Life Processes

All the essential functions that perform the maintenance and survival of living organisms are called life processes. These mainly include nutrition, respiration, transportation, and excretion.

1. Nutrition

Organisms can be Autotrophs (making their own food through photosynthesis like green plants) or Heterotrophs (dependent on others for food). In humans, digestion takes place in the mouth (salivary amylase), stomach (HCl and pepsin), and is completed in the small intestine, where nutrients are absorbed through villi.

2. Respiration

In all organisms, glucose first breaks down into pyruvate in the cytoplasm.

• Aerobic Respiration: In the presence of oxygen, it produces energy, CO2, and water in the mitochondria.
• Anaerobic Respiration: In the absence of oxygen, it produces ethanol in yeast and lactic acid in muscle cells.

In humans, alveoli in the lungs facilitate the exchange of gases, and hemoglobin carries oxygen throughout the body.

3. Transportation

In humans, the heart acts as a pump that circulates blood through arteries and veins via a double circulation system.

In plants:

• Xylem: Transports water and minerals upwards from the roots.
• Phloem: Transports prepared food from leaves to various parts of the plant.

4. Excretion

In humans, kidneys are the primary excretory organs. Their filtering unit is the nephron, which filters waste products like urea from the blood to form urine.

Plants excrete waste through transpiration, shedding leaves, and in the form of gums or resins.