An be inferred from the passage that: a. in an extinction event, there is a dramatic decrease in microbial life on earth. b. over 90% of easily observed, biologically complex species become extinct during a biotic crisis. c. the background extinction rate of animal and plant species is well below 50%. d. marine fossils are easier to find and thus more useful to those studying mass extinction events.

4.06 hc)a five-year review of threats to the southern resident orca population of the united states concluded that the top threats were prey availability, contaminants, and effects from recreational and whale watching vessels. further down the list are oil spills, disease, and effects from commercial vessels not targeting whales. how might this list be different if it were for transient whale populations, which have a larger average population size and live farther offshore in open waters? a)the transient population is more likely to be affected by contaminants. b)the transient population is less likely to be affected by whale watching vessels. c)the transient population is more likely to be affected by disease. d)the transient population is less likely to be affected by prey availability.

The first signs of cellular differentiation occur in the blastocyst. why is cellular differentiation important for the development of a fully formed human infant?

Competition occurs between species when