Campbell Bio 9+10(energy)

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Questions and Answers

What is the main difference between fermentation and aerobic respiration?

Fermentation occurs with oxygen, while aerobic respiration does not.

Fermentation produces more ATP than aerobic respiration.

Fermentation is more efficient than aerobic respiration.

Fermentation occurs without oxygen, while aerobic respiration requires oxygen. (correct)

In the context of aerobic respiration, what does the equation C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy represent?

The process of photosynthesis in plants.

The combustion of carbohydrates in the presence of oxygen. (correct)

The production of heat energy only.

The synthesis of glucose from carbon dioxide.

Which of the following correctly defines oxidation in the context of redox reactions?

A process where electrons are lost. (correct)

A process that increases the electronegativity of an atom.

A process involving the complete transfer of electrons.

A process where electrons are acquired.

What is true about the reducing agent in a redox reaction?

It is oxidized during the reaction. Signup and view all the answers

Why is less energy required to extract electrons from less electronegative atoms?

Because they hold their electrons less tightly. Signup and view all the answers

How does aerobic respiration compare to combustion of gasoline?

Aerobic respiration is more efficient than combustion of gasoline. Signup and view all the answers

Which type of respiration occurs more rarely than aerobic respiration?

Anaerobic respiration. Signup and view all the answers

What happens to an electron's potential energy when it moves closer to a more electronegative atom?

It loses potential energy. Signup and view all the answers

What is the main reason hydrocarbons are considered an excellent energy source?

They contain a high concentration of electrons capable of transferring to oxygen. Signup and view all the answers

What role does NAD+ play in cellular respiration during glucose breakdown?

It acts as an oxidizing agent, accepting electrons. Signup and view all the answers

Which step of cellular respiration primarily occurs in the cytoplasm?

Glycolysis Signup and view all the answers

What occurs at the end of the electron transport chain?

O2 forms water by reacting with H+ ions. Signup and view all the answers

Why cannot energy be released all at once during cellular respiration?

It would result in an explosion-like reaction. Signup and view all the answers

In the process of oxidative phosphorylation, which component is primarily responsible for ATP generation?

Energy from the electron transport chain. Signup and view all the answers

What is the role of dehydrogenase in cellular respiration?

To remove hydrogen atoms from glucose and convert NAD+ to NADH. Signup and view all the answers

During the citric acid cycle, what is produced alongside CO2?

NADH and FADH2. Signup and view all the answers

How is energy harvested during the electron transport chain?

Through the gradual transfer of electrons with associated energy release. Signup and view all the answers

What important characteristic of NAD+ makes it suited as an electron carrier?

It can easily switch between oxidized and reduced forms. Signup and view all the answers

What distinguishes substrate level phosphorylation from oxidative phosphorylation?

Transfers phosphate from a substrate molecule Signup and view all the answers

What is the primary role of pyruvate oxidation in cellular respiration?

To convert pyruvate to acetyl CoA Signup and view all the answers

How many molecules of NADH are produced per pyruvate in the citric acid cycle?

3 Signup and view all the answers

What is the purpose of GTP formed in step 5 of the citric acid cycle?

It can be used to directly power work in cells Signup and view all the answers

Which process does NOT occur in the mitochondria?

Glycolysis Signup and view all the answers

What does ATP synthase utilize to produce ATP?

A pre-existing ion gradient Signup and view all the answers

Which of the following correctly describes the electron transport chain?

Transfers electrons while using molecular oxygen as the final electron acceptor Signup and view all the answers

What is a defining characteristic of FADH2 in the electron transport chain?

It donates electrons at a lower energy level than NADH Signup and view all the answers

Which component is NOT part of the electron transport chain?

Citrate Signup and view all the answers

What type of reaction occurs as electrons are transferred between components in the electron transport chain?

Alternating between reduction and oxidation Signup and view all the answers

What happens to the carbon atoms introduced in the citric acid cycle?

Carbon atoms are completely lost as CO2 Signup and view all the answers

What is the main role of the multienzyme complex during pyruvate oxidation?

To catalyze the oxidation of the pyruvate Signup and view all the answers

What is the significance of the structure of the inner mitochondrial membrane in relation to the electron transport chain?

Its folding increases surface area for electron carriers Signup and view all the answers

What color light is least effective for photosynthesis according to the absorption spectrum of chlorophyll a?

Green light Signup and view all the answers

What is the primary function of carotenoids in plants?

To provide photoprotection Signup and view all the answers

Which component is NOT a part of a photosystem?

Oxygen molecules Signup and view all the answers

What distinguishes chlorophyll a from chlorophyll b?

Their color appearance under light Signup and view all the answers

What happens to an electron when a pigment absorbs a photon?

It increases in potential energy Signup and view all the answers

Which of the following statements is true regarding the excited state of electrons?

It typically reverts to the ground state rapidly. Signup and view all the answers

What tool is used to measure the absorption of light by pigments?

Spectrophotometer Signup and view all the answers

What is the primary role of the reaction-center complex in a photosystem?

To transfer electrons to a primary electron acceptor Signup and view all the answers

How does the action spectrum differ from the absorption spectrum?

It profiles how certain colors impact the rate of photosynthesis. Signup and view all the answers

What phenomenon occurs when chlorophyll fluoresces?

Release of photons in the visible spectrum Signup and view all the answers

Which process directly converts pyruvate into lactate?

Lactic acid fermentation Signup and view all the answers

What is the primary reason for dough rising during baking?

CO2 emissions from alcoholic fermentation Signup and view all the answers

Which of the following statements about lactate is correct?

It can be recycled into glucose in the liver. Signup and view all the answers

What distinguishes obligate anaerobes from facultative anaerobes?

Facultative anaerobes perform cellular respiration when oxygen is present. Signup and view all the answers

During which metabolic process is the majority of ATP produced?

Oxidative phosphorylation Signup and view all the answers

What happens to excess lactate produced in white muscle cells during exercise?

It is oxidized by red muscle cells. Signup and view all the answers

Which of the following statements about deamination is true?

It creates nitrogenous waste as a byproduct. Signup and view all the answers

How does beta oxidation contribute to cellular respiration?

It breaks down fatty acids into two-carbon fragments. Signup and view all the answers

Which of the following is a result of feedback inhibition?

Excess product inhibits enzyme activity. Signup and view all the answers

What role does phosphofructokinase play in glycolysis?

It regulates the speed of glycolysis. Signup and view all the answers

Which type of food molecule must undergo hydrolysis first before being processed in glycolysis?

Carbohydrates Signup and view all the answers

Which of the following statements about glycolysis is correct?

It can accept a variety of sugars, not just glucose. Signup and view all the answers

What characterizes the energy yield from one gram of fat compared to one gram of carbohydrate?

Fats yield twice the amount of ATP as carbohydrates. Signup and view all the answers

What is a major component synthesized from dihydroxyacetone phosphate?

Fat Signup and view all the answers

What is the primary role of the proton-motive force in cellular respiration?

To drive ATP synthesis through the movement of protons across the membrane Signup and view all the answers

Which of the following statements about ATP production from glucose is accurate?

The efficiency of converting glucose to ATP can vary based on cellular conditions. Signup and view all the answers

Why might hibernating mammals lower their metabolism rather than produce ATP?

To conserve body temperature and energy stored in fat Signup and view all the answers

How does NADH contribute to ATP synthesis in the mitochondria?

It donates electrons that pump protons across the mitochondrial membrane. Signup and view all the answers

In which scenario would only 1.5 ATP molecules be produced from FADH2?

When FADH2 enters the electron transport chain early. Signup and view all the answers

What is the consequence of proton channels that allow protons to reenter the mitochondrial matrix without ATP synthase?

They cause a decrease in ATP synthesis during hibernation. Signup and view all the answers

What distinguishes anaerobic respiration from fermentation?

Anaerobic respiration uses electronegative molecules other than oxygen. Signup and view all the answers

Which product is generated during alcoholic fermentation?

Ethanol Signup and view all the answers

What is the significance of Peter Mitchell's model of chemiosmosis?

It provided a framework to explain oxidative phosphorylation. Signup and view all the answers

What efficiency percentage does the conversion of glucose to ATP typically achieve?

34% Signup and view all the answers

What is the role of substrate-level phosphorylation in glycolysis?

To directly produce ATP without the electron transport chain Signup and view all the answers

Which of the following correctly describes a process during anaerobic respiration?

It does not require an electron transport chain. Signup and view all the answers

Which of these is a significant factor in determining ATP yield from glucose?

The type of cell metabolism involved Signup and view all the answers

During which stage of cellular respiration is the majority of ATP produced?

Electron Transport Chain Signup and view all the answers

What role does AMP play in phosphofructokinase activity?

It stimulates phosphofructokinase activity. Signup and view all the answers

Which of the following correctly describes the structure of chloroplasts?

They have a double membrane with thylakoids that create a third membrane system. Signup and view all the answers

What is the main product formed during the light reactions of photosynthesis?

ATP and NADPH. Signup and view all the answers

What does the Calvin cycle utilize from the light reactions?

NADPH and ATP. Signup and view all the answers

Why is Van Niel's conclusion about photosynthesis significant?

It established that oxygen comes only from water splitting. Signup and view all the answers

What happens to electrons during the light reactions?

They are transferred to NADP+ to form NADPH. Signup and view all the answers

What is the relationship between glucose and three-carbon sugars in photosynthesis?

Three-carbon sugars are intermediates that can be converted to glucose. Signup and view all the answers

Which of the following pigments is crucial for capturing light energy during photosynthesis?

Chlorophyll. Signup and view all the answers

How does the role of photosynthesis differ from cellular respiration?

Photosynthesis releases oxygen while respiration consumes it. Signup and view all the answers

During which phase of photosynthesis is water split, providing electrons?

Light reactions. Signup and view all the answers

What defines the wavelength of electromagnetic energy?

The distance between crests of waves. Signup and view all the answers

What is a primary characteristic of visible light on the electromagnetic spectrum?

It ranges from approximately 380-740 nm in wavelength. Signup and view all the answers

What is the purpose of chemiosmosis in photosynthesis?

To synthesize ATP using a proton gradient. Signup and view all the answers

Which pigment is associated with the reaction center complex of photosystem II?

P680 Signup and view all the answers

In the linear flow of electrons, what is the result of water splitting?

Production of oxygen gas Signup and view all the answers

What is created in the thylakoid space as a result of the electron transport chain between PS II and PS I?

A proton gradient Signup and view all the answers

Which process occurs only in photosystem I during the cyclic electron flow?

Regeneration of P700 Signup and view all the answers

What is the main difference between linear electron flow and cyclic electron flow?

One generates ATP while the other does not Signup and view all the answers

What role does NADP+ reductase play in photosynthesis?

Reduction of NADP+ to NADPH Signup and view all the answers

How does the structure of P680 and P700 chlorophyll a differ?

They are associated with different proteins Signup and view all the answers

What phenomenon explains the need for cyclic electron flow in some organisms?

Evolutionary significance as a leftover process Signup and view all the answers

Which of the following statements about the thylakoid membrane is accurate?

It houses photosystems II and I Signup and view all the answers

What does the energy from the proton motive force primarily contribute to?

Synthesis of ATP through chemiosmosis Signup and view all the answers

Why might cyclic electron flow be considered photoprotective in some plants?

It can prevent damage from excessive light Signup and view all the answers

What distinguishes the electron carriers in the thylakoid from those in the mitochondria?

They have notable differences in photophosphorylation Signup and view all the answers

What is the primary role of PEP carboxylase in C4 plants?

To fix CO2 to phosphoenolpyruvate Signup and view all the answers

How do C4 plants maintain a high concentration of CO2 in bundle-sheath cells?

By pumping CO2 from mesophyll cells to bundle-sheath cells Signup and view all the answers

What is one hypothesized benefit of converting C3 plants to C4 plants in response to climate change?

Enhanced resistance to high temperatures Signup and view all the answers

Why is photorespiration considered significant in plants?

It can drain away a significant amount of fixed carbon Signup and view all the answers

In CAM plants, what is the purpose of stomata opening at night?

To store CO2 as organic acids Signup and view all the answers

How do C4 plants avoid the negative effects of photorespiration?

Through the energy investment of ATP to concentrate CO2 Signup and view all the answers

What is a key difference between the processes in C4 and CAM plants?

C4 plants separate processes spatially while CAM plants do it temporally Signup and view all the answers

What role does cyclic electron flow play in bundle-sheath cells of C4 plants?

It generates ATP to replace energy loss during the Calvin cycle Signup and view all the answers

Which plant type is less likely to be affected by rising temperatures and water constraints due to climate change?

C4 plants Signup and view all the answers

How is G3P (glyceraldehyde 3-phosphate) used in plants?

It serves as a precursor for various organic compounds Signup and view all the answers

What distinguishes C4 plants from C3 plants in terms of energy expenditure?

C4 plants invest in ATP to minimize carbon loss from photorespiration Signup and view all the answers

Which type of plant primarily transports carbohydrates in the form of sucrose?

All types of plants Signup and view all the answers

What is the significance of C4 plants having evolved multiple times?

It shows the adaptability of the C4 pathway in different environments Signup and view all the answers

What is the primary source of electrons for the electron transport chain (ETC) in chloroplasts?

Water Signup and view all the answers

Which statement correctly describes the function of the proton pumps in chloroplasts compared to mitochondria?

Chloroplasts pump protons into the thylakoid space, while mitochondria pump into the matrix. Signup and view all the answers

What is the net gain of glyceraldehyde 3-phosphate (G3P) for each cycle of the Calvin cycle?

One molecule of G3P Signup and view all the answers

In the context of C3 plants, what occurs when the stomata close on hot, dry days?

Decrease in CO2 availability Signup and view all the answers

Which of the following correctly describes photorespiration?

It consumes oxygen and releases CO2 Signup and view all the answers

What compound does carbon enter the Calvin cycle as?

Carbon dioxide Signup and view all the answers

During the reduction phase of the Calvin cycle, what happens to 1,3-bisphosphoglycerate?

It is reduced to form glyceraldehyde 3-phosphate Signup and view all the answers

What is considered the most abundant protein in chloroplasts?

RuBP carboxylase-oxygenase (rubisco) Signup and view all the answers

How many ATP and NADPH are consumed for the net synthesis of one G3P in the Calvin cycle?

9 ATP and 6 NADPH Signup and view all the answers

Which compound is NOT produced as a by-product in the light reactions of photosynthesis?

Glucose Signup and view all the answers

In which environment do C3 plants tend to experience photorespiration more frequently?

High temperature and bright light environments Signup and view all the answers

What impact does photorespiration have on the Calvin cycle?

Decreases efficiency of photosynthesis Signup and view all the answers

What is the characteristic of glyceraldehyde 3-phosphate (G3P) produced in the Calvin cycle?

It contains three carbon atoms Signup and view all the answers

In the Calvin cycle, the regeneration of ribulose bisphosphate (RuBP) requires how many ATP?

3 ATP Signup and view all the answers

Study Notes

Energy and Cellular Processes

Organisms require energy for various functions, including polymer synthesis, active transport, movement, and reproduction
Energy enters and leaves systems (e.g., from light to heat), but biological chemicals are recycled
Organic compounds store potential energy, usable as fuels in exergonic reactions

Fermentation vs. Respiration

Fermentation is partial sugar breakdown without oxygen
Aerobic Respiration is more efficient and needs oxygen, common in eukaryotic and prokaryotic cells
Anaerobic Respiration uses reactants other than oxygen

Aerobic Respiration

Similar to gasoline combustion: Organic compound + Oxygen → Carbon dioxide + Water + Energy
Glucose breakdown: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP + Heat)
∆G = -686 kcal/mol

Redox Reactions

Oxidation-reduction reactions (redox) involve electron transfer
Oxidation: Loss of electrons
Reduction: Gain of electrons (reduction because electrons are negatively charged)
Reducing agent: Donates electrons
Oxidizing agent: Gains electrons
Not all redox involve complete electron transfer; some change electron sharing degree (e.g., methane combustion)

Cellular Respiration Steps

Glycolysis: Occurs in the cytoplasm; glucose broken down to pyruvate; NAD⁺ reduced to NADH
Pyruvate Oxidation: Pyruvate converted to Acetyl CoA
Citric Acid Cycle (Krebs Cycle): Pyruvate further oxidized, yielding CO₂, ATP, NADH, and FADH₂

Oxidative Phosphorylation

Occurs in the inner mitochondrial membrane in eukaryotes
Substrate-level phosphorylation: Smaller amount of ATP formed in glycolysis and Krebs Cycle
Oxidative phosphorylation: Most ATP synthesis from electron transport chain (ETC) and chemiosmosis

Electron Transport Chain (ETC)

Series of proteins in the inner mitochondrial membrane
Electrons transferred from NADH and FADH₂, releasing energy to pump H⁺ into intermembrane space
Oxygen (highest electron affinity) is the final electron acceptor, forming water
Electron transfer from NADH to oxygen is exergonic (-53 kcal/mol)

Chemiosmosis

H⁺ gradient across membrane drives ATP synthesis via ATP synthase (a molecular motor)
Proton-motive force: H⁺ gradient's potential energy used to synthesize ATP
Prokaryotes use chemiosmosis to generate ATP and for other cellular functions (e.g., nutrient transport, flagella rotation)

ATP Yield and Efficiency

Complete glucose breakdown yields 30-32 ATP
ATP synthesis efficiency is about 34% of glucose's energy content
Excess energy released as heat

Fermentation

Anaerobic ATP production
Lactic acid fermentation: Pyruvate converted to lactate, regenerating NAD⁺
Alcoholic fermentation: Pyruvate converted to ethanol and CO₂, regenerating NAD⁺

Other Energy Sources

Carbohydrates, proteins, and fats are processed
Deamination: Amino groups removed from proteins used in other metabolic pathways
Beta-oxidation: Breakdown of fatty acids into acetyl-CoA
Fats yield twice the amount of ATP per gram compared to carbohydrates

Regulation of Cellular Respiration

Feedback inhibition: End product inhibits enzyme(e.g., ATP inhibits phosphofructokinase)
Phosphofructokinase: Key enzyme in glycolysis regulated by ATP levels:
Citrate: Additional regulator of glycolysis controlling early stages

Photosynthesis

Photosynthesis overview

Photosynthesis converts light energy to chemical energy (sugars): 6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂
Oxygen released from water splitting
Chloroplasts are the sites of photosynthesis, with chlorophyll absorbing light
Photosynthesis involves two main stages: light reactions and the Calvin cycle

Light Reactions

Light energy converted to chemical energy (ATP and NADPH)
Water is split, releasing oxygen
Electron transfer through photosystems (PS II and PS I) via ETC
Chemiosmosis drives ATP synthesis during photophosphorylation
Light excites electrons, passing them through ETC components, producing ATP and NADPH
The flow of electrons and protons generates a proton gradient that is used to produce ATP using chemiosmosis

The Calvin Cycle

CO₂ incorporated into organic molecules (carbon fixation)
NADPH (reducing agent) and ATP supply energy for sugar synthesis
G3P (glyceraldehyde-3-phosphate): Three-carbon sugar produced
Rubisco is a key enzyme in carbon fixation, highly abundant
Three phases: carbon fixation, reduction, and regeneration

Photorespiration

Rubisco also binds with O₂ (photorespiration), decreasing sugar production
C₃ plants experience more photorespiration under high temperatures, lower CO₂ concentrations
C₄ plants and CAM plants have mechanisms to minimize photorespiration.

C₄ and CAM Plants

C4: -Spatial separation of carbon fixation and Calvin cycle CAM: -Temporal separation of carbon fixation and Calvin cycle (night vs. day)

Chlorophyll and Pigments

Chlorophyll absorbs light, mainly red and blue, reflecting green
Pigments like chlorophyll a and carotenoids broaden the range of light used for photosynthesis

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Description

Test your knowledge on the differences between fermentation and aerobic respiration, as well as the underlying chemical equations and concepts related to redox reactions. This quiz covers key topics such as electron transfer and energy production. Perfect for biology students looking to reinforce their understanding.