Tag: lichens

• Slime moulds are Saprophytic Protists.
• They move along decaying twigs and leaves engulfing organic material. 
• Under a suitable condition, they form aggregation called Plasmodium.
• During unfavourable condition, the plasmodium differentiates and form fruiting bodies bearing spores at their tips.
• The spores possess true walls.
• They are extremely resistant and survive for many years even under adverse conditions. 
• The spores are dispersed by air currents.
• So, the correct answer is 'Air currents'.

Lichens are formed by the physical association between fungal partner and the algal partner. The fungal partner acts as a mycobiont and algal partner acts as a phycobiont. In lichens, fungus grow around algae and provide bulk for their growth. The algae and fungus association is must for lichens to reproduce. So, they are physically dependent on each other. Here, both fungus and algae are in their thalloid forms.

a) The phycobiont part of lichen is the autotrophic part which constitutes algae. The function of autotrophic algae is to provide nutrition. It synthesizes organic food by the process of photosynthesis.
b) If the algal component is blue-green algae, then apart from photosynthesis phycobionts also carry out nitrogen fixation. Nostoc, blue-green algae consist of heterocysts that have the enzyme nitrogenase. Nitrogenase converts atmospheric nitrogen into a usable form of nitrogen.

• The components of lichen include fungi and algae.
• Algae may be cyanobacteria or green algae.
• Cyanobacteria belong to the kingdom monera as they are prokaryotic organisms.
• Green algae belong to Thallophyta of kingdom Plantae.
• Fungi belong to kingdom fungi.
• So the correct answer is " Any of the above".

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 SO$ _2$ (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. 

• The function of fungal part of a lichen is the absorption of water and minerals from the substratum and providing protection for the phycobiont.
• Food production is done by phycobiont.
• So, the correct answer is 'Absorption of minerals and Protection'.

• Mosses are small flowerless plants that typically grow in dense green clumps or mats, often in damp or shady locations.
  
• Lichens are multicellular, eukaryotic but they have symbiosis as their mode of nutrition where algal component provides nutrition and fungal component helps in mineral absorption and protection.
• Lichens contain unicellular cyanobacteria if the algal component contains cyanobacteria but all cells are not unicellular as fungal myceliae are multicellular.
• So the correct answer is 'A composite organism made up of a fungus, that grows symbiotically with an algae or a cyanobacterium.'