Kingdom protoctista

1. Some are autotrophs, for example Euglena, while others are heterotrophs.
2. They are all eukaryotes with most of them having locomotor structures.
3. Most of them live in moist places or in water.

1. Most are unicellular eukaryotes.
2. They reproduce by binary fission.

Amoeba is a free-living, unicellular organism found at the bottom of ponds and lichen.

1. Amoeba has two layers of cytoplasm: the outer layer is called ectoplasm and the inner layer is called endoplasm. Endoplasm is more fluid and contains granules and vacuoles.
2. Amoeba is found in fresh water.
3. They use pseudopodia (cell extensions) for locomotion and to engulf food.
4. Contractile vacuoles regulate the amount of water in the fresh water.
5. A temporary food vacuole is formed to hold and digest food particles.
6. Waste products such as urea and ammonia are excreted by simple diffusion.
7. Oxygen and carbon dioxide are exchanged by simple diffusion.
8. Amoeba reproduces by binary fission.

Amoeba

Amoeba is commonly used in laboratories to study cell structure and function.

Amoeba can cause diseases, for example Entamoeba histolytica causes amoebic dysentery in humans.

Euglena are characterized by the green scum that appears on stagnant water.

Euglena

1. They are unicellular.
2. They are found in both fresh water and salt water.
3. Euglena move using a flagellum.
4. Some have chloroplasts for photosynthesis while others are heterotrophic.
5. They reproduce asexually.
6. Some euglena have a pellicle, which is a flexible layer within the cell membrane. The pellicle helps euglena to change shape.

Euglena is used to treat sewage because of their unique capacity to change from being autotrophic to heterotrophic. When they photosynthesize they produce oxygen, and when they are heterotrophic they use oxygen. This helps to keep oxygen levels balanced in sewage treatment plants.

Euglena called phytoplankton are an important source of food for many types of aquatic micro-organisms.

Phytoplankton produce large quantities of oxygen during photosynthesis.

Euglena blooms can be harmful to fish. These are sudden increases in the number of microorganisms in the water.

1. They are unicellular and slipper-shaped.
2. Paramecia are heterotrophic.
3. They live in water.
4. They use cilia to move.
5. Their bodies are covered with a pellicle.
6. Food enters the organism through an opening called the oral groove.
7. Paramecia feed on bacteria and other small organisms.
8. They reproduce either sexually or asexually.
9. Contractile vacuoles regulate the amount of water in the cytoplasm.

1. Paramecia are eaten by small water animals.

1. Balantidium coli is a type of paramecia that causes disease. It invades and destroys the host's intestine, causing a disease called balantidiasis.