If yeast is an unicellular organism..why it is placed in Fungi kingdom...why not in Protista?
Because the most common answer to this is that wheather yeast is unicellular then also it is said to be a fungus on the basis of its characteristics because it is not perfect that only uncellular organism comes under protista. in kingdom fungi also unlicellular organism can also come based on the most favourable charater which they follow is the character is is mostly used in kingdom fungi..
IDEALLY yeast should belong to Kingdom protista
But it happens to be a descendant of the first member of Fungi, and thus shares joint ancestry with all other fungi in exclusion from all other organisms. That's why it's a fungus. Fungi are a monophyletic clade as well as a kingdom; i.e. one ancestor and all of its descendants.
Protists are a special group, also very diverse.
- Fungi have haploid nuclei Protists have 2 nuclei
- Yeasts reproduce via budding. Protists undergo either sexual or asexual reproduction.
- Fungi have cell wall made of chitin, none of the Protists exhibit chitinous wall.
- Yeasts also perform extra cellular digestion, but not all protists do this.
But for purpose of ease, just say
Yeast = haploid
Fungi = haploid
protists = diploid (Yeasts don't belong here)
Yeast reproduces sexually with the production of ascospores in an ascus or little sack thus they are members of the Ascomycetes in the Kingdom Fungi. Yeasts are also heterotrophic as are all fungi.
700 known yeasts really are fungi, although their colonies often look more like those of bacteria. Most fungi explore their surroundings by producing miles of fine, branching filaments called hyphae, but most yeasts have become more or less unicellular, with rounded cells. This is often an adaptation to living in a liquid medium of high osmotic pressure. This usually means media with a high sugar content, such as is found in the nectaries of flowers or on the surface of fruits, where if they present the least possible surface area (as close to spherical as possible), it makes it easier for them to control the movement of dissolved substances in and out of their cells. The cells of most yeast can be regarded as asexual propagules, and they produce more of the same by a variety of methods similar to those found in moulds. Some yeast is related to ascomycetes, others to basidiomycetes, and even zygomycetes sometimes take on a yeast-like appearance. Some yeasts make hyphae as well as unicells, and some are even exclusively hyphal, being recognizable as yeasts only by biochemical characters. Yeasts are, of course, among the most important fungi, because they raise bread, ferment sugars to make beer, wine, and spirits, and represent a concentrated food and a source of B vitamins