Obtaining Nutrients: Unicellular organisms must obtain nutrients from the environment in order to build new cells and obtain energy. This can be done through photosynthesis, in which organismsconvert light energy into chemical energy, or through heterotrophy, in which organisms consume other organisms to obtain nutrients.
Reproduction: Unicellular organisms must reproduce in order to create new individuals and maintain their population. Reproduction can occur through asexualreproduction, in which one organism divides into two or more identical organisms, or through sexual reproduction, in which two organisms combine genetic material to create a new, genetically diverse individual.
Respiration: Unicellular organisms must respire in order to release energy from nutrients. This can occur through aerobic respiration, in which organisms use oxygen to break down nutrients, or through anaerobic respiration, in which organisms break down nutrients without oxygen.
Waste Elimination: Unicellular organisms must eliminate waste products from their cells. This can occur through diffusion, in which waste products are transported out of the cell, or through active transport, in which energy is used to move waste products out of the cell.
Response to Stimuli: Unicellular organisms must respond to stimuli in their environment in order to survive. This can occur through chemosensation, in which organisms sense chemical changes in their environment, or through photoreception, in which organisms sense light.
