7.1 Energy Production through Cellular Respiration
Learn how living cells release energy from glucose through cellular respiration, and how different organisms obtain this main substrate.
Learning Objectives
- State the relationship between metabolic reactions (anabolism and catabolism) and energy.
- Define cellular respiration and identify glucose as its main substrate.
- Explain how humans, animals, and green plants acquire glucose for energy production.
- State the two types of cellular respiration and identify fermentation as an alternative pathway.
Pathways of Energy Production and Glucose Sources
Glucose is obtained differently by animals and plants, then enters aerobic respiration, anaerobic respiration, or fermentation.
Glucose Sources
Humans and animals obtain glucose through digestion of carbohydrates. Green plants trap light energy using chlorophyll during photosynthesis to produce glucose.
Energy Production Pathways
Aerobic respiration occurs in the presence of oxygen. Anaerobic respiration occurs in the absence of oxygen. Fermentation is an alternative pathway involving incomplete breakdown of glucose under limited or zero oxygen.
Short Explanation
Definition
Cellular respiration is the oxidation process of organic molecules through several stages to release energy needed by living cells. The main substrate is glucose.
Metabolism and Energy
Catabolism releases energy, while anabolism uses energy. Without energy, essential anabolic processes cannot occur.
Main Substrate
Glucose is the main substrate for cellular respiration. Chemical energy stored in glucose is released to yield cellular energy.
Acquisition of Glucose
Humans and animals obtain glucose through digestion of carbohydrates from consumed food. Green plants trap light energy using chlorophyll during photosynthesis to produce glucose.
Types of Cellular Respiration
Aerobic respiration occurs in the presence of oxygen. Anaerobic respiration occurs in the absence of oxygen.
Try to Answer First
Answer in your mind, then press “Check Answer”.
What is the main substrate used in cellular respiration to produce energy?
How do green plants obtain glucose for cellular respiration?
What is the primary difference in oxygen requirement between aerobic respiration and anaerobic respiration?
Common Mistakes
- Confusing the energy roles of anabolism and catabolism, thinking anabolism releases energy, whereas catabolism is the process that releases energy.
- Stating that cellular respiration occurs only in animals, forgetting that green plants also require cellular respiration to break down the glucose produced during photosynthesis.
- Overlooking fermentation as an incomplete breakdown of glucose that occurs in limited or zero oxygen conditions.
Concept Misunderstandings
Fermentation is just another name for aerobic cellular respiration.
Fermentation is an alternative pathway that involves the incomplete breakdown of glucose under conditions of limited oxygen or in the absence of oxygen.
Plants produce glucose only to feed animals.
Plants produce glucose through photosynthesis as a primary substrate for their own cellular respiration to release energy.
Summary
- Catabolism releases energy, whereas anabolism consumes energy.
- Cellular respiration is the multistage oxidation of organic molecules to release energy.
- Glucose is the primary substrate for cellular respiration.
- Animals gain glucose via carbohydrate digestion; plants produce glucose via photosynthesis.
- Cellular respiration is divided into aerobic respiration (with oxygen) and anaerobic respiration (without oxygen).
- Fermentation is an alternative pathway involving incomplete breakdown of glucose under limited or zero oxygen.
Short Activity
Objective: identify the main substrate, oxygen conditions, and alternative pathways of cellular respiration.
A. Objective Quiz
Which of the following is the main substrate used by cells to produce energy during cellular respiration?
Under which condition does aerobic respiration take place?
B. Fill in the Blanks
The metabolic process that breaks down molecules and releases energy is called .
In green plants, light energy is trapped by for the photosynthesis process to produce glucose.
C. Matching / Drag and Drop
Drag each process to its correct description. On a phone, tap a choice first, then tap the matching box. Tap the Answer Choices area to return a selected item.
C. Match the Process to Its Description
Write the correct process next to each description.
| Description | Process |
|---|---|
| 1. Cellular respiration that occurs in the presence of oxygen. | |
| 2. Cellular respiration that occurs in the absence of oxygen. | |
| 3. Incomplete breakdown of glucose in limited oxygen or without oxygen. | |
| 4. Metabolic process that uses energy to build substances like proteins. |
Answer choices: Aerobic respiration • Anaerobic respiration • Fermentation • Anabolism
