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WorksheetsUnit 3 Cellular Energetics AP Biology
Total questions: 28
Worksheet time: 7hrs 0mins
[8.15] A system at chemical equilibrium _____.
consumes energy at a steady rate
can do no work
has zero kinetic energy
releases energy at a steady rate
[8.28] Which of the following is the most correct interpretation of the figure?
ADP + Pi are a set of molecules that store energy for catabolism.
Energy from catabolism can be used directly for performing cellular work.
ATP is a molecule that acts as an intermediary to store energy for cellular work.
Pi acts as a shuttle molecule to move energy from ATP to ADP.
The following reaction
A --> B + C + heat
is a(n) _____ reaction.
endergonic
anabolic
exergonic
dehydration synthesis
exchange
Which of these reactions requires a net input of energy from its surroundings?
catabolic
endergonic
exergonic
hydrolysis
ATP --> ADP + P
The reaction
ADP + P --> ATP
is a(n) _____ reaction.
endergonic
spontaneous
chemical
hydrolysis
exergonic
What is the fate of the phosphate group that is removed when ATP is converted to ADP?
It is acquired by a reactant in an exergonic reaction.
It is acquired by a reactant in a spontaneous reaction.
It is broken down into one phosphorus and four oxygen atoms.
It is acquired by a reactant in an endergonic reaction.
Which of these is ATP?
What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?
dehydration synthesis
anabolism
hydrolysis
entropic
dehydration decomposition
In which region is the enzyme saturated with substrate?
region A
region B
region C
[8.30] Which of the following is true of enzymes?
Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
Enzymes increase the rate of chemical reaction by providing activation energy to the substrate.
Enzyme function is increased if the 3- D structure or conformation of an enzyme is altered.
Enzyme function is independent of physical and chemical environmental factors such as pH and temperature.
[8.44] In the figure, why does the reaction rate plateau at higher reactant concentrations?
The rate of the reverse reaction increases with reactant concentration.
Most enzyme molecules are occupied by substrate at high reactant concentrations.
The reaction nears equilibrium at high reactant concentrations.
Feedback inhibition by product occurs at high reactant concentrations.
[8.46] Which temperature and pH profile curves on the graphs were most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid?
curves 2 and 4
curves 1 and 4
curves 3 and 4
curves 1 and 5
[8.49] Which of the following represents the activation energy required for the enzyme-catalyzed reaction in the figure?
a.
b.
c.
d.
[8.62] In a biological reaction, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, a substance that resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the amount of succinate molecules to those of malonic acid reduces the inhibitory effect if malonic acid. Select the correct identification of the molecules described in the reaction.
Succinate dehydrogenase is the enzyme, and fumarate is the substrate in the reaction.
Succinate is the substrate, and fumarate is the product in the reaction.
Fumarate is the product, and malonic acid is a noncompetitive inhibitor in the reaction.
Succinate dehydrogenase is the enzyme, and malonic acid is the substrate in the reaction.
A series of enzymes catalyze the reaction X → Y Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme.
With respect to the enzyme that converts X to Y, substance A functions as _____.
an allosteric inhibitor
the substrate
an intermediate
a competitive inhibitor
[10.5] If photosynthesizing green algae are provided with CO2 containing heavy oxygen (18O), later analysis will show that all of the following molecules produced by the algae contain 18O EXCEPT _____.
glyceraldehyde 3-phosphate (G3P)
O2
ribulose bisphosphate (RuBP)
glucose
[10.20] As electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy?
It excites electrons of the reaction center of photosystem I.
It is lost as heat.
It is used to phosphorylate NAD+ to NADPH, the molecule that accepts electrons from photosystem I.
It is used to establish and maintain a proton gradient.
Carbon dioxide is split to form oxygen gas and carbon compounds _____.
during photosynthesis and respiration
during respiration
during photosynthesis
in neither photosynthesis nor respiration
[10.47] Refer to the figure. If the carbon atom of each of the incoming CO2 molecules is labeled with a radioactive isotope of carbon, which organic molecules will be radioactively labeled after one cycle?
C only
C, D, and E only
B, C, D, and E
B and C only
[10.61] Students conducted an experiment to determine the effect of light intensity on the rate of photosynthesis. They punched 40 leaf disks from spinach leaves and used a syringe partially filled with water to pull the gases from the leaf disks so that all leaf disks sunk to the bottom of the syringe. Ten (10) leaf disks from the syringe were placed in each of four cups and covered with 50 ml of the solutions as indicated below. All leaf disks were resting on the bottom of the cups when the experiment began. The volume of liquid in each cup and the temperature of the solutions were held constant. All cups were placed 0.5 meters from the designated light source. A large beaker of water was placed between the light and the cups to act as a heat sink to prevent a change in temperature. At the end of 10 minutes, the number of disks floating in each cup was recorded.
Cup 3 had the same rate of photosynthesis as Cup 1 because they had the same ratio of disks floating to wattage of light.
Cup 1 had a low rate of photosynthesis because 0.5 grams of baking soda did not provide a sufficient amount of CO2.
Cup 4 had the slowest rate of photosynthesis because it had the least baking soda.
Cup 2 had the highest rate of photosynthesis because 5 disks were floating at the end of 10 minutes using a 50 watt light bulb.
[9.8] The oxygen consumed during cellular respiration is involved directly in which process or event?
the oxidation of pyruvate to acetyl CoA
accepting electrons at the end of the electron transport chain
the citric acid cycle
glycolysis
If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure?
Oxaloacetate will accumulate and citric acid will decrease.
Oxaloacetate will decrease and citric acid will accumulate.
Both oxaloacetate and citric acid will accumulate.
Both oxaloacetate and citric acid will decrease.
[9.30] During aerobic respiration, electrons travel downhill in which sequence?
glucose → NADH → electron transport chain → oxygen
glucose → ATP → electron transport chain → NADH
food → glycolysis → citric acid cycle → NADH → ATP
glucose → pyruvate → ATP → oxygen
During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from?
carbon dioxide (CO2)
molecular oxygen (O2)
pyruvate (C3H3O3-)
glucose (C6H12O6)
When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the _____.
formation of ATP
creation of a proton gradient
reduction of NAD+
lowering of pH in the mitochondrial matrix
Even though plants cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. This will occur in _____.
cells that are storing glucose only
photosynthesizing cells in the light and in other tissues in the dark
photosynthetic cells in the light, while photosynthesis occurs concurrently
all cells all the time
New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and find it difficult to continue exercising. These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise. Which of the statements below is the best explanation of why athletes would need to monitor lactate levels?
During fermentation muscle cells receive too little pyruvate, thus athletes experience cramping and fatigue.
During aerobic respiration, muscle cells cannot produce enough lactate to fuel muscle cell contractions and muscles begin to cramp, thus athletic performance suffers.
During fermentation lactate levels increase, which indicates insufficient oxygen is reaching the muscles causing athletic performance to suffer.
During aerobic respiration, muscles cells produce too much lactate which causes a rise in the pH of the muscle cells, thus athletes must consume increased amounts of sports drinks, high in electrolytes, to buffer the pH.
The oxidation of glucose in the presence of oxygen involves glycolysis, pyruvate oxidation, and the citric acid cycle (Krebs cycle). Some energy is captured in glycolysis when glucose is converted to pyruvate (pyruvic acid). In the citric acid cycle (Krebs cycle), more energy is captured in the form of reduced electron carriers, NADH and FADH2.
Select the best explanation for why the eventual reoxidation of NADH and FADH2 is crucial for the continuation of the citric acid (Krebs) cycle.
Without oxidized electron carriers, oxygen will not accept the electrons at the end of the electron transport chain.
Phosphate cannot attach to ADP to form ATP without oxidized electron carriers.
In order for the cycle to continue, oxidized electron carriers must be available.
The presence of reduced forms of the electron carriers prevents the formation of ATP.
