Science 10 – Unit 3 – Cycling of Matter

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					Science 10 – Unit 3 – Cycling of Matter in Living Systems

                            Chapter 8 – Dynamic Cells

8.1 Membrane Properties
1. Why do cells need membranes?

2. In what ways is an aquarium of tropical fish similar or different form a cell?



Membrane structure
3. Label the following phospholipid molecule:
    hydrophilic           hydrophobic                 glycerol              fatty acids

4. Explain the structure of the cell membrane. Outline the differences between
   hydrophilic and hydrophobic and explain why these areas are important for the cell

5. Give an example of a substance beside the cell membrane that is hydrophilic and
   one that is hydrophobic.

Membranes Contain Proteins
6. Explain the function of proteins in the cell membrane and list some examples of
   substances that require proteins to move into the cell.

Membranes Are Fluid
7. Explain how the fluid – mosaic model of the cell membrane gives the cell certain

8. Fill in the parts of the following cell membrane diagram.

Membrane Function

A Biological Barrier
9. Why do cells need a mechanism for preventing substances from entering the cell?
   List a few of these substances.

10. Why do most organelles like lysosomes require a biological barrier from the rest of
    the cell?

A Selective Filter
11. How does the cell membrane regulate which particles enter and leave the cell?

12. What is meant when the cell membrane is referred to as semi-permeable?

8.2 Transport Across Cell Membranes

Particles Are In Constant Motion
1. Explain Brownian motion and how this principle relates to the selective permeability
   of the cell membrane.

Concentration Gradients
2. Read this section in the textbook and then use a situation from your day and explain
   the concepts of concentration gradient and equilibrium.

Particle Model and Diffusion
3. The following questions are a review of the particle model of matter learned in
   previous studies. Use the following word bank to complete the questions in the
   space provided.

      Particles (atoms)                   Slowly                         Vibrate
        High or Low                     In motion                        Faster

      a. All matter is made up of ____________.
      b. Particles that make up matter are always ____________.
      c. In a solid substance, particles may ___________ but remain in a fixed
      d. Particles in a liquid move ____________ than the particles in a solid.
      e. When a liquid is cooled, its particles move more ____________.
      f. Diffusion is the movement of particles from a region of ____________
          concentration to a region of ____________ concentration.

4. For each scenario, identify what is “diffusing” and explain why. Use scientific

      a. You open the window and smell the fragrant flowers in the garden.

      b. You finish painting a picture and decide to take a break. You dunk your
         paintbrush into some clean water. When you return, you notice that the water
         has turned green.

      c. It is late afternoon, and you meet a friend for tea. Your friend prefers hot tea,
         and you prefer iced tea. Both of you dip a tea bag into your cup of water. In
         the following boxes, draw what you expect to see after 1 min and after 10
          After 1 min

                hot tea                                  iced tea

         After 10 min

                hot tea                               iced tea
5. What is the relationship between temperature and the rate of diffusion? Why?

Predicting Solute Diffusion
6. Each of the 4 aquariums below has an impermeable partition that can be removed.
   Use arrows to show the movement of solutes when the partition is removed.

7. Each of the 4 aquariums below has a semi-permeable partition that prevents the
   flow of starch but allows sugar and NaCl to pass freely. Use arrows to show the
   movements of solutes and water.

Passive Transport

8. What is passive transport and identify the three types.

Diffusion Across Cell Membranes
9. Label areas of high and low concentration on the following diagrams.
    Add arrows to show molecular movement (use a thick arrow [  ] to show large
    movement and a thin arrow [ → ] to show lesser movement.

10. This diagram represents a cell with various molecular species in and around the cell.
    Use arrows to show the NET molecular diffusion of each species of molecule.




Bonus: What basic cell function could be occurring in the above cell?

11. What cell organelle regulates the exchange of matter and energy with its

12. Oxygen and carbon dioxide are able to cross the cell membrane by passive
    transport. What is passive transport and why is it called passive?

Osmosis: The Diffusion of Water Across a Membrane
13. How is osmosis different from diffusion?

14. While many substances enter and leave the cell by diffusion, osmosis refers
    specifically to the diffusion of water. Substances dissolved in water are called
    _______________ and water acts as a ___________________.
   Look at the diagram below. The solutions on either side of the semi-permeable
   membrane are of different concentration.

Whenever you have two solutions separated by a semi-permeable membrane, you have
an osmotic system. Living cells exist in an osmotic system. The solutions in an osmotic
system are given the following specific names to indicate their relative concentrations.

                                High                    Low
                               Strong                  Weak
                              Hypertoni               Hypotonic
                               c (10%                   (2%
                               Solute)                 Solute)

15. A hypertonic solution has a low ___________concentration but a high
    ____________ concentration.

16. A hypotonic solution has a low ___________ concentration but a high____________

17. Isotonic solutions have ____________________________________.

Examine diagram A on page 299.
18. Where is the concentration of water higher, inside or outside the cell?

19. In which direction is the water diffusing? __________________ NOTE: Water
    actually moves both ways but more diffuses__________________ than
    ______________. Look at the size of the arrows.

20. What will this do to the cell cytoplasm? What effect will this have on the cell?

21. Currently the outside of the cell would be labeled ____________, while the inside of
    the cell would be labeled ____________.

22. In diagram B what is this situation called? What way is the water moving?

Consider a paramecium (single celled water organism) living in a freshwater lake.
23. Do solutes within the cell make it isotonic, hypotonic, or hypertonic to the lake

24. If the cell membrane around the paramecium make it semi-permeable (that is,
    permeable to water, but impermeable to solutes), will water diffuse into or out of the

25. Hypothesize how a paramecium would deal with this situation.

26. Briefly explain what will occur in each of the following osmotic systems. Use the
    terms (hypotonic, isotonic, and hypertonic) and the permeability of the membrane in
    your explanation.

27. The following apparatus was set up and left undisturbed for 24 hours. After this
    time, a change had taken place in the size of the dialysis tubing. Describe what
    happened and why. Use the terms, hypotonic, hypertonic and semi-permeable
    membrane in your response.

The story of an undressed egg
In a sea of fresh and salt water.

Purpose: To demonstrate the process of osmosis

Naked egg
3% and 12% salt solution
distilled water
electronic balance

Water is the most abundant substance in the cell and in any living organism. Its
characteristics (specific heat, cohesion, surface tension, etc.) are critical to processes
inside the organism (i.e.: heat distribution) and in the biosphere (i.e.: climate, currents

Osmosis is the NET movement of water through a semi-permeable membrane from a
more diluted solution (hypotonic) to a more concentrated solution (hypertonic).
Remember water can pass simultaneously IN and OUT of the cell.

The cell membrane is said to be semi-permeable because it will allow some things to
pass through it while preventing other substances. Since water molecules are small
they will go in and out of a cell easily. Osmosis is NET movement.

As conditions outside the cell change (drier/wetter) the amount of water inside the cell
changes, it may swell or shrink.

Procedure: (see diagram)
An egg is a large single cell, it can be undressed by placing it in vinegar for about a day
and a half, all the shell is not gone do not try to remove it.
NOTE: Class data is necessary to complete this lab. Therefore everyone must bring an

- Remove your egg from your container with a spoon and rinse under tap water.
- Place the egg gently on a paper towel and pat it as dry as you can.
- Take the mass of the egg.
- Place egg in a solution of 12% salt. Be sure the egg is covered by the solution.
- Leave the solution for 8 minutes.
- Remove with a spoon, pat dry, determine it’s mass and record it on the data sheet.

- Rinse the egg in tap water and place it in a 3% solution for 8 minutes.
- Determine the mass of the egg and record on the data sheet.

- Rinse the egg in tap water and place in distilled water for 8 minutes.
- Determine the mass and record it on the data sheet.
- Calculate the change in mass of the egg in the various solutions.
- Collect and average the class data.
HELPFUL HINT: you may find it easier to have someone in your class act as a
secretary and record all the data for the class. Your teacher can then photocopy the
data for everyone.

Individual Data:
                     12% Salt              3% Salt Solution     Distilled Water
Starting mass g.     1. Dry egg            2. After 8 mins in   3. After 8 mins in
(dry egg)                                  12 %                 3%
Final Mass g.        2.                    3.                   4.
(after 8 minutes)
Change in mass
g. (+/-)


                     12% Salt              3% Salt Solution     Distilled Water
Average starting
mass g.
Average final
mass g.
 Change in mass
g. (+/-)

In the 12% solution, the egg (gained/lost) mass because the solution outside of the egg
was (hypotonic/hypertonic) relative to the concentration of the solution inside the egg.
There was movement of water both in and out of the egg but the net movement was

From your knowledge of osmosis, use the proper terminology to explain what happened

The 3% solution:

The distilled water.
________________________________Hint see #1 above

a) What do you think would happen if you left the egg (animal cell) in distilled water over

b) What do you think would happen if you left plant cells (carrot) over night in distilled

                               OSMOSIS IN POTATOES

Problem: Observe and interpret evidence of osmosis when samples of potato are
placed in various concentrations of salt solutions.


a) If the salt in the solution is more concentrated than in the potato cells, then osmosis
will carry water from _____________________to __________________.
b) If the salt in the solution is less concentrated than in the potato cells, then osmosis
will carry water from _____________________to __________________ and we will
observe that the potato


Test tubes        Cork borer                                 Razor blades
Potato            Distilled water/salt solutions             Ruler


   Fill the test tubes about ¾ full of various concentrations of a salt solution, NaCl(aq), as
    directed by your teacher. Label the test tubes so you will remember the
    concentration of the solution in each one.
   Use the cork borer to obtain 6-potato cores at least 4.0 cm long. Cut each bore in
    the same direction through the potato and work quickly so the cores do not dry out.
   Use the razor blade to trim the 6 cores to the same length and record it.
   Place the potato core in each test tube and leave it for 45-60 minutes.
   Remove each core from the test tubes. Measure each one and record its length.


                                    Potato Length     Potato Length     Change In
Test Tube         Concentration
                                    Initial (cm)      Final (cm)        Length (cm)
                  By Mass


1. In which solutions did the water diffuse into the potato cells? How do you know?

2. Describe the solutions identified in question 1 as hypotonic, isotonic, or hypertonic
   with respect to the potato.

3. In which solutions did the water diffuse out of the potato cells? How do you know?

4. Describe the solutions identified in question 3 as hypotonic, isotonic, or hypertonic
   with respect to the potato.

5. Which solution was the closest to being isotonic with respect to the potato cell? How
   do you know?

                          DIFFUSION AND OSMOSIS
                                FILM NOTES VC 4568

A: Random Movement
Example: ___________________________________________________________
Cause: _____________________________________________________________
Effect of increased temperature: _________________________________________

B: Diffusion
Definition: Movement form areas of ____________ concentration to areas of
__________________ concentration.
Diffusion is NOT affected by the presence of ____________________________

C: Diffusion Through A Membrane
A permeable barrier allows ____________________________________________
Which organelle controls the diffusion into and out of the cell? _________________
Label the diagram and identify a) which molecules are passing through the barrier and
b) evidence for your answer.


(Living/Dead) membranes are selectively permeable. What does this mean?

D: Osmosis
Definition: Diffusion of _________________ through a s______________
p____________________ m___________________.
Label the diagram and describe a) where is the water more concentrated (A OR B)?
b) Why the water level rises.


E: Diffusion and Osmosis in Living Organisms
When a flower wilts, ______________________ diffuses from __________________ to

Two examples of the force exerted by osmosis (osmotic pressure) is/are

Fill in the chart to describe three examples of the importance of diffusion to humans.
Sunstance              Diffuses into       From                 Organ Involved

Why does misting a plant keeps it from wilting?

Why does too much salt on plants kill them?

Facilitated Diffusion
28. What is facilitated diffusion, why is it necessary to the cell and what are some of
    the substances that are facilitated across the cell membrane?

Active Transport
29. Explain what active transport is and give an example.

30. Cells are not limited to using only one process to move materials across their
    membranes. Review the following diagrams. In the spaces below, describe the
    different types of transport that are shown.

Endocytosis and Exocytosis

31. Fill in the blanks on the diagram, using the following terms. You may have to use a
     term more than once.
Cell membrane           vesicle               phagocytosis           exocytosis
solid                   solute                Secreted solute        pinocytosis

32. Describe how the process shown in A works.

33. Describe how the process shown in B works.

34. Describe how the process shown in C works.

35. Is endocytosis a type of active transport or passive transport, or neither type of
    transport? Explain using complete sentences.

36. Explain receptor-mediated transport. Use complete sentences.

Membranes at Work

Water Purification
37. Explain how water is purified through the process of reverse osmosis.

Kidney Dialysis
              Use the following diagram to answer the questions below.

38. Why is the membrane in the dialysis machine semi-permeable?

39. If the blood has 0.1 % glucose and the dialysis machine has a concentration of
    0.1% is there a concentration gradient?

40. Given the situation in #2, one could expect glucose will:
      a. Move from the blood to the dialysis fluid
      b. Move from the dialysis fluid to the blood
      c. Not move at all
      d. Move in both directions equally

41. Would the blood, returning to the body, have more or less wastes in it? Using the
    terms, semi-permeable, concentration gradient and diffusion explain your answer.

42. Would blood cells pass through the tubing? Why or why not?

Controlled Delivery of Medications
43. Explain how the technology of a transdermal patch allows for the delivery of
    medications? Give three examples of substances that are delivered in this

8.3 Cell Size and Function
1.   How big can a cell be? The smallest cell is so small that you require very powerful
     light microscopes to see them. The largest is just large enough to be seen with the
     naked eye. What limits the size? Is there a relationship between the size of the
     organism and the rate of metabolism?

Acquire 27 sugar cubes from your teacher. Don’t eat these as they have bee handled
by people that are not as careful as you are. Assume that each side of the cube is 1cm
X 1cm X 1cm and that each cube is the same size.

Using the number of sugar cubes identified, construct a square and complete the
following table:
# of                           Surface Area                           Surface Area
sugar       Diagram            SA= l x w x # of                       to Volume
                                                      V= l x w x h
cubes                          sides                                  Ratio




2.   Why can’t you have a human sized amoeba?

The Importance of Surface Area to Volume Ratio
3. Why is it important that a cell stays small?

Cell Shape and Surface Area
4. Give three examples of where in living things does surface area to volume ratio is
Example             Description

From One Cell to Many Cells
5. What are some advantages to being multicellular?