Science 9 Module 5: Ecosystem: Life Energy (Photosynthesis and Cellular Respiration)

A set of QUESTION_AND_ANSWER style flashcards covering the key concepts of photosynthesis and cellular respiration as presented in the Life Energy module.

What is photosynthesis?

The process by which green plants, algae, and some bacteria convert light energy, carbon dioxide, and water into glucose and oxygen.

Where does photosynthesis occur?

In the chloroplasts of plant cells, mainly in the leaves' mesophyll cells.

Name the two major stages of photosynthesis.

Light-dependent reactions and the Calvin cycle (light-independent reactions).

What are the photosystems involved in the light-dependent reactions?

Photosystem II (PSII) and Photosystem I (PSI).

What are the main products of the light-dependent reactions?

ATP, NADPH, and oxygen gas (O2).

What molecule accepts electrons to form NADPH in photosynthesis?

NADP+ accepts electrons and H+ to form NADPH.

Where does the Calvin cycle take place?

In the stroma of the chloroplast.

What is Rubisco’s role in photosynthesis?

The enzyme that fixes CO2 to RuBP to form 3-PGA.

What is the first stable product of the Calvin cycle?

3-phosphoglyceric acid (3PGA).

What is PGAL and its role in photosynthesis?

3-phosphoglyceraldehyde; a 3-carbon intermediate used to synthesize glucose.

What energy carriers are produced in the Krebs cycle?

NADH and FADH2 (and a small amount of ATP).

Where does glycolysis occur and how many ATP does it yield?

Occurs in the cytoplasm and yields 2 ATP per glucose (net).

What is acetyl-CoA?

A two-carbon molecule formed from pyruvate that enters the Krebs cycle.

What happens in the Krebs cycle?

Acetyl-CoA combines with oxaloacetate to form citrate; CO2 is released; NADH and FADH2 are produced; oxaloacetate is regenerated.

What is the purpose of the Electron Transport Chain?

To transfer electrons through protein complexes, pump protons, and generate ATP via ATP synthase; oxygen is the final electron acceptor forming water.

Where is the Electron Transport Chain located?

In the inner mitochondrial membrane.

What is oxidative phosphorylation?

ATP production driven by the proton gradient across the inner mitochondrial membrane via ATP synthase.

What is the final electron acceptor in the ETC?

Oxygen (O2).

What is the overall equation for cellular respiration?

Glucose + Oxygen -> Carbon dioxide + Water + ATP (C6H12O6 + 6O2 -> 6CO2 + 6H2O + ATP).

Where does cellular respiration occur in eukaryotic cells?

Glycolysis in the cytoplasm; Krebs cycle and ETC in the mitochondria.

What is anaerobic respiration and what does it produce?

Respiration without oxygen, occurring in the cytoplasm; produces lactate (animal cells) or ethanol and CO2 (yeast) with lower ATP yield.

What is the difference between photosynthesis and cellular respiration?

Photosynthesis stores energy by building glucose using light energy; cellular respiration releases energy by breaking down glucose to ATP.

What are the roles of the chloroplast’s grana and stroma?

Grana (stacks of thylakoids) host the light-dependent reactions; stroma hosts the Calvin cycle.

What is the function of stomata and guard cells?

Stomata are openings for gas exchange; guard cells regulate opening and closing of stomata.