Energy and Enzymes: Cellular Respiration, Photosynthesis, and Metabolic Pathways

Q1. Using figure 7.2, describe photosynthesis and how it makes the macromolecules that are in your food.

Background

Topic: Photosynthesis and Energy Flow in Ecosystems

This question tests your understanding of how photosynthesis converts light energy into chemical energy, producing organic molecules that serve as the building blocks for macromolecules in food.

Key Terms:

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

• Macromolecules: Large molecules such as carbohydrates, proteins, and lipids, which are synthesized from smaller organic molecules.

• Chloroplast: The organelle where photosynthesis occurs.

Step-by-Step Guidance

1. Examine figure 7.2 and identify the main steps of photosynthesis: light energy is absorbed by chloroplasts, which use CO2 and H2O to produce organic molecules.

2. Understand that these organic molecules (such as glucose) are the starting materials for building macromolecules in food.

3. Recognize that the energy stored in these molecules is later used by organisms for cellular work.

4. Consider how these molecules are further processed to form carbohydrates, proteins, and lipids.

Try solving on your own before revealing the answer!

Final Answer:

Photosynthesis in chloroplasts uses light energy to convert CO2 and H2O into organic molecules (like glucose). These molecules are then used to build macromolecules (carbohydrates, proteins, lipids) found in food.

Q2. Using figure 7.2 again, describe how photosynthesis is related to cellular respiration.

Background

Topic: Relationship Between Photosynthesis and Cellular Respiration

This question tests your ability to connect the processes of photosynthesis and cellular respiration, showing how energy and matter cycle in ecosystems.

Key Terms:

• Cellular Respiration: The process by which cells break down organic molecules to release energy (ATP).

• ATP: Adenosine triphosphate, the energy currency of the cell.

Step-by-Step Guidance

1. Identify that photosynthesis produces organic molecules and oxygen, which are used as inputs for cellular respiration.

2. Cellular respiration occurs in mitochondria and breaks down these organic molecules to produce ATP, CO2, and H2O.

3. Recognize that the CO2 and H2O produced by respiration are recycled as inputs for photosynthesis.

4. Understand that energy flows from sunlight to chemical energy (in organic molecules) to ATP, and finally as heat.

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Final Answer:

Photosynthesis and cellular respiration are interconnected: photosynthesis makes organic molecules and oxygen, which are used in cellular respiration to produce ATP, CO2, and H2O. The products of respiration are then used again in photosynthesis, creating a cycle of energy and matter.

Q3. Describe how metabolic pathways break down macromolecules to get energy (using the word catabolic).

Background

Topic: Catabolic Pathways and Energy Release

This question tests your understanding of how catabolic pathways break down macromolecules to release energy for cellular processes.

Key Terms:

• Catabolic Pathways: Metabolic pathways that break down complex molecules into simpler ones, releasing energy.

• ATP: The main energy carrier in cells.

Step-by-Step Guidance

1. Recall that catabolic pathways involve the breakdown of macromolecules (carbohydrates, proteins, fats) into smaller molecules.

2. Understand that this breakdown releases energy, which is captured in the form of ATP.

3. Recognize that cellular respiration is a key catabolic pathway, breaking down glucose to produce ATP.

4. Consider how enzymes facilitate these reactions and how energy is transferred through intermediates like NADH and FADH2.

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Final Answer:

Catabolic pathways break down macromolecules into smaller molecules, releasing energy that is captured as ATP. Cellular respiration is a major catabolic pathway that converts glucose into ATP, CO2, and H2O.

Q4. Below is the equation for cellular respiration. In the table, list where each component of the reaction comes from.

Background

Topic: Inputs and Outputs of Cellular Respiration

This question tests your ability to identify the sources of reactants and products in the cellular respiration equation.

Key Terms and Formula:

• Cellular Respiration Equation: $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}$

• Glucose: Comes from food (photosynthesis in plants).

• Oxygen: Comes from the atmosphere (produced by photosynthesis).

• CO2 and H2O: Produced as waste products during cellular respiration.

• ATP: Produced during cellular respiration and used for cellular work.

Step-by-Step Guidance

1. Write out the balanced equation for cellular respiration.

2. Identify the source of each reactant: glucose (food), oxygen (air).

3. Determine where each product goes: CO2 (exhaled), H2O (used or excreted), ATP (used for cellular work).

4. Fill in the table with these sources and destinations.

Try solving on your own before revealing the answer!

Final Answer:

Glucose comes from food, oxygen from the air, CO2 is exhaled, H2O is used or excreted, and ATP is used for cellular work.