Bioenergetics Test Review
Enzymes and Metabolism
1. Define the following terms:
a. Anabolism – This is the assembly of molecules
b. Catabolism – This refers to the breaking down of a molecule
c. Dehydration – Joining of two compounds in association with the loss of a water molecule
between them.
d. Hydrolysis – The process of splitting a compound into fragments with the addition of
water; a kind of reaction that is used to break down polymers into simpler units, e.g.
starch into glucose.
e. Endergonic – absorbs energy from the environment
f.
Exergonic – releases heat to the environment
2. What is it about the shape of ATP that allows it to be used for energy?
Has 3 negative phosphates linked together which makes it highly unstable like a “compressed
spring”. Unstable, means it has the capacity to perform work.
3. What is a substrate?
This refers to the molecule that is being affected by the enzyme. (What the enzyme is grabbing
and working on.)
4. What type of organic molecule are most enzymes?
Proteins
5. What is the active site of an enzyme?
This refers to the location where the chemical reaction(s) is taking place between the enzyme and
substrate.
6. How do enzymes affect the reaction rate?
The energy of activation is lowered by the action of enzymes
7. What is activation energy?
This refers to the Free E used to start a chemical reaction in motion. (Essentially is the energy
needed to get the molecules moving and positioned so that it is possible to combine or be torn
apart.)
8. How does an enzyme affect activation energy?
Enzymes reduce by grabbing the molecule and positioning it correctly… we don’t have to wait for
nature to do it.)
9. In the diagram above, which is the activation energy with an enzyme? (A or B)
a. Reaction A requires (more or less) energy than reaction B?
10. What is the induced fit model?
Creates the Enzyme-Substrate Complex. (Complex means “more than one piece in the unit”.)
11. List 3 factors that can affect an enzymes ability to work optimally.
a.
b.
c.
Temperature – freeze/cold (cold things don’t move quickly) or Heat causing it to Denature
(“unfold”).
pH of the environment
Salt concentrations
12. How is an enzyme affected by being outside its “range” (such as pH or temperature range)?
Denatures
13. What does it mean when an enzyme is denatured?
unfolds
14. Describe two types of inhibitors, how are they different?
1. Competitive- These molecules compete for the active site. (This is because of similar
shape.)
a. These molecules slow down the reaction rate. (These molecules will be
removed.)
2. Non-competitive –These molecules attach somewhere other than the active site causing
the shape of the active site to change so the substrate can’t fit into it.
a. These molecules cause the reaction to stop completely
15. Explain what the diagram below is showing.
The point of this diagram is to show that enzymes work better in specific conditions. If
an enzyme is out of that condition, it can denature.
r

I would also encourage you to study the
parts of an enzyme.
Photosynthesis:
1. Draw a chloroplast and label the following: a) stroma, b)granum, c) thylakoid, d) thylakoid space
(The thylakoid space is simply the space between each thylakoid)
2. Where is the majority of chloroplast located in a plant?
Leaf
3. What is the name of the MAIN pigment that absorbs sunlight in chloroplast, and why is this
pigment green (NOTE: This is not the only pigment responsible for light absorption. It is just the
main one)?
* A light-absorbing pigment found in chloroplasts of plants, algae, and blue-green bacteria.
A. Found mainly in the mesophyll layer of ground tissue in plant leaves. (“meso” refers to “middle”)
B. “phyll” means “pigment”; “”chloro” means “green” (They reflect green light.)
4. How does a plant receive or release each of the following: a) oxygen, b) carbon dioxide, c)
sunlight, d) water
A) Stomata
B) Stomata
C) Leaf
D) Roots
5. What is the green tissue in the interior of leaves where chloroplast are located called?
Mesophyll
6. What is the balanced equation for photosynthesis (Draw arrows between the reactants and
products to show what product each reactant becomes)?
7. What is being reduced in this equation? What is being oxidized?
Carbon Dioxide to Glucose =Reduced
Water to Oxygen= Oxidized
8. What are the 2 stages of photosynthesis?
1. Light Reaction
2. Calvin Cycle
9. Explain in detail the following for each stage: a) where the stage occurs, b) What are the
reactants and products of each stage, c) what is the “purpose” of each stage. ( You obviously
won’t have this much).
Light Reaction of Photosynthesis
A. This process is used for converting sunlight into usable chemical Energy molecules. (These molecules are: ATP
and NADPH)
a. ATP = energy (like battery); The ATP made here in the chloroplast is used ONLY for making sugar (not
for any other processes the plant/algae needs it for).
b. NADPH = electron carrier
i. Remember electrons are responsible for all energy in nature. Hydrogen was the LEAST
ELECTRONEGATIVE element (wanted its electrons) the least. NADPH carrier the H on it to
the next stage where it will drop off H to release its electron to be used.
B. These two parts are occurring, in the presence of sunlight, at the same time on the Thylakoid membranes.
C. There are thousands of these Photosystems (I and II) on each Thylakoid membrane.
Step 1: Sunlight hits, and splits, the water in the stroma. It also hits the photosystems I (P700) and II (P680).
Step 2: 2 Excited electrons travel down the electron transport chains. They came from the Mg in the Chlorophyll A
molecule. (The 2 excited electrons were able to leave the Mg because the sunlight heated them up and
made
them move much faster. Fast enough to escape the pull from the nucleus’ positive protons) As the excited electrons go down the
electron transport chain, their excited kinetic E (also called Free E) is being
used to power the proteins called Proton pumps.
(Remember, a proton is a Hydrogen ion and is shown as
H+) As the electron go down their chain, their excited kinetic E
decreases.
A. P680’s 2 excited electrons
1. Free E of the electrons is used to actively transport protons (H+) into the confined thylakoid
space.
(As the [H+] goes up inside the space. The [H+] goes down in the stroma. So a concentration
gradien is created. This is a source of potential E now.) (It would be like blowing air into a
balloon. The pressure builds as more air is blown in. This is also an example of potential E.)
A. P700’s 2 excited electrons combine with NADP+, to make it negative so that NADPH can be generated.)
Step 3: The trapped H+, inside the Thylakoid, are released through the ATP Synthetase Complex. This is the group of enzymes
in the Thylakoid membrane that helps make ATP. Just look at its name. (This release of kinetic H+
powers the phosphorylation of ADP ATP.) (This would be like the air coming out of the blown up balloon and
turning a pinwheel.
A. This Kinetic movement of H+ produces a large amount of ATP.
B. This is an example of Energy Coupling (Two processes working together to make ATP. The first
process
was Active transport to pump the H+ into the Thylakoid to make the concentration gradient. The second process is a type of
diffusion. The H+ going from high [ ] to low [ ]. The kinetic movement of the H+ fuels the production of ATP.) This is
Chemiosmosis.
Step 4: ATP and NADPH will now be used to power the fixing of CO2 into sugar in Calvin Cycle.
Summary of Light reactions: Absorb solar energy and convert it to chemical energy stored in ATP and NADPH
Photosynthesis – Part 3
I. Calvin Cycle (A.K.A light independent reaction or dark reactions)
A. Called light independent reactions because they don’t directly require light. Even so, they still happen in the day
because they require the products of the light reactions (ATP and NADPH).
B. This part uses the ATP and NADPH of light reaction to make sugar using CO2.
C. Occurs in the stroma.
D. Carbon fixation – incorporation of carbon from inorganic CO2 into glucose using ATP and NADPH from light
reactions. There are 4 steps to making a single sugar molecule:
Step 1: 3 CO2 molecules will be used, in the chloroplasts stroma, by the enzyme Rubisco to make
G3P molecules. (Half of a sugar molecule.)
The energy to power the conversion comes from ATP and NADPH.
ATP provides the energy while NADPH provides the H to put onto CO2. Remember the ATP made
in the chloroplast is used only for making sugar.
Step 2: 1 G3P will be removed to put toward making sugar.
Step 3: The remaining G3P will be used to keep step 1 working.
Step 4: Repeat steps 1  3 to make the second half of the sugar molecule.
E. These sugars will be needed to feed the whole plant or algae. The sugars will be consumed in the process of cellular
respiration or stored to be used later or passed to consumers in a food chain.
Summary of Calvin Cycle: Take ATP and NADPH made from Light Reactions to convert CO2 into
glucose.
10. What is the the purpose of NADPH?
NADPH = electron carrier
i. Remember electrons are responsible for all energy in nature. Hydrogen was the LEAST
ELECTRONEGATIVE element (wanted its electrons) the least. NADPH carrier the H on
it to the next stage where it will drop off H to release its electron to be used.
11. What is carbon fixation?
The process by which photosynthetic organisms such as plants turn inorganic carbon (usually
carbon dioxide) into organic compounds (us. Carbohydrates).
12. Use the following terms to complete the diagram below showing a summary of Photosynthesis:
ATP and NADPH (together as one number), ADP + P and NADP+ (together as one number), light,
Light Reactions, Calvin Cycle, H2O, CO2, O2, Glucose
1) Light
2) H2O
3) CO2
4) Light Reactions
5) Calvin Cycle
6) ADP + P and NADP+
7) ATP and NADPH
8) O2
9) Glucose
Cell Respiration:
1. Which of the following make ATP for energy: prokaryotes, plants, animals?
All, but prokaryotes will not produce as much
2. Explain your answer for #1.
Organisms that perform cellular respiration instead of fermentation produce more ATP
3. Which of the following USE MITOCHONDRIA to make ATP: prokaryotes, plants, animals?
Plants and animals
4. Explain your answer for #3.
Prokaryotes do not have membrane bound organelles.
5. What is the balanced equation for cellular respiration (Draw arrows between the reactants and
products to show what product each reactant becomes – Remember to look for the flow of
hydrogens)?
6. What is being oxidized in cellular respiration? What is being reduced?
Glucose to Carbon Dioxide= Oxidized
Oxygen to Water = Reduced
7. Draw a mitochondria and label the following: a) outer membrane, b) inner membrane,
c) intermembrane space, d) cristae, e) mitochondrial matrix (The inner membrane space is
between the two membranes. )
8. What are the 3 stages of cellular respiration?
1) Glycolysis
2) Citric Acid Cycle/ Kreb’s Cycle
3) Oxidative Phosphorylation)
9. Which of these 3 stages produces ATP?
All of them
10. Which of the 3 stages produces the most ATP?
Oxidative Phosphorylation
11. Describe in detail what occurs during all 3 phases. Be sure to include a) where the stage occurs,
b) What are the reactants and products of each stage, c) what is the “purpose” of each stage
a.
b.
c.
Step 1: Glycolysis (This is the breaking Glucose into 2 molecules of Pyruvate.) (All organisms can
do this process as it occurs in the cytoplasm of a cell.)
Step 2: Kreb’s Cycle (also known as Citric Acid Cycle) (This is all about making Electron Carriers in
the continued breakdown of glucose to be carried to Step 3.)
Step 3: e- Transport Chain (also known as Oxidative Phosphorylation) (This is where the Free E
of the electrons is used to help make ATP.)
12. Oxidative phosphorylation involves the electron transport chain and chemiosmosis. Describe
these 2 processes, and how they work together to produce ATP.
a. Electrons move 2 at a time down the chain toward Oxygen. (Make H2O at end.)
b. Energy (electrons) from NADH and FADH2 is used to produce ATP.
c. Free Energy, from the electrons, fuels the active transport of H+ into the inner
mitochondrial space.
i.
ii.
H+ (ions/protons) are pumped into the space between the membranes using the Free E
released from electrons as they go down the chain.
The concentration of H+ builds inside the space (like blowing up a balloon) to create a
concentration gradient. High[ ] in between and low
[ ] in the center.
iii.
iv.
v.
vi.
The H+ are released using ATP Synthesizing Complex. (It would be like pulling the cork
in the sink.)
The H+ rush out (going from High [ ]–>Low [ ]) allowing the ATP
Synthase to use the Kinetic E to turn ADP  ATP in large amounts by phosphorylation.
This is another example of Energy Coupling – two processes working together to make
ATP. One process is Active transport and the other is facilitated diffusion. Also known as
Chemiosmosis.
The Electron Transport Chain can make 34 or 32 ATP
13. What is pyruvate, and what is its purpose?
Pyruvate that can be put into the Mitochondria, if oxygen is present and it is a Eukaryotic Cell,
where they will be broken down further.
14. What is the purpose of NADH and FADH2?
They are electron carriers
15. Which stage finishes breaking down sugar all the way to CO2?
Citric Acid Cycle
16. Which process occurs in ALL organisms (prokaryotic/eukaryotic, aerobic/anaerobic)?
Glycolysis
17. All of the following questions concern fermentation.
a. What is it? Converting the two Pyruvate to 2 molecules of Ethanol by cutting off CO2
and filling the open bond with H from the electron carriers
b. Where does it occur? Cytoplasm
c. Why do it? (Pros / Cons) To make ATP/ It makes less ATP
d. What organisms can do it? bacteria and Yeast –a fungus
e. Which organisms do Alcohol Fermentation? bacteria and Yeast –a fungus
f.
Which organisms do Lactic Acid Fermentation? animals
18. Use the following terms to complete the diagram below showing a summary of Cellular
Respiration: Glycolysis, Kreb’s Cycle (Citric Acid Cycle), Oxidative Phosphorylation (Electron
Transport Chain), NADH, NADH and FADH2 (as one number), ATP (will be used as multiple
numbers), Pyruvate, Mitochondria, Glucose
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
NADH
NADH and FADH2
Glycolysis
Glucose
Pyruvate
Mitochondria
Kreb’s Cycle/ Citric Acid Cycle
Oxidative Phosphorylation
ATP
ATP
ATP