GRE Subject Test: Biology : Understanding Bacteria
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Example Questions
Example Question #1 : Understanding Bacteria
Which bacterial reproductive process does not involve any genetic recombination?
Conjugation
Transformation
Binary fission
Transduction
Binary fission
Bacteria are capable of reproducing in a variety of ways. Binary fission is most similar to mitosis in animals, and does not involve any genetic recombination. DNA is replicated and passed to identical daughter cells.
In contrast, the other listed methods involve the incorporation of foreign DNA into the bacteria genome. In conjugation, plasmids are exchanged between bacteria via a sex pilus. In transformation the bacterium is capable of incorporating DNA directly from its surrounding environment. In transduction, a bacteriophage vector is used to introduce foreign DNA into the bacterial cell.
Example Question #2 : Understanding Bacteria
Penicillin is a drug that inhibits the formation of peptidoglycan. Based on this mechanism, which infection could be treated using penicillin?
Viral infection
Fungal infection
Bacterial infection
Allergic reactions
Bacterial infection
Peptidoglycan is most well-known for its role in the formation of bacterial cell walls. By inhibiting the production of peptidoglycan, penicillin prevents bacteria from fully developing and is very effective at treating bacterial infections.
Anti-histamines an anti-inflammatory medications can be used to help prevent the autoimmune response that triggers allergic reactions. Fungicides are used to kill fungal infections. Viruses are harder to treat, as they are not technically alive and cannot be "killed."
Example Question #3 : Understanding Bacteria
Which of the following microorganisms are single-celled and reproduce by binary fission?
Bacteria
Protozoa
Helminths
Fungi
Viruses
Bacteria
Bacteria are single-celled organisms that reproduce by binary fission, in which identical copies of the original cell are produced.
Viruses require living cells in order to multiply. The viruses invade cells and redirect the host organelles from their normal functions to instead replicate the virus. Fungi are very different from bactria in that their structure is more complex (eukaryotic) and they reproduce by budding (among other mechanisms). Protozoa include unicellular animal-like microorganisms. Common protozoan infections include malaria and sleeping sickness. Helminths are worm-like animals, including pinworms and tapeworms.
Example Question #38 : Microbiology
What is the significance of endospores?
They are produced by gram-positive bacteria which can survive extreme conditions
They allow gram-negative bacteria to reproduce
They allow fungi to store nutrients that can survive extreme conditions
They allow fungi to survive in extreme climates
They are produced by gram-positive bacteria which can survive extreme conditions
Endospores are produced by gram-positive bacteria and can lie dormant for years. Endospores are crucial to growth of gram-positive bacteria because they resist harsh conditions such as extreme temperatures, ultraviolet radiation, and many chemicals. Endospores are not used by fungi by any means. They are also uninvolved in the reproductive processes of bacteria.
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