Select Page

Q3 – Week 6 – 3/14 – 3/18

                                                                                                                                Jump to:  Tuesday,   Wednesday,  Thursday,  Friday ___________________________________________________________

3/16 – Monday  –   A Day – 

Main focus –                                                                                                                                                         
a)  To Calculate the water potential of extra cellular or intracellular fluid. 
b)  To identify how equilibrium, Flacid, Turgid concepts help setup water potential                      problems.

c)  To compare and contrast active and passive transport.

1.  Water potential = presentation slides 1 – 16
2.  Homework review – Water potential worksheet p.pdf . 
 Isotonic / Hypotonic / Hypertonic
equilibrium = water potential extra cellular = water potential intracellular
 Osmosis vs. diffusion
 Active vs. Passive transport
 Reverse Osmosis – Boat pump.
Last nights Key:

Water potential worksheet Key p.pdf
View Download


This weekend we are learning how water and why water passively diffuses into and out of cells through integral transmembrane proteins called aquaporins.  This diffusion of water is specifically called osmosis and its ability to move across the cell membrane is based on a mathematical concept called water potential (ψ).  Do not get intimidated by the ψ symbol.
The greater the ability for water to reach the aquaporins at the cell membrane the greater the ability the water has to perform osmosis.  We say that in this instance water has high water potential.
The highest water potential water can have is zero.  This would be with water with no solute particles.
                                                                                     ψ water = 0
The lower the ability for water reach the aquaporins at the cell membrane, the lower the ability water has to perform osmosis. We say that in this instance water has low water potential.  The lowest water potential will have the most negative number.
                                                                                  ψ water = negative
The factors that determine the ability of water to undergo movement across a membrane include the dissolved particles in the solution called the solute potential ψsolute  (solute potential) and ψpressure (pressure potential).  Pressure potential can be both positive or negative depending if the pressure helps water get to the membrane (positive) or if it prevents it (negative).
                                                            ψ water =   ψ  pressure  +  ψ solute
Dissolved particles get in the way of water reaching the aquaporins in the cell membrane and thus solute potential is always negative.
                                                                     ψsolute = – iCRT
              i = the number of particles the dissolved particle breaks apart into.
                                                   Example:   NaCl   —->  Na+   +   Cl–   (2 particles)
                                                             So NaCl (table salt) has an i = 2
              C = Concentration value = how much (Molarity)
              R = Gas Law Constant
              T = Temperature (kelvin scale)


There is movement of water in both directions BUT there is OVERALL NET movement of water TO THE Right!
This is because there is higher water potential on the left side of the semipermeable membrane AND there is Lower water potential on the right side due the dissolved particles (getting in the way of water reaching the membrane).  
           The formulas for water potential and solute potential are located in your reference table:


Water Potential  Presentation –

3: Water Potential Lecture:


3/7 – Monday Homework: –

1.  Please complete Water Potential 2 worksheet fixed.pdf and review with the key.
Please skip questions (i) on page 1 and 2.
Water Potential 2 worksheet fixed.pdf
View Download
Water Potential 2 worksheet KEY final.pdf
View Download
2 . Please complete Water Potential Form 2 below. 
*Also there is water potential review lecture that I posted (below the form) if what I did in class is getting you down like a very concentrated solution. 🙂
Water potential form 2:   It’s on Auto-grade!

In the last question please SCROLL TO SEE THE LAST COLUMN!!

2: Cell Membrane Form 2 – 21 -22


3/8 – Tuesday –  B  Day – 

Main focus –                                                                                                                                                          

a)  To observe how diffusion is affected by the ratio of surface to volume.

b)  To calculate water potential, solute potential and pressure potential of animal and plant cells.
1.  Review the Water Potential Form 2.                                                                                                                                         

Water potential Form 2 page complete key p.pdf 
View Download

2.  Begin the Diffusion Lab  –  

1.  Diffusion Lab – Surface area to volume ratio
2. Diffusion races – design a cell – Winner has the greatest mass to second ratio.
Why do we need cells? Why are they so small small?  Why are prokaryotes smaller than eukaryotes?


Diffusion Lab – Grodski new.pdf
View Download

3.  Begin the Water Potential Test


3/8 – Tuesday’s Homework: –

1. Please complete. the Water Potential Test as a take-home. I will have a 1 question bonus when you come in tomorrow.


3/9 – Wednesday –  A Day 

Main focus –                                                                                                                                                          
a) To calculate a surface area to volume ratio.

b) To determine that a high surface to volume ratio will increase the rate of diffusion.

1.  Complete an extra credit question for the Water Potential Test.

2. Complete the surface area to volume lab.

  1. No donut-like holes through the agar cell — cell membranes cannot sustain that shape.
  2. No poking, prodding, touching beaker containing agar cell in vinegar.
  3. Teacher determines when 100% diffusion takes place.
  4. Students mass agar at conclusion of race…cell must not break when handled. Disqualification if cell breaks upon massing (although you can be a bit lenient here).
  5. No slivers or shaved cells.  Cells must be at least 1 cm in width.
  6. Winner = highest ratio of mass divided by time.

Diffusion of acid into the agar shapes:

Today’s Cell Diffusion Races:


3/9- Wednesday’s Homework: –

1. Please complete Table 2 of the the Surface Area to Volume Lab by using the actual time code WHEN          EACH CELL COMPLETELY WENT CLEAR from the video posted above.  Please convert minutes to                    seconds.
2. Using Chapter 11, please answer the following question in the Cell Communication Form 2.                                      
2: Cell Membrane Form 2 – 21 -22


3/10 – Thursday –  B Day 

Main focus –                                                                                                                                                          
a)  To identify the different types of chemical signaling.
b)  To Review the Signal Transduction Pathway.

1.  Review the Diffusion Lab data from the video posted of the cell races.

2.  Water Potential in Guard cells that open and close stomata 
      (slide 23 – 24 of water potential presentation.)


3.   Cell Communication lecture – 

Water Potential  Presentation – slide 23 , 24 – Guard cells

Cell Communication Presentation – 

.  _____________________

3/9 -Thursday’s Homework: –

1. Please make another submission to last nights form.

2. Complete the mini-report  on the “Fight or Flight” response in the shared google doc that I give you.

     We started this in class.
 Please use the Google Doc that I have linked with you and complete the following:
        I would like a mini-report on the “Fight or Flight” response that must include the following:
A) Epinephrine – 
B) Signal Transduction pathway – of Epinephrine – (diagram of pathway)
     1) specifics about how the chemical signal produces a response
    2) What type of receptor was used (pages 211 – 213)
    3) How does does cAMP fit into the other parts of our course? 
C) Evolution
You must use the following the terms: – Please have them highlighted in your google Doc?
Cyclic AMP 
Adenyl cyclase
first messenger
second messenger
Phosphorylation cascade
Adrenal Gland
A Tortoise


Epinephrine pathway —-> Reception by extracellular glycoproteins that are specific for the Epinephrine (chemical messenger).  Although all receptors for Epinephrine are identical and only for Epinephrine the cell response is different for each different cell that has these same receptors.  
Some chemical messengers unlike Epinephrine (large and polar) can pass directly through the cell membrane BUT they still have a receptor molecule in the cytoplasm.


3/11 – Friday – A Day

Main focus –                                                                                                                                                          
a)  To Review the Transduction signaling pathway
b)  To discuss the “domino effect of relaying and activating cellular components’ that lead        to an amplified response.

C)  To identify that non-polar (hydrophobic) chemical messenger have reception from               within the cytoplasm.

1. Review of the Water Potential Test

2. Cell to Cell Communication Lecture Continues:

         a) Long distance vs short distance cell to cell signaling..
         b) Cell Apoptosis –
                1. Embryological development
                2. Life cycle of the lets say Painted Ladies
         c) Termination of signals – Phosphodiesterase (stops the Epinephrine secondary messenger cAMP)
          Apoptosis – programmed cell death.

Cell Communication Presentation – 


3/11 – Weekend Homework: –

1.  Please complete the Photosynthesis Lab – You should only have the conclusion left.

2. Please complete the Diffusion lab – (that we did in class this week) It is due Monday.

3. Complete the following form on another long distance chemical signaling pathway.

    Hormonal Pathway of the Reproductive Cycle.  Yes I DID CHANGE THE FORM!  
   Whatever you did on the what was posted will help you when we do that for Monday night. 
   Please use the following 3 videos to complete the form: You have 2 submissions for this form.

Hormonal Pathway 1 video:

Hormonal Pathway 2 video:

Hormonal Pathway 3 video:

3: Reproductive Cycle Form – Hormonal Pathway Example – 21-22

3: Cell Communication Concert Form 21 -22: For NEXT MONDAY!!!