Name: ____________________________________ Period: ______ Date: ________________
Unit 3: Cells and Cellular Transport Review Worksheet
Cells and Organelles
1. List the levels of biological organization in multicellular organisms from most simple to complex.
(cell, organism, organs, organelles, organ system, tissue)
Organelles – cells- tissue – organs- organ system- organism
2. Answer the following question, and then complete the table below. How are Prokaryotic and
eukaryotic cells alike? How are they different?
Prokaryotic cells are much small, no nucleus, circular DNA, lack membrane bound organelles. Eukaryotic
cells are 10x larger than a prokaryotic cells, more complex with membrane bound organelles and linear
DNA. Both contain DNA molecules and ribosomes.
Prokaryotic Cells
Nucleus Present
Eukaryotic cells
X
DNA present
X
X
Cell wall
X
Cell membrane
X
X
(plant cells only)
X
Simple
X
Complex
Ribosomes Present
X
X
X
3. Which organelles are only found in plant cells?
Cell wall, chloroplast and large central vacuole
4. List the organelles involve in production and export of proteins from the cell, starting from the
nucleolus, and explain the function each organelle.
The nucleolus will produce the ribosomes which are either free floating or attached to the
endoplasmic reticulum. The ribosomes will synthesize the proteins and the rough endoplasmic
reticulum will modify the proteins which are sent to the golgi apparatus to be prepared for export
from the cell.
5. Discuss the endosymbiosis theory and give evidence for the support of this theory.
According to the theory of endosymbiosis, two different types of prokaryotes may have come to have close
partnerships with each other.
For example, some small prokaryotes capable of performing photosynthesis (the process by which plant cells
capture the light energy from the sun and transform it into the chemical energy stored in food molecules) may
have come to live inside a larger “host” prokaryote.
The photosynthetic “boarder” may have made some of the energy from its photosynthesis available to the
host.
After a long while, the two cells may have become more and more dependent on each other until both cells
could not live without the other, and they became a single, more complex organism.
Eventually, the photosynthetic prokaryote evolved into a chloroplast, the organelle in plant cells in which
photosynthesis occurs.
A similar scenario might explain how a prokaryote unusually efficient at converting food and oxygen into easily
usable energy might take up residence in another prokaryote and evolve into a mitochondrion, the organelle
in plant and animal cells that converts the energy stored in food into a form usable by the cell.
The idea of endosymbiosis is supported by several observations.
1. Chloroplasts and mitochondria are similar in size to prokaryotic cells.
2. Chloroplasts and mitochondria have small amounts of circular DNA, similar to the organization of
DNA in prokaryotes and in contrast to the linear DNA strands found in the eukaryote’s nucleus.
3. Chloroplasts and mitochondria divide by splitting, just like prokaryotes.
4. Chloroplasts and mitochondria have internal structures called ribosomes, which are similar to those
found in bacteria.
(information taken from the notes on the powerpoint slide- see also the jeopardy game question.)
6. How could you explain the existence of other membrane bound organelles, other than the
mitochondria and chloroplast, in the eukaryotic cell?
The theory of invagination explains the origin of organelles in eukaryotes. The idea is that the plasma
membrane around the cell may have just folded in on itself to create the inner compartments, which
subsequently became modified and specialized.
Cell Transport
1. Fill in the blanks
A ____solvent_______ is a fluid in which a substance is dissolved.
A _____solute____ ___is a substance dissolved in a solvent.
A _____solution_____ is a combination of solute and solvent.
2. What is a concentration gradient?
___the difference in the concentration of molecules in a given space______
3. What does it mean for a molecule to diffuse down a concentration gradient?
___________the molecule will move from high to low concentration. __________
4. Because the cytoplasm of the plant and the animal cell have equal concentrations of solutes, we can say
that their cytoplasm are ______________________ (isotonic, hypertonic, or hypotonic) to each other.
5. If we put both a plant and animal cell into a solution that contains no solutes at all, the solution is
______________________________ (isotonic, hypertonic, or hypotonic) to the cytoplasm. __Water____ will
enter both cells through osmosis. The animal cell will likely __burst___, but the plant cell is protected because
the presence of a __cell wall____.
6. How does facilitated diffusion differ from simple diffusion. ____Facilitated diffusion will use transport
proteins to allow for molecules to move across the cell membrane___________
7. How is active transport different than simple diffusion and facilitated diffusion?
___Both facilitated and simple diffusion will NOT use energy and move molecules from an area of high to
low concentration. ___Active transport will require the use of energy and moves the molecules from an
area of low concentration to high concentration.________
8. Do you think that endocytosis and exocytosis can occur within the same cell? Explain your reasoning.
_____Yes, cells need to have both an intake of material and an export of material_________
9. Why does a plant like celery get limp when placed in a hypertonic solution?
______Water will diffuse out of the cell when placed in a hypertonic solution.______________
10. Complete the table by checking the correct column for each statement:
STATEMENT
Isotonic
Hypotonic
1. The concentration of solute in the solution outside the cell is
lower than the concentration of solute inside the cell.
X
2. When a cell is placed in this solution, water will enter the cell by
osmosis resulting in osmotic (turgor) pressure (causes a cell to
swell).
X
3. The concentration of solute in the solution is the same as the
concentration solute inside the cell.
4. The concentration of solute in the solution is higher than the
concentration inside the cell.(causes a cell to shrink)
Hypertonic
X
X
5. When this solution is injected into the body no cell disruption
occurs because no net gain of water occurs inside or outside of the
cell.
X
6. Putting a plant in this solution will result in water loss from
inside of the plant cell which will cause the plant to wilt.
X
11. In the figure of the U-tube below, side “A” is pure water and side “B” is a 10% starch solution. Why is
the level of side “B” rising? Which side is HYPERTONIC
compared to the other?
The water on side B is hypertonic. The water is rising since
the starch molecules are too large to pass through the
membrane to side A and therefore there is no water
diplacement due to the fact that the starch molecules are
unable to fill the space and reach equilibrium.
12. Match the term with its correct description:
a.
b.
c.
d.
e.
energy
facilitated diffusion
endocytosis
passive transport
enzymatic protein
f. active transport
g. exocytosis
h. receptor protein
i. recognition protein
j. channel protein
___J___ Transport protein that provides a tube-like opening in the plasma membrane through which particles
can diffuse
___A____ Is used during active transport but not passive transport
___C____ Process by which a cell takes in material by forming a vesicle around it
___E____ Accelerate chemical reactions on the cell membrane’s surface
___D____ Particle movement from an area of higher concentration to an area of lower concentration
___G____ Process by which a cell expels wastes from a vacuole (should say…vesicle)
___B____ A form of passive transport that uses transport proteins
___I____ Give each cell a “fingerprint” that makes it possible for the body’s immune system (which fights off
infections) to distinguish the cells that belong inside you from those that are invaders and need to be attacked
___F____ Particle movement from an area of lower concentration to an area of higher concentration
____H___ Bind to chemicals in the cell’s external environment and, by doing so, regulate certain processes
within the cell.
13. Match the term with its correct description:
a. transport protein
b. active transport
c. diffusion
d. passive transport
e. osmosis
f. endocytosis
g. exocytosis
h. equilibrium
__E__ The diffusion of water through a cell membrane
__C__ The movement of substances through the cell membrane without the use of cellular energy
__A__ Used to help substances enter or exit the cell
__B__ When energy is required to move materials through a cell membrane
__H__ When the molecules of one substance are spread evenly throughout another substance to become
balanced
__G__ A vesicle membrane fuses (becomes a part of) the cell membrane and the contents are released
__F__ The cell membrane forms around another substance in order to take molecules into the cell
__D__ When molecules move from areas of high concentration to areas of low concentration
14. Label the diagrams of cells using the following terms: diffusion, active transport, osmosis,
equilibrium. The arrows show the direction of transport. You may use the terms more than once!
High
CO2
levels
8 H2O
molecules
25 glucose
molecules
2 H2O molecules
5 glucose molecules
Low CO2 levels
_____Diffusion________
_____Osmosis______
10 H2O
molecules
High
protein
levels
2 H2O
molecules
8 H2O molecules
___Osmosis________
_____Diffusion______
Low protein levels
_Active transport__
10 H2O molecules
_Equilibrium__
Osmosis Practice Activity
Osmosis is the diffusion of water from an area of high concentration to an area of low concentration. Only
water moves in osmosis! The diagrams below show the concentration of water and salt inside the cell and the
concentration of water and salt surrounding the cell. Complete the sentences below by comparing the
concentration of the water inside the cell and the concentration outside the cell.
1.
5% NaCl
95% H2O
95% NaCl
5% H2O
a. Water will flow _____________________ (into the
cell, out
of the cell, in both directions).
b. The cell will ______________________ (shrink,
burst, stay the same).
2.
a. Water will flow _____________________ (into the cell, out
5% NaCl
95% H2O
5% NaCl
95% H2O
of the cell,
in both directions).
b. The cell will ______________________ (shrink, burst,
stay
the same).
3.
95% NaCl
5% H2O
5% NaCl
95% H2O
a. Water will flow _____________________ (into
the
cell, out of the cell, in both directions).
b. The cell will ______________________ (shrink, burst,
stay the same).
4. At which solution of concentration gradient is each cell diagram? (Hypotonic, Hypertonic, Isotonic)
a. _Hypotonic__
b. __Isotonic___
c. _Hypertonic__
5. This diagram is moving from a high to a low concentration: ___Osmosis__
6. Using a transport protein to move particles across the membrane: _Facilitated Diffusion___
7. Describe the processes occurring in the following pictures:
Endocytosis
exocytosis
Active transport
Cell Size
To maintain homeostasis, cells must have enough surface area to exchange materials. However, as cells grow
the surface area to volume ratio changes. As a result, there is a limit to cell growth because if a cell becomes
too large there is not enough surface area for the exchange of materials and homeostasis cannot be
maintained. When a cell reaches a critical surface area to volume ratio, it stops growing or is signaled to
divide.
Circle the correct answer.
a) A smaller cell has a greater surface area to volume ratio than a larger cell.
True or False
b) As a cell grows in size, the volume of its cytoplasm increases at a
slower rate than the surface area of its plasma membrane.
True or False
c) As the volume of a cell’s cytoplasm increases, its plasma membrane
becomes too small to absorb the amount of nutrients the growing cell
requires or excrete the increasing amount of waste it produces.
True or False
d) A cell can grow as large as it wants, as long as its environment provides
enough nutrients.
True or False
Cell Membrane:
1. Explain why the cell membrane can also be called the “fluid mosaic model” or the “phospholipid
bilayer”.
a. Mosaic is made of smaller components just like the cell membrane is made of smaller
components (proteins, lipids, etc. ) it is considered “fluid” since there is movement of
molecules in the membrane and the various molecules are not help in an anchored position.
b. The cell membrane is also called the phospholipid bilayer since it is made up of two
phospholipids. The hydrophilic phosphate heads and hydrophobic phosphate tails. The
hydrophobic interactions hold the phospohlipds (and the other embedded lipids) in the
correct orientation.
2. List and describe the function of the four transmembrane proteins found in the cell membrane, as well
as the function of cholesterol and the carbohydrate chain.
3. Explain why the phospholipids in the cell membrane orientate themselves the way they do and why
some proteins are surface and some are transmembrane.
a. The phospholipid has a hydrophilic head which will orientate itself to be in contact the
watery extracellular and intracellular material. The hydrophobic tails will push away from
the water and form the inner layer of the phospholipid bilayer.
b. Surface and transmembrane Proteins: (see slide 28 on powerpoint)
Some of these side chains are hydrophilic, others are hydrophobic, and as a protein is
assembled into its final shape, these side chains can cause parts of the protein to be attracted
to hydrophobic or hydrophilic regions.
Because a transmembrane protein has both hydrophobic and hydrophilic regions, part of the
protein can exist in the hydrophobic region in the center of the membrane while the other
resides in hydrophilic regions.
Peripheral membrane proteins, on the other hand, have an entirely hydrophilic structure, and
so can bind only to the head regions of the phospholipids.
As a consequence, they can be positioned on either the outer or inner side of the membrane.
Once membrane proteins are in place, the hydrophobic and hydrophilic forces keep them
properly oriented. Because all of the components of the plasma membrane are held in the
membrane in this manner, they can float around without ever popping out.
Cell Organelles:
List and describe the function of all the cell organelles (14 total) Be sure to be able to identify the organelle in
a diagram (review quiz).
1. Nucleus: controls cell activity
2. Nucleolus: manufactures ribosomes
3. Nuclear envelope: controls the movement of material in and out of the nucleus
4. Chromosomes: carries genetic information
5. Cell membrane: controls the movement of material in and out of the cell
6. Centrioles: aide in cell division
7. Ribosomes: site of protein synthesis
8. Rough endoplasmic reticulum: modifies proteins
9. Smooth endoplasmic reticulum: synthesizes lipids
10. Mitochondria: energy (ATP) production
11. Lysosomes: contains digestive enzymes for the breakdown of material
12. Golgi apparatus: processes molecules for shipment to other parts of the cell
13. Cytoskeleton: provides structural support and movement of the cell
14. Cytoplasm: allows for movement of molecules within the cell and holds the other organelles