Cell metabolism

Cell metabolism refers to the sum of all chemical reactions that occur within a cell to maintain life. In WJEC GCSE Biology, this topic focuses on two key processes: respiration and photosynthesis. Respiration is the process by which cells break down glucose to release energy, which is used for essential functions like muscle contraction, active transport, and maintaining body temperature. Photosynthesis, on the other hand, is the process by which plants and some bacteria convert light energy into chemical energy stored in glucose. Understanding these processes is crucial because they are the foundation of energy flow in ecosystems and the carbon cycle.

Cell metabolism is divided into two types: catabolic reactions, which break down molecules to release energy (e.g., respiration), and anabolic reactions, which build up molecules using energy (e.g., photosynthesis). For WJEC GCSE, you need to know the word equations for both processes, the conditions required, and how they are linked. For example, the products of photosynthesis (glucose and oxygen) are the reactants of respiration, and vice versa. This interdependence is key to understanding how energy flows through living organisms and why plants and animals rely on each other.

Mastering cell metabolism is essential for higher-level topics like enzyme action, limiting factors, and the carbon cycle. It also appears in practical contexts, such as investigating the rate of photosynthesis using pondweed or measuring respiration in germinating seeds. By the end of this topic, you should be able to explain how energy is transferred and transformed in cells, and why these processes are vital for life.