1. Autotrophs (Producers):
* Photosynthesis: These organisms, like algae and some bacteria, use sunlight, water, and carbon dioxide to produce their own food. They contain chlorophyll, a pigment that captures sunlight energy.
2. Heterotrophs (Consumers):
* Phagocytosis: This is the process of engulfing solid food particles. The cell membrane engulfs the particle, forming a food vacuole. Enzymes break down the food inside the vacuole.
* Pinocytosis: This is the process of engulfing liquid food particles. The cell membrane invaginates (folds inward), forming a vesicle that encloses the liquid.
* Absorption: Some unicellular organisms, like bacteria, absorb dissolved nutrients directly through their cell membrane.
* Parasitism: Some unicellular organisms, like parasites, live inside other organisms and obtain nutrients from their host.
Examples:
* Amoeba: Phagocytizes food particles like bacteria.
* Paramecium: Uses cilia to sweep food particles into its oral groove, then phagocytizes them.
* Euglena: Can photosynthesize and also engulf food particles.
Key points:
* Unicellular organisms lack specialized digestive systems found in multicellular organisms.
* They rely on various methods to acquire nutrients and energy.
* Their feeding strategies are essential for survival and growth.
Let me know if you have any other questions!
