Cellular Respiration
In which organelle does aerobic respiration occur?
Mitochondrion
How do phospholipids self-assemble into bilayers in water?
Hydrophobic tails cluster away from water, hydrophilic heads face water, forming a bilayer.
What is the function of chlorophyll in photosystem II?
It absorbs light energy to excite electrons that enter the electron transport chain.
What does a positive ΔG indicate about a reaction? What does a negative ΔG indicate?
It’s endergonic; it’s exergonic
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.
After glycolysis, how many carbons remain in each pyruvate?
3 carbons each (2 pyruvates × 3 = 6 total).
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 molecule is split during photosynthesis to release O₂?
Water.
What happens to enzymes when temperatures become too high?
The enzyme denatures.
What is the step of cellular respiration where all of the original glucose molecule has been totally broken down?
Kreb's cycle.
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.
This lipid is an important buffer, maintaining cell membrane fluidity in the face of both extreme heat and extreme cold temperatures
Cholesterol.
During oxidative phosphorylation, how is ATP actually synthesized?
Proton-motive force drives H⁺ through ATP synthase, which phosphorylates ADP to ATP (chemiosmosis).
A large steroid crosses the plasma membrane. There is a higher amount of steroid outside the cell than inside the cell. What type of transport is it going to use and which direction will it move?
Passive transport (simple diffusion) and it will go inside the cell.
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 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.
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).
An ab crunch requires +30 units of energy to happen. How many (minimum) ATP molecules would have to be used to power one ab crunch?
5 ATP molecules (hydrolyzing ATP releases 7.3 units of usable energy. 7.3 x 4 = 29.2 units. 7.3 x 5 = 36.5 units, which is more than enough to power an ab crunch).
Compare and contrast alcoholic fermentation vs lactic acid fermentation.
Both only involve the glycolysis step and regenerate NAD+. Lactic acid fermentation involves reducing pyruvate into lactic acid. Alcohol fermentation involves reducing pyruvate, but we make an intermediary product first (releasing CO2), eventually making ethanol.