Lichens, which are capable of initiating ecological succession even on a bare rock, are actually a symbiotic association of

Explicit definition: 'A lichen is a peculiar combination of an alga and a fungus' — directly states the usual partners in lichens.

A student could note that fungus, not bacteria, is named here and so seek external sources/maps of organism groups to check whether bacteria commonly replace fungi in lichens.

Gives a general rule/example of symbiosis: 'lichen ... is made up of algae and fungi living together' and explains the functional roles (alga = producer, fungus = support).

Use this functional-role pattern to ask whether bacteria can perform the same structural/support role or the algal producer role in lichens, then check microbial physiology references.

Another independent source (NCERT) states 'Lichens are formed by the association of two living organisms, a fungus and an alga', reinforcing the fungus–alga pattern across texts.

A student could treat repeated mention of fungus+alga as a strong pattern and look up exceptions (if any) in external taxonomic literature or field guides.

Defines algae as autotrophic producers that grow in moist situations — fits the cited role of algae in lichen as the food-manufacturing partner.

Combine this with the fungus–alga pattern to reason that the typical lichen partner needs photosynthetic capability (alga), which bacteria (except cyanobacteria) generally lack; then check whether cyanobacteria are ever lichen partners.

Gives an example of symbiosis between a non-fungal partner and algae (coral–zooxanthellae), showing symbiosis can involve algae with various hosts, not specifically bacteria.

Use this example to broaden inquiry: since algae commonly form symbioses with fungi and animals, a student could survey whether bacteria also commonly serve as algal partners in lichen-like associations.

Defines symbiosis and gives lichen as an example of algae + fungi living together with mutual benefit (producer = algae, structure/support = fungus).

A student could combine this with general knowledge that photosynthetic organisms can supply carbon compounds to non-photosynthetic partners to judge plausibility of the association.

Describes lichens as a ‘combination of an alga and a fungus’ and explains complementary roles (alga manufactures food; fungus absorbs/retains water).

A student could use the complementary functional roles to infer why such a two-organism association would be mutually beneficial and stable.

States lichens are formed by association of a fungus and an alga and notes their typical habitats (rocks, trees, clean air areas).

A student could check for the presence of lichens in such habitats on a map or locally to see if this ecological pattern matches the expected distribution of a fungal–algal association.

Defines fungi as non-green organisms lacking chlorophyll that often live as saprophytes or parasites, implying a fungus alone cannot photosynthesize.

A student could combine this with the idea that algae are photosynthetic to reason why a fungus might pair with an alga to obtain fixed carbon.

Gives a parallel example of symbiosis: corals living with unicellular algae (zooxanthellae) where algae provide photosynthetic products to animal host.

By analogy, a student could generalize that photosynthetic microbes often form symbioses with heterotrophic partners, supporting the plausibility of fungus–alga partnerships in lichens.

Explicitly states lichens are an association of a fungus and an alga (fungus + alga pattern).

A student could use this to judge the claim by checking whether the photosynthetic partner called 'alga' might sometimes be a bacterium (e.g., cyanobacterium) rather than a true alga.

Gives the mutualistic role: algae manufacture food while fungus provides structure — a clear fungus+alga mutualism model for lichens.

Use the functional roles to compare: if lichens always have a photosynthesizer and that partner is sometimes a bacterium, the statement could hold in some cases.

Again describes lichen as a combination of an alga and a fungus, reinforcing the standard definition.

Combine this repeated definition with knowledge of which organisms are classified as 'algae' versus 'bacteria' to test whether 'alga' might include bacterial types in some lichens.

Defines fungi as non-green, lacking chlorophyll and separate from photosynthetic partners — implying lichens need a separate photosynthetic organism.

A student could ask whether the photosynthetic partner must be a eukaryotic alga or could instead be a prokaryotic photosynthetic bacterium (cyanobacterium).

Mentions 'blue-green algae' (Anabaena, Spirulina) in the context of microbes, indicating that some organisms historically called 'algae' are microbial and often discussed with bacteria.

A student could extend this by checking whether 'blue-green algae' are bacteria (cyanobacteria) and whether such organisms serve as the photosynthetic partner in some lichens, which would make lichens bacteria+fungus in those cases.

Explicitly states lichens are formed by association of a fungus and an alga (not moss).

A student could combine this with basic knowledge that mosses are land plants (bryophytes) to doubt the fungus+moss claim and check sources for algae vs moss distinction.

Gives the same rule/example: lichen = algae + fungus, with roles (alga produces food, fungus provides support).

Knowing the functional roles, a student can contrast these with moss physiology (mosses are photosynthetic whole plants) to see why 'moss' is unlikely to be the fungal partner.

Describes lichen as an alga + fungus mutualism and treats them as distinct from mosses in habitat and form.

A student could use this to infer that lichens involve algae (photosynthetic cells) rather than multicellular mosses as the photobiont.

Defines fungi as non-green, lacking chlorophyll, distinguishing them from green plants like mosses.

Combine with lichen descriptions to reason that the photosynthetic partner in lichens must be green (an alga), not the non-photosynthetic fungal partner or a separate moss.

Lists pioneers in succession as 'microbes, lichens and mosses' separately, implying lichens and mosses are different kinds of organisms.

Use this separation to support the view that lichens are a distinct association (not simply fungi plus moss) and to prompt checking which organisms compose lichens.