The substances necessary for life are obtained by living organisms from the environment.

• Aerobic organisms, which include animals (with the exception of some parasites), plants, fungi and partially bacteria, oxygen is necessary for each cell to receive energy.
• Autotrophs synthesize organic matter (carbohydrates) from carbon dioxide and water during photosynthesis.
• Heterotrophs, which include representatives of such kingdoms as bacteria, fungi, animals, need organic matter.
• All inhabitants of the planet need water, without which life on Earth is impossible.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.