The Processes of Life

Ever wondered how scientists determine if something is actually alive? They look for seven key processes: movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition. If something performs these functions, it's considered living!

Enzymes are protein molecules that speed up chemical reactions in our bodies. They work best at their optimum temperature (around 37°C for humans), which is why maintaining body temperature is so critical. Each enzyme has a specific active site where substrate molecules fit perfectly—like a lock and key. When temperatures get too high, enzymes denature, changing their shape and becoming unable to function.

💡 Did you know? When enzymes denature, they don't get destroyed—their shape just changes! But at around 60°C, this change becomes permanent, making them useless.

Plants sustain themselves through photosynthesis, a remarkable process that converts carbon dioxide and water into glucose and oxygen using sunlight energy. The equation is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. The glucose produced is vital for plant growth and can be stored as starch for later use. The rate of photosynthesis depends on three main factors: light intensity, CO₂ concentration, and temperature.

All living organisms perform respiration to release energy from glucose. Aerobic respiration requires oxygen $C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O$, while anaerobic respiration occurs without oxygen, producing lactic acid in humans during intense exercise—that's what causes the painful "stitch" feeling!