Energy & Biological Systems
In biological terms, why is energy often defined as the capacity to do work? Give one cellular example.
What is energy allows cells to perform processes like active transport, movement, or synthesis of molecules?
What does the First Law of Thermodynamics state, and how does it apply to metabolism?
What is energy cannot be created or destroyed, only transformed during metabolic reactions?
Why is ATP considered the “energy currency” of the cell?
What is it stores and transfers energy for cellular processes?
What happens to electrons during oxidation and reduction?
What is oxidation loses electrons and reduction gains electrons?
What is the primary function of enzymes in biological reactions?
What is to speed up reactions by lowering activation energy?
Compare potential and kinetic energy using an example from biology.
What is potential energy is stored (e.g., in chemical bonds), while kinetic energy is energy of motion (e.g., molecules moving during reactions)?
Why does entropy increase according to the Second Law of Thermodynamics, and how do cells cope with this?
What is disorder increases, but cells maintain order by using energy and exporting entropy to their surroundings?
What happens during ATP hydrolysis, and why does it release energy?
What is ATP is converted to ADP + Pi, releasing energy from the breaking of the third phosphate bond?
Why do redox reactions occur together in biological systems?
What is electrons lost by one molecule must be gained by another?
Why don’t enzymes change the overall ΔG of a reaction?
What is they only lower activation energy, not the total energy change?
Why is heat considered a byproduct of energy transformations in cells?
What is energy transfers are not 100% efficient, so some energy is lost as heat?
What does a negative ΔG indicate about a reaction?
What is the reaction is spontaneous and releases energy (exergonic)?
Explain how ATP hydrolysis is used to drive endergonic reactions.
What is ATP hydrolysis (exergonic) is coupled to endergonic reactions to provide the needed energy?
Why are redox reactions essential for cellular respiration and photosynthesis?
What is they transfer energy through electron movement?
Explain how the induced fit model improves enzyme function.
What is the enzyme changes shape to better fit the substrate and catalyze the reaction?
Explain how organisms function as open systems and why this is important for survival.
What is organisms exchange both energy and matter with their surroundings, allowing them to maintain order and sustain life?
Compare spontaneous and nonspontaneous reactions in terms of energy and ΔG.
What is spontaneous reactions release energy and have negative ΔG, while nonspontaneous require energy input and have positive ΔG?
Why is ATP described as being in an “intermediate position” in metabolism?
What is it links catabolic (energy-releasing) and anabolic (energy-requiring) reactions?
Why do cells often transfer hydrogen atoms instead of free electrons?
What is free electrons cannot exist independently in cells, so they are transferred with protons?
How do temperature and pH affect enzyme activity at the molecular level?
What is they alter protein structure, affecting the active site and function?
Explain why energy conversions are essential for life, using photosynthesis as an example.
What is energy must be converted into usable forms; photosynthesis converts radiant energy into chemical energy stored in molecules?
Why are spontaneous reactions not always immediate in biological systems?
What is they still require activation energy to begin?
Describe how a coupled reaction involving ATP can result in an overall negative ΔG even if one step is positive.
What is the exergonic ATP hydrolysis releases more energy than the endergonic reaction requires, making the net ΔG negative?
Compare the roles of NADH and NADPH in cells.
What is NADH helps generate ATP (cellular respiration), while NADPH is used in photosynthesis?
Compare competitive and noncompetitive inhibition and their effects on enzyme activity.
What is competitive inhibitors bind to the active site, while noncompetitive inhibitors bind elsewhere and change enzyme shape?