1. Discover Activity: What is a Product of Respiration
Ch. 3-4 Respiration Key Concepts: What events occur during respiration? What is fermentation
Discover Activity: What is a Product of Respiration
Fill two test tubes half full of warm water. Add ½ teaspoon of sugar to one of the test tubes. Add a couple pinches of yeast to each test tube. Cover each test tube. Observe each test tube for the next 5 minutes.
What happened after adding the yeast to the test tube with sugar?
_____________________________________________________________________
2. What happened after adding the yeast to the test tube without sugar?
3. How can you account for any changes you observed. Hint: think about the title of the Discovery Activity.

2. RESPIRATION: simple food molecules to release the energy they contain.
The process by which cells break down
simple food molecules to release the energy they contain.
Storing and releasing energy: Energy stored in cells is like money in a savings account.
When cells need energy, they “withdraw” it by breaking down carbohydrates in the process of respiration
Two stages of respiration:
Stage 1: In the cytoplasm Stage 2: In the mitochondria
Glucose is broken down into smaller molecules. A small amount of energy is released.
Smaller molecules combine with oxygen to produce water and carbon dioxide. This reaction releases a large amount of energy.

3. The Respiration Equation
Sugar
Oxygen
Carbon
Dioxide
Water
Raw materials for respiration
Where does the sugar come from in this equation? __________________________________________________
Where does the oxygen come from in this equation? __________________________________________________

4. FERMENTATION: Examples of cells that us fermentation:
The process by which cells break down molecules to release energy without using oxygen.
Examples of cells that us fermentation:
Single-celled organisms living:
1. deep in the ocean
2. mud of lakes or swamps
Benefit of fermentation:
Provides energy for cells without using oxygen.
But… amount of energy released is much lower than during respiration.
Highly magnified yeast
cells

5. Examples of Fermentation
Alcoholic Fermentation:
Yeast and other single-celled organisms break down sugars.
Products: alcohol, carbon dioxide, and small amounts of energy
Lactic Acid Fermentation: Occurs in your body during intense physical activity when your muscle cells use oxygen faster than it could be replaced.
Product: lactic acid
*makes your muscles feel weak and sore

6. Section 3-4 Assessment 1.a. What happens during respiration?
What is the equation for respiration?
Compare the equations for respiration and photosynthesis. Explain why cellular respiration adds carbon dioxide to the atmosphere, but photosynthesis does not.
2.a. What is the process in which cells obtain energy without using oxygen?
How would athletes be affected if this process could not take place?
Is this process more likely to occur during a short run or a long walk? Explain your answer.