Cellular Respiration and Photosynthesis Overview

A comprehensive set of flashcards covering key concepts in cellular respiration and photosynthesis.

What is the primary purpose of cellular respiration?

To break down glucose and other organic molecules to produce ATP.

How does fermentation differ from cellular respiration?

Fermentation occurs without oxygen and produces ATP only through glycolysis, while cellular respiration uses oxygen and produces much more ATP.

What molecule acts as the final electron acceptor in aerobic respiration?

Oxygen (O2).

In glycolysis, how many net ATP are produced per glucose molecule?

2 net ATP.

Where does the citric acid cycle occur in eukaryotic cells?

In the mitochondrial matrix.

What role does NADH play in respiration?

It carries high-energy electrons from food breakdown to the electron transport chain.

Define substrate-level phosphorylation.

ATP production by direct transfer of a phosphate group to ADP from an intermediate substrate.

What is oxidative phosphorylation?

The production of ATP powered by the electron transport chain and chemiosmosis.

How does the electron transport chain generate a proton gradient?

Electrons release energy as they move through protein complexes, pumping protons across the inner mitochondrial membrane.

What enzyme uses the proton-motive force to make ATP?

ATP synthase.

Why is oxygen essential in aerobic respiration?

It accepts electrons at the end of the electron transport chain, allowing continuous ATP production.

Compare obligate anaerobes and facultative anaerobes.

Obligate anaerobes cannot survive in oxygen, while facultative anaerobes can switch between aerobic respiration and fermentation.

What is the primary function of photosynthesis?

To convert light energy into chemical energy stored in sugars.

Where in the chloroplast do the light reactions take place?

In the thylakoid membranes.

Where in the chloroplast does the Calvin cycle take place?

In the stroma.

What is photophosphorylation?

The formation of ATP using a proton gradient generated by light-driven electron transport.

What are the inputs and outputs of the light reactions?

Inputs: light, water, NADP+, ADP + Pi; Outputs: ATP, NADPH, O2.

What is the role of rubisco in the Calvin cycle?

It catalyzes the first step of carbon fixation by attaching CO₂ to RuBP.

Define carbon fixation.

The incorporation of inorganic CO₂ into organic molecules during the Calvin cycle.

How is NADPH used in photosynthesis?

It donates high-energy electrons for reducing carbon molecules in the Calvin cycle.

What are the products of the Calvin cycle?

G3P, ADP + Pi, and NADP+.

How does photorespiration reduce efficiency in plants?

Rubisco binds O2 instead of CO2, consuming ATP and reducing carbon fixation.

Compare autotrophs and heterotrophs.

Autotrophs make their own organic molecules from CO2, whereas heterotrophs consume other organisms for organic molecules.

Why are chlorophyll molecules essential to photosynthesis?

They absorb light energy and transfer it to electrons, starting the electron transport chain.

What is cyclic electron flow, and when does it occur?

Electrons cycle back to Photosystem I, producing extra ATP but no NADPH or O₂.

What is the relationship between photosynthesis and cellular respiration?

Photosynthesis stores energy in sugars, while respiration releases that energy, forming a biological cycle.

Why is photosynthesis considered the foundation of ecosystems?

It provides the organic molecules and energy that support nearly all food chains.