19. Which is NOT true regarding keystone species? (a) Keystone species can be mutualists with other
species.
(b) Keystone species are often rare individuals in a
community
(c) Keystone species are most likely to be commensalists.
(d) Some keystone species are habitat engineers.

The roman empire fell around the 5th century, and as islam spread in the 7th century, trade between europe and china slowed. chinese traders were blocked from westward expansion into europe when the chinese army was defeated by muslim fighters in the area known as syr darya. the trade routes, known as the silk road, fell into disuse, and trade between the far east and europe nearly stopped. it wasn't until the 13th century when the mongols invaded and controlled central asia and large parts of the middle east that extensive trade along these routes was opened again. based upon the paragraph above and your knowledge of the mongols, which of the following statements is correct? a. the mongols unified regions along the silk road, allowing for safe transport of goods. b. muslims controlled busy trade routes into china from the 5th to the 7th centuries. c. without access to european markets, the chinese were unable to obtain raw materials. d. the mongols replaced the roman empire as the dominant force in western europe.

The average act score follows a normal distribution, with a mean of μ = 21.1 and a standard deviation of σ = 5.1. what is the probability that the mean iq score of 50 randomly selected people will be more than 23? 0 1 0.9958 0.3547 0.0042

Stereotypes can influence the way we think about a specific group of people. this is especially common in racial and ethnic group, but it is not reserved specifically for those groups. stereotypes can also apply to school groups, cliques, and neighborhoods. a stereotype is similar to which of the following terms: a)feature detectors b)texture gradient c)perceptual set d)stereogram e)relative clarity