Ace Your AQA GCSE Biology Paper 1 2025 – Dive Into the World of Science and Score Big!

Metabolism in biological terms encompasses the sum of all chemical reactions that occur within a cell or an organism. It includes both the processes that break down molecules to obtain energy (catabolism) and those that build complex molecules from simpler ones (anabolism). Each of these processes is vital for sustaining life, as they enable organisms to convert the food consumed into energy, maintain cellular functions, and support growth and repair.

Choosing the option referring to the sum of all reactions provides a broader and more comprehensive understanding of metabolism than any of the other options, which focus on specific aspects. For instance, while the breakdown of glucose is an important metabolic pathway, it represents just one part of the entire metabolic landscape. Similarly, the consumption of nutrients is integral to metabolism, but it is not a complete definition as it does not include the myriad of reactions that also release energy or participate in biosynthesis. The energy output of cellular processes is another essential facet of metabolism, yet it too only captures a part of the total metabolic activity occurring within a cell or organism. Thus, defining metabolism as the sum of all reactions encompasses all these processes and their interconnections.