Cellular Respiration
In which organelle does aerobic respiration occur?
Mitochondrion
What would happen if a red blood cell were placed in a hypotonic solution?
Water would enter the cell, causing it to swell and potentially burst.
What is the function of chlorophyll in photosystem II?
It absorbs light energy to excite electrons that enter the electron transport chain.
What happens to enzyme activity when temperature is too high?
It denatures.
What molecule produced by photosynthesis is broken down during cellular respiration?
Glucose.
After glycolysis, how many carbons remain in each pyruvate?
3 carbons each (2 pyruvates × 3 = 6 total).
How do phospholipids self-assemble into bilayers in water?
Hydrophobic tails cluster away from water, hydrophilic heads face water, forming a bilayer.
What molecule is split during photosynthesis to release O₂?
Water.
What does feedback inhibition do?
Stops a pathway when enough product accumulates.
Why are mitochondria and chloroplasts considered evidence of endosymbiosis?
They have their own DNA, ribosomes, and double membranes, replicate independently.
What would happen if oxygen were unavailable for cellular respiration?
The electron transport chain would stop, NADH could not be oxidized, and ATP production would drop, leading to fermentation.
How do proteins embedded in the membrane contribute to selective transport?
Integral proteins act as channels or pumps allowing only specific molecules to pass.
What is the main output of the Calvin cycle per three CO₂ molecules fixed?
One molecule of G3P (glyceraldehyde-3-phosphate).
What is the difference between competitive and allosteric inhibition?
Competitive binds to active site, allosteric binds elsewhere and changes enzyme shape.
Both photosynthesis and respiration rely on redox reactions. Which one is overall endergonic, and why?
Photosynthesis is endergonic, energy is absorbed from sunlight to make glucose.
During oxidative phosphorylation, how is ATP actually synthesized?
Proton-motive force drives H⁺ through ATP synthase, which phosphorylates ADP to ATP (chemiosmosis).
Explain how the sodium-potassium pump maintains membrane potential.
It uses ATP to pump 3 Na⁺ out and 2 K⁺ in, creating an electrochemical gradient.
Compare chemiosmosis in chloroplasts vs mitochondria.
Both use H⁺ gradients to drive ATP synthase, but chloroplasts pump H⁺ into thylakoids, mitochondria into intermembrane space.
What does a positive ΔG indicate about a reaction? What does a negative ΔG indicate?
It’s endergonic; it’s exergonic
Each NADH yields about 3 ATP and each FADH₂ yields 2 ATP. If one glucose makes 10 NADH and 2 FADH₂, how much ATP from the ETC alone?
(10 × 3) + (2 × 2) = 30 + 4 = 34 ATP from oxidative phosphorylation.
Why is membrane fluidity critical for cell function, and what happens if temperature drops too low?
Proper fluidity allows protein mobility and permeability. if too low, membrane solidifies, transport and signaling fail.
Explain how ATP and NADPH from the light reactions are used in the Calvin cycle.
ATP provides energy; NADPH provides reducing power to convert CO₂ into G3P (a sugar).
What are cofactors and coenzymes, and how do they help enzymes?
Cofactors are inorganic ions; coenzymes are organic molecules. Both assist in catalysis by stabilizing the enzyme-substrate complex. Cofactors are inorganic ions; coenzymes are organic molecules. Both assist in catalysis by stabilizing the enzyme-substrate complex.