Here's why:

* Yeast: Yeast is a single-celled fungus that uses alcoholic fermentation as its primary method of energy production in the absence of oxygen. They convert sugars like glucose into ethanol (alcohol) and carbon dioxide. This process is essential for baking bread, brewing beer, and making wine.

* Plants: While not as common, some plants also utilize alcoholic fermentation under anaerobic conditions. For example, some plants submerged in water or with limited oxygen access can ferment sugars to produce ethanol. This process is less efficient than aerobic respiration, but it allows the plant to survive in oxygen-deprived environments.

Key points about alcoholic fermentation:

* Anaerobic process: It occurs in the absence of oxygen.

* Sugar conversion: It converts sugars (like glucose) into ethanol and carbon dioxide.

* Byproduct: The carbon dioxide produced is responsible for the bubbles in bread and the fizz in beer and champagne.

* Energy production: While less efficient than aerobic respiration, it provides a small amount of ATP (energy) to the organism.

Other types of fermentation:

While alcoholic fermentation is the most common type in yeast and some plants, other forms of fermentation exist in different organisms, such as:

* Lactic acid fermentation: This process occurs in bacteria and animal muscle cells, producing lactic acid as a byproduct. This is responsible for the sour taste of yogurt and the burning sensation in muscles during intense exercise.

* Propionic acid fermentation: This process is used by certain bacteria to produce propionic acid, which contributes to the flavor of Swiss cheese.

So, while many types of fermentation exist, alcoholic fermentation is the primary type found in yeast and some plants.