bio u1 frq

1. The laws of thermodynamics are fundamental principles that govern the behavior of energy in natural systems. These laws are crucial in understanding how energy is transferred and transformed in biological systems, including living organisms.

   Prompt A: Explain the first and second laws of thermodynamics. Provide examples of how each law applies to biological processes in living organisms.

• First Law (Energy Conservation): Energy cannot be created/destroyed; only transformed.

Example: Cellular respiration converts glucose energy → ATP.

• Second Law (Entropy): Energy transfer increases disorder (entropy).

Example: Heat loss during metabolism increases entropy in the environment.

1. The laws of thermodynamics are fundamental principles that govern the behavior of energy in natural systems. These laws are crucial in understanding how energy is transferred and transformed in biological systems, including living organisms.

   Prompt B: The second law of thermodynamics states that the entropy of an isolated system will tend to increase over time, leading to a state of greater disorder. Given this principle, explain why life does not violate the second law of thermodynamics despite the high degree of order and organization observed in living organisms. Include a discussion of how living systems maintain order and what role energy plays in this process.

• Life does not violate the 2nd law: organisms are open systems.

• Living systems maintain order by using constant energy input (e.g., food, sunlight).

• Energy use increases entropy in surroundings (heat release), balancing local order.

2. Gibbs free energy (ΔG) is a thermodynamic quantity that predicts the spontaneity of a reaction and is central to understanding energy transformations in biological systems. In living organisms, Gibbs free energy plays a critical role in driving biochemical reactions necessary for life.

   Prompt A: Define Gibbs free energy and explain how it determines whether a reaction is spontaneous or non-spontaneous. Include a discussion of the relationship between Gibbs free energy, enthalpy (ΔH), entropy (ΔS), and temperature (T). Provide an example of a biological reaction, and explain how Gibbs free energy is used to determine its spontaneity.

• Definition: ΔG = ΔH – TΔS.

• ΔG < 0 → spontaneous; ΔG > 0 → non-spontaneous.

• Example: Breakdown of glucose (exergonic, ΔG < 0) in respiration releases energy.

2. Gibbs free energy (ΔG) is a thermodynamic quantity that predicts the spontaneity of a reaction and is central to understanding energy transformations in biological systems. In living organisms, Gibbs free energy plays a critical role in driving biochemical reactions necessary for life.

   Prompt B: Discuss how cells use Gibbs free energy to couple exergonic (energy-releasing) and

   endergonic (energy-consuming) reactions. Explain the significance of ATP in this process and provide specific examples of how ATP hydrolysis is used to drive biological processes that are essential for cellular function.

• Cells couple exergonic and endergonic reactions.

• ATP hydrolysis (ΔG < 0) powers unfavorable processes.

• Examples: Active transport (Na⁺/K⁺ pump), muscle contraction, DNA/RNA synthesis.

3. Enzymes are crucial biological catalysts that speed up chemical reactions in living organisms by lowering the activation energy required for these reactions. This ability to facilitate biochemical processes plays a significant role not only in the daily functioning of cells but also in the broader context of evolution.

Prompt A: Describe how enzymes lower the activation energy of biochemical reactions. Include a discussion of the enzyme-substrate complex and the induced fit model. Explain how these mechanisms contribute to the efficiency and specificity of enzyme activity.

• Enzymes lower activation energy.

• Form enzyme-substrate complex; induced fit = enzyme adjusts shape for substrate.

• Ensures reaction specificity and faster rates.

3. Enzymes are crucial biological catalysts that speed up chemical reactions in living organisms by lowering the activation energy required for these reactions. This ability to facilitate biochemical processes plays a significant role not only in the daily functioning of cells but also in the broader context of evolution.

Prompt B: Discuss the importance of enzymes in the context of evolution. How do enzymes enable evolutionary processes by allowing organisms to adapt to different environments? Provide specific examples of how enzyme activity can influence evolutionary fitness and the development of new traits in populations.

• Enzymes enable survival in diverse environments → evolutionary advantage.

• Mutations altering enzymes allow adaptation (e.g., lactase persistence in humans).

• Can shape new traits → antibiotic resistance enzymes in bacteria.

4. Macromolecules such as carbohydrates, lipids, proteins, and nucleic acids are essential to life, and their structures and functions are largely determined by the functional groups they contain. These functional groups play a critical role in the chemical properties and biological activities of these molecules.

Prompt A: Identify and describe the major functional groups found in macromolecules. For each

functional group, provide examples of macromolecules in which they are commonly found and explain how these functional groups contribute to the structure and function of the macromolecules.

• Hydroxyl (–OH): Carbohydrates → polarity, solubility.

• Carbonyl (C=O): Sugars → structure.

• Carboxyl (–COOH): Proteins/lipids → acidity.

• Amino (–NH₂): Proteins → base, peptide bonds.

• Phosphate (–PO₄): Nucleic acids/ATP → energy transfer.

• Methyl (–CH₃): DNA/proteins → regulation.

4. Macromolecules such as carbohydrates, lipids, proteins, and nucleic acids are essential to life, and their structures and functions are largely determined by the functional groups they contain. These functional groups play a critical role in the chemical properties and biological activities of these molecules.

Prompt B: Choose one type of macromolecule (carbohydrates, lipids, proteins, or nucleic acids) and discuss how the functional groups within this macromolecule influence its properties and biological functions. Include specific examples of how these functional groups affect the molecule's behavior in biological systems. 

• Amino (–NH₂) + Carboxyl (–COOH): form peptide bonds.

• R-group diversity (polar, nonpolar, charged) → folding/structure.

• Example: Hydrophobic side chains fold inward → stabilize tertiary structure.

5. Proteins are essential macromolecules that carry out a wide range of functions in biological systems, from catalyzing metabolic reactions to providing structural support. The function of a protein is intimately connected to its structure, which is organized into four levels of folding: primary, secondary, tertiary, and quaternary.

Prompt A: Describe the four levels of protein folding (primary, secondary, tertiary, and quaternary structure). For each level, explain how the specific interactions and bonds contribute to the overall shape of the protein.

• Primary: Amino acid sequence; peptide bonds.

• Secondary: α-helices, β-sheets; hydrogen bonds.

• Tertiary: 3D shape; hydrophobic interactions, ionic bonds, disulfide bridges.

• Quaternary: Multiple polypeptides; hemoglobin as example.

5. Proteins are essential macromolecules that carry out a wide range of functions in biological systems, from catalyzing metabolic reactions to providing structural support. The function of a protein is intimately connected to its structure, which is organized into four levels of folding: primary, secondary, tertiary, and quaternary.

Prompt B: Discuss how changes or disruptions at any level of protein folding can affect the function of a protein. Provide examples of how mutations, environmental changes, or incorrect folding can lead to diseases or disorders, illustrating the importance of proper protein structure for biological function. 

• Misfolding disrupts function.

• Mutations → sickle-cell anemia (abnormal hemoglobin).

• Misfolded proteins → Alzheimer’s, cystic fibrosis.

6. ATP is the primary energy currency of the cell, essential for powering various biological processes. The production of ATP through chemiosmosis involves the creation and utilization of an electrochemical gradient across a membrane, a process central to cellular respiration and photosynthesis.

Prompt A: Explain how an electrochemical gradient is established across a membrane in the mitochondria during cellular respiration. Discuss the roles of the electron transport chain and the movement of protons (H⁺ ions) in generating this gradient.

• Electron transport chain pumps protons (H⁺) into intermembrane space.

• Creates electrochemical gradient (proton motive force).

6. ATP is the primary energy currency of the cell, essential for powering various biological processes. The production of ATP through chemiosmosis involves the creation and utilization of an electrochemical gradient across a membrane, a process central to cellular respiration and photosynthesis.

Prompt B: Describe how ATP synthase uses the electrochemical gradient to synthesize ATP. Include a discussion of the mechanism by which the flow of protons through ATP synthase drives the production of ATP. Explain the significance of this process for cellular energy production and provide examples of how disruptions in this process can affect cellular function.

• ATP synthase allows H⁺ to flow back into matrix.

• Proton flow rotates enzyme → catalyzes ADP + Pi → ATP.

• Essential for energy; disruption (e.g., cyanide blocking ETC) stops ATP production → cell death.