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Everything you need to know about microbial diversity. Some of the questions are as follows:-
Q.1. What are protoctista?
Ans. Lynn Margulis in 1985 placed algae and protozoa together and called the group protoctista instead of calling protista.
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Q.2. What is protista?
Ans. A kingdom of organisms that lacks true tissue differentiation which include many algae and protozoa. Ernst Haeckel who in 1886 divided organisms into plants, animals and protists, included all microorganisms-bacteria, fungi, algae and protozoa. Whittaker in 1965 Maker in 1965 who proposed 5 kingdoms, included protozoa and algae only under Protista.
Q.3. What is Chromista?
Ans. It is a proposed taxonomic kingdom which will include diatoms and brown algae based on occurrence of chloroplasts in the lumen of rough endoplasmic reticulum instead of being in cytosol as found in plants.
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Q.4. Which are the four classical groups of protozoa based on locomotion?
Ans. The four classical groups are:
(1) Ciliophora, which include ciliates,
(2) Mastigophora which include flagellates,
(3) Sarcodina (pseudopod formers) and
(4) Sporozoa (spore forming parasites).
Q.5. What are slime moulds?
Ans. Slime moulds are members of Gymnomycota fungi which are phagotrophic i.e. ingest nutrients in particulate forms like most of the protozoa. They possess tubular mitochondrial cristae and form no walls in their trophic phase.
Q.6. Explain the evolution of mitochondria in protozoa.
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Ans. In the process of evolution of protozoa the structure of mitochondria also evolved. The mitochondria were formed initially from endosymbiotic prokaryotes had discoid cristae. This was followed by the evolution of tubular cristae and finally flat plate like cristae evolved in protozoa. However, in some anaerobic protozoa they lost the mitochondria. The protozoa with flat plate like cristae further resulted in the evolution of fungi and animals.
Q.7. What is the recent definition of protozoa proposed by Cavalier Smith?
Ans. They are predominantly cellular eukaryotic microorganisms with often phototrophic nutrition- without cell walls in their vegetative growth state. However, cell walls are found in spore. Some species have chloroplasts in the cytosol but have no starch. Nor do phycobihsomes have stacked thylakoids but possess three envelope membranes instead of having two envelope membranes.
Q.8. How can you say that Hexamita and Giardia (Metamonada); and Enterocytozoon (Microsporia) are the exceptional protozoa which developed before the evolution of endosymbiotic mitochondria?
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Ans. Hexamita and Giardia (Metamonada); and Enterocytozoon (Microsporia) lack mitochondria.
Q.9. Why do some protozoa and methanogenic archaea occur together in association in the rumen of some cattle?
Ans. Because some protozoa release molecular hydrogen which is utilized by the archaea.
Q.10. What are hydrogenosomes?
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Ans. The hydrogenosomes are organelles in which enzyme hydrogenase is localized.
Q.11. What is the function of glycosomes found in some protozoa?
Ans. Glycosomes are specialized structures found in some protozoa in which glycolysis occurs, e.g., in trypanosomes which are flagellated protozoa and exist as blood parasites.
Q.12. What lead to the evolution of contractile vacuoles in some protozoa?
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Ans. They evolved for the purpose Osmoregulation, i.e., to remove water from the cell and to prevent rupture of the cell.
Q.13. What is a cytosome?
Ans. A cytosome is a mouth like region lined with cilia that help in passing the food particle into the groove.
Q.14. What are rhoptries?
Ans. These are two to several elongated electron dense bodies which extend to the cell membrane of some protozoa within the polar ring.
Q.15. What is merogony or schizogony?
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Ans. They are multiple fissions which occur in some protozoa (e.g. Plasmodium).
Q.16. What is plasmatomy?
Ans. A form of sexual reproduction in which a multinucleate protozoan cell is divided to form two or more smaller but multinucleate daughter cells.
Q.17. Why are cysts formed by protozoa?
Ans. Cyst formation is a resting dormant stage for the protozoa to withstand adverse conditions.
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Q.18. What is excystation?
Ans. The process by which the cyst returns to actively growing vegetative condition.
Q.19. What is the complex feature of malaria causing apicomplexan protozoa, Plasmodium?
Ans. In Plasmodium, the merogony and part of gametogony take place in human hosts and sporogony in mosquito hosts.
Q.20. How are the sporozoites of malaria parasite Plasmodium inoculated by the female mosquito?
Ans. The female mosquito injects saliva containing plasmodium sporozoites into the blood stream of vertebrates. The sporozoites move into liver parenchymal cells where they multiply by asexual reproduction after seven days.
Q.21. How did fungi evolve?
Ans. The fungi evolved from protozoa due to evolution of chitinous walls in the trophic phase.
Q.22. What is dimorphism in fungi? Give an example.
Ans. The nature of existing in two structural forms is called dimorphism, e.g., Mucorrouxii grows in a yeast like form in the atmosphere with a high percentage of CO2 but forms filamentous mycelia at normal atmospheric concentrations of carbon dioxide.
Q.23. Name a fungus that is an opportunistic pathogen and can cause serious infections in humans.
Ans. Mucor.
Q.24. Name the four major classes of fungi named by classical botanists.
Ans. These are:
1. Zygomycetes,
2. Ascomycetes,
3. Basidiomycetes and
4. Deuteromycetes.
Q.25. Name the fungus which has been used for expression of viral, prokaryotic and eukaryotic genes by recombinant DNA technology and is useful for production of recombinant vaccines such as Hepatitis B.
Ans. Saccharomyces cerevisiae.
Q.26 . What are moulds?
Ans. Filamentous fungi are called moulds.
Q.27. What is mycelium?
Ans. Interwoven hyphae or the tuft of fungal hyphae is called mycelium (plural, mycelia).
Q.28 . Which is the group of fungi in which dolipore septa occur? What is their function?
Ans. Dolipore septa are found in Basidiomycetes. The dolipore septa are specialized connections between the cells of their hyphae. The pores in the septum allow the flow of materials from one cell to another.
Q.29. What are Zygomycetes?
Ans. Zygomycetes are filamentous fungi which typically have coenocytic mycelia. The septa in them are formed only at the time of sexual reproduction.
Q.30. How is Neurospora useful in genetic studies?
Ans.The spores of Neurospora can be isolated from the ascus and its genotype can be readily determined.
Q.31. Why is Amanita phalloides known as the death cap?
Ans. It is a deadly poison and most deaths due to mushroom poisoning have been attributed to Amanita phalloides.
Q.32. Which is the first fungus described in literature?
Ans. Mushroom is the fungus that was described first of all in the Rig-Veda comparing its cap with the head of a devil or a wicked person which can be easily blown away even by a light current of air.
Q.33. What is a pyrenoid?
Ans. The pyrenoid is a differentiated region in the chloroplast of algae where the reactions of Calvin cycle take place. The pyrenoid regions contain ribulose 1, 5-diphosphate carboxylase. The storage products are also associated with the pyrenoids.
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Q.34. Give the range of variations of structure of chloroplasts in algae.
Ans. The chloroplasts in red algae possess separate thylakoids with phylicobilisomes on their surfaces. The chloroplasts of green algae are in stacks and have pyrenoids with starch storage granules. The chloroplasts in diatoms and brown algae have thylakoids arranged as groups of three.
Q.35. Name the Dinoflagellate algae which causes red tide.
Ans. Gonyaulax.
Q.36. What are the applications of alginic acid which is one of the normal constituents of cell wall of brown algae?
Ans. The alginic acid is used as an additive in ice-cream and is also used as a sizer in paper and textile industry.
Q.37. What is a major characteristic of blooms of dinoflagellates at sea?
Ans. The blooms of dinoflagellates cause toxic red tides.
Q.38. What are puntae?
Ans. The holes in silica walls of diatoms are called puntae.
Q.39. What are Prochlorons?
Ans. The prochlorons are the individuals of the genus Prochloron which is one of the two genera of Prochlorohytes (order Prochlorales) which are placed under Group II of oxygenic phototrophic bacteria, according to 9th edition of Bergey Manual of Determinative Bacteriology (1994).
The second genus of the Prochlorophytes (order Prochlorales) is Prochlorothrix. The Prochloron is unicellular while Prochlorothrix is filamentous. The individuals of Prochloron are unicellular, spherical without evident mucilaginous sheath. They divide by binary fission by equatorial constriction.
So far the genus is found almost exclusively associated as extracellular symbonts of colonial ascidians (chiefly didemnids) on subtropical and tropical marine shores. The only species is Prochloron didemni. The Prochlorophytes resemble cyanophytes i.e., cyanobacteria from which they differ in that they form chlorophylls a, and b and lack accessory red or blue bilin pigments.
The electron micrographs of the photosynthetic bacterium Prochloron possesses extensive internal membranes. These membranes are known to be the sites of chemiosmotic generation of ATP by this bacterium which derives the energy for ATP formation from light energy. The photosynthetic membranes or chromatophores are cylindrically shaped vesicles in Prochloron.
