M5 Biology 2 – SC30242
Name / #: _______________________________________
Respiration Lesson 3 – Aerobic vs. Anaerobic Respiration
Introductory Activity: Exercise!!! What happens when exercise the same muscle(s) for a long time without giving
them any rest? Describe the how it feels! Why does it feel this way, and where does this burning come from? How
do you feel after a long or strenuous sports match? Do you feel sore the day after performing fun sports? Why?
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Graphing our Oxygen Debt – Play rock-paper-scissors in your group to see who the brave volunteer will be. Have
them do some exercise: 20 push-ups, 30 jumping jacks, and 10 “burpees.” Complete the graph below!
Count # of beats in
Resting Rate
Immediately after
2 minutes later
12 minutes later
20 seconds and
(before exercise)
exercise
multiply by 3
Heart Rate
(Beats per minute)
What do you notice about the heart-rate immediately after exercise, and then two minutes later? Why does the
heart-rate not immediately decrease once the exercise has been completed? Take a guess!
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Cellular Respiration Part 1: Where does our body’s energy come from?
1) ATP stands for _______________________________. It is the main energy molecule, and the perfect energy
storage ‘currency’ used by most organisms’ cells. The ATP molecule is composed of a sugar molecule,
__________________, which is attached to a base, ____________________, and a string of three
____________________ molecules, which can be ________________ when energy is needed, or
___________________ when extra energy, from sunlight (in plants) or from food, needs to be stored!
2) An enzyme, _______________________, triggers the release of a phosphate group from ATP to create ADP,
which stands for Adenosine Di-Phosphate; lots of energy is also released in the process!! Further energy can
be produced by releasing another phosphate molecule, which forms AMP.
AMP stands for: ______________________.
When extra energy is available, the reverse reaction occurs, and phosphate groups are added back on.
AMP
ADP
ATP
What is ATP used for in our body’s cells, and particularly in our muscles? (see textbook p.226-227)
Cellular Respiration Part 2 -- Aerobic Vs Anaerobic Overview
3) PREDICT: Is all the energy that comes from our food used at one time? What
would happen without our body’s ability to create and utilize ATP when energy
is needed? Observe what happens when food energy is released all at once!
________________________________________________________________
4) The first stage of cellular respiration is called _________________, and occurs WITHOUT _______________,
in the cytoplasm of cells. It is a VERY fast process; in just a few milliseconds, __________ of ATP molecules
can be produced!
a. Why is the speed of glycolysis significant to our lives??
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b. What is a disadvantage to the speed of the anaerobic glycolysis process?
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5) Glycolysis comes from two Greek words:
Glukus, meaning ____________, and lusis meaning to loosen or release!
6) During glycolysis, 2 ATP molecules are used to break down a single 6-Carbon glucose molecule and re-form
the bonds to produce TWO (2) Pyruvic Acid molecules (each using 3 of the Carbon atoms from glucose) and
enough energy to form FOUR (4) ATP molecules.
Anaerobic Respiration Input
Anaerobic Respiration Output
Net Output:
Net Equation:
Aerobic and anaerobic processes produce and use ATP at incredibly high rates. One estimate states that
more than 2 x 1026 molecules or ~160kg of ATP is formed in the average human body EACH DAY!!
Complete the right side
of the compare and
contrast chart. Quiz
yourself -- Complete the
rest later when you
study for the test and
exam!!
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M5 Bio Lesson 4 – Aerobic Vs. Anaerobic Respiration Part 2: Oxygen Debt, the Sequel!!
1) Two molecules of pyruvic acid are produced for every molecule of ____________________ that’s consumed
during ___________________________.
2) Another important molecule for all steps of cellular respiration is called NAD+, which stands for
_________________ _____________________. The ‘+’ represents a missing electron from the NAD+
molecule. For every ONE molecule of glucose broken down during glycolysis, TWO NAD+ molecules are
given electrons (See Fig. 9-8, p. 263). An NAD+ molecule gets back its electrons by bonding with a hydrogen
atom, to become _____________.
3) NADH is brought inside the mitochondria of the cell, where the electrons are used as part of the aerobic
process called the _________________________ transport chain (E.T.C.), which requires
_________________ to operate!
4)
Without Oxygen, the NADH molecules can’t drop off their electrons at the E.T.C.! Because glycolysis
happens so quickly when we need ATP (especially during exercise), soon there’s nowhere for the NADH
molecules to go with their electrons, and no more NAD+ available for glycolysis! Without ____________
molecules, glycolysis can’t happen!!
5) A process called ___________________ allows cells to recycle the extra electrons from NADH, which
regenerates NAD+ and allows ____________ production through ________________ to continue!
In humans, the main waste product of this process causes a burning sensation that damages the cells, and
limits how long it can be used for fueling glycolysis!
a. This type of fermentation is called _____________________ _______________ fermentation,
represented by the following chemical equation:
Pyruvic Acid + NADH  Lactic Acid + NAD+
b. How many times must this happen to power the breakdown of ONE glucose molecule?
6) What happens to this ‘waste’ that our cells produce in times of desperate need? ________________ is
required to help clear our cells of the lactic acid that builds up, hence the term “______________ Debt”!
7) This acidic waste product limits how much ‘hard’ exercise we can do to about 60-90 seconds.
Time:
30 seconds
60
90
120
150
# of taps
8) When doing intense exercise, glycolysis and lactic acid fermentation provides enough ATP for ~ 90 seconds in
the average person.
a. How long did you last before you really felt the ‘burn’? ________ seconds.
b. How long before you were unable to continue at an ‘extreme’ pace? ___________ seconds.
c. Despite a deep burning sensation, you probably weren’t breathing heavily after this exercise (if you
were, start going to the gym!). Does this mean there was no ‘oxygen debt’ acquired? (y / n)
Why (or why not?) _____________________________________________________________.
d. Why would you breathe much more heavily after, say, a 90 second sprint than an exercise like what
we just did?
Anaerobic + Aerobic Respiration Summary Questions (answer them in your Biology notebook ):
i)
Explain ‘Oxygen Debt’ in terms of anaerobic respiration, and our body’s need to rest for several minutes,
even after we’ve stopped exercising.
ii)
When most people suffer a heart-attack, their heart stops beating. The heart is the most active muscle
in our body, and requires a constant supply of blood; those that survive are often left with scar tissue on
their heart itself, putting them at risk for future heart attacks and problems. Explain how this scar tissue
forms, using your knowledge of cellular respiration!
iii)
Explain why we would be in ‘trouble’ during strenuous exercise or sports matches if our body’s cells
couldn’t perform Lactic Acid fermentation, and had to respire anaerobically the same way that yeast
does.
iv)
Draw a cartoon or write a story to represent the different Aerobic and Anaerobic respiratory processes
we’ve covered so far. If you can’t think of a different idea, think of each process in terms of a factory,
restaurant, business, market-place, or perhaps a town that uses ATP as a currency or perhaps to stay
alive. Next week, each group will make a poster that utilizes the best idea your group can come up with
to explain cellular respiration and the complex processes within it.
v)
List 5 important products that utilize fermentation in their manufacturing process. What does this
process do to the food that has had a major impact on human survival, both in the past and in the
present?
i)
When we exercise, our muscles require large amounts of oxygen to help provide them with energy.
Muscle cells also contain larger numbers of mitochondria than other cells; why is this?
ii)
Certain desert animals obtain all their water from the food they eat… but food doesn’t provide them
with all the water they need. Aside from drinking, where does the rest of the water come from?
More about Oxygen Debt:
Unlike aerobic respiration which provides 38 units of ATP per molecule of glucose Anaerobic only provides 2
molecules of ATP so it is far less effective at supply the body with energy.
Once the period of exercise is over the body needs to convert the lactic acid back into pyruvic acid. This conversion
needs oxygen…. So our body builds up an oxygen debt we owe cells oxygen to convert lactic acid into Pyruvic acid.
At the end of anaerobic exercise we often feel very out of breathe and tired. This period of heavy breathing after
anaerobic exercise is our body paying off the oxygen debt -- and converting the outstanding lactic acid back into
Pyruvic acid.
Answers: