Guided Practice
Learning Objectives
In this guided practice lesson, you will apply your knowledge of cell organelles and cellular respiration to solve problems with step-by-step guidance.
- Apply understanding of organelle functions to identify structures from descriptions
- Trace the pathway of cellular respiration through the cell
- Analyze diagrams and data related to cell structure and function
- Practice scientific reasoning with scaffolded support
Worked Examples
Example 1: Identifying Organelles by Function
Problem: A scientist observes a cell that is producing large amounts of protein for export. Which organelle would you expect to be most abundant in this cell?
Solution:
- Identify the key function: protein production for export
- Recall which organelle synthesizes proteins: ribosomes
- Recall which organelle processes and packages proteins for export: rough endoplasmic reticulum and Golgi apparatus
- Answer: Rough endoplasmic reticulum (and Golgi apparatus) would be abundant
Example 2: Tracing Energy Flow
Problem: Describe the path of a glucose molecule as it is broken down for energy in a cell.
Solution:
- Glucose enters the cytoplasm
- Glycolysis occurs in the cytoplasm, producing pyruvate
- Pyruvate enters the mitochondria
- The Krebs cycle occurs in the mitochondrial matrix
- The electron transport chain occurs in the inner mitochondrial membrane
- ATP is produced as the final energy currency
Practice Quiz
Test your understanding with these 10 questions. Click on each question to reveal the answer.
1. Which organelle is known as the "powerhouse of the cell" because it produces ATP?
Answer: Mitochondria
Explanation: Mitochondria are the site of cellular respiration, where glucose is broken down to produce ATP, the cell's main energy currency.
2. A cell is observed to have an extensive rough endoplasmic reticulum. What type of molecule is this cell likely producing in large quantities?
Answer: Proteins
Explanation: The rough endoplasmic reticulum is studded with ribosomes and is the site of protein synthesis, particularly for proteins that will be exported from the cell.
3. Where does glycolysis take place in the cell?
Answer: Cytoplasm
Explanation: Glycolysis is the first stage of cellular respiration and occurs in the cytoplasm, not in any membrane-bound organelle.
4. Which organelle contains its own DNA and ribosomes?
Answer: Mitochondria (and chloroplasts in plant cells)
Explanation: Mitochondria contain their own circular DNA and ribosomes, supporting the endosymbiotic theory that they evolved from ancient bacteria.
5. What is the primary function of the Golgi apparatus?
Answer: To modify, sort, and package proteins and lipids for transport
Explanation: The Golgi apparatus receives proteins from the rough ER, modifies them (often by adding carbohydrates), and packages them into vesicles for transport.
6. How many ATP molecules are typically produced from one glucose molecule during cellular respiration?
Answer: 36-38 ATP molecules
Explanation: Complete oxidation of glucose through glycolysis, the Krebs cycle, and oxidative phosphorylation produces approximately 36-38 ATP molecules.
7. Which structure controls what enters and exits the cell?
Answer: Cell membrane (plasma membrane)
Explanation: The cell membrane is selectively permeable, allowing some substances to pass while blocking others, thus controlling the cell's internal environment.
8. What are the products of the Krebs cycle?
Answer: CO2, NADH, FADH2, and a small amount of ATP
Explanation: The Krebs cycle produces carbon dioxide as a waste product, and electron carriers (NADH and FADH2) that will be used in the electron transport chain.
9. A plant cell has a structure that animal cells lack. This structure provides support and protection. What is it?
Answer: Cell wall
Explanation: Plant cells have a rigid cell wall made of cellulose outside their cell membrane, providing structural support and protection.
10. During which stage of cellular respiration is the most ATP produced?
Answer: Oxidative phosphorylation (electron transport chain)
Explanation: The electron transport chain produces approximately 34 of the 36-38 total ATP molecules from cellular respiration, making it the most productive stage.
Next Steps
- Review any questions you found challenging
- Continue to the Lab Analysis lesson to apply these concepts to experimental data
- Return to this practice quiz periodically to reinforce your understanding