Question

Why are plants and animals dependent on light?

Answer 1

Ans. Light or sunlight has served as the primary source of energy since the evolution of life on earth. All the organisms irrespective of the being plant, animal or any other kind directly or indirectly depend of light for energy. In absence of sunlight, the sustenance of life on earth can’t prolonged.

# Dependence of plant on light: Plants exhibit relatively direct dependence on light for compensating their energy needs because sunlight is directly required for photosynthesis- the biological process that converts solar energy (light) into chemical energy (carbohydrate, ATP). It is the chemical energy produced during photosynthesis that plants use to drive all of their metabolic and physiological processes.

# Dependence of Animals on light: Because of lacking chloroplasts, the animals don’t have the ability to converts solar energy into chemical energy through photosynthesis. Instead, animals indirectly depend on solar energy for obtaining chemical energy because they consume the chemical energy stored in plants by the virtue of photosynthesis.

Unlike plants, most animals can perform their normal physiological activities at optimum only in an environment of certain minimum temperature, below which their optimal physiological activities in decreased. For this reason, the animals need a direct or indirect exposure of sunlight that keeps their body or the environment warm.