Kingdom Fungi

 Biology XI Notes

Kingdom Fungi - Short Questions Answers

Chapter # 08
Short Questions Answers
Section III - Biodiversity

Kingdom Fungi

Q.1: Describe the structure of the body of Fungi?

Ans: Structure of the Body of Fungi:

• The fungi have a very simple body. In the majority of fungi, the body consists of a network of branched thread-like structures, called the Hyphae. When the hyphae form a mass, it is known as mycelium.

• The mycelium is of two types:

  • Coenocytic Mycelium:
    In Zygomycota, the mycelium is unseptate and multinucleate; it is called coenocytic mycelium. The septa are only formed at the time of reproduction.
  • Septate Mycelium:
    In Ascomycetes and Basidiomycetes, the mycelium is septate and hyphae are divided into cells. The cells may be uninucleate or multinucleate.

• The cells of mycelium are filled up with colorless cytoplasm, which contains nuclei and vacuoles. The food is stored in the form of glycogen or oil; starch is absent.

• In some fungi, mycelium is not present. They have a single-celled structure, e.g., Yeast. The cell wall of mycelium does not consist of true cellulose. It is composed of Chitin or Fungal cellulose.

(Fig. 8-1: Types of Hyphae of Fungi - Illustration showing Septate Mycelium and Coenocytic Mycelium)

Q.2: Describe Saprophytic and Parasitic nutrition of Fungi?

Ans:
Saprophytic Fungi: (Saprotrophs)
These fungi obtain their food energy from dead organic matter. They secrete out digestive enzymes, which digest the organic matter, and then the organic molecules are absorbed by fungi by the help of modified hyphae, called rhizoids. These fungi are the decomposers. They particularly decompose cellulose and lignin, present in plant cell walls.

Parasitic Fungi:
The parasites depend upon other living plants and animals. They cause many diseases in plants, animals, and human beings. When the parasitic fungi grow on the external surface of the host body, they are called ectoparasites, and when they live inside the host body, they are termed as endoparasites.

Q.2 (continued): Parasitic fungi absorb their food from other organisms by the help of special structures, called haustoria. Parasitic fungi are of three types:

• Obligate Parasite:
  These fungi obtain their food completely from the host body. They cannot grow on a culture medium. e.g., Rust fungi, Mildews.

• Facultative Parasites:
  They grow on their host as well as on artificial culture medium.

• Predator Fungi:
  Some fungi are predators i.e., they are carnivores and obtain their food from some animal bodies. For example, oyster mushroom (Pleurotus ostreatus) paralyzes the nematodes and takes nitrogenous nutrients from their body. Some species of Arthrobotrys also obtain their food from nematodes.

Q.3: What are the symbiotic fungi?

Ans: Symbiotic Fungi:
Some fungi form an association with other living organisms, in which both the organisms are mutually benefited. This type of association is called symbiosis and fungi are called Symbiotic fungi.

Symbiotic fungi are of two types:

• Lichens:
  • It is a very important group of algae and fungi which live together and form a beneficial type of association, called symbiosis. Both are useful to each other.
  • In lichens, fungi absorb water and salts and supply them to algae, while algae manufacture food material; in this way, both form a useful relationship. They cannot survive without each other.
  • Lichens are ecologically very important.
  •  They are bioindicators of air pollution.

(Fig. 8-2: (A-E) Lichens - Various Types of Lichens: (A) Crustose; (B) Foliose; (C) Fruticose (erect); (D) Fruticose (pendant); (E) Basidiolichen)

• Mycorrhizal Fungi:
  Some fungi form an association with the roots of higher plants. This association is mutualism, in which both organisms live together on a mutual basis. Both get benefits.

The hyphae of fungi help in the absorption of important substances, like phosphorus, zinc, copper, and other nutrients. The plant gets all these substances, and as a result of which, the plant supplies organic compounds to the fungus. In this way, fungi and higher plants live together.

There are two types of mycorrhizal fungi:

(Fig. 8-3: Types of Mycorrhiza)

Q.4: Describe different methods of Asexual Reproduction of Fungi?

Ans: ASEXUAL REPRODUCTION:
Asexual reproduction takes place by the following methods:

• Fragmentation:
  In this process, the hyphae divide into many small pieces, called fragments. Each fragment develops into a new mycelium of fungus.

• Budding:
  In yeast, small bodies are produced from the cells, called buds. These buds are separated from parent cells and grow into new fungi by simple cell division.

• Spore Formation:
  It is a common method of reproduction. The spores are produced in special reproductive organs, called sporangia. These spores are haploid and without flagella (non-motile). These spores are dispersed to other places, and during favorable conditions, germinate into new mycelium of fungi.

• Conidia Formation:
  These are special asexual spores, produced externally on the particular branches, called conidiophores. On these conidiophores, these spores are formed in chain-like manner. These spores are called conidia. The conidia are dispersed by wind and germinate into new fungi during favorable conditions.

Q.5: Describe the Sexual Reproduction in Fungi?

Ans: SEXUAL REPRODUCTION:
Sexual reproduction takes place in all fungi except Deuteromycetes. In this process, gametes are produced, which are either morphologically similar, called isogametes, or they are different, known as heterogametes. In such cases, the male organs are antheridia and female are oogonia. When the protoplasts from the two opposite (organs) are brought in contact, it is called plasmogamy. When the fusion of two nuclei occurs through...

Q.6: What is the classification of Fungi?

Ans: CLASSIFICATION OF FUNGI:
Fungi are classified into four divisions or phyla:

• Zygomycota
• Ascomycota
• Basidiomycota
• Deuteromycota

Q.7: Describe the characters of division Zygomycota of Fungi?

Ans: DIVISION - ZYGOMYCOTA:

• Zygomycota is the smallest group of fungi, including about 600 species. In this group, bread molds and other saprophytic fungi are present.
• These fungi have coenocytic mycelium, i.e., it is multinucleate and unseptate. The septa are formed only at the formation of sporangia or gametangia.
• In these fungi, there is a complete absence of motile cells.
• Asexual reproduction takes place by spores produced in sporangia.
• Sexual reproduction takes place by the fusion of isogametes; due to which zygospores are formed, so the group is called zygomycota.

Q.8: Describe the Asexual Reproduction of Zygomycota (Rhizopus)?

Ans: ASEXUAL REPRODUCTION:
It takes place during favorable conditions. At the time of reproduction, many erect branches arise from the mycelium, called sporangiophores. At the tip of each sporangiophore, a rounded body is formed, into which the cytoplasm, nuclei, and oil globules are transferred from the mycelium. The oil globules arrange themselves to form a layer, and the rounded body divides into two parts. The upper larger part is called sporangium, while the smaller lower part is known as columella.

In the sporangium, the cytoplasm is very dense, and it contains many nuclei; in columella, the cytoplasm is thin, without any nucleus.

Q.9: Describe the Sexual Reproduction of Zygomycota (Rhizopus)?

Ans: SEXUAL REPRODUCTION:
It takes place during unfavorable conditions. At the time of sexual reproduction, two hyphae of opposite strains (+ and -) come parallel to each other. Each hypha produces an outgrowth, the papilla, which divides into two cells. The lower cell is called basal cell or suspensor cell. The upper cell is called gametangium. In each gametangium, a gamete is formed. These gametes are externally similar, so they are known as isogametes.

The isogametes are fused together, this process is called conjugation. As a result of conjugation, a zygospore is formed.

Germination Of Zygospore:
The zygospore produces a branch, called sporangiophore. At the tip of sporangiophore, a sporangium is produced. The nucleus and reserved cytoplasm of zygospore are migrated into the sporangium. The nucleus divides by meiosis into many nuclei, then cytoplasm also divides into many pieces, each piece of cytoplasm surrounds the nucleus; in this way, many spores are formed.

After the maturation of spores, the wall of sporangium ruptures and all spores become free. They remain in air and by the availability of organic food substance, they germinate into new mycelium of fungus.

Q.10: What are the characters of division Ascomycota of Fungi?

Ans: DIVISION - ASCOMYCOTA:
It is the second division of fungi. This is a group of advanced fungi. In Ascomycota Yeasts, common molds, morals, truffles are included. Many plant pathogens are also in this group, such as powdery mildew etc.

Characters:

• Ascomycota is the sub-division of fungi. It is a Latin word, derived from two words ascos means bladder and mykos means fungi, so they are called sac-fungi.
• In this group both saprophytic and parasitic fungi are included. The saprophytic fungi depend upon dead organic substances. The parasitic fungi obtain their food from other plants and cause many diseases, such as leaf curl of peach, apple scab, and chestnut blight etc.
• According to the structure, different types of fungi are present in this group. Yeasts are unicellular fungi. In advanced fungi, the body is called mycelium. It is branched and septate. The mycelium consists of many hyphae. Each cell of hypha is uninucleate or multinucleate.

Q.11: Describe the Asexual Reproduction of Division Ascomycota of Fungi?

Ans: ASEXUAL REPRODUCTION:
In ascomycota asexual reproduction takes place by different methods, such as conidia, budding, fission, etc., but conidia formation is the most common method.

Conidia Formation:
It is the most common method of reproduction. They are important asexual bodies. They are produced on branches, called conidiophores. They are formed in a chain-like manner.

These conidia are dispersed to different places and during favorable conditions, these conidia develop into new mycelium of fungus.

Q.12: Describe the Sexual Reproduction of Division Ascomycota?

Ans: SEXUAL REPRODUCTION:
In Ascomycota, sexual reproduction takes place by the formation of male and female reproductive organs. The male organs are called antheridia and female are called ascogonia. They are usually developed at the apex of hyphae.

Q.13: What is Ascocorp? Describe different kinds of Ascocorp of Fungi?

Ans: FRUITING BODY: (ASCOCORP)
In Ascomycota a protective fruiting body is developed, called ascocarp. In the ascocarp asci are present.

The diploid zygote nucleus divides by meiosis into eight nuclei. These are surrounded by pieces of cytoplasm and change into ascospore pores. The cell in which ascospores are formed is called ascus. Many asci are formed in this manner.

There are three types of ascocarps.

1. Apothecium:
   It is a cup-shaped, saucer or disc-shaped ascocarp. It is open and its cavity is lined with a single row of asci which are freely exposed. Apothecium is formed in Morchella, Peziza.

2. Perithecium:
   It is a flask-shaped ascocarp. The asci are present in the ascocarp. At the apex of perithecium, a pore or opening is present, called ostiole. Perithecium is found in Erysiphe.

3. Cleistothecium:
   It is a rounded and completely closed fruit body without any ostiole. The asci are arranged in the inner side, and the ascospores are liberated out by the rupturing of the wall of ascus and cleistothecium or by the decay of fruit body. It is found in yeast, Aspergillus.

Q.14: Describe the Structure of Saccharomyces (Yeast)?

Ans: SACCHAROMYCES (YEAST):
The yeast belongs to the class Ascomycetes of fungi. It consists of a single cell and mostly lives as a saprophyte on fruits, leaves, soil, and sugar materials.

Structure:
Yeast is a unicellular and microscopic fungus. Its cells are rounded, oval-shaped, or rod-shaped. Each cell is covered by an outer chitinous wall. In the cell, cytoplasm is present. In the center of the cell, nucleus is present, which contain

s a large vacuole, called nuclear vacuole.

Q.15: Describe the Asexual Reproduction of Yeast?

Ans: ASEXUAL REPRODUCTION:
Asexual reproduction is of two types:

1. Budding:
   In this process, smaller cells are produced from yeast cell.

2. Fission:
   In this process, one cell divides into two cells by a simple process.

Q.16: Describe the Sexual Reproduction of Yeast?

Ans: SEXUAL REPRODUCTION:
It takes place by the fusion of two cells. By the fusion of two cells, a barrel-shaped structure is formed, known as ascus. The zygote nucleus divides by meiosis and produces eight nuclei. The cytoplasm also divides, and each nucleus is surrounded by a piece of cytoplasm; it is called ascospore. In this manner, eight ascospores are developed. When the ascospores are mature, the wall of ascus ruptures, and they become free. They form new yeast cells.

Q.17: What is the importance of Yeast?

Ans: IMPORTANCE OF YEAST:
Positive Importance:

• Yeast is used in alcohol fermentation.
• It is used in beer formation.
• It is useful to prepare bakery products.
• Cryptococcus contains vitamins, in is used as food material.

Negative Importance:

• It spoils many foodstuffs, especially cheese and tomato.
• It causes many diseases, such as:
  • Yeast vaginitis causes a disease in women, called vaginal thrush.
  • Cryptococcus produces a disease of the central nervous system, called cryptococcosis.
  • Candida causes diseases of skin, nails, and lungs, known as moniliasis.

Q.18: Describe the Characters and Reproduction of Basidiomycota of Fungi?

Ans: CHARACTERS OF DIVISION - BASIDIOMYCOTA:
Basidiomycota is an advanced group of fungi. In this group, smut fungus, rust fungus, puff balls, bracket fungi, jelly fungi, bird’s nest fungi, and mushrooms are included.

Vegetative Structure:
The mycelium of basidiomycotina fungi is advanced; it is branched and septate. The cell wall is composed of chitin. The mycelium is intracellular or intercellular. Each cell contains cytoplasm and nucleus. The mycelium with uninucleate cells is called primary mycelium (prokaryotic mycelium), and with two nuclei is called secondary mycelium (dikaryotic mycelium).

Reproduction in Basidiomycota:
In Basidiomycetes, the sexual reproductive structure is called Basidium. Due to the name basidium, the class is called basidiomycetes.

The basidium is a club-shaped structure. In the basidium, two nuclei are migrated from the mycelium. The two nuclei are fused together in the basidium to form zygote. It is the only diploid cell in the life cycle.

After the formation of zygote meioses takes place, and it divides into four haploid nuclei. At the end of basidium, four stalks are produced, called sterigmata (singular: sterigma). The tip of sterigma becomes swollen, and each nucleus is migrated into swollen end; it results in the formation of four basidiospores. After maturation, the basidiospores are separated from sterigma. They can germinate during favorable conditions and develop into new mycelium of fungi.

Q.19: Describe the Characters of Deuteromycota (Fungi-Imperfecti)?

Ans: CHARACTERS OF DIVISION DEUTEROMYCOTA:

• It is an artificial group of fungi. In this class, all those fungi are included which do not have sexual reproduction.
• In this group, mostly fungi of ascomycetes or basidiomycetes are included. The mycelium is branched and septate. In the cells, cytoplasm and many nuclei are present.
• Reproduction usually takes place by conidia, but acervulus, synnema, or coremium are also formed as reproductive organs.

Genetic Recombination: Although sexual reproduction is absent in deuteromycetes, there is the process of genetic recombination. In this process, hyphae of different genetic types are fused together. From such fusion, certain hyphae arise, in which genetic recombination occurs, called parasexuality. In parasexuality, exchange of chromosome portions occurs between common hyphae. Genetic recombination is responsible for the production of pathogenic types of wheat rust.

Q.20: Describe the Economic importance of Fungi?

Ans: ECONOMIC IMPORTANCE OF FUNGI: Fungi do not possess chlorophyll, due to which they are unable to manufacture their food. They are either parasite or saprophyte organisms. Economically, they are useful and as well as harmful. Their importance is as follows:

Useful Importance:

Food

• Many mushrooms are used as food material in various countries of the world.
• Yeast is used in bakeries to prepare many items.
• Penicillium is used in the cheese industry.

Preparation of Acids and Alcohols:

• From Aspergillus, many acids are prepared, such as citric acid, gluconic acid, gallic acid, and Kojic acid, etc.
• Penicillium is used to obtain alcohol.
• From yeast, beer is synthesized.

Medicines:

• From many fungi, antibiotic medicines are obtained such as:
• From Penicillium, the world-famous antibiotic Penicillin is isolated. Other antibiotics like Citrin, Clavicin, and Notatin are also obtained.
• From other fungi, chloromycetin, neomycin, and terramycin are obtained.
• Yeast is used to prepare vitamin B.

Soil-Fertility:
Fungi decompose dead bodies of other living organisms due to which many compounds are added in the soil. It increases the fertility of soil.

Atmosphere Cleaners:
Fungi use dead bodies of plants and animals as their food, so they clean our world. They are called cleaners.

Harmful Importance:

Food Spoilage:
Many fungi are saprophytes. They destroy our foodstuff, such as Mucor, Rhizo pus, Aspergillus and Penicillium etc.

Plant Diseases:
Many fungi attack our crops and cause a heavy loss, for example:

• Rust and Smut fungi damage the wheat, maize, oat, and other plants.
• Phytophthora fungus causes Late-blight disease in potato and tomato.
• Albugo causes white-rust disease in Radish, Turnip, and Cauliflower.
• Downy-mildew and Powdery-mildews are the diseases of many plants which are produced by fungi.

Animal Diseases:
The fungi are also responsible for producing many diseases in man and other animals, such as:

• Penicillium causes Penicillosis disease in man and animals.
• Aspergillus produces Aspergillosis in man.
• In man, the disease of skin, mouth, and gums is called Moniliasis. It is caused by a fungus, Candida.
• The ring-worm fungi also cause diseases of hairs, nails, and skin in man.

Spoilage Of Leather And Paper Goods:
The fungi destroy our leather goods, such as suitcases, shoes, bags, etc. They also damage the fibers, paper, and wood.

Poisonous Mushrooms:
Many mushrooms are poisonous; they are harmful to man and may cause death, e.g., Death-stools and Toad-stools.

Q.21: Distinguish between the following:

Ans: Zygomycota and Ascomycota

Zygomycota	Ascomycota
This is the primitive class of Fungi, which contain unseptateand multinucleate mycelium i.e., coenocytic mycelium.	This is an advanced class of Fungi, which contain septate mycelium

	They are saprophyte in nature. They are saprophyte as well as parasites. Their asexual reproductive bodies are called spores, produced in sporangia. Their asexual reproductive bodies are mostly conidia, which are without sporangia. Sexual reproduction is isogamy i.e., fusion of two similar gametes. Sexual reproduction is oogamy, i.e., dissimilar gametes. They do not have any fruiting body. Fungi and Plants: Fungi Plants These are simple organisms having thread-like structures, their body is called mycelium. They are well-developed living organisms, their body consists of root, stem, and leaves. They do not contain chlorophyll, they are parasites or saprophytes i.e., heterotrophs. They contain chlorophyll i.e., they are autotrophs. They do not require sunlight and water. They require sunlight & water. They are non-flowering. Higher plants (angiosperms) produce flowers.