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Q. Most biologists believe that immunes system’s defense against infections largely rests on its ability to distinguish self molecules from non-self molecules. This concept seems central to our understanding of immune function. Numerous immunologists have developed an alternative hypothesis: that the immune system’s effectiveness rests mostly on its ability to […]

A 67-year-old patient with severe sepsis undergoes a full infectious work-up upon admittance to the intensive care unit. Cultures of urine, blood, sputum, and cerebral spinal fluid are obtained. The cultures do not yield a specifi organism, so further analysis of the sample is done to determine the characteristics of […]

1. Explain why microbial cells are excellent models for understanding cell function in higher organisms. 2. What are the similarities between viruses and truecells. 3. Elaborate on how chemolithotrophy and photoautotrophy have influenced microbial competition, and thus, microbial habitats. 4. Explain why prokaryotes tend to adapt more rapidly to changing […]

Q. Some prey form groups (aggregate) in the presence of a predator. One benefit of aggregation may result from defensive action by the entire group, but another potential benefit lies in reducing the per-individual likelihood of death. Detailed studies of the behaviours of individual fish in schools demonstrate that fish […]