| Updated On - Jul 2, 2024
Fungi are unique organisms that have their own kingdom. They are not animals, microorganisms, or plants but they are related to plants and animals because they have eukaryotic cells that are highly complex. Fungi can grow both sexually and asexually, which makes their reproductive systems complicated. Also, plants and bacteria are symbiotic partners for them. They even cause illness in several plants and animals. Mycology is the branch of science concerned with the study of fungi.
Key Terms: Fungi, Classification of fungi, Eukaryotic Organisms, Kingdom Fungi, Mycology, Structure of Fungi, Unicellular Fungi, Structure of Mushrooms, Yeasts, Penicillin.
What are Fungi?
Fungi are eukaryotic organisms that consist of microorganisms like yeasts, moulds, and mushrooms. These organisms belong to the kingdom fungi. They have a cell wall and are widely distributed. In the world of living organisms, they are known as heterotrophs.
The major examples of fungi are yeasts, rusts, stinkhorns, puffballs, truffles, moulds, mildews, and mushrooms.Fungi are heterotrophic (cannot produce their own food) in nature and play significant roles in ecological nutrient cycling. Fungi reproduce in both sexual and asexual ways, and they have a mutualistic relationship with both plants and microorganisms.
For Example- The formation of dark spots on bread that have been left out there for a few days, or the mushrooms, and yeast cells, which are often employed in the creation of alcohol and bread. Also, they are prevalent in the majority of skin problems as well as other fungal disorders. Fungus always develops in moist and warm environments.  Fungi on bread |
Read more: Phylum Protochordata
Structure of Fungi
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Structure of Fungi is such that the reproductive body of fungi is a thallus, which can be unicellular or multicellular. Based on the climate, dimorphic fungi can transition from unicellular to multicellular states. Yeasts are the common name for unicellular fungus. Unicellular fungi include Saccharomyces cerevisiae (baking yeast) and Candida species (thrush-causing fungi).
Structure of Fungi
The vast majority of fungi are multicellular creatures. There are two different physical states in which they might be found: vegetative and reproductive. The vegetative state is characterized by a network of fine thread-like components known as hyphae, while the reproductive state might be more visible. The structure of a multicellular fungus is detailed as follows:
- Except for yeast cells, mostly every fungus has a fibrous structure.
- Fungi are generally comprised of long thread-like filaments known as hyphae. Each hypha is made up of one or more cells that are enclosed by a cylindrical cell wall.
- The body of a fungus, known as the mycelium, is made up of a mass of hyphae.
- Fungi have chitin and polysaccharide-based cell walls. It is made up of protoplast, which is then transformed into cell membranes, cytoplasm, cell components, and nucleus.
- The nucleus is thick and transparent, with chromatin strands running through it. A nuclear membrane protects the nucleus.
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Classification of Fungi
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Kingdom Fungi are categorized according to distinct modes. The kingdom Fungi is divided into five primary divisions based on their method of sexual reproduction or subatomic characteristics. The following is a list of the different types of fungi:
Classification of Fungi
On the Basis of Mode of Nutrition
Saprophytic: Fungi derive their food by feeding on dead and decaying plants and animals. For example - Penicillium, Aspergillus, and Rhizopus.
Parasitic: Fungi get their energy by feeding on certain living beings (plants or animals) and obtaining nutrients from them. For example - Puccinia Taphrina.
Symbiotic: These fungi survive by forming a mutually advantageous interdependent connection with other organisms. For example - Mycorrhizae and Lichens. Lichens are the result of a mutualistic relationship between algae and fungus. Algae and fungi strengthen each other in this situation because fungi give protection for algae and algae produce carbohydrates for fungi in the converse.
On the Basis of Spore Formation
The five fundamental phyla of fungi of fungi are as follows:
- Chytridiomycota (Chytrids)
- Zygomycota (conjugated fungus)
- Ascomycota (sac fungus)
- Basidiomycota (club fungus)
- Phylum Glomeromycota
The Deuteromycota is an unconnected family of fungus that all have one thing in common: they reproduce exclusively by asexual reproduction. All the five major phyla are described below in detail:
- Basidiomycota (Club Fungus): The fungus in the Phylum Basidiomycota is distinguished by the club-shaped blossoms, or basidia, which are the enlarged terminating cell of a hypha that is plainly visible just below a regular microscope. Basidiomycetes have a generational life cycle. Sexual reproduction is the most common method of producing spores rather than asexual reproduction.
- Chytridiomycota (Chytrids) The Chytridiomycetes are the only group in the Phylum Chytridiomycota. The chytrids are known to be the most elementary and fundamental Eumycota or real fungi. Chytrids contain chitin in their cell membranes, just like all fungus. The majority of chytrids are single-celled. With the help of a small flagellum, they generate reproductive cells and diploid asexual spores that swim.
- Zygomycota (Conjugated Fungus): These are made up of two distinct cells that are merged together. The sexual cells are referred to as zygospores, whereas the asexual cells are referred to as sporangiospores. The septum is missing from the hyphae. Rhizopus stolonifer, a well-known bread mold that spreads quickly on the outside of the bread, fruits, and vegetables, is one of them. The majority of species are saprobes (who feed on decaying organic matter), however, some are parasitic.
- Ascomycota (Sac Fungus): The Phylum Ascomycota is home to the vast percentage of known fungus, which is distinguished by the production of a sac-like structure carrying haploid ascospores. Sexual spores are known as Ascospores. Conidiospores are used for asexual reproduction. Various ascomycetes, like yeasts used in bakeries, brewing, and wine fermentation which are considered gourmet delights, serve a positive role. Ascomycetes not only infiltrate and damage crops but often create harmful bioactive substances that leave crops unsuitable for human consumption.
- Glomeromycota: The Glomeromycota is a relatively recent phylum with roughly 230 species living in close proximity to tree roots. According to fossil records, trees and their root saprophytes have been linked for a long time. All members of this group begin to form arbuscular mycorrhizae, in which the hyphae engage with root cells that form a mutually advantageous relationship in which the plants provide the fungus with carbon and energy is produced in the form of carbohydrates, as well as the fungus provides the plant with required minerals from the soil.
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Read More: Animal Kingdom
Importance of Fungi
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Fungi are important to human life in several aspects, despite our common perception of them as disease-causing organisms that decompose food. They have a huge impact on the health of human groups since they are a part of the nutrition cycle of the ecosystem. The survival of human beings depends on fungi in a variety of ways. They have the ability to grow anywhere and transform into human food. Many more projects are carried out with the help of these organisms. The following are some of the uses of fungi.
Food
Gourmet delights such as mushrooms, morels, and truffles, as well as mycoproteins generated from the rhizomes of specific species of fungi, are consumed by humans. They are employed in the production of high-protein foods. Yeast works as a fermentation factor when mushrooms are eaten raw.
Farming
Medicine
Certain types of fungi are capable of killing bacteria. As a result, they're employed to treat many ailments. Many different types of fungi are grown and involved in making antibiotics. When fungi are grown to make medications, their reproductive activities kick into high gear.
Medicines are naturally produced by fungi to eliminate or hinder bacterial growth, hence reducing their competitiveness in the natural habitat. Fungi can be used to produce essential drugs like Penicillin and Cephalosporins. The usage of the red bread mould called Neurospora crassa has resulted in several improvements in biological evolution.
Read More: Economic importance of Fungi
Characteristics of Fungi
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Characterstics of Fungi are-
- Fungi reproduce by means of spores.
- Fungi can be unicellular or filamentous.
- Fungi are eukaryotic, non-vascular, non-motile and heterotrophic organisms.
- Fungi exhibit the phenomenon of alternation of generation.
- Fungi cannot perform photosynthesis as they lack in chlorophyll.
- Fungi store their food in the form of starch.
- Biosynthesis of chitin occurs in fungi.
- The nuclei of the fungi are very small.
- The fungi have no embryonic stage and get developed from the spores.
- The mode of reproduction in a fungi is sexual or asexual.
- Some fungi are parasitic and can infect the host.
- Fungi produce a chemical called pheromone which leads to sexual reproduction in fungi.
- Examples of common fungi are mushrooms, moulds and yeast.
Things to Remember
- Fungi are eukaryotic organisms that consist of microorganisms like yeasts, molds, and mushrooms.
- These organisms belong to the kingdom fungi.
- The reproductive body of fungi is a thallus, which can be unicellular or multicellular.
- Based on the climate, dimorphic fungi can transition from unicellular to multicellular states.
- There are two different physical states in which they might be found: vegetative and reproductive. The vegetative state is characterized by a network of fine thread-like components known as hyphae, while the reproductive state might be more visible.
- The kingdom Fungi is divided into five primary divisions based on their method of sexual reproduction or subatomic characteristics.
- Fungi are classified based on the mode of nutrition into Saprophytic, Parasitic, and Symbiotic.
Previous Year Questions
- The imperfect fungi which are decomposers of litter … (NEET 2015)
- Cell wall of fungi is composed of …
- Identify the odd one out … (KCET 2021)
- A hyphae which is multinucleated and asptate is known as … (WBJEE 1999)
- Puccinia forms uredia and … (NEET 1998)
Sample Questions
Ques. What are Fungi? (2 marks)
Ans. Fungi are eukaryotic organisms that consist of microorganisms like yeasts, molds, and mushrooms. These organisms belong to the kingdom fungi. They have a cell wall and are widely distributed. In the world of living organisms, they are known as heterotrophs. The major examples of fungi are yeasts, rusts, stinkhorns, puffballs, truffles, molds, mildews, and mushrooms.
Ques. Which kingdom is connected to the kingdom fungi? (2 marks)
Ans. Fungi are closely connected to animals in the animal kingdom. It has been confirmed by the research of phylogenetics. According to the evolutionary tree, animals have evolved from fungus millions of years ago.
Ques. What is the location of the Thallus? (2 marks)
Ans. The Thallus is found in the bodies of fungi, algae, and bacteria. It is one of the most important reproductive organs in the human body. It also aids fungal growth. The thallus develops into tissue in higher species which is called Connective tissue.
Ques. Explain the importance of fungi in brief. (2 marks)
Ans. Fungi are crucial to human life in several aspects, despite our common perception of them as disease-causing organisms that decompose food. They have a huge impact on the health of human groups since they are a part of the nutrition cycle of the ecosystem. The survival of human beings depends on fungi in a variety of ways. They have the ability to grow anywhere and transform into human food.
Ques. How are fungi classified based on the mode of nutrition and spore formation? (2 marks)
Ans. Fungi are classified based on the mode of nutrition into Saprophytic, Parasitic, and Symbiotic. The Chytridiomycota (Chytrids), Zygomycota (conjugated fungus), Ascomycota (sac fungus), Basidiomycota (club fungus), and the newly identified Phylum Glomeromycota are known as the five fundamental phyla of fungi based on the spore formation.
Ques. How do fungi help in medicinal purposes? (2 marks)
Ans. Some certain types of fungi are capable of killing bacteria. As a result, they're employed to treat many ailments. Many different types of fungi are grown and involved in making antibiotics. When fungi are grown to make medications, their reproductive activities kick into high gear. Medicines are naturally produced by fungi to eliminate or hinder bacterial growth, hence reducing their competitiveness in the natural habitat. Fungi can be used to produce essential drugs like Penicillin and Cephalosporins.
Ques. What is the principle underlying the use of cyanobacteria in agricultural fields for crop improvement? (2 marks)
Ans: Cyanobacteria (BGA) are autotrophic microbes. Cyanobacteria are widely distributed in aquatic and terrestrial environments. Nostoc, Anabaena and Oscillatoria are BGA that can fix atmospheric nitrogen. These organisms can fix atmospheric nitrogen in specialised cells called heterocysts, e.g., Nostoc and Anabaena. In paddy fields cyanobacteria serve as an important biofertiliser. BGA also adds organic matter to the soil and increases its fertility.
Ques. How is the five-kingdom classification advantageous over the two kingdom classification? (3 marks)
Ans: Two Kingdom systems of classification with Plantae and Animalia kingdoms.
- Two kingdom classification did not distinguish between the prokaryotes and eukaryotes. E.g.: It brought together the prokaryotic bacteria and blue-green algae with other groups (like plants, fungi and animals) which were eukaryotic.
- Two kingdom classification did not distinguish between the unicellular and multicellular organisms. E.g:: Chlamydomonas (unicellular) and Spirogyra (multicellular) were placed together under algae.
- This system did not distinguish between autotrophic/photosynthetic (green algae and plants) and heterotrophic/non-photosynthetic organisms (fungi).
Ques. Polluted water bodies usually have a very high abundance of plants like Nostoc and Oscillitoria. Give reasons. (3 marks)
Ans: Polluted water bodies (ponds, ditches and rivers etc.) usually have nutrient contents (such as nitrate, phosphates) domestic sewage primarily contains biodegradable organic matter. The presence of a large number of nutrients in waters also causes excessive growth of Planktonic (free-floating algae) called an algal bloom, which imparts a distinct colour to water bodies.
Algal bloom causes deterioration of the water quality and fish mortality. Some bloom by forming algae, mainly Nostoc and Oscillatoria, are extremely toxic to human beings and animals.
Ques. Diatoms are also called ‘pearls of the ocean’, why? What is diatomaceous earth? (2 marks)
Ans: The diatoms are unique organisms, because of their distinctive cell walls. The walls are embedded with silica and thus the walls are indestructible. It shows sculpturing and ornamentation that is why Diatoms are also called ‘Pearls of Ocean’.
Diatoms have left behind a large amount of cell wall deposits in their habitat; this accumulation over billions of years is referred to as ‘diatomaceous earth’. Being gritty this soil is used in polishing, filtration of oils and syrups. Diatoms are the chief ‘producers’ in the oceans.
Ques. Neurospora - an ascomycetes fungus has been used as a biological tool to understand the mechanism of plant genetics much in the same way as Drosophila has been used to study animal genetics. What makes Neurospora so important as a genetic tool? (2 marks)
Ans: Neurospora is used as a genetic tool because it is easy to grow and has a haploid life cycle that makes genetic analysis simple since recessive traits will show up in the offspring. Beadle and Tatum exposed Neurospora crassa to X-rays, causing mutations. This led them to propose the “one gene, one enzyme” hypothesis that specific genes code for specific proteins.
Ques. At a stage of their cycle, ascomycetes fungi produce fruiting bodies like apothecium, perithecium or cleistothecium. How are these three types of fruiting bodies different from each other? (2 marks)
Ans: An apothecium is a wide, open, saucer-shaped or cup-shaped fruit body. It is sessile and fleshy. A cleistothecium is a globose, completely closed fruit body with no special opening to the outside. Perithecium are flask-shaped structures opening by a pore or ostiole (short papilla opening by a circular pore).
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