Bacteria are microorganism. They are so small to see with naked eye. In order to see them electron microscope is used. Bacteria are of many kinds according to their shapes. Round shaped spiral shaped comma shaped rod shaped. Bacteria are unicellular. They have chloroplast. They have no distinct nucleus. They are parasitic and live on other organisms.
Advantages: The advantages of bacteria are following. Bacteria are used in making yogurt cheese etc. These are also used in making these items on industrial scale. These are used in making medicines. Like insulin antibiotics etc.
Disadvantages: The disadvantages of bacteria are following. Cause disease in human and animals. Like typhoid cholera dysentery etc cause rotten of food. Produce at high temperature in foods.