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AP Biology Energy Exam Study Guide
Enzymes, Cellular Respiration, Metabolic Patterns, and
Photosynthesis
1. In which orientation must these two amino acids be brought together to form a dipeptide bond?
2. Why is this particular orientation necessary?
Which form of nitrogen can plants assimilate and how do they obtain it?
Which form of nitrogen can plants assimilate and how do they obtain it?Nitrate NO3
-
Obtained from nitrogen-fixing bacteria (either free-living in the soil or as symbiots in root-nodules) or through decomposition of dead organic matter
What is nitrogen-fixation?
What is nitrogen-fixation? It is when atmospheric nitrogen, N2 is transformed into a form of nitrogen that plants can assimilate: NO3
- (nitrate); plants need nitrogen for protein-building because each amino acid has an amino-group (and contains N)
What is denitrification?
What is denitrification? It is when prokaryotes (bacteria) convert NO3
- back into atmospheric N2
Which of the following represents:a. Nitrogen fixation by prokaryotesb. Assimilation of nitrate by photosynthetic eukaryotesc. Denitrification by anaerobic prokaryotes
Which of the following represents:a. Nitrogen fixation by prokaryotesb. Assimilation of nitrate by photosynthetic eukaryotesc. Denitrification by anaerobic prokaryotes
1. Define activation energy:2. Which of the following indicates the activation
energy of an uncatalyzed reaction?3. Which of the following indicates the activation
energy of a catalyzed reaction?
1. Activation energy is the energy that must be added to make bonds unstable enough to break
2. Which of the following indicates the activation energy of an uncatalyzed reaction? C
3. Which of the following indicates the activation energy of a catalyzed reaction? B
Describe & explain the effect of temperature on enzymatic reaction rate:
A
B
C
D
Describe and explain the rate at A – DAnd, what was the Vmax you calculated for the graph?
Highest rate is between 5 and 20 min. because substrate is abundant: 17.3 µmol/mL ∙ min. (c)
Slow rate due to lag-time substrate must get into liver cells
Rate slows as substrate starts to run out
Rate zero because ran out of substrate
1. Are the enzymes shown sensitive to pH?2. Explain how you know:3. What would the graph look for an enzyme that
was not sensitive to pH?
1. Are the enzymes shown sensitive to pH? yes2. Explain how you know: change in slope indicates a
change in rate (optimal of 4 at pH 2, 5 at pH 8)3. What would the graph look for an enzyme that
was not sensitive to pH? It would be a horizontal line, having a zero slope, indicating a constant rate
Describe and explain the relationship between temperature and rate of enzymatic reaction:
Increasing temperature increases the rate at which the enzyme and substrate collide, thus increasing the rate of reaction up to an optimal point, beyond which, a further increase of temperature denatures the enzyme and thus the reaction rate drops to zero.
Explain the relationship shown in this graph:
Explain the relationship shown in this graph: The reaction rate is fastest when substrate is plentiful (A), as substrate runs out the rate slows (B), when substrate is gone, the rate becomes zero (C)
A
B
C
How many more times NADPH rate is achieved with Mg++ at 2 minutes than Zn++ at 2.5 minutes?
How many more active is NADPH production with Mg++ at 2 minutes than Zn++ at 2.5 minutes?0.125/0.075 = 1.67 times
Time
(min.)
Product
produced (µM)
0 0
10 5.1
20 8.6
30 10.4
40 11.1
50 11.5
a. Calculate the rate from 10 to 20 seconds:
b. Calculate the rate from 40 to 50 seconds:
Time
(min.)
Product
produced (µM)
0 0
10 5.1
20 8.6
30 10.4
40 11.1
50 11.5
a. Calculate the rate from 10 to 20 seconds:
(8.6 ЦM – 5.1 ЦM)/(20 s – 10 s) = 0.35 ЦM/min.
b. Calculate the rate from 40 to 50 seconds:
(11.5 ЦM – 11.1 ЦM)/(50 s – 40 s) = ЦM/min.
a. Calculate the mean rate of product formed in the
first 20 seconds:
a. Calculate the mean rate of product formed in the
first 20 seconds:
(13 moles – 0 moles)/(20 s – 0 s) = 0.65 moles/s
Not including harvesting a plant (biomass), list two ways that the rate of photosynthesis can be measured:
Not including harvesting a plant (biomass), list two ways that the rate of photosynthesis can be measured:
The rate at which CO2 is absorbedThe rate at which O2 is released
What happens to the reactant CO2 during photosynthesis?
What happens to the reactant CO2 during photosynthesis?It is “fixed” or assimilated into sugars
What happens to the reactant H2O during photosynthesis?It is “split” during the light reactions. The hydrogen atoms and electrons go into sugar-building. The oxygen atoms are released as oxygen gas.
16O
H H
18O 18OC+ 16O16O
18O
H H
16O 16OC+ 18O18O
Photosynthesis: Trail #1
Photosynthesis: Trail #2
1. What question was the van Niel experiment designed to answer?
2. What was the answer?3. Explain how the experiment showed this:
16O
H H
18O 18OC+ 16O16O
18O
H H
16O 16OC+ 18O18O
Photosynthesis: Trail #1
Photosynthesis: Trail #2
1. What question was the van Niel experiment designed to answer? What is the source of O2
2. What was the answer? H2O3. Explain how the experiment showed this:
radioactive labeled 18O
Van Niel wanted to discover whether the oxygen gas produced by photosynthesis came from the splitting of CO2 or from H2O. How did he answer this question? And what did he find?
Van Niel wanted to discover whether the oxygen gas produced by photosynthesis came from the splitting of CO2 or from H2O. How did he answer this question? And what did he find? He introduced radioactively labeled oxygen, 18O in the form of labeled CO2 to one group of plants and labeled H2O to another group of plants. The oxygen gas produced during photosynthesis was only labeled in the group that received labeled H2O, thus the oxygen derived from photosynthesis comes from the splitting of water.
Where do the light reactions take place?
Where does the Calvin Cycle take place?
Where do the light reactions take place?In the thylakoid membrane of the chloroplastWhere does the Calvin Cycle take place?In the stroma of the chloroplast
What is the significant outcome of the Calvin Cycle?
What is the significant outcome of the Calvin Cycle?Carbohydrate is built (anabolic reaction) from atmospheric CO2 and the e-, and H+ that were derived from H2O and carried from the light reactions by NADPH
CALVIN CYCLE/CARBON FIXATION
STROMATHYLAKOID
co2
C6H12O6
H2O
O2
Light
ATP
ADP
NADPH
NADP+
PCHLOROPHYLL
LIGHT REACTIONS 1. Where do the light-reactions occur?
2. What reactant comes in, what happens to it, and which product comes out?
3. Name 2 sources of potential energy that light-energy is transformed into:
4. Where does the Calvin cycle take place?5. What reactant comes in? And how is it
modified using ATP and NADPH?6. What product comes out?
CALVIN CYCLE/CARBON FIXATION
STROMATHYLAKOID
co2
C6H12O6
H2O
O2
Light
ATP
ADP
NADPH
NADP+
PCHLOROPHYLL
LIGHT REACTIONS1. Where do the light-
reactions occur? Thylakoid membrane
2. What reactant comes in, what happens to it, and which product comes out? H2O, it is split by light and an enzyme into oxygen gas, H+, and e-
3. Name 2 sources of potential energy that light-energy is transformed into: light energy is transformed into ATP and NADPH4. Where does the Calvin cycle take place? The stroma
5. What reactant comes in? And how is it modified using ATP and NADPH? CO2, ATP is energy to connect CO2, Hydrogen ions and e- from NADPH to build glucose
6. What product comes out? glucose
Electron Flow During Light Dependent Reaction
ETC
ATP Synthase
Chlorophyll
Light energy boosts an electron’s potential energy
High-energy electron donated to electron carrier NADP+ → NADPH (GER = gain electrons reduced)
Electrons are replaced by splitting water into 02, H+, and e-
Electron Flow During Light Dependent Reaction
ETC
Chlorophyll
2. How are e- replaced?
1.How are e- boosted in energy?
3.Name enzyme
4.Name final electron acceptor
5. What are the ATP and NADPH used for?
What are the main events of the Calvin Cycle?
ATP energy (made during the light reaction) is used to build 3-C sugars from CO2 and the H+ and e- (these were stripped from H2O during the light reactions) and carried by NADPH.
Glucose = C6H12O6
6CO2 provide C & O atoms
NADPH provides the Hydrogen atoms and high energy electrons (both originated from water molecules)
ATP is the energy source to build in this anabolic reaction.
1. When a plant grows from a seedling to an adult, where does the mass come from?
2. If a plant is placed in the dark, what will happen to its mass and why?
1. When a plant grows from a seedling to an adult, where does the mass come from? Photosynthesis uses light energy to build carbohydrate from atmospheric CO2 and the hydrogen atoms from H2O (the majority of mass from biomass comes from CO2)
2. If a plant is placed in the dark, what will happen to its mass and why? In the dark the plant can not add mass through photosynthesis, but must still perform cellular respiration to recycle ATP in order to maintain homeostasis. The plant will lose mass as stored carbohydrate is broken down and releases as CO2 and H2O (most of the mass loss is from CO2)
What would you expect the graph of dissolved oxygen over a 24 hr. period in a lake to look like and why?
With light available from dawn to dusk, photosynthesis adds more oxygen than is removed by cellular respiration. From dusk to dawn photosynthesis so no additional oxygen is added, while cellular respiration continues to remove oxygen.
The fact that the process of glycolysis is present and virtually identical in all three Domains: Archaea, Bacteria, Eukarya suggests what?
The fact that the process of glycolysis is present and virtually identical in all three Domains: Archaea, Bacteria, Eukarya suggests what?
A common ancestor for all forms of life on Earth
Fuel: i.e. Glucose
5. Has the fuel been oxidized or reduced? Explain:
6. Is oxygen oxidized or reduced? Explain:
7. What happens to the oxygen at the end?
1. Which bonds represent high energy e-?
2. Describe the change in potential energy of the e-
3. Name the molecules that carry the e- to the ETC
OH+
H+
4. Which part of the diagram represents oxidative phosphorylation?
What is the significance of fermentation for human cells?
What is the significance of fermentation for human cells? Muscle cells can produce some ATP anaerobically (allowing breathing and heart-rate to catch up) but produce lactic acid as a byproduct.
What differences would you expect in organisms that rely on fermentation versus cellular respiration and why?
What differences would you expect in organisms that rely on fermentation versus cellular respiration and why?They would not require oxygen as fermentation occurs in the absence of oxygen.They would grow more slowly or require a greater amount of carbohydrate because fermentation releases only a small fraction of the amount of energy stored in sugar molecules.
What are the final electron acceptors of the electron transport chain in:
a. The chloroplastb. The mitochondrion
What are the final electron acceptors of the electron transport chain in:
a. The chloroplast NADP+, which is reduced (GER: Gain Electrons Reduced) to NADPH
b. The mitochondrion Oxygen, which is reduced to water (with the gain of H+)
What is being shown in the models above?
NADH donates electrons to the ETC. As e- are passed along the ETC, the loss of potential energy is used to pump H+ ions against their electrochemical gradient. When the H+ ions flow down their electrochemical gradient, ATP synthase catalyzes the reaction: ADP + Pi → ATP. This is only possible because a membrane separates a low H+ from a high H+ environment.
What is the role of NAD+ and FAD during cellular respiration?
What is the role of NAD+ and FAD during cellular respiration?
To accept/carry electrons during REDOX reactions that breakdown glucose
Which process occurs both in the mitochondrial inner membrane and the thylakoid membrane?
H+ are pumped across a membrane to create an electrochemical gradient and diffusion of H+ back down that gradient is used by ATP synthase to synthesize ATP.
In the cellular respiration lab, what was the purpose of the KOH that you added to the absorbent cotton ball?
CO2 combines with KOH to form a solid precipitate in order to provide accurate volumetric measurements of oxygen gas consumption
In the cellular respiration lab, what was the purpose of the respirometer with glass beads?
Given: V = nRTP
What effect would a decrease in atmospheric pressure have on the volume of oxygen gas?
What effect would a decrease in pressure have on the volume of oxygen gas?
PV = nRT; V = nRTP
The glass-bead vial is a control, to measure the change in gas volume due to temperature and pressure changes during the experiment. We can thus adjust the experimental treatment data .
A decrease in atmospheric pressure would result in an increase in the volume of oxygen gas.
A decrease in temperature would result in a decrease in the volume of oxygen gas.
Under which situation will the average respiration rate (mL O2/g/min) for each animal be higher and why?
Cat at 10⁰C or 20 ⁰C
Isopod at 10⁰C or 20 ⁰C
Cat at 10⁰C or 20 ⁰CAt 10⁰C because the cat is an endotherm (maintains a constant body temperature) and at lower environmental temperature the cat will need to increase cellular respiration to increase internal heat production.
Isopod at 10⁰C or 20 ⁰CAt 20 ⁰C because the isopod is an exotherm (body temperature matches environment) and thus body temperature and cellular respiration rate will increase with environmental temperature.
What do you expect to occur to the mass of an animal kept several days without food and a plant kept in the dark?
Explain your prediction:
What do you expect to occur to the mass of an animal kept several days without food and a plant kept in the dark? mass of both the plant and animal will decreaseExplain your prediction:The plant and animal are being withheld a source of energy from their environments. Both will tap into their stored energy supplies such as fats for the animal and starch for the plants. They will combust these stored fuels to continue performing cellular respiration. They will release the mass of these molecules as CO2 and H2O (products of cell. Resp.)
Metabolic Rate vs. Body Size
1. What is the relationship between body size and total daily energy (Kcal) demand?
2. What is the relationship between body size and kcal/kg demand?
For which animal would you expect a larger O2
consumption per gram tissue: cat or cow?
The higher the metabolic rate, the higher the oxygen consumption and thus the mouse would consume more oxygen per gram of tissue than the cow.
Explain the pattern in the graph:
Explain the pattern in the graph:
A
B
CD
A - shivering to stay warmB - as temp. ↑ need to generate heat during cell. Resp. ↓C – optimal environmental tempD – panting to stay cool
How does the diagram above support the claim that different species of organisms use different metabolic strategies to meet their energy requirements for growth, reproduction, and homeostasis?
Animals store energy as glycogen and fats while plants use starch.
Describe the ATP cycle:
Describe the ATP cycle:Energy released from the catabolic breakdown of fuel molecules during cellular respiration recycles ATP (ADP +pi → ATP). ATP is hydrolyzed (back to ADP) to perform cellular work such as anabolic (building) reactions such as building macromolecules. ADP must again be recycled back to ATP.
Above is one of the reversible chemical reactions which occur in our blood.
1. What does this reaction have to do with pH?2. What metabolic process could be responsible
for this?3. How can normal pH be restored?
Above is one of the reversible chemical reactions which occur in our blood.
1. What does this reaction have to do with pH? When CO2
dissolves in water, carbonic acid is created, and pH decreases
2. What metabolic process could be responsible for this? Cellular respiration
3. How can normal pH be restored? Increased breathing rate can help to unload the excess CO2 generated during vigorous exercise and can thus restore normal blood pH
Describe the different mechanisms of nitrogenous waste production:
1. Ammonia – excreted directly, diluted by lots of water (highly toxic).
2. ATP can be used to convert ammonia to urea and uric acid. They are less toxic (can be concentrated) and do not require dilution by lots of water.
