A chemical leaks into a pond that selectively kills off the phytoplankton (a producer). Many of the other organisms in the pond die over a short period of weeks, and the overall species diversity declines. The phytoplankton in this pond could be considered a good example of .

1) A keystone species
2) An edge species
3) An indicator species
4) A core species
5) None of the above

Astudy that involves interviews of adults is eligible for expedited review. the researcher wants to add an adolescent population (aged 12 to 17) to the study and has designed a parental permission and assent process. no additional changes are planned. which of the following statements about review of the revised protocol is accurate? the research would only be eligible for expedited review if the adolescents are capable of understanding the same consent forms used for the adult population.the research would only be eligible for expedited review if the adolescents have been declared to be emancipated minors.the new research would need full review by a convened irb because children are a protected population.unless the nature of the questions would raise the level of risk to > minimal for adolescents, the research would still qualify for expedited review.

Why did working women earn one-thrid to one-half as much as men

It is widely assumed that people need to engage in intellectual activities such as solving crossword puzzles or mathematics problems in order to maintain mental sharpness as they age. in fact, however, simply talking to other people—that is, participating in social interaction, which engages many mental and perceptual skills—suffices. evidence to this effect comes from a study showing that the more social contact people report, the better their mental skills. which of the following, if true, most seriously weakens the force of the evidence cited? (a) as people grow older, they are often advised to keep exercising their physical and mental capacities in order to maintain or improve them. (b) many medical conditions and treatments that adversely affect a person's mental sharpness also tend to increase that person's social isolation. (c) many people are proficient both in social interactions and in solving mathematical problems. (d) the study did not itself collect data but analyzed data bearing on the issue from prior studies. (e) the tasks evaluating mental sharpness for which data were compiled by the study were more akin to mathematics problems than to conversation.