25. The cells of prokaryotic organisms lack a Short Answer 26. What did Thucydid

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Question

25. The cells of prokaryotic organisms lack a Short Answer 26. What did Thucydides lean by observing the Athenian plague? 27. Why was the invention of the microscope important for microbiology? 28. What are some ways people use microbes? 29. What is a phylogenetic tree? 30. Which of the five kingdoms in Whitaker's phylogenetic tree are prokaryotic;, and which are eukaryotic? 31. What molecule did Woese and Fox use to construct their phylogenetic tree? 32. Name some techniques that can be used to identify and differentiate species of bacteria. 33. Describe the differences between bacteria and archaea 34. Name three structures that various protozoa use for locomotion. 35. Describe the actual and relative sizes of a virus, a bacterium, and a plant or animal cell. Critical Thinking 36. Explain how the discovery of fermented foods likely benefited our ancestors. 37. What evidence would you use to support this statement: Ancient people thought that disease was transmitted by things they could not see. 38. Why is using binomial nomenclature more useful than using common names? F10 F7 FS 5

Explanation / Answer

26. Thucydides

Thucydides were Greek Historians which hailed between 460 to 390 BC. Athenian Plague which was endemic and occurred somewhat during 410 to 430 BC, took the lives of almost 1/3rd of total population of Thucydides. After the Athenian plague was over, these Greek Thucydides observed that the people which survived the endemic plague, did not get infected by further exposure of Plague. That is, they developed immunity against the plague.

27. Microscope was invented to study microbes by Sir Antony Van Leuvenhock. This invention was necessary because microbes cannot be studied by naked eyes. So to study the detailed sturucture, size of microbes etc., invention of microscope was very useful.

28. Microbes are used by people in many ways. Some of the important ways that people use microbes are production of food, like curdling of milk, fermentation, process of making cheese, yogurt etc, in all processes microbes are used. Fermented food uses microbes. Brewing industry as well as pharmaceutical industry uses microbes to a large extent. Now a day, microbes are used in diagnosis of many diseases as well as agricultural practices.

29. Phylogenetic tree is a pictorial representation of evolutionary relationships among organisms, in a form of flow chart like structure. It is a branched diagram. Based on the similarities and differences of genetic characters among organisms , a common ancestor is derived from the tree. This is a tool of bioinformatics, which is mostly used in characterization of organisms and their taxa.

30. Whittaker’s phylogenetic classifications which included five kingdoms, namely, Monera, Protista, Plantae , Fungi and Animalia. Out of these five kingdoms, Monera and Protista were Prokaryotes, rest were eukaryotes because of distinct cell structure and enveloped organelles.

31. The molecule chosen by Woese and Fox, to construct phylogenetic tree was 16s rRNA. This was because , this is the molecule which is conserved across same species of an organism. So based on the differences in the 16s rRNA subunit, different genera could be classified, which was of immense help in taxonomy.

32. The techniques which can be used to identify species of bacteria are, FAME analysis or Fatty acid methyl Ester, and 16s rRNA analysis. These are conserved regions in a species.

33. Main differences between bacteria and archea are as follows:

Bacteria

Archea

Cell was has peptidoglycan

Cell wall does not have peptidoglycan

Membrane lipids have ester bonds

Membrane lipids have ether bonds

Contains one RNA polymerases

Contains three RNA polymerases

34. Three main locomotory structures used by protozoans are Cilia, Flagella and Pseudopodia. Flagella is used by most bacteria nad other protozoans, pseudopodia are false legs used for amoeboid movement and cilia are used by protozoans like Paramecium.

35. Animal cell – 10 to 30 micrometers

Plant cell – 10 t0 100 micrometers

Bacteria l cell – 0.5 to 5.0 micrometers

Viral cell – 40 to 400 nanometers