Ann is a healthy 26-year-old white female. Since the beginning of this current golf season, she has noted increased short­ness of breath and low levels of energy and enthusiasm. These seem worse during her menses. Today, while playing poorly in a golf tournament at a high, mountainous course, she became […]

What is a phylogenetic tree and how and why does the phylogeny-based identification of microorganisms work (in other words, which are the principles of evolution that phylogeny-based identification is based upon)? Draw a (hypothetical)phylogenetic tree of seven organisms, four of which showing no evolutionary divergence to each other and the […]

Population growth rates are small numbers, but they can have a significant impact on population. Let us compare three different scenarios and discuss some population growth issues.Assume the world population at the beginning of 2015 was about 7.2 billion. If the projected 2015 average annual population growth rate for the […]

Q. Most biologists believe that immune system’s defense against infections largely rests on its ability to distinguish self molecules from nonself molecules. This concept seems central to our understanding of immune function. However, like all scientific ideas, it is not beyond question. Some immunologists have developed an alternative hypothesis: that […]