VACUOLES
They are of 4 types -
1. Sap Vacuole -
Outer membrane of sap vacuole is called Tonoplast. Sap vacuole contains amino sugars, carotenoids, proteins, minerals etc. Matrix of sap vacuole is called Cell Sap. Sap vacuole helps in osmoregulation. Anthocyanine pigment is also present in cell sap, which is responsible for violet, yellow & orange colour.
2. Contractile Vacuole -
These are present in protists. eg. Amoeba & Paramecium. C.V. helps in water balancing or osmoregulation, also helps in excretion.
3. Food Vacuole -
These are present in protists. They store ingested food. These are also known as gastric vacuole, because they are analogue to elimentry canal of higher animals.
4. Gas Vacuole -
These are present in Cyanobacteria or Photosynthetic green / purple bacteria. These are also known as pseudovacuole or air vacuole. Each gas vacuole protects from U.V. rays. Gas vacuole also help in buoyancy or floating. Proteineous membrane is also present around the gas vacuole.