Energy

Summary and Exam Tips for Energy

Energy is a subtopic of Energy and Respiration, which falls under the subject Biology in the Cambridge International A Levels curriculum. Energy is essential for all living organisms to maintain metabolism, with autotrophs using light energy and heterotrophs using chemical potential energy. Adenosine Triphosphate (ATP) is the universal energy currency, synthesized during respiration and photosynthesis, and is crucial for processes like active transport and anabolic reactions. ATP is a phosphorylated nucleotide composed of ribose sugar, adenine base, and three phosphate groups. Its hydrolysis releases energy, which is used for cellular functions. The energy values of respiratory substrates vary, with glucose being the primary substrate. When glucose is scarce, cells can use proteins and fats, which release different energy amounts. The Respiratory Quotient (RQ), the ratio of carbon dioxide produced to oxygen consumed, helps identify the substrate used in respiration and indicates the presence of anaerobic respiration. Investigating RQs involves using respirometers to measure oxygen consumption and calculate RQ values, providing insights into the metabolic processes of organisms.

Exam Tips

• Understand ATP Structure and Function: Be familiar with the components of ATP and its role as the universal energy currency. Know the energy release during ATP hydrolysis.
• Respiratory Substrates: Learn the energy values of different substrates like glucose, proteins, and fats, and how they contribute to ATP production.
• Respiratory Quotient (RQ): Practice calculating RQ and understand its significance in determining the type of substrate being respired and the presence of anaerobic respiration.
• Photosynthesis and Respiration: Grasp the conversion of solar energy into chemical energy during photosynthesis and its subsequent use in respiration.
• Practical Investigations: Be prepared to describe and conduct experiments using respirometers to measure RQ values, ensuring you understand the setup and calculations involved.