This is a series of twenty questions related to biology. The topics cover everything from evolution to the different kingdoms of the world. Attention is given to bacteria and viruses which are very important to all living things whether or not we are aware of this reality.
¶ … Disease Control. You have been called to a remote area of Uganda to study a mysterious disease that is causing respiratory ailments in a small village. You isolate a bacterium from several patients that seems like a good candidate for the pathogen. How can you determine if this bacterium is causing the illness?
I would investigate the bacteria to determine if it had genetic markers consistent with known disease-causing bacteria. I would first prescribe antibiotics to patients and if this cleared up the respiratory ailments then I would assume this bacteria is the cause of the disease.
As a U.S. Department of Agriculture field representative, you counsel a young farmer to plant alfalfa in fields with soils that have low nitrogen levels. You know alfalfa can host certain bacteria.
a. Explain your reasoning.
The growth of alfalfa will ultimately improve the soil, adding much-needed nitrogen and producing a better harvest.
b. How will the alfalfa and its associated bacteria help "fertilize" this farmer's soil?
Bacteria will break down dead matter, and in so doing will add nutrients like nitrogen to the soil.
3. Distinguish between all the following:
a. Obligate anaerobe / obligate aerobe:
Obligate aerobes require oxygen to survive while obligate anaerobes do not an in fact are harmed if exposed to oxygen.
b. Photoautotroph / photoheterotroph:
Photoautotrophs get all the energy they need from light through photosynthesis while photoheterotrophs require additional nutrients to formulate energy.
c. Chemolithotroph / chemoheterotroph:
Chemolithotrophs require minerals to create energy while chemoheterotrophs require oxidation of organic molecules to generate energy.
d. Endotoxin / exotoxin:
Endotoxins are those which are located within the cell wall while exotoxins are released outside of the cell wall.
e. Gram (-) / Gram (+) bacteria:
Gram (+) bacteria have thicker cell walls than Gram (-). Also, Gram (+) bacteria have teichoic acid and more peptidoglycans.
f. Negative single strand RNA virus / positive single stranded RNA virus:
Negative single strand RNA viruses have an antisense strand as opposed to positive single strand RNA viruses which have a sense strand.
4. A friend tells you she "hates" bacteria and declares her intention to eradicate all bacteria from her home using different disinfecting & sterilizing products. How do you respond to her "outrage"? Support your response with 4 specific examples.
I would explain to her that bacteria are necessary for continued life on earth, including human beings. Although there are negative bacteria which can cause harm, there are many bacteria which are beneficial to humans. These include: lactobacillus acidophilus which is yogurt, yeast which makes bread and cake, coliform bacteria in the intestines which helps break down food, streptomyces are used to make antibiotics, and rhizobium which breaks down matter to put nutrients into the soil which then grows fruit and vegetables.
5. Lateral gene transfer is very common among bacteria.
a. Describe 3 mechanisms of lateral gene transfer.
i. Transformation: genetic alteration of a cell
ii. Transduction: bacterial DNA is moved from one bacteria to another iii. Conjugation: bacteria transfers genetic material to another cell through contact
b. How can lateral gene transfer be beneficial to bacteria?
This process allows bacteria to respond and adapt to their environments more rapidly by acquiring larger DNA sequences from other bacteria.
c. How can lateral gene transfer complicate the study of phylogenetic relationships among bacteria & possibly the 3 domain system?
DNA becomes mixed between different bacteria and therefore the individual genetic material can become complicated, making it difficult to understand the clear differences between organisms.
6. Woese's studies led to the 3 domain system that replaced the 5 kingdom system.
a. Why did the 5 kingdom system become "obsolete"?
Protista, fungi, plantea, and animalea have all been placed under the category eukarya while bacteria are so diverse that they have required their own classification.
b. Discuss why nucleotide sequencing of ribosomal RNA has been useful in evolutionary biology.
Since RNA sequences differ between species due to mutations, biologists can examine the nucleotide sequence and determine potential connections between species which are no longer similar but may have a shared evolutionary ancestor.
c. Name a few unexpected outcomes of Woese's studies & 3 domain system.
i. Organisms originally given their own kingdom have been linked and shown to be genetically close
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