The E. coli that normally live in the human large intestines and produce vitamin K that the body uses would be best described as participating in a _______ relationship.
saprobic
commensal
parasitic
mutualistic
The Correct Answer is D
A. saprobic: A saprobic relationship refers to organisms that obtain nutrients by decomposing dead or decaying organic matter. Saprobes, such as many fungi and bacteria, play an important role in environmental nutrient cycling. The E. coli in the human intestine are not primarily decomposing dead tissue but instead living within a host and interacting with host physiology.
B. commensal: In a commensal relationship, one organism benefits while the other is neither significantly helped nor harmed. Although many normal microbiota are considered commensal, intestinal E. coli provide a measurable benefit to the host by synthesizing vitamin K and certain B vitamins. The host receives a physiological benefit, this interaction is more than commensal.
C. parasitic: A parasitic relationship occurs when one organism benefits at the expense of the host, often causing harm or disease. Pathogenic bacteria demonstrate parasitism by damaging tissues, stealing nutrients, or producing toxins. E. coli that reside in the colon as part of the normal microbiota do not harm the host and instead contribute to normal metabolic functions.
D. mutualistic: Mutualism describes a symbiotic relationship in which both organisms benefit. In the human colon, E. coli receive nutrients and a stable environment for growth, while the host benefits from bacterial synthesis of vitamin K, which is essential for blood clotting processes. This reciprocal exchange of benefits characterizes a mutualistic relationship.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Transcription is the process by which a segment of DNA is copied into RNA by RNA polymerase. In eukaryotic cells, transcription occurs within the nucleus, where DNA is housed, allowing for the synthesis of messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA) before RNA is processed and exported to the cytoplasm for translation. In prokaryotic cells, which lack a membrane-bound nucleus, transcription occurs in the nucleoid region, where the circular DNA resides. Therefore, transcription takes place in the nucleus of eukaryotes or at the nucleoid in prokaryotes.
Correct Answer is B
Explanation
A. Visible to the naked eye: Organisms that can be seen without magnification, such as plants and animals, are not the focus of microbiology. Microbiology specifically investigates microscopic life forms that cannot be easily observed with the unaided eye.
B. Too small to be seen without magnification: Microbiology studies organisms that require a microscope or other magnification tools to be observed. This includes bacteria, viruses, fungi, protozoa, and some algae. Understanding these organisms is essential for medical, environmental, and industrial applications.
C. Only bacteria and viruses: While bacteria and viruses are major subjects of microbiology, the field also encompasses fungi, protozoa, and microscopic algae. Limiting the scope to just bacteria and viruses would exclude significant groups of microorganisms.
D. Only disease-causing organisms: Not all microorganisms cause disease. Many play beneficial roles, such as in digestion, nutrient cycling, and biotechnology. Microbiology studies both pathogenic and non-pathogenic organisms to understand their structure, function, and ecological impact.
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