Question

The two microorganisms which live in symbiotic association in lichens are

• A. Fungus and Protozoa
• B. Alga and Bacteria
• C. Bacteria and Protozoa
• D. Alga and Fungus

Answer 1

The correct option is D

Alga and Fungus

The correct option is Option D

Explanation of correct option:

Alga :

1. The photosynthetic eukaryotic members of the kingdom Plantae do not bear stems, leaves, and roots.
2. They are simple, autotrophic, aquatic plants that grow in moist stones, wood, and soils.
3. Algae are classified into three classes based on their color i.e Chlorophyta (green algae), Rhodophyta (red algae), and Phaeophyta (brown algae).
4. The algae form a symbiotic association with a fungus called lichen, in which algae provide nutrition to fungus.
5. Vegetative reproduction takes place by fragmentation.
6. The form and size of algae vary from colonial forms such as Volvox to filamentous forms Spirogyra and ulothrix.

Fungus :

1. The heterotrophic eukaryotic organism grows in moist areas.
2. They are also called decomposers as they break down the complex organic matter into inorganic matter that can be utilized by other organisms such as plants.

Lichen :

1. The lichens are considered plant-like organisms that are formed by the symbiotic association between algae and fungi.
2. The symbiotic association between blue-green alga and fungus of class ascomycetes and basidiomycetes.
3. In this association, algae prepare food by photosynthesis which is utilized by fungi, which provides shelter or space for algae to grow.
4. Lichens have both economic (humans used it for extraction of dye and medicines ) and environmental importance (play an important role in nitrogen fixation).

Explanation of incorrect answer:

Option A:

Algae :

1. The photosynthetic eukaryotic members of the kingdom Plantae do not bear stems, leaves, and roots.
2. They are simple, autotrophic, aquatic plants that grow in moist stones, wood, and soils.
3. Vegetative reproduction takes place by fragmentation.
4. The form and size of algae vary from colonial forms such as Volvox to filamentous forms Spirogyra and ulothrix.

Protozoa:

1. The single-celled eukaryotic members of the Kingdom Protista live as parasites or predators.
2. They are heterotrophic i.e depend on other organisms for deriving nutrition.
3. Some members of this group are found in the freshwater, and sea, while some live in the body of living organisms to complete their life cycle.
4. A number of laboratory research suggest different protist species feed and grow on bloom-forming algae.

Option B:

Algae :

1. The photosynthetic eukaryotic members of the kingdom Plantae do not bear stems, leaves, and roots.
2. They are simple, autotrophic, aquatic plants that grow in moist stones, wood, and soils.
3. Vegetative reproduction takes place by fragmentation.
4. The form and size of algae vary from colonial forms such as Volvox to filamentous forms Spirogyra and Ulothrix.

Bacteria :

1. The single-celled microorganism is found in deserts, hot springs, and marshy areas.
2. The majority of bacteria are heterotrophic i.e can not prepare their own food, but few of them can prepare food through Photosynthesis.
3. The researchers found that interaction between algae and bacteria helps in the production of antibiotics.

Option C:

Bacteria :

1. The single-celled microorganism is found in deserts, hot springs, and marshy areas.
2. The majority of bacteria are heterotrophic i.e. can not prepare their own food, but few of them can prepare food through Photosynthesis.

Protozoa :

1. The single-celled eukaryotic members of the Kingdom Protista live as parasites or predators.
2. They are heterotrophic i.e. depend on other organisms for deriving nutrition.
3. Some members of this group are found in the freshwater, and sea, while some live in the body of living organisms to complete their life cycle.
4. In an ecosystem, Protozoa feed on bacteria to obtain nutrition, but bacteria defend themselves by secreting chemical substances and making cell walls resistant.

Final Answer: The two microorganisms which live in symbiotic association in lichens are Alga and Fungus.