Page 1 :
Lichens
Page 2 :
Introduction, Lichen Is such an association of an alga and a fungus In which two, organism remain so closely associated with each other that they, appear to be a single plant, Lichen has been defined as a stable self supporting association of a, mycobiont and a phycobiont .The mycobiont is the fungal partner and, phycobiont – photosynthetic partner in a lichen association
Page 7 :
• Identify the bio indicator of SO2 pollution from the following:, A) Orchids, • C) Lichen, , B) Water hyacinth, D) Aloe vera
Page 8 :
• What is meant by lichenometry?, • A) Study regarding the age of lichens., • B) Study of the age of exposed rock surfaces based on the size of, lichen thalli., • C) Study regarding the calculation of the period in which lichens, evolved., • D) Study regarding the succession of various forms of lichens
Page 17 :
• Lichen with a 3-dimensional branching, bushy appearance, like a, leafless shrub is called, • A) Fruticose lichen, B) Foliose lichen, C) Crustose lichen, , D) Anastomose lichen
Page 21 :
Internal structure, • The algal and fungal components of thallus are almostly uniformly, distributed , without the formation distinct cellular layaers .this is, called homomerous thallus, • Algal and fungal components are arranged in distinct cellular layers, .this is called heterogeneous condition, • Structure of Crustose lichen, • Homomerous thallus, • Structure of Foliose lichen, Heteromerous thallus four layers – upper cortex ,algal layer, Medulla, and the lower cortex
Page 26 :
Propagules associated with lichen thallus, • Breathing pore: These are the areas in the Cortex where loosely, interwoven hyphae are present.In Foliose lichen they develop only in the, upper cortex. breathing Pores are supposed to function in gaseous, exchange, • Cyphellae : These are the neat circular depression present only on the, lower surface of certain lichen , function – gas exchange, • Pseudocyphellae : looser hyphal medullary tissue comes to the surface of, the lichen thallus in the form of discrete . These are also present in lower, cortex
Page 28 :
• Cyphellae in lichens are analogous to ----------------- in higher plants, A) Palisade tissue, , B) Epidermis, , C) Bundle sheath, , D) Stomata
Page 30 :
• Cephalodia : some of the lichen have 2 phycobionts of which one is, blue – green algae and other is green alga , it’s a 3 membered, symbiosis, • Isidia : An isidium is a small and corticated outgrowth present on the, upper surface of lichen thallus .it is made up of both fungal hyphae, and algal cells, • Soredia: A soredium is a small but non – Corticated bud like, outgrowth present on the upper surface of the lichen thallus .It is, made up of only a few algal cells enclosed by only a few fungal, hyphae
Page 31 :
• In Lichens following special vegetative structure is formed as, respiratory organs, A) Soredia, , B) Isdia, , C) Cyphellae., , D) Medulla
Page 36 :
• Vegetative reproduction in lichens takes place by, A) soredia, B) Isidia, • C) fragmentation D) all the above
Page 40 :
Asexual spores, • 1. Conidia, In several lichens ,the fungal component forms conidia on, conidiophores .conidia get released from the lichen and form new, fungal mycelia . These mycelia, in turn ,come in contact with suitable, algal components and form new lichens
Page 42 :
• Oidia : the hyphae of certain lichen break up into. Small bodies called, oidia .The oidia may germinate into hyphae, • Pycniospores:These are the condia formed in flask – shaped structure, ,called pycnidia ,which remain embedded in the thallus .pycniospores, get liberated from the lichen Undergo germination and form fungal, mycelia .These mycelia come in contact with suitable algal component, and form new lichens
Page 44 :
• Spermatia are unicellular , uninucleate, non – motile ,colourlesa and, walled male gametes produced. On large numbers in each, spermagonium, • Disseminated by wind
Page 48 :
Economic importance, 1) Biochemical weathering and pedogenesis, • The Crustose lichen affect the chemistry of the rock on which they, grow – biological weathering, • Mycobiont, soluble organic acids like oxalic acid Secrete, • The process of formation of this new soil is called pedogenesis, • Thalli mix with soil and soil become fertile
Page 49 :
Drugs from lichen, • 1 usnic acid – Produced from many lichen have antibiotic properties , they, inhibit gram positive bacteria, • 2 antiseptic Creams – usno and evosin are available in market well known, for tumor inhibitors, • 3) erythrin obtained from Roccella montagnei- Used for heart disease, • 4) protolichesterinic acid obtained from certain algae used as anticancer, drug, • 5) components like lichenin isolichenin exhibit anti tumor properties, • 6) Lobaria pulmonaria and cetaria islandica in tuberculosis and lung disease, • 7) some lichen are used with tabacco for hallucinogenic effect
Page 52 :
• Usnic acid, a dibenzofuran derivative has been utilized in medicine,, perfumery and cosmetics This was isolated by the German scientist, W. Knop in 1844. Name the lichen/s yield usnic acid, A) Usnea, , B) Cladonia, , C) Lecanora, , D) All the above
Page 57 :
• Food from lichen : Cladonia rengiferina ( reindeer moss) serve as, common food in tundra region for many animals including reindeer, and musk, • Sps of parmelia ,Lecanora ,cetraria are eaten by man , horses,cattle, • Poison – letharia vulpina ( wolf moss) is used as a poison for Wolves ,, • Vulpinic acid is present in this lichen , which is responsible for its, poison
Page 60 :
• Which among the following lichen is/are used as a source of food?, , 1. Iceland moss (Cetraria islandica)., 2. Wila (Bryoria fremontii), • 3. Rock tripe (Umbilicaria esculenta), • A) 1 & 3, B) 1 & 2, C) 2 & 3, D) 1, 2 & 3
