Lichens and Their Significance Practice Questions
38 free Lichens and Their Significance practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Lichens are best described as an association between:
- A Two different species of algae
- B An alga and a nitrogen-fixing bacterium
- C A fungus and an alga or cyanobacterium
- D A fungus and a moss-like bryophyte
Correct answer: A fungus and an alga or cyanobacterium
Lichens represent a symbiotic association between a fungal partner (mycobiont) and an algal or cyanobacterial partner (phycobiont). Both partners live together and benefit from each other.
In a lichen thallus, the fungal component mainly provides:
- A Food and energy through photosynthesis
- B Protection and absorption of water and minerals
- C Nitrogen fixation from the atmosphere
- D Chlorophyll for light-driven energy production
Correct answer: Protection and absorption of water and minerals
The fungal partner provides protection, anchorage, and absorbs water and minerals. The algal partner performs photosynthesis and supplies food.
Which partner in lichens is capable of photosynthesis?
- A The fungus alone
- B The alga or cyanobacterium
- C Both partners equally
- D Neither of the partners
Correct answer: The alga or cyanobacterium
The algal or cyanobacterial component contains chlorophyll. It synthesizes carbohydrates through photosynthesis for the lichen.
Lichens are considered good indicators of air pollution because they:
- A Grow rapidly in polluted areas
- B Accumulate heavy metals only
- C Are highly sensitive to sulphur dioxide
- D Can survive in extreme industrial waste
Correct answer: Are highly sensitive to sulphur dioxide
Lichens are extremely sensitive to sulphur dioxide pollution. Their absence in an area often indicates poor air quality.
Which type of lichen has a flat, leaf-like thallus?
- A Crustose
- B Foliose
- C Fruticose
- D Gelatinous
Correct answer: Foliose
Foliose lichens have a dorsiventral, leaf-like thallus. They are loosely attached to the substratum.
Crustose lichens are characterized by:
- A Hanging, freely branched structures
- B Broad leaf-like lobes on the surface
- C Crust-like growth tightly attached to substratum
- D A free-floating aquatic growth habit
Correct answer: Crust-like growth tightly attached to substratum
Crustose lichens form a thin crust over rocks or bark. They are firmly attached and cannot be removed without damaging the surface.
Fruticose lichens differ from foliose lichens in having:
- A A flat, dorsiventral thallus
- B A crust-like tightly attached appearance
- C Erect or pendulous branched thallus
- D No fungal component at all
Correct answer: Erect or pendulous branched thallus
Fruticose lichens have cylindrical, branched, and often hanging thalli. This distinguishes them from the leaf-like foliose forms.
Which of the following correctly describes the relationship in lichens?
- A Parasitism
- B Commensalism
- C Mutualism
- D Saprophytism
Correct answer: Mutualism
Both partners in lichens benefit from the association. The fungus receives food, while the alga gets protection and moisture.
The algal partner in most lichens commonly belongs to:
- A Rhodophyceae
- B Chlorophyceae
- C Phaeophyceae
- D Bacillariophyceae
Correct answer: Chlorophyceae
Most lichen algae are green algae belonging to Chlorophyceae. In some lichens, cyanobacteria may also serve as the photosynthetic partner.
Which ecological role is commonly played by lichens?
- A Primary consumers of plants
- B Secondary consumers of animals
- C Pioneer species in succession
- D Top predators of the food chain
Correct answer: Pioneer species in succession
Lichens act as pioneer species on bare rocks. They initiate ecological succession by breaking down rocks and forming soil.
Lichens contribute to soil formation mainly by:
- A Producing large amounts of biomass
- B Secreting acids that weather rocks
- C Fixing carbon dioxide
- D Accumulating organic debris only
Correct answer: Secreting acids that weather rocks
Lichens secrete organic acids that slowly break down rocks. This process helps in the formation of soil during primary succession.
Which component of lichens is responsible for nitrogen fixation in some species?
- A Fungal hyphae
- B Green algae
- C Cyanobacteria
- D Both partners equally
Correct answer: Cyanobacteria
When cyanobacteria are present as the algal partner, they can fix atmospheric nitrogen. This enriches the ecosystem with nitrogen.
Lichens are classified under which major group in biological classification?
- A Algae
- B Fungi
- C Plantae
- D Protista
Correct answer: Fungi
Lichens are classified under fungi because the fungal partner dominates structurally. Their reproductive structures are also fungal.
Which of the following best explains why lichens can survive extreme environments?
- A Only the fungal body of the lichen
- B Only the algal body of the lichen
- C The combined body of fungus and alga
- D The spore-bearing reproductive structure
Correct answer: The combined body of fungus and alga
Lichens can tolerate extreme drying and temperature fluctuations. This allows them to survive in harsh environments like tundra and deserts.
The thallus of a lichen refers to:
- A Only the fungal body
- B Only the algal body
- C The combined body of fungus and alga
- D The reproductive structure
Correct answer: The combined body of fungus and alga
The thallus is the vegetative body formed by both fungal and algal components. It functions as a single integrated unit.
Which statement about lichens is correct?
- A They reproduce only sexually
- B They lack any symbiotic association
- C They show slow growth rates
- D They grow only in aquatic habitats
Correct answer: They show slow growth rates
Lichens grow very slowly due to their simple structure and harsh habitats. Some species may grow only a few millimeters per year.
Which of the following is a direct economic significance of lichens?
- A Large-scale production of antibiotics
- B Manufacture of natural rubber latex
- C Source of food dyes and litmus
- D Production of fuel and biogas
Correct answer: Source of food dyes and litmus
Lichens are used in the preparation of dyes and litmus. These have applications in laboratories and traditional industries.
Why are lichens absent in highly polluted urban areas?
- A Lack of sunlight
- B High temperature
- C Sensitivity to air pollutants
- D Competition with mosses
Correct answer: Sensitivity to air pollutants
Lichens are extremely sensitive to air pollutants, especially sulphur dioxide. High pollution levels prevent their survival.
The fungal partner in lichens usually belongs to:
- A Lack of adequate sunlight
- B Consistently high temperature
- C Sensitivity to air pollutants
- D Competition with faster mosses
Correct answer: Sensitivity to air pollutants
Most lichen-forming fungi belong to Ascomycetes. A few species may involve Basidiomycetes as the fungal partner.
Which of the following best summarizes the significance of lichens?
- A They are the major producers in the oceans
- B They indicate air quality and aid in succession
- C They act as the primary decomposers in forests
- D They fully replace higher plants in ecosystems
Correct answer: They indicate air quality and aid in succession
Lichens are important indicators of air pollution and act as pioneer species in ecological succession. They play a crucial role in ecosystem development.
In lichens, the algal partner primarily performs which function?
- A Water absorption
- B Protection
- C Photosynthesis
- D Reproduction
Correct answer: Photosynthesis
The algal partner synthesizes food through photosynthesis, which supports both partners.
The fungal component of lichens mainly provides:
- A Food production
- B Chlorophyll for photosynthesis
- C Shelter and water absorption
- D Nitrogen fixation
Correct answer: Shelter and water absorption
The fungus provides structure, protection, and absorbs water and minerals from the environment.
Which type of lichen forms a thin layer tightly attached to the substrate?
- A Foliose
- B Fruticose
- C Crustose
- D Gelatinous
Correct answer: Crustose
Crustose lichens form a thin crust firmly attached to surfaces like rocks or bark.
Which lichen type is characterized by a leaf-like structure?
- A Crustose
- B Foliose
- C Fruticose
- D Leprose
Correct answer: Foliose
Foliose lichens have flat, leaf-like thalli that are loosely attached to the substrate.
Fruticose lichens are typically:
- A Flat and leaf-like
- B Crust-like
- C Gel-like
- D Bushy and branched
Correct answer: Bushy and branched
Fruticose lichens have a three-dimensional, branched, bushy appearance.
Which algal group is most commonly found as the photosynthetic partner in lichens?
- A Red algae
- B Brown algae
- C Diatoms
- D Green algae
Correct answer: Green algae
Most lichens contain green algae, though some have cyanobacteria as their photosynthetic partner.
Some lichens can fix atmospheric nitrogen due to the presence of:
- A Ascomycete fungi
- B Green algae
- C Cyanobacteria
- D Moss
Correct answer: Cyanobacteria
Cyanobacteria in lichens can fix atmospheric nitrogen, enriching the soil.
Lichens are classified under which kingdom?
- A Plantae
- B Protista
- C Monera
- D Fungi
Correct answer: Fungi
Lichens are classified under Kingdom Fungi because the fungal partner dominates the structure.
What is the thallus in lichens?
- A Reproductive organ system
- B Leaf-like structure
- C Undifferentiated body
- D Root system
Correct answer: Undifferentiated body
The thallus is the undifferentiated body of the lichen without true roots, stems, or leaves.
Which ecological role do lichens commonly perform?
- A Primary production and colonization
- B Predation on smaller organisms
- C Decomposition of dead organic matter
- D Parasitism on surrounding plants
Correct answer: Primary production and colonization
Lichens are pioneer species that colonize bare surfaces and contribute to primary succession.
Lichens help in soil formation by:
- A Breaking rocks and adding organic matter
- B Consuming and breaking down soil particles
- C Absorbing nutrients
- D Fixing carbon only
Correct answer: Breaking rocks and adding organic matter
Lichens secrete acids that weather rocks and contribute organic matter, aiding soil formation.
Which of the following best describes the relationship in lichens?
- A Predation
- B Commensalism
- C Competition
- D Mutualism
Correct answer: Mutualism
Both partners benefit: the fungus gains food, and the alga gains protection and moisture.
Which product is obtained from lichens and used in dyes?
- A Litmus
- B Tannins
- C Latex
- D Gum
Correct answer: Litmus
Litmus is a natural dye obtained from lichens, commonly used as an indicator.
Which environmental condition favors the growth of lichens?
- A Dry, unpolluted areas
- B Highly polluted areas
- C Waterlogged soils
- D Urban industrial zones
Correct answer: Dry, unpolluted areas
Lichens thrive in clean, unpolluted environments and can tolerate dryness.
Which component determines the classification of lichens?
- A Fungal partner
- B Algal partner
- C Environmental factors
- D Substrate
Correct answer: Fungal partner
Lichens are classified based on the fungal component, which dominates the association.
Which of the following is a direct economic use of lichens?
- A Perfumes and dyes
- B Fuel production
- C Timber harvesting
- D Fertilizer only
Correct answer: Perfumes and dyes
Lichens are used in perfumes and dyes due to their aromatic compounds.
Which type of reproduction is commonly seen in lichens?
- A Sexual only
- B Asexual only
- C Budding and binary fission
- D Both sexual and asexual
Correct answer: Both sexual and asexual
Lichens reproduce both sexually (via fungal spores) and asexually (via fragments like soredia).
Which feature allows lichens to survive in extreme habitats?
- A High metabolic rate and rapid cell division
- B Symbiotic association and desiccation tolerance
- C Rapid reproduction through prolific sporulation
- D Large thallus size and dense cellular structure
Correct answer: Symbiotic association and desiccation tolerance
The symbiotic relationship and ability to withstand desiccation allow lichens to survive extreme conditions.