C4.2.13 Heat loss to the environment in both autotrophs and heterotrophs Notes

Heat Loss to the Environment in Autotrophs and Heterotrophs

1. Energy flows through ecosystems, but it isn’t perfectly efficient.
2. A significant portion is lost as heat during cellular respiration.
3. This heat loss is a key reason why ecosystems need a constant energy supply from the sun.

Why Does Heat Loss Occur?

1. Cellular respiration is the process by which organisms convert the chemical energy in carbon compounds into ATP, the energy currency of cells.
2. However, energy transformations are governed by the second law of thermodynamics, which states that all energy transfers are inefficient, with some energy always lost as heat.

How Does Heat Loss Happen?

1. During Cellular Respiration: Energy is released as heat at every stage of cellular respiration:
   1. Glycolysis and the Krebs Cycle: Enzymatic reactions release energy, but not all of it is captured in ATP.
   2. Electron Transport Chain: Energy from electron movement is used for ATP synthesis, but some energy is lost as heat.
2. When ATP is Used: Energy continues to dissipate as heat when ATP is used for cellular activities like muscle contraction or active transport.

Heat Loss in Autotrophs and Heterotrophs

1. Autotrophs
   1. Plants and algae store energy from sunlight in glucose during photosynthesis.
   2. When this glucose is used for growth or reproduction, energy is released, with some lost as heat.
2. Heterotrophs
   1. Animals and fungi consume organic molecules for energy.
   2. During respiration and movement, a large portion of this energy is lost as heat.

Real-World Implications

1. Thermoregulation: Birds and mammals use heat from cellular respiration to maintain body temperature, allowing survival in various climates.
2. Food Production Efficiency: Plant-based diets are more energy-efficient than meat-based ones because fewer energy transfers occur.