Which factors are essential for most organisms to survive?

• A. Biotic interactions only
• B. Water, food, light, and oxygen
• C. Water and minerals only
• D. Temperature alone

Answer: (B)

Life needs a few basic resources to keep metabolism going and to grow. Water is the essential medium for chemical reactions and the transport of nutrients and wastes throughout the organism. Food, or nutrients, supplies the chemical energy and the building blocks organisms use to build and repair tissues. Oxygen is used in cellular respiration by many organisms to efficiently extract energy from nutrients, producing the ATP cells need to power activities. Light provides the energy source for photosynthesis in producers, which creates sugars that fuel the rest of the ecosystem. Together, these resources cover the essential needs for most organisms: access to water, a source of energy/nutrients, and, for those that rely on respiration, oxygen, with light supporting energy capture in photosynthetic life.

Relying only on biotic interactions wouldn’t supply the actual resources organisms need to survive. Water and minerals alone don’t provide energy or enable respiration, and temperature by itself doesn’t supply the materials or energy required for life.