Dispatch pg 88—Draw AND summarize this diagram in your
big notebook using the terms: low concentration gradient,
high concentration gradient, protein, lipid bilayer, ATP
simple
diffusion
facilitated
diffusion
active
transport
ATP
Getting organized
• Draw an outline of procedures for parts
A, B, C in your packet
Write questions that you have for each
section
• Note, page 7 out of order in packet
Lab report
• 1 page background on topic
• Graphs for parts A, C
• All 3 data tables
• 2 page discussion on why for A, B, C
Movement of Water
• Diffusion
–Random movement of molecules
from an area of HIGH concentration
to a LOW concentration
• Eventually reaches DYNAMIC
EQUILIBRIUM
Osmosis
• Movement of
WATER through a
semi-permeable
membrane, from
areas of high
water
concentration to
area of low water
concentration
Osmosis
• Things that can affect the movement of
substance across membranes
• Gravity
Pressure
Solute concentration
Water Potential
• High water potential = Purer water,
LESS SOLUTE
• Low water potential = less water,
MORE SOLUTE
Osmotic Potential
• The pressure required to stop the
osmotic movement of water across
a membrane
Maintaining Structure
• Tugor
– Water pressure within cells that
maintains rigid cell walls
• Plasmolysis
– Loss of turgor in cells
– Water diffuses OUT of
cells
Objectives
After doing this laboratory, students
should be able to
• measure the water potential of a
solution in a controlled experiment
• dermine the osmotic concentration
of living tissue or an unknown
solution from experimental data
• relate osmotic potential to solute
concentration and water potential
Set up of a gradient
• Outside the cell represented by the cup
• Inside the cell represented by dialysis
tubing
Part A
• Make a predication, based on your
knowledge of molecular size &
movement, which molecule will move
in or out of the tubing.
• Cups will have water, bags will have
0.2, 0.4, 0.6, 0.8, 1.0 M of sucrose
Logistics
•
Leave space in “cell”. Tie knot at the end of the
tubing
1)
• 2) Groups combine data, 1 group can make 2
bags, 1 group can make 3 bags
Tables 1,2,3
Tables 4 +5
Tables 6+7
Tables 8 +9
3) Beakers not labeled so record color
4) Label cups
• Fill in data, calculate changes
• Graph changes, make calculations
Tube Contents
Distilled Water
0.2 M Sucrose
0.4 M Sucrose
0.6 M Sucrose
0.8 M Sucrose
1.0 M Sucrose
Initial Mass
Final Mass
Percent Change in Mass
Part B—Use Elodea cells to view
plasmolysis. This must be verified
• PLASMOLYSIS
Part C
• Design an experiment to show how
much water and sugar is in a
potato.
• Independent____________
• Dependent_______________
To leave copy in NOTEBOOK
• Data table for C
• hypothesis
Part C – Osmosis in Living Cells
• Find change in mass in potato cores
surrounded by different sucrose
solutions over 24 hours.
– Graph changes, find potato molarity
– Calculate water & osmotic potential
Distilled 0.2 M
Water sucrose
0.4 M
0.6 M
sucrose sucrose
1.0 M
0.8 M
sucrose sucrose
Logistics
1) Be safe when using knife
2) Make sure potato pieces are
similar sizes
3) Label cups
Dispatch
1) Label each side as hypertonic, hypotonic or
isotonic
2) What is plasmolysis?
3) What needs to be in this lab report?
4) What would you ask a former Lawndale student
who is now in college?
Annotate water potential paper
and answer 1-2
Last 3 assignments of the semster—FRQs + Final + Diffusion lab report
Morris’
Office Hours
Number of students
with that grade
Period 2 AP BiologyGrade distributions
12
10
8
6
4
2
0
Series1
F
D
C
B
A
Grades
W—Lunch
Th—Lunch
+ After
school
Fr—After
school
15
10
Series1
5
0
F
D
C
B
A
Grades
Period 5 AP Biology Grade Distribution
Number of students
with that grade
T—Lunch
Number of students
with that grade
Period 6 AP Biology Grade Distribution
10
8
6
Series1
4
2
0
F
D
C
Grades
B
A
3 assignments + ways to get a
high score
• 2 FRQs…work through all 10
possible FRQs
• Final……flashcards + review book
• Lab……..do it! Ask questions
Bring an approved calculator, no cell
phones
Lab report
• 1 page background on topic
• 2 data tables for parts A, C
• 2 Graphs for parts A, C
• Descriptions before and after for part B
• 2 page discussion on why for A, B, C
• Packet with questions answered
Turn in quality work—there may not be time for retakes
Calculator Policy
•
A four-function calculator (with square root) is permitted on both the multiple-choice and
free-response sections of the AP Biology Exam since both sections contain questions
that require data manipulation. No other types of calculators, including scientific and
graphing calculators, are permitted for use on the exam. Scientific calculators have a
more complicated, multi-row layout that includes various special-use keys, including
ones for trigonometric and logarithmic functions such as SIN, COS, TAN, TRIG, LOG,
and LN. In contrast to scientific calculators, four-function calculators do not include
trigonometric and logarithmic functions, statistical capabilities, or graphing capabilities.
Students may bring up to two four-function calculators (with square root) to the exam.
Four-function calculators have a one line display
1) simple layout of numeric keys (e.g., 0-9)
2) arithmetic operation keys (e.g., +, -, ×, and ÷)
3) limited number of special-use keys (e.g., %, +/-, C , and AC).
4) Simple memory buttons like MC, M+, M-, and MR may also be included on a four-function
calculator.
Advice: Go to 99cent store
Concentration of water
• Direction of osmosis is determined by
comparing total solute concentrations
– Hypertonic - more solute, less water
– Hypotonic - less solute, more water
– Isotonic - equal solute, equal water
water
hypotonic
hypertonic
Osmosis is just diffusion of water
• Water is very important to life,
so we talk about water separately
• Diffusion of water from
HIGH concentration of water to
LOW concentration of water
–across a
semi-permeable
membrane
Water Potential
•
Water potential (MegaPascal, or Ψ) is
the sum of pressure potential (ΨP) and
solute potential (ΨS):
Ψ = ΨP + ΨS.
•
•
•
•
The addition of solutes reduces water
potential (to a negative value).
Application of physical pressure
increases water potential.
The increased physical pressure can
reverse the effects of the solutes .
A negative pressure reduces water
potential (on the other side).
Do you understand
Osmosis…
.05 M
.03 M
Cell (compared to beaker)  hypertonic or hypotonic
Beaker (compared to cell)  hypertonic or hypotonic
Which way does the water flow?  in or out of cell
Managing water balance
• Cell survival depends on balancing
water uptake & loss
freshwater
balanced
saltwater
1
Managing water balance
•
Hypotonic
– a cell in fresh water
– high concentration of water around cell
• problem: cell gains water,
swells & can burst
• example: Paramecium
– ex: water continually enters
Paramecium cell
KABOOM!
• solution: contractile vacuole
– pumps water out of cell
–
– ATP
plant cells
• turgid = full
• cell wall protects from bursting
No problem,
here
freshwater
Pumping water out
• Contractile vacuole in Paramecium
ATP
2
Managing water balance
I’m shrinking,
• Hypertonic
I’m shrinking!
–a cell in salt water
–low concentration
of water around
cell
• problem: cell loses
I will
water & can die survive!
• example: shellfish
• solution: take up
saltwater
3
Managing water balance
• Isotonic
That’s
perfect!
–animal cell immersed in
mild salt solution
–no difference in
concentration of water
between cell &
I could
be better…
environment
• problem: none
– no net movement of water
» flows across membrane equally, in both
balanced
Plasmolysis
• Plasmolysis is the process in plant
cells where the cytoplasm pulls
away from the cell wall due to the
loss of water through osmosis.
This occurs in __________solution.
Your tasks
1) Calculate % change in mass for A + C
(Final mass-Initial mass / Initial mass )X100=
2) Figure out which color solution is 0.2,
0.4, 0.6, 0.8, 1.0 and confirm with Morris
3) Graph part C (look at zucchini set up)
4) Share with group WHYs for each part
(Hypertonic, hypotonic, water potential,
diffusion/osmosis, sucrose, membrane,
water etc)
5) Outline FRQs or make flashcards for
final
•
•
Calculator Policy
A four-function calculator (with square root) is permitted on both the multiple-choice
and free-response sections of the AP Biology Exam since both sections contain
questions that require data manipulation. No other types of calculators, including
scientific and graphing calculators, are permitted for use on the exam. Four-function
calculators have a one line display and a simple layout of numeric keys (e.g., 0-9),
arithmetic operation keys (e.g., +, -, ×, and ÷), and a limited number of special-use
keys (e.g., %, +/-, C , and AC). Simple memory buttons like MC, M+, M-, and MR
may also be included on a four-function calculator.
•
Scientific calculators have a more complicated, multi-row layout that includes various
special-use keys, including ones for trigonometric and logarithmic functions such as
SIN, COS, TAN, TRIG, LOG, and LN. In contrast to scientific calculators, fourfunction calculators do not include trigonometric and logarithmic functions, statistical
capabilities, or graphing capabilities. Students may bring up to two four-function
calculators (with square root) to the exam.
12 min dispatch—Take out FRQ for final and annotate 1
question, then solve below (use aproved calculator)
What happens to a protein
after translation?
• Pick up a script and practice with a
partner.
• http://bcs.whfreeman.com/thelifewire/cont
ent/chp04/0402002.html
• Answer is your notebook what happens to
a protein AFTER translation pg 104-109
• Pg 138—Exocytosis and endocytosis
Dispatch
Dispatch
1) Draw and explain exocytosis. Use the book pg
138
2) What would Darwin say about genetic
engineering? Use book pg 397 and your
knowledge of Darwin
3) What would Darwin say about Hardy-Weinberg?
3) The allele frequency of dominant is 0.7, what
percent of population is heterozygous?
Take out FRQ paper
Biotechnology
•Combining DNA of 2
or more species
Insulin is made by using
recombinant DNA
So are
crops
And our meats
Tools—copy on pg 88
• DNA scissors are restriction
enzymes. These cut the desired
genes.
• DNA glue is ligase. This is used to
glue the 2 pieces of DNA together.
• Plasmid is the circle DNA from a
bacteria. When bacteria reproduce
they make multiple copies of the
Transport in humans and
plants
• What do humans transport? How?
• What do plants transport? How?
Hint pg 775
•
•
•
•
•
•
•
•
•
•
•
•
PROBLEM ONE: The initial molar concentration of the cytoplasm inside a cell is 2M and
the cell is placed in a solution with a concentration of 2.5M.
Initially, free energy is greater inside the cell than outside
It is possible that this cell is already in equilibrium with its surroundings.
Initially, solute concentration is greater outside the cell than inside.
Water will enter the cell because solute potential is lower inside the cell than outside.
The cell will become flaccid because the pressure potential is greater outside the cell
than inside.
The cell is already in equilibrium with its surroundings because of the combination of
pressure potential and solute potential inside and outside the cell.
Initially, the cytoplasm is hypertonic to the surrounding solution.
Initially, the numerical value of the solute potential is more negative inside the cell than
outside.
Net diffusion of water will be from inside the cell to outside the cell.
At equilibrium, the molarity of the cytoplasm will have increased.
At equilibrium, the pressure potential inside the cell will have increased.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
PROBLEM ONE:
A
B The cell must lose water to reach equilibrium. There is no way
pressure can build up to bring the cell to equilibrium.
A
B Water will leave the cell because solute potential is higher
inside the cell than outside.
B The cell will become more flaccid because the solute potential
is greater inside the cell than outside.
B The cell is not in equilibrium because there is no pressure
potential inside the cell and none will build up when water leaves the cell.
B ...... cell is hypotonic to the surrounding solution.
B ...... more negative outside the cell than inside.
A
A
B ..... pressure potential inside the cell will remain zero.
Osmotic Potential of Sucrose
• Draw the straight line that best fits
your class data.
• The point
10
where it
8
crosses the 6
4
x-axis
2
represents 0
-2
the molar
-4
concentration
of potato.
12
Dist
H20
0.2 M
0.4 M
0.6 M
0.8 M
1.0 M
Osmotic Potential of Sucrose
=-ICRT
I = the ionization constant (for sucrose this is 1
because sucrose does not ionize in water)
C = osmotic molar concentration
(to be determined)
R = pressure constant (handbook value R = 0.0831
liter bars/mole °K)
T = temperature °K (273 + °C of solution)
Designed by
Anne F. Maben
These images are for
viewing only and may not
be published in
any form
Explain the endosymbiotic
theory
Describe Cytoskeleton
Identify the hypertonic and
hypotonic and/or isotonic
Results
•
•
•
•
•
•
Yellow—0.0 M
Dark green—0.2 M
Black—0.4 M
Blue—0.6 M
Clear—0.8 M
Olive green—1.0 M
Why + 5 WORDS FROM WORD BANK
Water potential
• http://www.phschool.com/science/b
iology_place/labbench/lab1/watcalc
.html
Part C – Osmosis in Living Cells
• Fill in data, calculate changes
• Graph changes, make calculations
Beaker Contents
Distilled Water
0.2 M Sucrose
0.4 M Sucrose
0.6 M Sucrose
0.8 M Sucrose
1.0 M Sucrose
Initial Mass
Final Mass
Percent Change in Mass
A Review
•Which size cube has the BIGGEST
surface to Volume ratio?
•Why is this important?
Osmotic Potential of Sucrose
• Draw the straight line that best fits
your class data.
• The point
10
where it
8
crosses the 6
4
x-axis
2
represents 0
-2
the molar
-4
concentration
of potato.
12
Dist
H20
0.2 M
0.4 M
0.6 M
0.8 M
1.0 M
Osmotic Potential of Sucrose
=-ICRT
I = the ionization constant (for sucrose this is 1
because sucrose does not ionize in water)
C = osmotic molar concentration
(to be determined)
R = pressure constant (handbook value R = 0.0831
liter bars/mole °K)
T = temperature °K (273 + °C of solution)
Dispatch
• Look at this data
and answer
WHY
And
use the following
terms (substrate,
enzyme,
denature, bonds,
active site)
Conditions
Products Created (mm)
Cold
12 mm
Hot
45 mm
Salt
33 mm
Acid
7 mm
Control
37 mm