Therefore, exocytosis / endocytosis is a process that releases substances outside a cell, and exocytosis / endocytosis is a process that takes substances into a cell.
11.Active transport / Facilitated diffusion drives molecules across a membrane against a concentration gradient, from low concentration to high concentration.
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