Cellular respiration

Definition

Cellular respiration is a metabolic process that converts biochemical energy from nutrients into adenosine triphosphate (ATP), and releases waste products. This process is essential for all living organisms, as it provides the energy needed for various cellular functions and plays a crucial role in the flow of energy and the cycling of nutrients within ecosystems.

5 Must Know Facts For Your Next Test

1. Cellular respiration can occur both aerobically (with oxygen) and anaerobically (without oxygen), with aerobic respiration being more efficient in producing ATP.
2. The overall equation for aerobic cellular respiration can be summarized as: glucose + oxygen → carbon dioxide + water + ATP.
3. Glycolysis, the first stage of cellular respiration, occurs in the cytoplasm and breaks down glucose into pyruvate, producing a small amount of ATP.
4. The Krebs cycle, or citric acid cycle, takes place in the mitochondria and generates electron carriers that are used in the electron transport chain to produce the majority of ATP.
5. Cellular respiration not only provides energy but also contributes to the cycling of carbon within ecosystems, as it releases carbon dioxide back into the atmosphere.

Review Questions

• How does cellular respiration contribute to energy transfer within ecosystems?
  • Cellular respiration is vital for energy transfer within ecosystems because it allows organisms to convert stored energy from food into usable ATP. This process provides energy that fuels various life activities such as growth, reproduction, and movement. As organisms respire, they release carbon dioxide, which is then utilized by plants during photosynthesis, thus linking these two processes and ensuring the continuous flow of energy through food webs.
• Compare and contrast aerobic and anaerobic respiration in terms of efficiency and products.
  • Aerobic respiration is more efficient than anaerobic respiration in generating ATP. Aerobic processes produce up to 36-38 ATP molecules per glucose molecule by fully oxidizing glucose using oxygen. In contrast, anaerobic respiration yields only 2 ATP molecules per glucose molecule as it does not utilize oxygen and results in byproducts such as lactic acid or ethanol. This efficiency difference has significant implications for how organisms adapt to their environments based on oxygen availability.
• Evaluate the role of cellular respiration in the context of nutrient cycling, particularly regarding carbon cycling.
  • Cellular respiration plays a crucial role in nutrient cycling by facilitating the movement of carbon through ecosystems. During respiration, organisms convert carbohydrates back into carbon dioxide, which is released into the atmosphere. This carbon dioxide is then reabsorbed by plants during photosynthesis, creating a continuous cycle between producers and consumers. The balance between photosynthesis and cellular respiration is fundamental for maintaining ecosystem health and stability, illustrating how these processes are interconnected within carbon cycling.

Related terms

ATP: Adenosine triphosphate (ATP) is the primary energy carrier in cells, storing and providing energy for various biochemical reactions.

Photosynthesis: Photosynthesis is the process by which green plants and some other organisms convert light energy into chemical energy stored in glucose, which can later be used in cellular respiration.

Aerobic respiration: Aerobic respiration is a type of cellular respiration that requires oxygen to produce ATP, occurring in the mitochondria of eukaryotic cells.