Test: Lichen & Mycorrhiza - Class 11 MCQ

A lichen is a composite organism that emerges from algae or cyanobacteria living among the filaments (hyphae) of the fungi in a mutually beneficial symbiotic relationship. The fungi benefit from the carbohydrates produced by the algae or cyanobacteria via photosynthesis.

Litmus is a blue dye extracted from various species of lichens. Although these lichens grow in many parts of the world, almost all litmus is extracted and packaged in Holland. Litmus is red at pH 4.5 and blue around pH 8.3. While most litmus is used to make litmus papers, some is used as a colouring for beverages. Litmus is obtained from certain lichens, especially Rocella tinctoria.
Thus, the correct answer is option B.

According to Crombic, the relation between an algae and a fungi is helotism. Which is a kind of master-slave relationship, where the algal partner acts as a slave to the fungal partner, because, algae is an autotroph  however, the fungal partner may hinder the reproduction and nutrition of the algae.
So, the correct answer is 'Helotism'

Lichens, which are a composite organisms, arose due to a mutual symbiotic relationships between green algae/cyanobacteria and fungi. While the algal or cyanobacterial cells help in photosynthesis by reducing atmospheric carbon-dioxide into organic carbon sugars, the fungi helps to absorb this sugar alcohols. The algal component are called as photobionts or phycobionts. Most lichen fungi belong to Ascomycetes.
Thus, the correct answer is option A.

Pioneer species are the first organisms that colonise an area. Lichens are the pioneer organism that starts the life on a newly exposed rock surface and this type of succession is lithosere. Lichens grew on the rock surface and over the time period it converts the rock into the soil. Thus, the correct answer is option B.

In pteridophytes, meiosis or R/D occurs at the time of spore formation. The spores germinate to give rise to inconspicuous, small but multicellular, free-living, mostly photosynthetic thalloid gametophytes called prothallus. Prothallus tepresents the gametophytic phase in pteridophytes.

The majority of the lichens contain eukaryotic autotrophs belonging to the Chlorophyta (green algae) or to the Xanthophyta (yellow-green algae). About 90% of all known lichens have a green alga as a symbiont. Among these, Trebouxia is the most common genus, occurring in about 20% of all lichens

Lichens are used as the indicators of air pollution. These structures grow on tree bark and rocks. Air pollutants which are in the gaseous forms get dissolved in the rainwater, especially SO₂ (sulphur dioxide) can damage lichens, and check them from growing. In places where lichens are not growing, it indicates that the air is heavily polluted with sulphur dioxide and other pollutants. 
Thus, the correct answer is option A.

Lichens are used as the indicators of air pollution. These structures grow on tree bark and rocks. Air pollutants which are in the gaseous forms get dissolved in the rainwater, especially SO₂ (sulfur dioxide) can damage lichens, and check them from growing. In places where lichens are not growing, it indicates that the air is heavily polluted with sulfur dioxide and other pollutants. In cities, SO₂ is one of the most common air pollutants as it releases from the vehicles.
Thus, the correct answer is option C.

An arbuscular mycorrhiza (plural mycorrhizae or mycorrhizas, a.k.a. endomycorrhiza) is a type of Symbiosis mycorrhiza in which the fungus (AM fungi, or AMF) penetrates the cortical cells of the roots of a vascular plant. (Not to be confused with ectomycorrhiza or ericoid mycorrhiza).

 Usnea is a genus of mostly pale grayish-green fruticose lichens that grow like leafless mini-shrubs or tassels anchored on bark or twigs.

Reindeer moss, (Cladonia rangiferina) a fruticose (bushy, branched) lichen found in great abundance in Arctic lands. Reindeer moss is not a moss; it is lichen, which is a combination of fungus and algae sharing a symbiotic relationship and forming a new plant. It rarely reaches more than 17 centimetres in height. Caribou and reindeer can smell lichen through the snow, and paw down to eat it. Reindeer moss has the ability to convert sunlight into food in low temperature and low light conditions. Its tissue is not easily damaged by frost. Thus, the correct answer is option B.

Lichens are symbiotic associations i.e. mutually useful associations, between algae and fungi. The algal component is known as phycobiont and fungal component as mycobiont, which are autotrophic and heterotrophic respectively. Algae prepare food for fungi and fungi provide shelter and absorb mineral nutrients and water for its partner.
Lichens are very good pollution indicators – they do not grow in polluted areas.
So, the correct answer is 'Option B- Provides protection, anchorage and absorption for the alga'.
So the correct option is C.

The slowest growing plants in the world are lichens . Lichens do not have roots that absorb water and nutrients as plants do, but like plants, they produce their own food by photosynthesis. When they grow on plants, they do not live as parasites, but instead use the plants as a substrate.

Fruticose lichen ususally round in cross secetion (terete), and most are branched. They can be like little shrubs growing upward, or they can hang down in long strands. The fruticose lichens have much branched cylindrical, ribbon-like, flattened or sometimes filamentous thalli. 

The united protoplasmic mass of two gametes is called (zygote) zygospore. Prior to germination the diploid zygospore nucleus undergoes meiosis and forms 4 nuclei, three of these abort and only one is functional. It undergoes transverse division to give, rise single filament.

Penicillium ascomycetous fungi are of major importance in the natural environment as well as food and drug production. Some members of the genus produce penicillin, a molecule that is used as an antibiotic, which kills or stops the growth of certain kinds of bacteria.

Isogamy is the fusion of two morphologically similar gametes. Example: Spirogyra and some species of Chlamydomonas. Sexual reproduction of Spirogyra involves conjugation, which may be defined as a primitive type of isogamy, called as aplanogametic isogamy.

Zygospores form the diploid reproductive stage in many fungi; it is formed by the nuclear fusion of haploid cells. After formation this zygospore waits for environmentally favourable conditions such as ambient temperature, heat and light or chemotactic signals from the plants.
At the onset of right reactions it would sprout into a plant. In mucor the zygosporangium contains only one zygospore which is developed as a result of sexual reproduction. 

Mucor is a microbial genus of approximately 40 species of moulds commonly found in soil, digestive systems, plant surfaces, some cheeses like tomme de savoie, rotten vegetable matter and iron oxide residue in the biosorption process.Bread mold fungus, Rhizopus stolonifer. The picture at the right, believe it or not, shows one of the most common fungi in the world, the Bread Mold Fungus, Rhizopus stolonifer.

Mycorrhizae, mycorrhiza or mycorrhizas) is a symbiotic association between a fungus and the roots of a vascular host plant. The term mycorrhiza refers to the role of the fungi in the plants' rhizosphere, its root system.

Lichens are pioneer in succession in a new terrain and colonise bare rocks. They are the pioneers of plant kingdom. Since they are able to establish themselves on bare rocks and initiate formation of soil, they are called "farmers of nature".

In Ulothrix, two isogametes from two different filaments come together and fuse by their anterior end to form zygospore. The zygote germinates by meiosis and produces four haploid zoospores, each of which swims for a certain period, then loses its flagella and attaches to a substrate and grows into a new filament. Thus, the correct answer is option B.

Symbiosis in lichens is the mutually helpful symbiotic relationship of green algae and/or blue-green algae (cyanobacteria) living among filaments of a fungus, forming lichen.

Living as a symbiont in a lichen appears to be a successful way for a fungus to derive essential nutrients, as about 20% of all fungal species have acquired this mode of life. The autotrophic symbionts occurring in lichens are a wide variety of simple, photosynthetic organisms commonly and traditionally known as “algae”. These symbionts include both prokaryotic and eukaryotic organisms.

Vesicular-arbuscular mycorrhiza (VAM) is formed by the symbiotic association between certain phycomycetous fungi and angiosperm roots. It improves plant growth through phosphorous nutrition. In addition to phosphorous, they also help in the uptake of other nutrient elements. Nutrient absorption by fungal symbionts is due to external hyphae of the fungus proliferating beyond the nutrient depletion zone and reaching the source of nutrients. Mycorrhizal fungi appear to be extremely advantageous to crops grown in soils with low fertility.
So, the correct answer is 'Phosphate nutrition'

This chlorophyll resides mostly in the chloroplasts and gives leaves their green color. The range of light absorption in leaves is extended by some accessory pigments such as the carotenoids, but does not cover the entire visible range - that would make the leaves black!

Sexual reproduction in Spirogyra occurs by the method of conjugation. Conjugation is the process of fusion of two gametes out of which one acting as the male gamete passes through the conjugation tube to the female gamete. 

In Spirogyra all the cells of the filament can form the gametes, which are morphologically similar and are referred to as isogametes. This phenomena of sexual reproduction is known as isogamous type of sexual reproduction. But at the time of conjugation one of the two isogametes shows motility and is considered as the male gamete. This phenomenon is referred to as physiological anisogamy.

Penicillium and Rhizopus are multicellular fungi whereas yeast is unicellular fungi which is the main difference. Yeast has a thread like hypha but other fungi have septate hyphae.
So, the correct answer is 'Unicellular'

Named for their beautiful spiral chloroplasts, Smooth or wavy margin spirogyras are filamentous algae that consist of thin unbranched chains of cylindrical cells. They can form masses that float near the surface of streams and ponds, buoyed by oxygen bubbles released during photosynthesis.

Pond silk is the common name of Spirogyra (algae) because it is very slimy.
Spirogyra is a  genus (about 400 species) of freshwater green algae which are found in shallow ponds, ditches and amongst vegetation at the edges of large lakes, generally growing free-floating.
Cells are joined end-to-end in an unbranched, largely unspecialised, stiff filament and are cylindrical with one or two spirally-wound chloroplasts on which many pyrenoids are borne. The cell wall is of two layers, the outer of cellulose and the inner of pectin. Filaments can be several centimeters in length. It generally has a rather silky feel and a shiny green colour.