BCLN BIOLOGY 12 – Rev Sept 2016
2014
Unit 1 ~ Learning Guide
Name:
INSTRUCTIONS
Complete the following notes and questions as you work through the related
lessons. You are required to have this package completed BEFORE you write your
unit test. Do your best and ask questions about anything that you don't
understand BEFORE you write the unit test.
U1L1 NOTES: INTRODUCTION (video)
Homeostasis:
Examples:
1. Blood Glucose Concentration remains about 0.01%
2. PH of blood is always near 7.4 (slightly basic)
3. Blood pressure in the brachial artery averages near 120/80
4. Blood temperature averages ~ 37°C
5. Pancreatic Juice (pH 8.5) neutralizes stomach acids so
that food entering the small intestine is basic.
6. CO 2 concentration in our blood stimulates our breathing.
Negative Feedback:
Control centers in the
_that cause specific body reactions.
Once normalcy is reached, the
is NO LONGER
stimulated. (This is why the process is called
_).
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1
2
3
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Positive Feedback:
Instead of achieving normalcy,
Negative Feedback tends to
system. Positive Feedback leads to
a
.
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U1L1 PRACTICE: INTRODUCTION
1. A woman is being tested for diabetes mellitus. Her blood glucose levels are
measured and recorded over a period of time (data given below). Please
graph the data and answer the associated questions.
Graphing Tips:
! the independent variable is always placed on the x-axis (in this case, time)
! the dependent variable is always placed on the y-axis (in this case, blood
glucose levels as they are dependent on the time)
! each axis needs an informative title that includes units of measurement such
as hours and mg/dL
! the graph needs an informative title
! each square on the graph must represent a consistent value such as 1 hour (xaxis)
or 20 mg/dL (y-axis)
Table 1. Blood Glucose Levels in Patient X over Time.
Time (h)
Blood Glucose
Levels (mg/dL)
0
1
2
3
4
5
100
110
100
80
90
100
Figure 1. Blood Glucose Levels in Patient X over Time
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a. The normal range for blood glucose levels is 70-110 mg/dl. Does Patient X
always remain within the normal range?
b. Does Patient X have any apparent problems with glucose regulation? Why or
why not?
c. Which type of feedback mechanism (positive or negative) is used to regulate
blood glucose levels? Explain your reasoning.
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U1L3 NOTES: WATER (web notes and video)
Water – The Universal Solvent
Because water is the substance that makes life
possible as we know it on Earth, astronomers hope
to find evidence of water on newly discovered plants
orbiting distant stars.
Life on Earth began in the water and evolved there
for 3 billion years before spreading onto land.
Terrestrial organisms are still
tied to water. In fact, most
cells are surrounded by water
and cells themselves are
about 70-95% water.
Background Information
Life as we know it, is based on the
. To be "organic" a molecule must have a carbon atom in it.
For example, vinegar (CH 3 CH 2 OH) is organic, whereas
is not.
The organic molecules in living things are easily grouped into four types.
Understanding these four biochemicals is the focus of Unit 2.
If Not Organic, Why is Water so Incredibly Important?
What happens to the quality of life if the chemical conditions of living things change?
In the formation of
, atoms must bond together to form
. In order to
do this, the
around the various nuclei in
the compound must also be stable. This stability can be achieved through some
degree of
between the atoms.
If the atoms share t he electrons reasonably equally, their association is termed
bond.
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Ionic Bonds
The alternative is a very unequal sharing of electrons.
This is called an
where it seems as though one atom
actually gives
. Neutral atoms
become
when
they
lose
electrons
and
when they gain
electrons.
In between these two extremes is what is termed
.
Polar covalent
molecules have
(regions with
slight positive and negative natures). A water
molecule is an example of this kind of molecule.
Structure of Water
In a covalent bond atoms
to become stable. If
the electrons in a covalent bond are not shared equally by the two atoms, the
molecule is then called a
.
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Polar Molecules
Any
molecule
that
ends
with
. Hence it would be a
the other being the positive dipole.
a
different
charge
is
called
a
. One end being the negative dipole and
Therefore, water molecules behave as
with
one another.
causes water to have some degree
of structure that extends beyond the individual molecules and cause a community
water effect. The overall property is called
,
i.e. the attraction of the
.
This means that water molecules are
to
one another. The negative charge on the oxygen attracts the positively charged
hydrogen some
distance
away
to
produce
a
weak
bond
called
a
.
YOU SHOULD WATCH THE STRUCTURE OF WATER
VIDEO BEFORE PROCEEDING ANY FURTHER!
Hydrogen Bonding
Although hydrogen bonds are weak, the vast number of these bonds gives water
its unique properties. Each water molecule can form hydrogen bonds with
up to
neighbors.
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Water is the Solvent of Life
A
is a mixture of one or more soluble substances, called
, dissolved in a liquid called the
.
A sugar cube in a glass of water will eventually dissolve to form a uniform mixture
of sugar and water. The dissolving agent is the
and the
substance that is dissolved is the
. In our example, water
is the solvent and sugar the solute.
Can you identify the solvent and solute in each of the following
solutions?
Example 1: 15 g baking soda and 100 ml of water?
Solvent:
Solute:
Example 2: Nail polish removed by acetone?
Solvent:
Solute:
Example 3: 1.00L ethylene glycol and 875 mL water?
Solvent:
Solute:
Example 4: Chromium dissolved in hydrochloric acid?
Solvent:
Solute:
Some Key Properties of Water Include:
1. Water acts as a Solvent
Water
chemical substances especially other
and
is
able
to
.
dissolve
Since
many
blood
is
mainly
water, the ability of water to dissolve and transport substances greatly aids
in bringing about necessary
.
2. Water acts as a Temperature Moderator
Water moderates temperature and climate (both internal and external
climates). Water can absorb a great deal of
.
Water
also releases heat
slowly. This property is referred to as a
.
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BCLN BIOLOGY 12 – Rev Sept 2016
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As a liquid evaporates the most energetic molecules are carried away leaving
the lower kinetic energy molecules behind which cools the surface of the liquid
that remains .
Internal example -
External example - Oceans keep surrounding land masses cool in summer
and warmer in winter.
3. Water has a "weird" Density
Liquid water is
than ice (very rare for compounds). Most
materials contract as they solidify, but
water expands. Therefore, ice forms on top of
water
levels.
This oddity has
important
consequences for life. If ice
sank, eventually all ponds, lakes, and even
oceans would freeze solid. During the summer,
only the upper few inches of the ocean would
thaw.
Instead,
the
surface layer of ice
insulates liquid water below, preventing it from
freezing and allowing life to exist under the
frozen surface.
4. Water is Transparent
Light
organisms below.
5. Water is Cohesive/Adhesive
Water molecules
keeps surfaces
to the
.
This
of water
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. Diffusion of gases occurs much more
efficiently
moist surfaces.
(sticking to
each other) among water molecules plays a key role in the transport of water
against gravity in plants.
, is a measure of
the force necessary to stretch or break the surface of a liquid and is related
to cohesion.
Water has a
than most other liquids because hydrogen bonds among surface water
molecules
the surface. Water
behaves
as if covered by an invisible film. Some animals can
on water without breaking the
surface.
(clinging of one substance to another) contributes too,
as water adheres to the walls of the blood vessels.
****Note: Focus on the properties of water that apply to the human body.****
YOU SHOULD WATCH THE FUNCTION OF WATER
VIDEO BEFORE PROCEEDING ANY FURTHER!
What are four important functions of water in the human body?
Example 1:
Example 2:
Example 3:
Example 4:
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U1L3 PRACTICE: WATER
1. Sketch a ball and stick diagram of a water molecule. Label the atoms and
indicate the partial charges that exist in a water
2. What type of bonds are found between hydrogen and oxygen atoms within a
single water molecule?
3. What type of bonds form between two or more water molecules?
4. Use a diagram with 5 water molecules to illustrate hydrogen bonding between
water molecules (start with one molecule in the middle). How many water
molecules can hydrogen bond with a single water molecule?
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BCLN BIOLOGY 12 – Rev Sept 2016
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5. List 3 everyday examples of the cohesive and/or adhesive properties of water.
6. Water is a
(especially other
excellent
molecule. Water
many substances
molecules). This property makes water an
.
7. Use several examples each to explain how water is essential to life on Earth as
we know it with respect to the following properties:
a. Water acts as a Solvent
b. Water acts as a Temperature Moderator
c. Water acts as a Lubricant and Transportation Facilitator
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8 Please indicate whether the statements below are true or false. Please
correct any false statements.
T / F
a. Water molecules can attract other water molecules by
hydrogen bonding.
T / F
b. Hydrogen bonds are stronger than ionic or covalent bonds.
T / F
c. The majority of our cellular reactions occur in water.
T / F
d. Large lakes and oceans tend to moderate local temperatures.
T / F
e. Water is an organic molecule.
U1L4 NOTES: pH, ACIDS AND BASES (web notes and video)
pH
Organisms are sensitive to changes in pH (
).
Acids
An
is a substance that
in a solution. For example when
hydrochloric acid is added to water, hydrochloric acid dissociates to form hydrogen
ions and chloride
ions:
HCL " H+ + ClThe addition of H+ makes a solution more acidic.
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Bases
A base is a substance that increases the hydroxide ion concentration in a solution.
For example when sodium hydroxide is added to water, sodium hydroxide dissociates
to form sodium ions and hydroxide ions:
NaOH " Na+ + OHSolution with more
The pH scale is used to describe how
(the opposite of acidic) a solution is.
are basic solutions.
YOU SHOULD WATCH THE ACID AND BASES VIDEO AND THE pH SCALE
VIDEO BEFORE PROCEEDING ANY FURTHER!
pH Scale
The pH scale, ranging from 1 to 14, compresses the range of concentrations by
employing logarithms. In other words every number on the pH scale is a multiple of
10. pH = -log [H+] or [H+] = 10 -pH
A pH of 7 is a neutral pH where the .
[OH-]
[H+]
=
A pH that ranges between 7 and 14 has more hydroxide ions than hydrogen
ions making it a basic solution and a pH that ranges between 1 and 7 has more
hydrogen ions than hydroxide ions making it an acidic solution. W e can
calculate the the difference in hydrogen ion concentrations at different pH levels by
multiplying or dividing by 10.
For example a pH 6 has
more H+ than at pH 7. A pH of 3
has
more H+ than pH 5 and so
on.
Try the following pH comparisons:
Example 1: pH of 14 has
Example 2: pH of 6 has
more H+ than a pH of 12
more H+ than a pH of 11
The pH scale is just a comparison between the [H+] and [OH-].
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YOU SHOULD WATCH THE SECOND pH SCALE VIDEO and THE
BUFFERS BEFORE PROCEEDING ANY FURTHER!
Buffers
Most
which
control the
in your body, can only operate at
certain
levels. If pH levels change too drastically these biochemicals will
denature
(lose their shape) and no longer function properly.
Example:
• Blood must be at a pH close to
or else we may become ill.
• At the wrong pH the blood cannot transport
as
efficiently.
As you can see then the
can be
+
disrupted by changes to the H and OH concentrations away from their
.
To maintain cellular pH values at a constant level,
.
The function of Buffers is to
when H+ or OH- is added to the solution.
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Buffers are
.
Buffers accept hydrogen ions from the solution when they are in excess and
donate hydrogen ions when they have been depleted
The buffer keeps pH constant
.
Acids are molecules that dissociate to release
ions.
In this respect water acts as a
. HCI on the other
hand is a
because it dissociates to a much greater
extent. Systems with HCI in them have a lot of free
floating around.
Bases are molecules that release
. Molecules like
. Bases have a
because the H+ in an acidic environment will combine with OH- from a base and
form
.
YOU SHOULD WATCH THE DEMONSTRATIONS OF BUFFERS AT
WORK VIDEO BEFORE PROCEEDING ANY
FURTHER!
Note: The first graph shows pH
change without a buffer, while
the second graph shows pH
change with a buffer.
U1L4 PRACTICE: pH, ACIDS AND
BASES
1. Please define the following terms
a. acid
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b. base
c. pH
d. buffer
2. Indicate whether the following pH values represent an acidic, basic or neutral
solution.
a. pH 0:
b. pH 12:
c. pH 7:
d. pH 3:
3. Hydrochloric acid (HCl), a strong acid, is added to a beaker of pure water:
a. What is the pH of the pure water in the beaker before the acid is added?
b. How does the hydronium ion concentration change after the acid is added?
c. What happens to the pH of the solution in the beaker as the acid is
added?
4. How much has the hydrogen ion concentration changed in a solution if its pH
value goes from 6 to 4? Remember to indicate whether this change represents
an increase or decrease in hydrogen ion concentration.
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5. pH balance is very important to biological systems.
a. Why?
b. What prevents rapid or large changes in pH in biological systems?
c. Give an example of where pH balance is important and regulated in a
living organism.
~ END OF BIOLOGY 12 UNIT 1 LEARNING GUIDE ~
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BCLN BIOLOGY 12 – Rev Sept 2016
2014
UNIT 1 ANSWER KEY
U1L1 PRACTICE: INTRODUCTION
1.
A woman is being tested for diabetes mellitus. Her blood glucose levels are measured
and recorded over a period of time (data given below). Please graph the data and answer the
associated questions.
a. The normal range for blood glucose levels is 70-110 mg/d. Does Patient X always
remain within the normal range?
- Yes…ranges from 80-110 mg/dl
b. Does Patient X have any apparent problems with glucose regulation? W hy or why not?
- No…blood glucose levels appear to remain within a normal range
suggesting homeostatic mechanisms are functioning correctly to
regulate blood glucose levels
c. W hich type of feedback mechanism (positive or negative) is used to regulate
blood glucose levels? Explain your reasoning.
- negative feedback loop as the process is maintaining normalcy
(blood glucose between 70-110 mg/dl) as opposed to moving levels
towards an extreme as would a positive feedback loop
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BCLN BIOLOGY 12 – Rev Sept 2016
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U1L3 PRACTICE: WATER
1. Sketch a ball and stick diagram of a water molecule. Label the atoms and indicate the
partial charges that exist in a water molecule. (2 marks)
2. W hat type of bonds are found between hydrogen and oxygen atoms within a single
water molecule? (1 mark)
- Covalent bond (intramolecular)
3. W hat type of bonds form between two or more water molecules? (1 mark)
- Hydrogen bond (intermolecular)
4. Use a diagram with 5 water molecules to illustrate hydrogen bonding between water
molecules (start with one molecule in the middle). How many water molecules can hydrogen
bond with a single water molecule? (3 marks)
4 water molecules can hydrogen bond with
a single water molecule
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5. List 3 everyday examples of the cohesive and/or adhesive properties of water. (3 marks)
- answers may vary but may include;
o movement of water up plant stems
o the ability of water bugs to "stand" on water
o water clinging to a surface such as blood vessels
6
Water is a polar molecule. W ater dissolves many substances
(especially other polar molecules). This property makes water an excellent solvent
7
Use several examples each to explain how water is essential to life on Earth as we know it with
respect to the following properties:
a. Water acts as a Solvent
- dissolves charged and polar molecules such as salts which can then be
transported throughout the body
- dissolves charged such as salts that can then react with one another to form
new ionic compounds
b. Water acts as a Temperature Moderator
- the polarity/hydrogen bonding of water makes it slow to heat and cool
meaning that it helps to maintain a relatively constant body temperature and
global temperature
- the polarity/hydrogen bonding of water also results in it having a high heat
of evaporation making it (in the form of perspiration) an effective coolant on
the surface of the skin
c.
Water acts as a Lubricant and Transportation Facilitator (3 marks)
- the polarity/hydrogen bonding of water makes it cohesive/adhesive such that it
fills and flows through vessels easily making it an effective transport medium
- the polarity/hydrogen bonding of water allows it to remain in a liquid state
at body temperature 9as opposed to a gas as is comparable for most
similar molecules) making it an effective transport medium
- the polar nature of water allows it to stick to other surfaces (adhesion)
which provides lubrication required for the movement of joints, blinking of
eyes etc.
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8 Please indicate whether the statements below are true or false.
false statements.
Please correct any
T / F
a. Water molecules can attract other water molecules by hydrogen bonding.
T / F
b. Hydrogen bonds ions are weaker than or covalent bonds.
T / F
c.
T / F
d. Large lakes and oceans tend to moderate local temperatures.
T / F
e. Water is an organic molecule.
The majority of our cellular reactions occur in water.
U1L4 PRACTICE: pH, ACIDS AND BASES
1. Please define the following terms (4 marks):
a. Acid = compound that releases hydrogen ions in aqueous solutions (increase H+ ions in
solution)
b. Base = compound that releases hydroxide ions in aqueous solutions (increase OH- ions in
solution)
c. pH scale = describes how acidic or basic a solution is, a negative log scale referring to
the concentration of hydrogen ions (H+) within a solution
d. buffer = a substance that resists changes in pH despite the addition of an acid or
base
2. Please indicate whether the following pH values represent an acidic, basic or neutral solution.
a. pH 0: acid
b. pH 12: base
c. pH 7: neutral
d. pH 3: acid
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3. Hydrochloric acid (HCl), a strong acid, is added to a beaker of pure water
a. W hat is the pH of the pure water in the beaker before the acid is added?
-
by definition the pH of pure water is 7 (neutral)
b. How does the hydrogen ion concentration of the solution in the beaker change does after
the acid is added?
-
by definition acids increase the hydrogen ion concentration of a solution
c. W hat happens to the pH of the solution in the beaker as the acid is added?
4.
pH decreases
How much has the hydrogen ion concentration changed in a solution if its pH value goes from 6
to 4? Remember to indicate whether this change represents an increase or decrease n
hydrogen ion concentration.
Thus, the hydrogen ion concentration has increased a 100 fold when pH shifts from 6 to 4.
5. pH balance is very important to biological systems.
a. W hy?
-
Because many cellular activities require the action of enzymes which are
proteins whose three-dimensional structures and accompanying functions are
dependent on a particular pH…changing the pH changes the structure and
inhibits the enzyme's functions and therefore, inhibits cellular activities
b. W hat prevents rapid or large changes in pH in biological systems?
-
buffers
c. Give an example of where pH balance is important and regulated in a living organism.
-
Answers may vary but may include;
o
in the blood (pH ~7.4) to maintain protein structure such as that of
hemoglobin…regulated using the bicarbonate buffer system and
hemoglobin itself
o
in the stomach (pH ~ 2) to ensure activation of digestive
enzymes such as pepsin while also beginning to denature (unfold)
ingested proteins…regulated by parietal cells that release
hydrochloric acid
o
in the small intestine (pH ~ 7) to ensure the activation of
digestive enzymes such as trypsin…regulated by bicarbonate
released into the small intestine by the pancreas
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