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WorksheetsCollege Biology Unit 3 Review
Total questions: 91
Worksheet time: 23hrs 45mins
Which of the following processes is responsible for extracting energy from sugars in cells?
Photosynthesis
Cellular Respiration
Bioluminescence
Thermodynamics
According to the first law of thermodynamics energy...
Can be destroyed
Can be created and destroyed
Cannot be transformed
Can be transformed but can not be created or destroyed
Enzymes speed up metabolic reactions by...
Raising the activation energy
Lowering the activation energy
Eliminating the need for energy
Increasing the temperature of reactions
Which of the following describes competitive inhibition of an enzyme?
The inhibitor binds to a site other than the active site
The inhibitor competes with the substrate for the active sit
The enzyme's active site is modified by heat
The reaction reaches its maximum rate immediately
Which of the following describes noncompetitive inhibition of an enzyme?
The inhibitor binds to a site other than the active site
The inhibitor competes with the substrate for the active sit
The enzyme's active site is modified by heat
The reaction reaches its maximum rate immediately
Which type of inhibitor binds at the allosteric site rather than the active site?
Competitive inhibitor
Noncompetitive inhibitor
Substrate inhibitor
Feedback inhibitor
Which of the following best describes feedback inhibition?
The end product of a pathway speeds up the reaction
The end product of a pathway inhibits a key enzyme
The reactants increase the rate of the pathway
The pathway proceeds until all products are formed
What happens to an enzyme if the temperature is too high?
The enzyme becomes denatured
The enzyme activity increases
The enzyme remains unaffected
The enzyme binds to more substrates
How does an induced fit enhance enzyme activity?
By slowing down the reaction
By allowing the substrate to leave the active site
By changing the enzyme’s shape for better substrate binding
By breaking down the enzyme’s structure
Which of the following best explains why a reaction in a closed system eventually reaches equilibrium?
The reaction stops because all substrates are used up
There is no free energy change (ΔG) to drive further reactions
The enzymes denature at equilibrium
Competitive inhibitors block further reactions
Why is a phosphorylated intermediate important in ATP-mediated energy coupling?
It lowers the energy of activation of the reaction
It acts as a stable molecule that stores energy for long periods
It increases the ΔG of the reaction, making it spontaneous
It is more reactive, allowing the coupled exergonic reaction to drive an endergonic one
What would most likely happen to cellular metabolism if the concentration of ADP suddenly increased?
The rate of ATP synthesis would decrease
The rate of exergonic reactions would decrease
The regeneration of ATP would increase
The enzymes would become inactive
In what way does a noncompetitive inhibitor decrease the activity of an enzyme?
It binds directly to the active site and prevents substrate binding
It binds to the enzyme away from the active site, altering the enzyme’s shape
It competes with the substrate for binding to the allosteric site
It reduces the enzyme’s affinity for cofactors
Which of the following is a consequence of the second law of thermodynamics in biological systems?
Organisms create ordered structures from less organized forms
All reactions in biological systems release heat as a byproduct
Energy transformations decrease the entropy of the universe
The maintenance of cellular organization requires an input of energy
If the free energy change (ΔG) of a reaction is positive, which of the following is true?
The reaction is spontaneous and will proceed without energy input
The reaction is exergonic and releases free energy
The reaction is endergonic and requires energy input to proceed
The reaction is at equilibrium and cannot perform work
How does feedback inhibition regulate metabolic pathways?
It increases enzyme activity by allowing more substrate to bind
It binds to the active site of enzymes to prevent competitive inhibition
The end product of the pathway inhibits an earlier enzyme in the pathway
It denatures enzymes, halting metabolic reactions permanently
Why can cells never reach metabolic equilibrium?
Reactions in the cell are irreversible
Cells are open systems with a constant flow of materials
The enzymes are constantly inhibited by feedback mechanisms
Cells store too much energy to ever achieve equilibrium
In the context of enzyme kinetics, what does a lower Michaelis constant (Km) indicate about an enzyme's affinity for its substrate?
The enzyme has a lower affinity for its substrate
The enzyme requires more substrate to reach half of V(max)
The enzyme has a higher affinity for its substrate
The enzyme's reaction rate is lower at high substrate concentrations
Which of the following is most directly responsible for the catalytic activity of enzymes?
The number of amino acids in the enzyme's primary structure
The specific folding of the enzyme into its three-dimensional shape
The enzyme’s ability to absorb thermal energy from its surroundings
The concentration of cofactors in the enzyme's environment
Enzymes that catalyze consecutive steps in a metabolic pathway often cluster together in a cell.
The cell can be affected by toxic intermediates
The enzymes in a pathway do not have enough reaction substrate to function efficiently
Pathway intermediates are prevented from entering alternative metabolic pathways
Enzyme crowding decreases the efficiency of each enzyme in the pathway
Glycolysis is responsible for breaking glucose down into what?
CO2
H2O
Acetyl CoA
2 Pyruvic Acids
True or False: This is the cellular respiration equation:
C6H12O6 + O2 ------> CO2 + H2O
True
False
During which phase of cellular respiration is the most ATP harvested?
Glycolysis
Krebs Cycle
Electron Transport Chain
Citric Acid Cycle
In each phase of cellular respiration there is a certain amount of chemical energy harvested in the form of ATP. On a perfect day, with everything running at 100% efficiency, how many molecules of ATP can we harvest from 1 molecule of glucose?
38
23
4
2
When an organism is in a low oxygen situation, such as running sprints, cellular respiration ceases and the organism must use a different metabolic pathway for creating energy without oxygen. What do we call this process?
Acidification
Hydrolysis
Fermentation
Citric Acid Cycle
During the Krebs cycle, pyruvic acid molecules are broken down to harvest 2 ATPs. What is created and released as a byproduct of that reaction?
CO2
H2O
Neither of these
Both of these
Many electrons are excited during the first two phases of cellular respiration. These electrons hitch a ride on special electron carriers and are dropped off at the Electron Transport Chain. These electrons travel down the ETC and eventually get oxidized. Once this happens, O2 gets converted into…
C6H12O6
H2O
CO2
O2
What are the net products of photosynthesis?
6 CO2, 6 H2O, Energy
6 O2 and 6 H2O
C6H12O6 and 6 O2
6 CO2 and C6H12O6
What are the products of the light reaction directly needed by the Calvin cycle in photosynthesis?
H ions and carbon dioxide
Photons absorbed by chlorophyll
FADH2 and Oxygen
ATP and NADPH
When will lactic acid build up in animal cells?
When there is excess carbon dioxide
When the cells produce too much ATP
When there is not enough oxygen to fuel the mitochondria
When the cells need to remove excess oxygen to avoid damaging their components.
What is the only component of aerobic respiration that requires oxygen?
The Electron Transport Chain
Pyruvate Oxidation
Krebs Cycle
Glycolysis
What is the final electron acceptor in the electron transport chain/chemiosmosis
pathway and what compound is formed as a result of this process?
O2; H2O
H2O; Acetyl CoA
NAD+; NADH
Pyruvate; Glucose
There is a group of enzymes that transfer a phosphate group from ATP to another molecule or vice-versa.
Isomerases
Dehydrogenases
Aldolases
Kinases
Which of the following best describes the role of chlorophyll in the light reactions of photosynthesis?
Chlorophyll directly participates in the Calvin cycle to produce glucose.
Chlorophyll absorbs light energy, initiating the transfer of electrons and H+ ions to NADP+.
Chlorophyll acts as a catalyst in the regeneration of RuBP.
Chlorophyll transports CO₂ directly to the Calvin cycle.
Which statement correctly differentiates between cyclic and linear electron flow in photosynthesis?
Linear electron flow uses only photosystem II, whereas cyclic electron flow uses only photosystem I.
Linear electron flow produces both ATP and NADPH, while cyclic electron flow produces only NADPH.
Cyclic electron flow involves photosystem I only, and does not produce NADPH, only ATP.
Cyclic electron flow occurs in the Calvin cycle, while linear electron flow occurs in the light reactions
What is the function of RuBP (ribulose bisphosphate) in the Calvin cycle?
RuBP acts as the primary electron acceptor in the light reactions.
RuBP is regenerated in the final phase of the Calvin cycle to continue carbon fixation.
RuBP transfers H+ ions across the thylakoid membrane during the Calvin cycle.
RuBP reduces NADP+ to NADPH during the light-dependent reactions.
Which of the following correctly describes the relationship between photorespiration and photosynthesis?
Photorespiration enhances the photosynthetic output by adding more CO₂ to the Calvin cycle.
Photorespiration reduces the efficiency of photosynthesis by using ATP and releasing CO₂.
Photorespiration produces sugar by utilizing excess oxygen in plant cells.
Photorespiration occurs in C4 plants to increase CO₂ fixation efficiency.
Photorespiration occurs in C4 plants to increase CO₂ fixation efficiency.
C4 plants store CO₂ in the form of malate in bundle-sheath cells, while C3 plants directly use CO₂ in the Calvin cycle.
C4 plants capture CO₂ through photorespiration, whereas C3 plants use NADPH as the main electron carrier.
C4 plants are incapable of photosynthesis under low light, unlike C3 plants.
C4 plants perform cellular respiration in bundle-sheath cells instead of mesophyll cells.
Which of the following best explains the purpose of light absorption by pigments in chloroplasts?
To break down glucose and produce CO₂.
To reduce CO₂ into sugars during the Calvin cycle.
To absorb specific wavelengths of light energy, facilitating electron excitation for ATP and NADPH production.
To bind with chlorophyll a and b for more efficient light capture.
Which part of the leaf is primarily responsible for gas exchange and allows CO₂ to enter while releasing O₂?
Cuticle
Mesophyll
Stomata
Phloem
What is the main function of the cuticle in a leaf?
Conducts water and minerals from roots to leaves
Contains chlorophyll and captures light for photosynthesis
Protects the leaf and prevents excessive water loss
Allows CO₂ and O₂ to diffuse into and out of the leaf
In which part of the leaf does the majority of photosynthesis occur?
Spongy mesophyll
Palisade mesophyll
Lower epidermis
Xylem
Which layer of the leaf contains air pockets that facilitate gas exchange?
Cuticle
Upper epidermis
Palisade mesophyll
Spongy mesophyll
RuBisCO catalyzes the joining of carbon dioxide with RuBP during carbon fixation. In an experiment, researchers apply a toxin to a plant cell that inhibits RuBisCO. Which of the following explains the most likely effect this toxin will have on the Calvin cycle?
ATP synthase will not catalyze the formation of ATP on the thylakoid membrane
Carbon and oxygen will not be released after the breakdown of CO2
Excited electrons will not be transferred across the electron transport cgain
Carbon dioxide will not be converted into carbohydrates.
The cytochrome b6f complex is an integral thylakoid membrane protein that forms an electrochemical gradient by pumping protons. In an experiment, researchers apply a toxin to a plant cell that inhibits the cytochrome b6f complex.
Which of the following explains the most likely effect of this toxin on the light reactions of photosynthesis?
H+ ions will move across the thylakoid membrane using simple diffusion
NADP+ will be reduced to NADPH
ATP synthesis will not occur
Carbohydrates will not be produced in the stroma
Which of the following statements best describes the relationship between autotrophs and heterotrophs?
Autotrophs produce their organic molecules from CO2 and other inorganic molecules, whereas heterotrophs obtain their molecules from compounds
Both autotrophs and heterotrophs produce some of their organic molecules from CO2 and other inorganic molecules
Heterotrophs produce their organic molecules from CO2 and other inorganic molecules, whereas autotrophs obtain their organic compounds produced by other organisms
Heterotrophs are considered the producers of the biosphere, whereas autotrophs are consumers
Which of the following statements best describes the conditions under which the Calvin cycle and cellular respiration occurs in plants?
The Calvin cycle and cellular respiration both occur in the dark and the light.
The Calvin cycle occurs only in the dark, and cellular respiration occurs in both the dark and the light.
The Calvin cycle and cellular respiration both occur only in the light.
The Calvin cycle occurs only in the light, and cellular respiration occurs only in the dark.
Which of the following statements best describes the relationship between photosynthesis and cellular respiration?
Photosynthesis occurs only in plants; cellular respiration occurs only in animals.
Cellular respiration runs the biochemical pathways of photosynthesis in reverse.
Photosynthesis stores energy in complex organic molecules; cellular respiration releases energy from complex organic molecules.
Photosynthesis is catabolic; cellular respiration is anabolic.
Which of the following processes is directly associated with photosystem I?
Generating molecular oxygen
Receiving electrons from the thylakoid membrane electron transport chain
Extracting hydrogen electrons from the splitting of water
Passing electrons to NADP+
Which of the following events are associated with chemiosmosis in chloroplasts?
The pH of the stroma increases and ATP is synthesized.
The pH of the stroma decreases and ATP is hydrolyzed.
The pH of the cytosol outside the chloroplast decreases and ATP is synthesized.
The pH of the thylakoid space increases and ATP is synthesized.
P680+ is said to be the strongest biological oxidizing agent. The strong oxidizing potential of P680+ is essential for its function because it_____.
is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system
Is the receptor for the most excited electrons in either photosystem of photosynthesis
Transfers its electrons to reduce NADP+ to NADPH
Obtains electrons from the oxygen atom in a water molecules
Which of the following processes is most directly driven by light energy?
Carbon fixation in the stroma
Creation of a pH gradient by pumping protons across the thylakoid membrane
Oxidation of chlorophyll molecules
Reduction of NADP* molecules
In autumn, chlorophyll is degraded in the leaves of deciduous trees. Which of the following statements bests explains the change in color from green shades to shades of yellow, orange, or red?
Sugars from sap fill the leaves prior to winter.
In the absence of photosynthesis, the leaves produce energy exclusively by aerobic cellular respiration.
Degraded chlorophyll appears yellow, orange, or red.
Other pigments such as carotenoids remain in the leaves after the chlorophyll is degraded.
Which of the following statements best explain the ability of CAM plants to synthesize sugars in the daytime while keeping their stomata closed to reduce water loss?
They fix CO2 into sugars in the bundle-sheath cells.
They use photosystem I and photosystem Il at night.
They fix CO2 into pyruvate in the mesophyll cells.
They fix COz into organic acids during the night.
Most sugar is transported from the leaves to the rest of the plant in the form of which of the following molecules?
Sucrose
G3P
Starch
Glucose
What is the difference between losing an H+ and losing a hydrogen atom?
Losing H+ means losing a proton, while losing a hydrogen atom means losing both a proton and an electron.
H+ and a hydrogen atom are identical.
Losing H+ means losing an electron, while losing a hydrogen atom means losing a proton only.
Losing H+ refers to gaining energy, while losing a hydrogen atom releases energy
What is the function of NAD+, FADH, and NADP+ in cellular respiration and photosynthesis?
They act as electron carriers that transport high-energy electrons.
They serve as energy-storing molecules.
They provide structural support for the electron transport chain
They directly produce ATP during phosphorylation.
What distinguishes substrate-level phosphorylation from oxidative phosphorylation?
Oxidative phosphorylation produces ATP using a proton gradient, while substrate-level phosphorylation directly transfers a phosphate group.
Substrate-level phosphorylation uses oxygen, while oxidative phosphorylation does not.
Substrate-level phosphorylation occurs in the mitochondria, while oxidative phosphorylation occurs in the cytoplasm.
Oxidative phosphorylation occurs only during glycolysis.
How is oxygen used in cellular respiration?
It breaks down glucose in glycolysis.
It acts as the final electron acceptor in the electron transport chain, forming water.
It provides energy for ATP synthase to produce ATP.
It catalyzes the Citric Acid Cycle.
Which statement about the Citric Acid Cycle is correct?
It begins with pyruvate and produces glucose.
It starts with acetyl-CoA, produces NADH, FADH2, and ATP, and follows glycolysis.
It occurs in the cytoplasm and produces NADPH.
It produces water directly and drives chemiosmosis.
Where is the electron transport chain located, and what drives the building of the H+ gradient?
It is located in the cytoplasm, and NADH provides energy for the H+ gradient.
It is in the mitochondrial matrix, and ATP hydrolysis pumps H+ across the membrane.
It is embedded in the inner mitochondrial membrane, and energy from electron movement pumps H+ across the membrane.
It is in the chloroplast thylakoids, and oxygen provides energy to drive the gradient.
What drives the chemiosmotic generation of ATP?
The phosphorylation of ADP by enzymes
The splitting of glucose into pyruvate.
The flow of H+ ions down their concentration gradient through ATP synthase.
The direct release of energy from electron carriers like NADH and FADH2.
Which are products of the Calvin Cycle, and how are they utilized?
Glucose and oxygen, which are directly used in glycolysis.
G3P, which is used to form glucose and regenerate RuBP.
ATP and NADPH, which provide energy for light reactions.
CO2 and water, which are used to power the light reactions.
What is the main function of chemiosmosis in cellular respiration?
To produce ATP by transferring electrons through the electron transport chain.
To convert glucose into pyruvate during glycolysis.
To synthesize NADH from NAD++.
To create a proton gradient across the mitochondrial membrane.
During chemiosmosis, how are protons (H+) transported across the mitochondrial membrane?
They move from the mitochondrial matrix into the cytoplasm.
They move from the cytoplasm into the mitochondrial matrix
They move from the inner mitochondrial membrane to the outer mitochondrial membrane.
They are pumped from the matrix to the intermembrane space.
What role does ATP synthase play in chemiosmosis?
It breaks down ATP into ADP and inorganic phosphate.
It pumps electrons across the inner mitochondrial membrane.
It uses the flow of protons through it to synthesize ATP.
It transports oxygen from the cytoplasm into the mitochondria.
Select all of the microorganisms that are responsible for fermentation.
Bacteria
Yeasts
Molds
Virus
Select all of the following that are used to control fermentation.
water
pH
temperature
salt
What type of pH slows or stops fermentation?
Acidic (<7)
Basic (>7)
Neutral
Cellular respiration is the process that our cells use to ….
convert sugar (glucose) into energy (ATP)
break food down into smaller molecules (sugars)
makes acid
breathe
Please identify the proper locations for each step of cellular respiration.
Glycolysis = Cytoplasm
Glycolysis = Mitochondria
Citric Acid Cycle = Cytoplasm
Citric Acid Cycle = Mitochondria
Oxidative Phosphorylation = Cytoplasm
ATP synthesis by ATP synthase is driven by
H+ movement
electron movement
NADH movement
FADH2 movement
Which of the following processes creates the most ATP during aerobic cellular respiration?
glycolysis
fermentation
electron transport chain
Citric acid cycle
What does FADH2 and NADH bring to the electron transport chain?
Oxygen
Water
Electron
ATP
Please indicate the correct equation(s) for Cellular Respiration. (2 answers)
Glucose + Oxygen --> Carbon Dioxide + Water + Energy
C6H12O6 + O2 --> CO2 + H2O + ATP
Carbon Dioxide + Water + Energy --> Glucose + Oxygen
C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O + ATP
