Energy (Cambridge International A-Level Biology)
Exam board Cambridge International · A-LevelUpdated 2025-10-05
The Need for Energy
Spec point —
12.1.1· outline the need for energy in living organisms, as illustrated by active transport, movement and anabolic reactions, such as those occurring in DNA replication and protein synthesis
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Living organisms are composed of cells, and within each cell, many activities and processes are constantly being carried out to maintain life
- Work in a living organism requires energy
| Type of work | Examples |
|---|---|
| Transporting substances across membranes | - Active transport using the sodium-potassium pump in cell membranes - Exocytosis of digested bacteria from white blood cells |
| Anabolic reactions | - Synthesis of DNA from nucleotides - Synthesis of proteins from amino acids |
| Movement | - Cellular movement of chromosomes via the spindle - Mechanical contraction of muscles |
| Maintaining body temperature | - Occurs only in mammals and birds |
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