Which of these equations describes aerobic cellular respiration?
a. glucose → lactic acid + energy
b. energy + carbon dioxide + water → glucose + oxygen + water
c. glucose → ethyl alcohol + carbon dioxide + energy
d. glucose + oxygen → carbon dioxide + water + energy
The Correct Answer and Explanation is:
The correct answer is:
d. glucose + oxygen → carbon dioxide + water + energy
Explanation:
Aerobic cellular respiration is a process by which cells convert glucose (a simple sugar) into usable energy in the form of adenosine triphosphate (ATP). This process occurs in the presence of oxygen and is the primary way that most cells, especially those in humans and other aerobic organisms, generate energy.
The general equation for aerobic cellular respiration is:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP)
This equation represents the complete oxidation of one molecule of glucose (C₆H₁₂O₆) in the presence of oxygen (O₂). Here’s a breakdown of the components:
- Glucose (C₆H₁₂O₆): This is the main fuel molecule for aerobic respiration. Glucose is a six-carbon sugar that enters the cells through the bloodstream and is broken down in the cytoplasm and mitochondria.
- Oxygen (O₂): Oxygen is required for aerobic respiration. It acts as the final electron acceptor in the electron transport chain, which takes place in the mitochondria.
- Carbon dioxide (CO₂): During the process, glucose is oxidized, and carbon dioxide is produced as a waste product. It is then expelled from the body when we exhale.
- Water (H₂O): Water is also a byproduct of aerobic respiration, formed when oxygen accepts electrons and combines with protons.
- Energy (ATP): The primary goal of aerobic respiration is to generate ATP. Through a series of biochemical reactions (glycolysis, the citric acid cycle, and oxidative phosphorylation), the cell extracts the energy stored in glucose and transfers it into ATP, which the cell uses for various functions, such as muscle contraction, nerve transmission, and biosynthesis.
Why the other options are incorrect:
- a. glucose → lactic acid + energy: This describes anaerobic respiration or lactic acid fermentation, which occurs in the absence of oxygen.
- b. energy + carbon dioxide + water → glucose + oxygen + water: This describes photosynthesis, the process by which plants convert light energy into chemical energy.
- c. glucose → ethyl alcohol + carbon dioxide + energy: This describes alcoholic fermentation, which is also anaerobic and occurs in yeast cells.
In conclusion, aerobic cellular respiration requires both glucose and oxygen and results in the production of carbon dioxide, water, and energy, making option d the correct equation.