Unit Title: Cells
Grade: 10th Grade Biology
Cells
Enduring Understandings:
Essential Questions:
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A cell is the basic unit of life.
The processes that occur at a
cellular level provide the energy
and basic structure organisms need
to survive.
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Cells can be Eukaryotic or
Prokaryotic.
Cells involve chemical reactions.
Cells can be multicellular or
unicellular.
Cells range in size from one
millimeter down to one micrometer.
Cells and the importance of
proteins in cell function.
Cells need a surface area of plasma
membrane large enough to
adequately exchange materials.
The surface-area-to-volume ratio
requires that cells be small.
Size limits how large the actively
metabolizing cells can become.
The cell membrane is a phospholipid
bilayer with embedded proteins.
Cholesterol is a lipid found in
animal plasma membranes; it
stiffens and strengthens the
membrane.
The plasma membrane is
asymmetrical; glycolipids and
proteins occur only on outside and
cytoskeletal filaments attach to
peripheral proteins only on the
inside surface.
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1
What are the similarities and
differences between plant/animal
& bacterial cells?
Why is it important to study cells?
How do cell structures enable a
cell to carry out basic life
processes?
How does a cell transport
materials across the membrane?
How does a cell maintain
homeostasis both within itself and
as part of a multicellular organism?
What role does the nucleus play in
cell function?
What are the two types of cells?
What are the benefits of cells being
so small?
What is the cell theory?
What is meant be a mosaic
structure of the plasma membrane?
What are the diverse functions of
the embedded proteins of the
plasma membrane?
What is meant by a semi
permeable membrane?
What is the difference between
active and passive transport?
What is the importance/roll of
cholesterol in cell membranes?
How are cell structures adapted to
their functions?
Unit Title: Cells
Grade: 10th Grade Biology
Cells
Critical Content:
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Critical Content:
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Plant cell
Animal cell
Staining
Mounting
Cells
Cell Membrane
Selectively Permeable
Cell Theory
Hydrophilic
Hydrophobic
Nucleus
Passive Transport
Light Microscope
Cytoplasm
Diffusion
Electron Microscope
Nuclear Envelope
Facilitate Diffusion
Eukaryotes
Chromosomes
Aquaporins
Prokaryotes
Chromatin
Osmosis
Organelles
Nucleolus
2
Isotonic
Homeostasis
Vacuole Hypertonic
Unicellular
Lysosomes
Hypotonic
Multicellular
Cytoskeleton
Osmotic Pressure
Tissue
Ribosomes
Phospholipid head
Triglyceride tail
Active Transport
Organ
Smooth Endoplasmic Ret.
Endocytosis
Organ System
Rough Endoplasmic Ret.
Exocytosis
Golgi Apparatus
Chloroplasts
Mitochondria
Cell Wall
Cell Membrane
Unit Title: Cells
Grade: 10th Grade Biology
Cells
Critical Skills:
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Compare and contrast cells
Recognize a variety of different cells
Differentiate between active transport in the cell membrane and
passive transport
Identify the key role of the nucleus in cell function
Use amicroscope to view cells
Describe the similarities and differences in eukaryotic and
prokaryotic cells.
Describe the structure and function of the nucleus (and all other
organelles).
Compare and contrast the structure and function of chloroplasts
and mitochondria.
Generate a “T” list of proteins based on structural and functional
importance to the cell membrane and ribosomal proteins
Explain multicellular verses a unicellular organism
Determine the major similarities and difference between a plant
and an animal cell.
Defend the cell theory
Organize biological hierarchy/levels of organization from simplest
to more complex
Describe the processes a cell uses to take in materials and release
materials through the cell membrane
3
Unit Title: Cells
Grade: 10th Grade Biology
Big Idea:
The cell theory states that all organisms are composed of cells, that cells are the
structural and functional unit of organisms, and that cells come only from preexisting cells.
Learning Targets
3.1.1
3.1.2
Cells have particular structures that underlie their functions
Most cell functions involve chemical reactions.
3.1.3
Cells store and use information stored in DNA to guide their
function.
3.1.4
Cell functions are regulated through changes in the activity of the
functions performed by proteins and through the selective
expression of individual genes
Plant cells contain chloroplast, the site of photosynthesis.
3.1.5
3.1.6
Cells can differentiate, and complex multicellular organisms are
formed as a highly organized arrangement of differentiated cells
4
Focused
Assessed
Unit Title: Cells
Grade: 10th Grade Biology
Performance Tasks and Suggested Learning Experiences
with Ideas for Differentiation
Construct and present a 3D cell model (may use materials
of choice as long as the item relates to both structure and
function – such as a battery is for energy therefore it would
be a mitochondrion). Each student will be assigned one of
the 200 different types of the cell in the human body, a
virus, a plant cell, or a prokaryotic organism’s cell.
Students will work in small groups to create a poster that
advertises the importance of learning about cells. Posters
should include the three parts of the cell theory
Students will be able to diagram and label all parts to the
cell and their function.
Students will take an oral or written exam of differentiated
assessment practices: true and false, multiple choice, essay,
matching, short answer, and completion.
Predict the effect of osmotic conditions on animal versus
plant cells
Have students work in small groups to create pictograms
with cells and solutions relating the concepts: hypertonic,
hypotonic and isotonic. Afterwards have each group share
with the class and allow groups to make adjustments as
needed.
Students will create a podcast explain in storyline format of
how a plant and animal cell obtain energy through cellular
respiration and photosynthesis. Assign half the students to
do photosynthesis and the other half to do cellular
respiration. Have groups trade and create an assessment to
accompany their podcast.
Have students build a model of cell city with factories
(structures) and figures to represent workers carrying out
the jobs (functions) of the organelles.
Have students write a brief essay on how lysosomes are
structurally and functionally a type of protein enzyme
5
Remediation:
 Cells Matching
(definitions)
 Cell Jigsaw puzzle
 Have students make
a T chart to
organize cell
structure and
function
information
 Skeleton notes
 Chunked/shorten
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Plant Cell Coloring
Animal Cell Coloring
On Line labs
Animal Cell Coloring
Activity
Cell theory flash
cards with
pictograms to help
with memorization
Unit Title: Cells
Grade: 10th Grade Biology
Students will act out a skit involving students who are
assigned the following roles: hydrophobic, hydrophilic,
water, structural protein, functional protein, etc. – teacher
will film and the put the video on high speed so students
can understand what is meant by a fluid membrane. Not
only do the phospholipids heads move around as needed
but so do the proteins. Set to music!
Students will design a miniature menu from a creative
restaurant where they will create a dining experience that
will connect exocytosis and endocytosis to cell eating and
drinking.
Ask students to recite the three parts of the cell theory
Students will conduct a microscope lab identifying cell
structures
Students will conduct a microscope lab identifying a
prokaryote and a eukaryote cell
Cheek Cell Lab
Egg Lab (osmosis)
Fermentation lab –cellular respiration lab
Photosynthesis lab – Chlorophyll response
Chromatography lab with spinach
Students give examples of cell differentiation
Animal Cell Diagram (label and describe organelles)
Cell City Analogy Activity
Cells and Their Organelles activity
Compare and Contrast (prokaryotic and eukaryotic cells)
Compare and Contrast Animal and Plant cell organelles
Students will arrange a variety of teacher selected items that
represent the following items to scale: DNA, virus,
prokaryotic cell, eukaryotic cell (chicken egg),
mitochondrian, and giant amoebae – cells are small.
See sample lab located at the end of this unit
6
Extension:
 Online or Virtual
Lab activity
 Research how the
health of an
individual depends
on the health of
their organelles
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Create a Cell
Structures book
Cell Analogies
Collage
Cell Model – create a
3 dimensional plant
or animal cell.
Animal Cell Parts
Book
Propose a cell
diagram project
Unit Title: Cells
Grade: 10th Grade Biology
Resources
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Biology, by Miller and Levine (Pearson)
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Cells Alive table of Contents
Great Cells Alive WebQuest from biologycorner.com plus an online quiz that follows.
Lots and lots of cell activities here!
"Inside a Cell" allow students to point to an organelle and find out the name and
function.
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The Science Teacher’s Book of Lists, by Barhydt and Morgan
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A tour of the cell is found at Virtual Cell
A great video is The Inner Life of the Cell
Web sites that are good resources:
Biology Corner – www.biologycorner.com
Awesome Science – www.nclark.net
Science Spot Classroom – www.sciencespot.net
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7
Unit Title: Cells
Grade: 10th Grade Biology
Partial Outline of Cells and Their Processes
Review of Biochemistry
Organic Compounds
 A compound is a combination of 2 or more atoms
 An organic compound is a compound that contains carbon atoms that have combined
with each other
o Carbon can bond to a number of different atoms so carbon can form many
different types of compounds
 An inorganic compound is a compound with no combination of carbon atoms
 6 most common elements in organic molecules: SPONCH-sulfur, phosphorus,
oxygen, nitrogen, carbon, hydrogen
The Four Types of Organic Compounds (The Molecules of Life)
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Carbohydrates: Sugars used for short term energy; Made of monosaccharides
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Lipids: Fats and oils used for long term energy; Made of fatty acids
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Proteins: Made up of amino acids; used for construction materials and chemical
reactions in the body
8
Unit Title: Cells
Grade: 10th Grade Biology
o
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Enzymes: Special types of proteins that speed up chemical reactions in the
body but are not changed by the reactions
Nucleic acids: DNA and RNA; contains genetic information; made up of nucleotides
Cells
A cell is the smallest unit that is alive and can carry on all the processes of life
Cells make up organisms (living things)
o Unicellular organisms are made up of 1 cell
o Multicellular organisms are made up of many cells
 Cells contain organelles, which are specialized compartments that carry out a
specific function
 Types of cells
o Eukaryotic cells contain a nucleus, such as animal and plant cells
o Prokaryotic cells contain no nucleus, such as bacteria
Animal Cells
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Usually “roundish”
9
Unit Title: Cells
Grade: 10th Grade Biology
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Organelles include
o nucleus: controls cell activities
o cell membrane: controls what enters and leaves the cell and also protects
the cell
o endoplasmic reticulum (ER): tunnels for compounds to move through the cell
o Golgi body: processes and stores protein
o Ribosomes: make proteins
o Mitochondria: Makes energy for the cell
o Lysosome: Has enzymes that digest waste and old organelles
o Cytoplasm: Fills the empty space of the cell
o Vacuole: Stores food, water, and waste
o Centrioles: Help in cell division and is only found in animal, not plant, cells
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Inside the nucleus: chromosomes
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DNA strands in the nucleus that contain the directions on how to make
and keep an organism alive
Made up of genes, which are traits of an organism
Cells will die if their DNA is damaged or removed
Plant Cells
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Usually square
10
Unit Title: Cells
Grade: 10th Grade Biology
A typical plant cell
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Organelles include
o Everything that an animal cell has plus more
o Chloroplast: Traps sunlight to make food for the plant
o Cell wall: Protects the cell
11
Unit Title: Cells
Grade: 10th Grade Biology
Bacterial cells
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Smaller and simpler than plant or animal cells
Bacteria are unicellular
No nucleus
Have a single closed loop of DNA, cell wall, cell membrane, cytoplasm and ribosomes
Some have a capsule (shell for protection), pili (short hair like structures to hold
onto host cells), and flagella (whip like structure for movement)
Viruses
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Noncellular entities with a simple structure and cannot reproduce on their own
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Unit Title: Cells
Grade: 10th Grade Biology
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Much smaller than a bacterial, animal or plant cell
Parts of a virus
o Nucleic acid inside the virus – can be either DNA or RNA
o Capsid: protein coat to protect the nucleic acid inside the virus
o Spikes: help the virus to attach to host cells
There is much controversy on whether viruses are alive or not because they cannot
reproduce on their own—They do not have the organelles needed to reproduce
o Viruses must invade a living cell and use the cell’s tools to reproduce
o Host cell: An animal, plant or bacterial cell that is invaded by a virus
o Viruses harm and/or kill the host cell that they infect
Cell membrane
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Made up of molecules called phospholipids
Phospholipid bilayer is the 2 layers of phospholipids that make up the cell membrane
Cell membrane is fluid, which means that it is constantly flowing and moving over
the cell
Cell membrane is selectively permeable, which means that it allows small compounds,
but not large ones, to pass right through
There are different ways that materials are transported across the cell membrane
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Unit Title: Cells
Grade: 10th Grade Biology
Passive transport: requires no energy
 Diffusion: compounds move from high to low concentration
 Osmosis: diffusion of water
o Active transport: requires energy
 Endocytosis: large compound are brought into the cell
 Exocytosis: large compounds are exported out of the cell
Types of solutions
o Hypotonic solutions cause water to move into the cell so the cell swells up
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Hypertonic solutions cause water to move out of the cell so the cell shrivels
up
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Unit Title: Cells
Grade: 10th Grade Biology
o
Isotonic solutions cause no net movement of water into or out of the cell
Photosynthesis
 Process by which organisms use energy from sunlight to make their own food
(glucose)
 Glucose is a simple sugar
 Photosynthesis occurs in the chloroplasts of plant cells and some bacteria
 Chloroplasts have a green pigment called chlorophyll
 Steps of photosynthesis
o 1. Light reaction: chlorophyll in the chloroplasts absorbs sunlight
o 2. Dark reaction: The energy from the sunlight is used to make glucose
 Light energy is completely changed into chemical energy (glucose)
 Chemical equation for photosynthesis
15
Unit Title: Cells
Grade: 10th Grade Biology
6CO2 + 6H2O + light energy  C6H12O6 + O2
Cellular Respiration
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Process that breaks down glucose in order to make energy for an organism
ATP: compound that stores energy in an organism
Occurs in the mitochondria of the cell
Two types of cellular respiration
o Aerobic respiration: requires oxygen to occur
 Mostly happens in animals and plants
 There are 3 steps in aerobic respiration
 Step 1 is glycolysis: glucose is cut in half
 Step 2 is the citric acid cycle: glucose halves get electrons
chopped off of them
 Step 3 is the electron transport chain: electrons combine with
oxygen and are used to make a lot of ATP
 Chemical equation for respiration
C6H12O6 + O2  6CO2 + 6H2O + ATP energy
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 Aerobic respiration is the opposite of photosynthesis
Anaerobic respiration: does not require oxygen to occur
 Mostly happens in bacteria and yeast
 Also called fermentation
 Makes less ATP than aerobic respiration
Sample Osmosis and Diffusion Lab
Osmosis and Diffusion
The plasma membrane enclosing every cell is the boundary that separates the cell from its
external environment. It is not an impermeable barrier, but like all biological membranes, is
selectively permeable, controlling which molecules move into and out of the cell. For example,
nutrients enter the cell and waste products of metabolism leave. The cell takes in oxygen for
respiration, and expels carbon dioxide. The membrane also regulates the concentration of ions
by transporting them one way or the other across the plasma membrane. This regulation of
every interaction with environment allows cells to maintain homeostasis, a steady internal state
in changing conditions.
Diffusion and passive transport:
Molecules are in constant motion, moving around randomly (Brownian movement).
One result of this random motion is diffusion, the net movement of molecules from an area
where their concentration is high to an area where their concentration is lower. This is a
spontaneous process, requiring no input of energy. In a liquid, a solute (dissolved substance) will
16
Unit Title: Cells
Grade: 10th Grade Biology
diffuse in a solvent (dissolving agent, most often water in biological systems) and eventually
become uniformly distributed.
If a membrane separates the region of high concentration from the region of low
concentration, the principle is the same. If a substance is more concentrated on one side of a
membrane than on the other, it diffuses across the membrane from the region of higher
concentration to the region of lower concentration, as long as the membrane is permeable to
that substance. This is called passive transport, because it requires no energy to make it happen.
Much of the movement of molecules across the cell membrane occurs this way. By comparison,
active transport goes against the concentration gradient, and requires the input of energy.
Remember that in either case, cell membranes are selectively permeable, and not all substances
move across freely. For example, the cell typically retains the large organic molecules it
synthesizes.
Water is one molecule that easily crosses the cell membrane. The net diffusion of water
through a selectively permeable membrane from the side of high water concentration to the side
of low water concentration is termed osmosis. The higher the concentration of solute (dissolved
particles), the lower the concentration of free water molecules.
What implications does osmosis have for cells? When a cell is placed in a solution in
which the concentration of all solute particles is lower than the cell (and therefore, the
concentration of water is higher), then water will move into the cell. Such a solution is called
hypotonic. If the solute molecules are unable to pass through the cell membrane, a hypotonic
solution will cause a cell to swell from the osmotic uptake of water. Conversely, if a cell is
placed in a solution with a high particle (low water) concentration relative to the cell, that cell
will lose water. The latter cell is in a hypertonic solution, defined as a solution that will make a
cell shrink because of the osmotic loss of water. A cell in an isotonic solution will have no net
water uptake or loss. Note that each of these terms is relative to the inside of the cell.
Brownian Movement
 Place a drop of diluted India ink (a suspension of particles) on a clean slide, add a coverslip,
and examine with your microscope using high power and reduced illumination. Focus
carefully until you see the entire field of jiggling particles. The India ink particles “bombard”
each other and are being “bombarded” by water molecules.
The same energy that produces the movement of the ink particles causes diffusion of
molecules. When a gradient exists, if there is no membrane blocking particle movement,
diffusion will ultimately result in a uniform distribution.
 Place about 50 ml of water in a small beaker. Set the beaker on a white piece of paper at
your table for a few minutes, until you are convinced that there are no more ‘currents’ in the
beaker. Drop ONE drop of Methylene blue into the beaker.
17
Unit Title: Cells
Grade: 10th Grade Biology
 Immediately record the appearance of the beaker, with respect to the concentration of
Methylene blue (the blue color).
 After 3 minutes, record the appearance of the beaker again, with respect to the concentration
of Methylene blue. Has there been a change? What might have caused the change?
Diffusion of Water Across Cell Membranes: Osmosis
Consider a hypothetical animal cell with a composition of 10% protein and 90% water in
an environment of 100% water (pure water). Remember the definition of diffusion. Water is
more concentrated outside the cell, so it will move into the cell (from 100% concentration to
90% concentration). In this case, the protein molecules are too large to pass out of the cell
membrane. If this movement of water (osmosis) continues unchecked, the cell may burst like a
balloon. Plant cells have a rigid cell wall that prevents them from bursting. They become firm or
turgid under the above conditions (that’s why plants wilt from a lack of water). You looked at
plant cells in under different saline concentrations last week.
Osmosis Experiment
Sometimes, we use non-living models to study living systems. In this experiment, dialysis
tubing is used to represent a differentially permeable membrane. When you make up a dialysis
bag, think of it as a simplified cell.
Obtain three pieces of equal length of dialysis tubing, and several lengths of string. Fold
over one end of the tubing and tie it closed with the string (you may also simply tie a knot in
one end, but be careful not to put small rips in the tubing). To each tube, add 5 ml of 30%
sucrose solution. Then, squeeze the bag gently to remove excess air, fold over the top, and tie it
off with string. The bag should not be tight or turgid. Leave some slack in the bag as room for
expansion, but get the air out. Briefly rinse the bags in running tap water, and then gently dry
them on paper towels. Carefully weigh each bag to the nearest 0.1 g and record the results
below. BE SURE TO KEEP TRACK OF WHICH BAG IS WHICH! After weighing, place one bag
in each of three labeled beakers containing: (1) tap water, (2) 30% sucrose, (3) 60% sucrose.
Allow the bags to remain undisturbed for thirty minutes. Then, remove the bags, quickly rinse
and dry and reweigh. Again, record the results below.
Table 1. Weight (g) of dialysis bags
Tap Water
30% Sucrose
Weight at Time 0 min
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60% Sucrose
Unit Title: Cells
Grade: 10th Grade Biology
Weight at Time 30
min
Change in Weight
 Which solution is hypotonic to the ‘cell’? ___________________________
 Which solution is hypertonic to the ‘cell’? ___________________________
 What would have happened in the following three beakers if the cell were filled with tap
water instead of 30% sucrose solution?
Tap Water
30% Sucrose
60% Sucrose
Diffusion across a differentially permeable membrane: Dialysis
Dialysis is the diffusion of solute molecules across a differentially permeable membrane.
The cell membrane is differentially permeable. Thus, through dialysis, certain substances may
enter a cell, and certain metabolic products, including wastes, may leave. Depending on the
permeability of a membrane, small solute molecules may pass through, while larger molecules are
held back. Utilizing this principle, it is through dialysis that artificial kidney machines remove the
smaller waste particles from the human bloodstream.
The following experiment demonstrates the separation of different-sized molecules by
dialysis. The two molecules used are starch (a large molecule) and sodium chloride (salt, a small
molecule). In order to determine the presence of each of these molecules, we must be able to
test for them.
Sodium chloride (NaCl) plus silver nitrate (AgNO3) produces a dense white precipitate.
So, if we add silver nitrate to a solution and a precipitate forms, we may conclude that sodium
chloride is present.
Starch plus iodine produces a blue-black color. So, if we add iodine to a solution which
then turns blue-black, we may conclude that starch is present.
 Add 2 drops of sodium chloride and 2 drops of silver nitrate to a culture tube. Record your
results.
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Unit Title: Cells
Grade: 10th Grade Biology
 As a control, in a second tube, add 2 drops of tap water and 2 drops of silver nitrate. Record
your results.
 Add 2 drops of starch solution and 2 drops of iodine to a culture tube. Record your results.
 Again, as a control, add 2 drops of tap water to another tube, and 2 drops of iodine. Record
your results.
Now you have seen what positive and negative tests for both sodium chloride and starch
look like, so you are ready to proceed with an experiment to test the permeability of a
membrane.
Obtain another length of dialysis tubing and tie off one end like you did in the osmosis
experiment. Fill the bag with 2 ml of starch solution, and 2 ml of sodium chloride solution.
Gently squeeze the air out, and tie off the top. Rinse the cell off in tap water, and briefly place it
on a paper towel while you perform the control test below.
Control
 Fill a beaker with tap water, and then place 2 drops from the beaker into each of two wells
on a spot plate. Test one well with 2 drops of silver nitrate, and the other with 2 drops of
iodine. Record your results below. (You could just write the results you got above here –
there is no need to do it again.)
Beaker water -
silver nitrate test
iodine test
(time 0 min)
Experiment
 Now, place the ‘cell’ in the beaker, and record the time __________:_________
 After 30 minutes, remove the cell and place it on a paper towel. Place two drops from the
beaker into each of two wells on a spot plate. Test one well with 2 drops of silver nitrate,
and the other with two drops of iodine. Record your results below (+/-).
Beaker water -
silver nitrate test
iodine test
 What can you conclude from this experiment?
 Why did you do the control?
Osmotic Potential of Plant Cells
20
Unit Title: Cells
Grade: 10th Grade Biology
As you saw last week with the Elodea leaf, living cells have some amount of water inside them,
and some amount of dissolved substance (solute: sugars, salts, proteins). In this part of the lab,
you will measure the amount of water either taken up or lost from living plant cells (cells of
potato tubers), and infer the proportion of the cytoplasm that is water, and the proportion that
is solute.
Procedure:
Skin a potato and cut the tuber into small cubes (approximately 1cm each). You will need
approximately 40 cubes. Divide the cubes into 4 groups of 10. Each group will be immersed for
30 minutes in a different solution. The four solutions you will use are:
A. distilled water (water concentration 100%)
B. 2% saline solution (water concentration 98%)
C. 4% saline solution (water concentration 96%)
D. 8% saline solution (water concentration 92%)
Decide which of your four groups will go into each solution. Blot the cubes dry with a paper
towel, and place them on a weighing boat (dry it first too if it is moist) and weight them to the
nearest 0.01g. Record the initial weight (t=0) on Table 2 below. Place each group of cubes in
their appropriate solutions, and wait 30 minutes (you might be collecting data from the other
two experiments during this time).
At the end of 30 minutes, remove the groups and blot them dry again (being sure to keep track
of which group is which). Record the weight after 30 minutes in the table below. In order to
account for different initial weights, you need to calculate the percent change in mass for each of
your four groups. To calculate the percent change, use the formula:
% change = (weight after 30 minutes – initial weight)/initial weight X 100
Record the % change in the table.
Table 2. Change in weight in potato tissue
Solution
Initial Weight (t=0)
Final Weight (t=30)
0% salt
2% salt
4% salt
8% salt
 Which group had the least amount of change in mass?
 Which group had the greatest amount of gain in mass?
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% Change
Unit Title: Cells
Grade: 10th Grade Biology
 Which group had the greatest loss of mass?
 Which group was in the most hypertonic solution? The most hypotonic?
 What can you infer about the internal tonicity of potato tuber cells? Approximately how
much solute and how much water are present?
When you are done with the lab, open all the ‘cells’, pour the contents down the drain, dispose
of the tubing and potato cubes, rinse and dry all your equipment, and wipe off your lab bench.
22