CLEP Biology - 1.4 Energy Transformations

What is cellular respiration?

The process by which cells convert glucose into ATP to fuel cellular functions.

What are the three main stages of cellular respiration?

Glycolysis, Krebs Cycle, and Electron Transport Chain.

Where does glycolysis occur?

In the cytoplasm.

What is the main purpose of glycolysis?

To break down glucose into two pyruvate molecules, producing a small amount of ATP and NADH.

How many ATP are produced during glycolysis?

2 net ATP.

What happens to pyruvate in the presence of oxygen?

It is converted to acetyl CoA and enters the Krebs Cycle.

Where does the Krebs Cycle take place?

In the mitochondrial matrix.

What are the main products of the Krebs Cycle?

ATP, NADH, FADH₂, and CO₂.

What is the electron transport chain (ETC)?

A series of proteins in the inner mitochondrial membrane that transfers electrons and generates ATP.

What role does oxygen play in the ETC?

It acts as the final electron acceptor, forming water.

How many ATP molecules are produced in total from one glucose molecule during cellular respiration?

Approximately 32-38 ATP.

What is NADH?

An electron carrier that transfers high-energy electrons to the ETC.

What is FADH₂?

An electron carrier similar to NADH, produced in the Krebs Cycle.

What is anaerobic respiration?

Respiration without oxygen, resulting in fermentation.

What are the two types of fermentation?

Lactic acid fermentation and alcoholic fermentation.

Where does lactic acid fermentation occur in the body?

In muscle cells during intense exercise when oxygen is low.

What is the main purpose of fermentation?

To regenerate NAD⁺ so glycolysis can continue in the absence of oxygen.

What is photosynthesis?

The process by which plants, algae, and some bacteria convert light energy into glucose.

What are the two main stages of photosynthesis?

Light-dependent reactions and the Calvin Cycle.

Where do the light-dependent reactions occur?

In the thylakoid membranes of the chloroplast.

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

ATP, NADPH, and oxygen.

What is chlorophyll?

A green pigment that captures light energy for photosynthesis.

What is the Calvin Cycle?

The set of light-independent reactions in photosynthesis that produce glucose.

Where does the Calvin Cycle take place?

In the stroma of the chloroplast.

What molecule is fixed into glucose in the Calvin Cycle?

Carbon dioxide (CO₂).

What is the primary function of NADPH in the Calvin Cycle?

To provide electrons and energy for carbon fixation.

What molecule is released as a byproduct of the light-dependent reactions?

Oxygen (O₂).

What is the overall equation for photosynthesis?

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.

How is ATP produced in the light-dependent reactions?

By ATP synthase, using a proton gradient created across the thylakoid membrane.

What are photosystems I and II?

Complexes in the thylakoid membrane that capture light energy to drive the light-dependent reactions.

What is the role of water in photosynthesis?

Water is split to provide electrons, releasing oxygen as a byproduct.

What enzyme is crucial for carbon fixation in the Calvin Cycle?

Rubisco.

What is the main purpose of ATP in cellular processes?

To provide energy for various cellular functions.

What is carbon fixation?

The process of incorporating CO₂ into organic molecules, like glucose.

What are stomata?

Small openings on leaves that allow gas exchange, letting CO₂ in and O₂ out.

What role do NADP⁺ and NADPH play in photosynthesis?

NADP⁺ carries electrons from the light-dependent reactions to the Calvin Cycle as NADPH.

Why is oxygen considered a byproduct of photosynthesis?

Because it is released when water is split during the light-dependent reactions.

What energy sources power the Calvin Cycle?

ATP and NADPH produced in the light-dependent reactions.

In which cell organelle does photosynthesis take place?

The chloroplast.

What is oxidative phosphorylation?

ATP production in the ETC, powered by a proton gradient.

Which cycle in cellular respiration produces CO₂?

The Krebs Cycle (Citric Acid Cycle).

What happens to pyruvate if oxygen is not available?

It undergoes fermentation to regenerate NAD⁺.

What are accessory pigments?

Pigments like carotenoids that help absorb additional light wavelengths.

What are the products of glycolysis?

2 pyruvate, 2 ATP, and 2 NADH.

What is the main purpose of the light-dependent reactions?

To convert light energy into ATP and NADPH.

Which molecules act as electron carriers in cellular respiration?

NADH and FADH₂.

How many ATP are produced from one glucose in aerobic respiration?

About 32-38 ATP.

What structure within chloroplasts captures light energy?

Thylakoid membranes.

How do plants store the energy produced in photosynthesis?

As glucose, which can be broken down later for ATP.

What is the purpose of the proton gradient in the ETC?

To drive ATP production via ATP synthase.