(i) Staphylococcus aureus and Clostridium botulinum.
(ii) Thiobacillus denitrificans and Micrococcus denitrificans.
(iii) Lactobacillus acidophyllus.
(iv) Acetobacter acetic
(v) Pseudomonas fluorescens and Clostridium sp.
(vi) Escherichia coli and Agrobacterium tumefaciens.

Protozoans take in water in bulk. As that mostly live in aquatic environments.They are highly likely to burst due to excessive in take of water.
Therefore, protozoans need to osmoregulate continuously to keep only the required amount of water in their cells. They get rid of excess water through contractile vacuoles.

Archaebacteria are able to tolerate high temperature ae well as  high acidity.
These bacteria are chemoautotrophic which obtain energy for synthesis of food by oxidising suphur. Under anaerobic conditions they oxidise sulphur to sulpuric acid.
2S + 2H₂O + 3O₂ \(\rightarrow\) 2H₂SO₄
Thermoacidophiles are able to tolerate high temperature as well as acidity, due to the presence of temperature as well as acidity due to the presence of 
(i) branched chain lipids in the cell membranes.
(ii) special resistant enzymes capable of operating under aerobic conditions.

The two kingdom classification system was given by Linnaeus in 1758. Lesser number of organisms were known then in comparison to what the world knows today. He classified all the known living beings into two categories - Animalia and Plantae on the basis of the presence or absence of cell wall in their cells. As bacteria, blue-green algae, fungi, algae, mosses, ferns, gymnosperms, and angiosperms have their cells surrounded by cell walls, unlike animals, therefore, they were placed together under kingdom-Plantae.

Phylogeny is the evolutionary history of an organism. It shows the true kinship of organism. Such relationships are not clear in all cases. Only fossil record can provide such relationship, but complete records are not available for such studies. Hence, the phylogenetic relationships are ascertained from morphology, cytology, genetics, physiology, and biochemistry for the correct classification of the organisms.

The fairy rings form as the mycelium of the mushroom fungus spreads in the soil from a central point. It grows peripherally, so that the younger hyphae will appear that cause young fungal hyphae to form compact masses that grow into mushrooms. This is the reason, the mushrooms appear growing in a circle or ring

Deuteromycetes is an artificial class of fungi which has been created to include all those fungi. Ther mycelium is usually septate. Coenocytic forms are not known. Clamp connections, typical of Basidiomycetes are absent. It is believed that most members of Deutromycetes are actually Ascomycetes in which sexual reproduction is either absent or yet to be discovered. Hence, are considered as fungi imperfecti.

Euglena is a taxonomic puzzle since, it shows both plant and animal characters. Absence of cell wall is an animal feature and presence of chloroplast is a plant character of Euglena. It have mixotrophic nutrition. In the presence of sunlight it can photosynthesise its food and in the absence of sunlight, it behaves like a hetrerotroph by predating on other smaller organisms.

Cyanobacteria are the most self contained photosynthetic organisms. They can, therefore, live under every type of environment and on every type of substrate. Because of this fact, they are one of the earliest colonizers of barren areas.

Mycorrhiza is a mutually beneficial or symbiotic association of fungi with roots of higher plants. Orchids grow as an epiphyte on plants, have their roots associated with fungi right from the seedling stage.
Many orchids cannot survive without mycorrhizae associations. Many forest trees such as pines appear stunned if mycorrhizal associations are absent. In the presence of these associations, these plants absorb 2 - 3 times more nitrogen, potassium, and phosphorus compared to without them.