Cellular respiration

Definition

Cellular respiration is the process by which cells convert glucose and oxygen into energy, carbon dioxide, and water. This biochemical process is essential for producing adenosine triphosphate (ATP), the energy currency of the cell, which powers various cellular activities. It plays a critical role in energy flow within ecosystems, as organisms utilize the energy stored in organic compounds to support their metabolic functions.

5 Must Know Facts For Your Next Test

1. Cellular respiration consists of three main stages: glycolysis, the Krebs cycle, and oxidative phosphorylation.
2. In aerobic conditions, cellular respiration produces a net gain of about 36 to 38 ATP molecules per molecule of glucose.
3. Carbon dioxide produced during cellular respiration is released back into the atmosphere and is utilized by plants for photosynthesis, creating a cyclical relationship between the two processes.
4. In anaerobic conditions, some organisms switch to fermentation, producing less ATP and generating byproducts like lactic acid or alcohol.
5. Cellular respiration is crucial for maintaining the balance of nutrients in ecosystems, as it helps decompose organic matter and recycle carbon back into the atmosphere.

Review Questions

• How does cellular respiration contribute to energy flow in ecosystems?
  • Cellular respiration is vital for energy flow in ecosystems because it allows organisms to break down glucose and release stored energy in the form of ATP. This process not only provides energy for various metabolic functions in living organisms but also produces carbon dioxide as a byproduct. The carbon dioxide is then utilized by plants during photosynthesis, forming a crucial link between producers and consumers in an ecosystem.
• Compare and contrast aerobic cellular respiration with anaerobic fermentation in terms of their processes and outcomes.
  • Aerobic cellular respiration requires oxygen and consists of glycolysis, the Krebs cycle, and oxidative phosphorylation, yielding approximately 36 to 38 ATP molecules per glucose molecule. In contrast, anaerobic fermentation occurs without oxygen and typically results in only 2 ATP molecules from glycolysis, with byproducts like lactic acid or ethanol. While aerobic respiration is more efficient in energy production, fermentation allows organisms to survive in oxygen-poor environments.
• Evaluate the role of cellular respiration in nutrient cycling within ecosystems and its impact on environmental balance.
  • Cellular respiration plays a critical role in nutrient cycling within ecosystems by facilitating the decomposition of organic matter and recycling essential elements like carbon. As organisms respire, they release carbon dioxide back into the atmosphere, which is then used by plants for photosynthesis. This process helps maintain ecological balance by ensuring that energy flows through food webs and that nutrients are continually recycled, supporting life at various trophic levels.

Related terms

Photosynthesis: The process used by plants, algae, and some bacteria to convert light energy into chemical energy in the form of glucose, which serves as a primary energy source.

ATP (Adenosine Triphosphate): The molecule that carries energy within cells; it is produced during cellular respiration and is used to fuel various biological processes.

Fermentation: An anaerobic process that allows cells to produce energy without oxygen by breaking down glucose into lactic acid or ethanol, providing an alternative pathway for energy production.