While giving a presentation about a new vaccine, a public health nurse says excitedly "Our goal is to make sure that 95% of the population gets this vaccine right away - every man, woman and child who can!" Why did the nurse set a goal of only 95% of the population, instead of 100%? What are some groups that sometimes can't get vaccines, when other people can?
The nurse is probably referring to people who are unable to receive this particular vaccine for a medical reason, including suppressed immune systems or allergies to the material in the vaccine. Some groups that may not be able to receive particular vaccines right away include babies and young children, the elderly, pregnant women, and people with conditions that suppress the immune system, such as HIV/AIDs.
Koala fingerprints are so similar to human fingerprints that it's hard for crime experts to tell them apart! But the only other animals with fingerprints are the primates, closely related to humans. There are no common ancestors between koalas and humans with fingerprints! Is this an example of convergent or divergent evolution? Why?
This is an example of convergent evolution - where two genetic lineages independently converge on the same trait. In other words, the trait of having swirly little lines on our fingers was advantageous for both primates and koalas, so over many generations, we both developed into animals with fingerprints. A key hint to let you know that this was convergent evolution was the lack of a common ancestor between primates and koalas with the trait. In divergent evolution, a lineage starts out with the same traits, but over time splits into two different groups, with traits or habitats that are so different that those groups no longer breed.
"Nonplussed" is a word that describes a person's state, like "excited" or "confused". "Non" is a prefix that means "not". "Plussed" is not actually used as a word to describe a state - but if it were, what would it mean? Use the dictionary to look up the definition of "nonplussed" if you need to.
The Oxford English Living Dictionary currently lists "So surprised and confused that one is unsure how to react" as the first definition of "nonplussed." Because the "non" means "not", if we assume that "non" is used as a prefix here, "plussed" should describe the state of being NOT so surprised and confused that one is uncertain how to react. There are many possible ways to phrase the answer. In one version, "plussed" might describe the state of being prepared to react. In another, "plussed" might describe the state of being alert and attentive. The important part is that our definition of "plussed" means the opposite of "so surprised and confused that one is unsure how to react," since we have removed the "non" prefix from "nonplussed".