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6. Although most bacteria in the Division Eubacteriophyta are heterotrophic, there are some autotrophic species which produce ATP and glucose by oxidizing chemicals in their environment (chemosynthesis) or by utilizing light energy in their thylakoid membranes (photosynthesis). Some of the photosynthetic species have pigments similar to chlorophyll a in higher plants, but they do not produce oxygen as a by-product of photosynthesis. The photosynthetic Eubacteriophyta include purple sulphur bacteria, purple nonsulphur bacteria, green sulpur bacteria and prochlorobacteria. The prochlorobacteria are quite distinct from other members of the Eubacteriophyta because they possess both chlorophylls a and b of higher plants. The prochlorobacteria also produce oxygen like the Division Cyanophyta, but unlike the cyanobacteria they do not have phycobilin accessary pigments. [It should be noted here that some biologists place the prochlorobacteria in the Division Cyanophyta.]
The following simplified equation shows photosythesis of purple sulfur bacteria:
CO2 + 2 H2S = CH2O + H2O + 2 S
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Carbon dioxide + hydrogen sulfide react with bacteriochlorophyll &
sunlight to form carbohydrate (CH2O e.g. glucose) + water + sulphur.
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Compare the above equation with photosynthesis in green plants:
CO2 + 2 H2O = CH2O + H2O + 2 O2
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Carbon dioxide + water react in the presence of chlorophyll
& sunlight to form carbohydrate (CH2O) + water + oxygen.
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The photosynthetic Division Cyanobacteria contain chlorophyll a in their thylakoid membranes. Chlorophyll a is also present in thylakoid membranes within chloroplasts of higher plants. These bacteria also produce oxygen as a by-product of photosynthesis. In fact, a photosynthetic cell from a cyanobacterium is reminiscent of a chloroplast, and some biologists believe that chloroplasts may have evolved from photosynthetic bacterial cells. This tentative explanation for the origin of chloroplasts is known as the Endosymbiont Hypothesis. Cyanobacteria also contain blue phycocyanin and red phycoerythrin pigments. Phycocyanin and phycoerythrin are accessary pigments called phycobilins which are also found in the red algae (Division Rhodophyta). Except for the prochlorobacteria, other bacteria in the Division Eubacteriophyta capable of carrying on photosynthesis do not produce oxygen and they do not have chlorophyll a. The prochlorobacteria have both chlorophyll a and chlorophyll b of higher plants, but do not have the phycobilins of the cyanobacteria. Because of their chemistry and cell structure they are probably the best candidates for precursors of chloroplasts. These remarkable green bacteria were discovered on marine invertebrates called sea squirts (Phylum Chordata) by Dr. Ralph Lewin of Scripps Institute of Oceanography in La Jolla, California.
Halobacteria in the Division Archaebacteria have a unique photosynthetic pigment in their membranes but they do not produce oxygen. Like photosynthetic plants, the halobacteria produce their own ATP; but unlike green plants, they utilize bacteriorhodopsin instead of chlorophyll. The exact mechanism of ATP production is complicated and beyond the scope of this article, but it involves a "proton pump" across their cell membrane similar to the chemiosmotic mechanism for ATP synthesis in the chloroplasts and mitochondria of eukaryotic cells in higher organisms. Positively-charged hydrogen ions (protons), forced to one side of the membrane, flow back through special channels (pores) in the membrane as ATP (adenosine triphosphate) is enzymatically produced from ADP (adenosine diphosphate) and P (phosphate). These bacteria are especially interesting because the chemiosmotic mechanism for generating ATP does not require an electron transport system as in other photosynthetic bacteria and higher plants. Strains of these amazing bacteria have also been shown to survive anaerobically without free atmospheric oxygen while deeply embedded in thick salt crust. Bacteriorhodopsin is remarkably similar to the light sensitive pigment (rhodopsin) in the rod cells of human eyes which enables us to see in dim light. Thus, when we enter a dimly lighted room, it takes about 30 minutes for our eyes to adjust fully as the rhodopsin gradually increases in concentration. Of course, a flash of light can instantaneously break down your rhodopsin level, much to the chagrin of star-gazers who have become accustomed to the darkness.
Be sure to look up the links to articles about flowering plants, because a number of questions on Exam #1 refer to flowering plants (angiosperms) in the Division Anthophyta. For example, flowering plants have co-evolved in time and geographical distribution with insects (Class Insecta), resulting in some truly remarkable methods of pollination.
Part II, Matching: Questions 37-75.
Part III, Matching: Questions 76-96.
Most of these answers can be found at the Major Divisions Of Life. Be sure to read the questions carefully to see if I am asking for a kingdom, division, phylum, class, or a general term applied to a specific group. For example, the Division Eubacteriophyta includes the "true bacteria" or "eubacteria." Many answers can also be found at the The Five Kingdoms Of Life and at the Diversity Of Flowering Plants. Some answers refer to categories at the Major Divisions Of Life that include one or more divisions. This is particularly true of the Kingdom Plantae. For example, nonvascular plants include the Division Bryophyta, while vascular plants include the remaining nine divisions in this kingdom. "Pteridophytes" are vascular plants that do not produce seeds, while "spermatophytes" are vascular plants producing seeds. Thallophytes include the Kingdoms Monera, Protista and Fungi. They have a body called a thallus and typically produce zygotes that do not develop into multicellular embryos within female sex organs. Embryophytes include the Kingdom Plantae in which the zygotes develop into multicellular embryos within female sex organs called archegonia or within embryo sacs of flowering plants.
Throughout these pages there are numerous links to other pages. Click on these links to see images and more information about specific divisions or classes. For example, the Division Anthophyta includes many thousands of species of flowering plants (angiosperms), from minute wolffia plants only one millimeter long (1/25th of an inch) to giant eucalyptus trees 100 meters tall (over 300 feet). This enormous division also includes very unusual and specialized parasitic flowering plants (such as the broomrapes) and mycotrophic flowering plants that obtain nutrients from the roots of nearby forest trees via mycorrhizal soil fungi.
Note: When answering these questions, use the classification system adopted by Wayne's Word (see the above classification outlines). Do not use classification schemes used in other books or web sites on the Internet. This is not to say that only one system is correct, but in order to grade these questions objectively, it is necessary to follow one system.
Using The FIND Command To Locate Answers Quickly
As I stated above, most of the answers to Exam #1 can be found at the Major Divisions Of Life and the Five Kingdoms Of Life. I hate to make all of this too easy, but I also hate to see students getting frustrated and confused with all this high memory load information. Try going to the Major Divisions Of Life. Then do FIND (Edit-Find or ctrl-F) and type in a word or phrase. Example #1: Lets say you are trying to find the division of algae characterized by cells with a conspicuous transverse groove. Just type in the word "transverse" and you should go immediately to the Division Pyrrophyta (dinoflagellates). I don't have any photos or illustrations of this division on Wayne's Word, but you can easily do an Internet search and find a lot of additional information and images. Try using an Internet search engine on the Wayne's Word home page, such as Simplify.net or Mamma.com. Example #2: Suppose you are trying to find the fungal division that includes the sexually transmitted anther smut of flowering plants. Use the FIND command again (Edit-Find or ctrl-F) and type in the word "smut" and you should go immediately to the Class Basidiomycetes. REMEMBER that this question wants the correct division (not the class), so scroll up to the Division Eumycota (true septate fungi) to which the Class Basidiomycetes belongs. You might want to look at my link to Anther Smut and read about this debilitating disease of flowering plants. Another important page for using the FIND command is the Diversity Of Flowering Plants because several questions on Exam #1 refer to this division (Division Anthophyta). Remember that there is also a nifty SEARCH button at the top right of this page that searches every file on the server where Wayne's Word is located. This works very well, especially if you are lucky enough to have a fast cable or DSL connection. For some questions you might have better luck going to the above pull down menu or tables. You can often eliminate a lot of divisions by just looking at the outline of major phyla or outline of divisions.
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Pteridophytes: Spores but no seeds
Go Back To The Major Divisions Of Life