🧬 Part 1: Understanding Cellular Respiration

1. Which of the following best defines aerobic respiration?

Energy release from glucose without oxygen

Glucose oxidation using oxygen to produce ATP, CO₂, and water

Photosynthesis in plant cells

Breakdown of proteins for energy

2. What are the main products of anaerobic respiration in yeast?

Lactic acid and ATP

Ethanol, CO₂, and ATP

Water and oxygen

Glucose and oxygen

3. When do cells typically perform anaerobic respiration? (Select all that apply)

During intense exercise when oxygen is limited

When oxygen is abundant

In environments with no oxygen available

During normal resting conditions

4. Fill in the blanks:

Aerobic respiration requires __________ and produces more __________ than anaerobic respiration. In muscle cells during intense exercise, anaerobic respiration produces __________ acid as a by-product.

🔬 Part 2: Yeast Respiration Investigation

5. Before conducting the yeast experiment, predict what will happen when yeast is mixed with sugar solution in a sealed container:

6. During the experiment, what evidence shows that anaerobic respiration is occurring?

The balloon inflates due to CO₂ production

The solution changes colour

The temperature decreases

Oxygen bubbles are produced

7. Record your observations from the yeast experiment:

8. Explain why the balloon inflated during the experiment. What gas was produced and why?

💭 Part 3: Critical Thinking

9. Compare the energy efficiency of aerobic and anaerobic respiration. Why might organisms still use anaerobic respiration despite it producing less ATP?

10. Give two real-life examples where anaerobic respiration is important:

Example 1: _________________________________

Example 2: _________________________________

11. Why is anaerobic respiration important for survival, even though it produces less energy than aerobic respiration?