Learn: Nutrition, Respiration, and Excretion as Life Processes

Welcome!You've already learned about the characteristics shared by living things, such as nutrition, respiration, and excretion. Today, we'll build on that foundation and explore these processes in more depth to understand how they support life.

What is nutrition?Nutrition is the process by which organisms obtain the energy and nutrients needed for growth, repair, and survival. Plants produce their own food through photosynthesis, while animals consume other organisms for energy.

Types of nutritionOrganisms can be classified based on how they obtain their food:Autotrophic nutrition — Organisms make their own food (e.g., plants).Heterotrophic nutrition — Organisms rely on consuming other organisms for food (e.g., animals).

RespirationRespiration is the process that releases energy from glucose so cells can perform their functions. This energy is stored as ATP (adenosine triphosphate), which is used for activities like movement, growth, and repair.

Types of respirationThere are two types of respiration:Aerobic respiration — Requires oxygen and produces more energy. Equation: glucose + oxygen → carbon dioxide + water + energy.Anaerobic respiration — Occurs without oxygen and produces less energy. Word equation for animals: glucose → lactic acid + energy.

ExcretionExcretion is the removal of metabolic waste products from the body. These wastes can include carbon dioxide, urea, and excess salts, which are harmful if they accumulate in the body.

Excretion in humansHumans excrete metabolic waste through three main organs:Lungs — Remove carbon dioxide, a waste product from respiration.Kidneys — Filter blood, remove urea, excess salts, and water, and produce urine.Skin — Removes excess salts and water through sweat.

Review Time!Great work! You've learned about the processes of nutrition, respiration, and excretion. Now let's test your understanding with a few questions.