Energy and Thermodynamics Overview (Exam 2)

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Questions and Answers

What is the primary role of adenosine triphosphate (ATP) in living organisms?

Energy transfer molecule (correct)

Catalysis of biochemical reactions

Storage of genetic information

Synthesis of structural proteins

Which reaction is characterized by the products containing more energy than the reactants?

Endergonic reaction (correct)

Anabolic reaction

Catabolic reaction

Exergonic reaction

Which statement accurately describes the First Law of Thermodynamics?

Energy will spontaneously flow from disordered to ordered states.

Energy is created when moving from potential to kinetic states.

Energy cannot be created or destroyed; it can only be transformed. (correct)

Energy can be lost as heat only during endergonic reactions.

During cellular respiration, how many ATP molecules are produced from one molecule of glucose?

36 ATP Signup and view all the answers

What specific role does NAD+ play in cellular respiration?

Electron transfer molecule Signup and view all the answers

What type of energy is stored in molecules such as glucose?

Potential energy Signup and view all the answers

Which phase of cellular respiration produces no ATP?

Transition phase Signup and view all the answers

What occurs during oxidation in a redox reaction?

Loss of electrons Signup and view all the answers

What is the primary purpose of glycolysis in cellular respiration?

To convert glucose into pyruvate Signup and view all the answers

During the energy investment stage of glycolysis, how many ATP are consumed?

Two ATP Signup and view all the answers

What is produced from each pyruvate during the transition phase?

One acetyl Coenzyme A and one NADH Signup and view all the answers

Which component is a byproduct of the Krebs cycle?

Carbon dioxide Signup and view all the answers

How many times does the Krebs cycle occur for one glucose molecule?

Twice Signup and view all the answers

In the Krebs cycle, how many NADH are produced from one cycle?

Three NADH Signup and view all the answers

Which macromolecule's stored energy is primarily utilized during cellular respiration?

Sugars Signup and view all the answers

The net gain of ATP from glycolysis is?

Two ATP Signup and view all the answers

What is the result of pyruvate accepting electrons from NADH?

Lactic acid formation Signup and view all the answers

Which option correctly describes a primary characteristic of anaerobic respiration?

It produces lactic acid as a byproduct. Signup and view all the answers

How much ATP is produced as one glucose molecule moves through the Krebs cycle?

2 ATP Signup and view all the answers

Which step produces the most electron carriers during cellular respiration?

Krebs cycle Signup and view all the answers

What is the primary function of the electron transport chain?

Power ATP synthesis through hydrogen ion transport Signup and view all the answers

Which of the following best describes the role of oxygen in cellular respiration?

Accepts electrons at the end of the electron transport chain Signup and view all the answers

Which term describes animals that maintain a stable internal body temperature through metabolic processes?

Endothermic Signup and view all the answers

What describes conformers in terms of internal conditions?

They allow internal conditions to fluctuate. Signup and view all the answers

Which term describes animals with a relatively constant body temperature?

Homeotherms Signup and view all the answers

Which of the following is a mechanism of heat transfer that involves the movement of air or water?

Convection Signup and view all the answers

What physiological state reflects decreased activity and metabolism in animals?

Torpor Signup and view all the answers

Which adaptation is NOT typically associated with heat conservation in animals?

Panting Signup and view all the answers

What is a key advantage of counter-current heat exchange in animals?

It enhances heat transfer efficiency. Signup and view all the answers

Which of the following dietary types is characterized by consuming plant-based materials?

Herbivores Signup and view all the answers

What do smaller mammals require more of compared to larger mammals to maintain their body temperature?

More energy Signup and view all the answers

Which response is a behavior adaptation for thermoregulation?

Huddling Signup and view all the answers

What occurs after the 6-carbon compound oxidizes to NAD+ in the Krebs Cycle?

It generates NADH and releases CO₂. Signup and view all the answers

Which molecule acts as the final electron acceptor in the Electron Transport Chain?

Oxygen Signup and view all the answers

In the Krebs Cycle, what is the main purpose of the 4-carbon compound?

To produce ATP through substrate-level phosphorylation. Signup and view all the answers

What is the end product of alcohol fermentation in yeast?

Ethanol Signup and view all the answers

What is the primary role of ATP synthase in cellular respiration?

To add phosphate to ADP to form ATP. Signup and view all the answers

What process occurs during chemiosmosis in mitochondria?

H+ ions move down their electrochemical gradient. Signup and view all the answers

Which statement is true regarding the transition phase of cellular respiration?

It occurs in the mitochondria and involves converting pyruvate to acetyl CoA. Signup and view all the answers

During which process is lactic acid produced?

Lactic acid fermentation Signup and view all the answers

How many total ATP molecules are generated from one glucose molecule after complete oxidation in cellular respiration?

32 Signup and view all the answers

What is the role of NAD+ in cellular respiration?

To accept electrons and become reduced to NADH. Signup and view all the answers

What drives the pumping of H+ ions across the inner mitochondrial membrane during the Electron Transport Chain?

Electrons from NADH and FADH2 Signup and view all the answers

In anaerobic conditions, which of the following allows glycolysis to continue producing ATP?

Fermentation Signup and view all the answers

What happens to the carbon skeleton of glucose during cellular respiration?

It is completely oxidized to CO2. Signup and view all the answers

What is produced during the Krebs Cycle besides ATP?

NADH and FADH2 Signup and view all the answers

Study Notes

Energy: The Capacity to Do Work

Energy is the capacity to bring about movement against an opposing force; the ability to do work.
Potential energy is stored energy (e.g., chemical energy in food, hydroelectric dam).
Kinetic energy is energy in motion (e.g., running, biking, flying).

Thermodynamics

First Law of Thermodynamics: energy cannot be created or destroyed, only transformed. Excess energy is released as heat.
Second Law of Thermodynamics: energy moves from order to disorder (entropy). Entropy is the measure of disorder.

Exergonic and Endergonic Reactions

Exergonic reactions release energy because reactants have more energy than products (e.g., cellular respiration).
Endergonic reactions require energy because products have more energy than reactants (e.g., photosynthesis).

Cellular Respiration and Photosynthesis

Photosynthesis is the conversion of light energy to chemical energy:
- 6H2O + 6CO2 → C6H12O6 + 6O2
- Water + Carbon dioxide → Glucose + Oxygen
Cellular Respiration is the process where living things extract energy stored in molecules:
- C6H12O6 + 6O2 → 6CO2 + 6H2O + 36ATP + Heat
- Glucose + Oxygen → Carbon dioxide + Water + 36 ATP + Heat

ATP: The Energy Transfer Molecule

Adenosine triphosphate (ATP) is the main molecule for energy transfer in living things.
Adenosine diphosphate (ADP) is the lower-energy form of ATP.
Phosphorylation is the addition of a phosphate group to a molecule, which increases its energy level.

Oxidation-Reduction Reactions

Oxidation is the loss of electrons.
Reduction is the gain of electrons.
Redox reactions involve the transfer of electrons between molecules.

NAD: Electron Carrier

Nicotinamide adenine dinucleotide (NAD+) is an electron carrier that transfers electrons from hydrogen atoms.

Cellular Respiration: Four Stages

Cellular respiration breaks down glucose into 36 ATP in four stages:
- Glycolysis: 2 ATP produced in the cytosol.
- Transition Phase: No ATP produced, takes place in the mitochondria.
- Krebs Cycle: 2 ATP produced in the mitochondria.
- Electron Transport Chain: 32 ATP produced in the mitochondria.

Macromolecules and Energy

We eat food to obtain energy stored in the chemical bonds of macromolecules (e.g., sugars).
This energy is captured and converted into ATP during cellular respiration.
ATP is used for the production of tissue and cell activities, or excreted as waste.

Glycolysis: Breakdown of Glucose

Glycolysis breaks down one glucose molecule into two pyruvate molecules.
Occurs in the cytosol (outside mitochondria) and is present in all living things.
Two stages:
- Energy Investment Stage: Requires 2 ATP.
- Energy Harvesting Stage: Produces 4 ATP and 2 NADH.

Transition Phase: Acetyl CoA Formation

Coenzyme A (acetyl CoA) is added to pyruvate to produce Acetyl Coenzyme A.
Carbon dioxide is a byproduct.
One NADH molecule is produced per pyruvate molecule.
Takes place in the inner compartment of mitochondria.

Krebs Cycle: Energy Production

Takes place in the inner compartment of mitochondria.
One glucose molecule (2 pyruvate) produces:
- 4 CO2
- 6 NADH
- 2 ATP
- 2 FADH2
Each turn of the Krebs Cycle involves a sequence of reactions:
- Acetyl CoA combines with 4-carbon oxaloacetic acid to form 6-carbon citric acid.
- Citric acid undergoes oxidation steps, releasing CO2 and producing NADH.
- The 4-carbon compound is regenerated, completing the cycle.

Electron Transport Chain: ATP Synthesis

Energy from electrons is used to pump H+ ions from the inner to the outer compartment of mitochondria, creating a gradient.
Oxygen is the final electron acceptor.
Chemiosmosis is the movement of ions across a semipermeable membrane down their electrochemical gradient.
ATP synthase uses energy from H+ ions to add phosphate to ADP, producing ATP.

Anaerobic Pathways: Energy Production Without Oxygen

Anaerobic pathways occur without oxygen:
- Glycolysis: produces 2 ATP.
- Fermentation: regenerates NAD+ from NADH to allow glycolysis to continue.
Aerobic pathways occur with oxygen:
- Cellular Respiration: produces 36 ATP.

Fermentation: Anaerobic Energy Production

Fermentation regenerates NAD+ from NADH, enabling continued glycolysis in the absence of oxygen.
Alcohol fermentation: occurs in yeast, producing ethanol.
Lactic acid fermentation: occurs in animals when oxygen supply is limited, producing lactic acid.

Summary of Cellular Respiration Steps

Step	Location	Input	Output	Electron Carriers	ATP
Glycolysis	Cytosol	Glucose	Pyruvate	2 NADH	2
Transition Phase	Inner compartment of mitochondria	Pyruvate, Coenzyme A	Acetyl-Coenzyme A, CO2	2 NADH -	-
Krebs Cycle	Inner compartment of mitochondrion	Acetyl Coenzyme A	CO2	6 NADH, 2 FADH2	2
Electron Transport Chain	Inner membrane of mitochondrion	Oxygen (O2)	H2O	10 NADH, 2 FADH2	32

Lactic Acid Fermentation

Lactic acid is produced when pyruvate accepts electrons from NADH
Occurs when oxygen delivery to cells is lagging, causing a burning sensation in muscles

Anaerobic and Aerobic Contributions

Energy from anaerobic respiration is used for short bursts of activity

Cellular Respiration Review

NAD+ becomes reduced when it gains an electron
Oxygen is required to make ATP
Cellular respiration is considered an exergonic reaction because it releases energy
The Krebs cycle produces the most electron carriers
2 ATPs are generated per glucose molecule processed through the Krebs cycle
The electron transport chain uses energy from electrons to power the active transport of hydrogen ions
The electron transport chain uses energy from electrons to attach phosphate groups to ADP
Oxygen acts as the final electron acceptor in the electron transport chain

Homeostasis

Homeostasis is the physiological state of internal stability
Regulators use internal mechanisms to control external fluctuations
Conformers allow internal conditions to change in response to external fluctuations

Thermoregulation

Thermoregulation is the process by which animals maintain their body temperature within a normal range
Endotherms maintain their body temperature through metabolic heat, including birds, mammals, and some insects
Ectotherms rely on external sources to regulate their body temperature, including most reptiles, fish, and invertebrates
Poikilotherms are animals whose body temperature fluctuates with the environment
Homeotherms are animals with a relatively constant body temperature

Heat Exchange with the Environment

Conduction is the direct transfer of heat
Convection is the transfer of heat by the movement of air or water across a surface
Radiation is the emission of electromagnetic waves
Evaporation is the loss of heat when a liquid changes into a gas

Adaptations for Thermoregulation

Insulation includes hair, feathers, and fat (blubber)
Behavior responses include basking, huddling, burrowing, and hot tubbing
Evaporative heat loss includes sweating, panting, and defecation

Energy Conservation

Torpor is a physiological state of decreased activity and metabolism
Hibernation is long-term torpor with decreased body temperature in response to winter cold and food scarcity
Estivation is decreased metabolic rate and activity during hot summer months

Vasodilation and Vasoconstriction

Vasodilation is the widening of superficial blood vessels, increasing heat transfer
Vasoconstriction is the decreasing of the diameter of superficial blood vessels, decreasing heat transfer

Counter-current Heat Exchange

Warm arterial blood from the core comes in close contact with veins returning from extremities
Arterial blood remains slightly warmer than venous blood, resulting in heat transfer
Returning blood is almost as warm as arterial blood

Animal Diets

All animals are heterotrophic
Herbivores eat plants
Carnivores eat meat
Omnivores eat both plants and meat
Insectivores eat insects
Three nutritional needs for animals include:
- Chemical energy for cellular processes
- Organic building blocks for macromolecules
- Essential nutrients

Trade-offs of Thermoregulatory Strategies

Endotherms
- Pros:
  - Can be active in cold environments
  - Can maintain a stable body temperature
- Cons:
  - Require more energy than ectotherms
  - Can overheat in hot environments
Ectotherms
- Pros:
  - Low energy requirements
  - Can survive in environments with limited food resources
- Cons:
  - Not active in cold environments
  - Vulnerable to temperature fluctuations
Smaller endotherms have a greater surface area to volume ratio
Smaller endotherms lose heat to the environment more easily, requiring more energy to maintain a constant body temperature

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Description

Explore the fundamental concepts of energy, including potential and kinetic energy, and the laws of thermodynamics. This quiz covers vital topics such as exergonic and endergonic reactions, as well as the processes of cellular respiration and photosynthesis. Test your understanding of these essential scientific principles!