In a local park, several environmental changes are noted; crayfish eggs in the lake are fewer than normal. When tested, the water from the lake has an elevated level of aluminum. What addition to the lake is the most likely cause of these conditions? A)
acid rain
B)
lead from batteries
C)
sulfur dioxide particulates from a near-by factory
D)
carbon monoxide from cars near-by
E)
increased ozone from sun exposure

Examine the two squirrel populations in the accompanying figure. the populations are separated by a geographic barrier. if after a long period of time the two species are no longer separated, what evidence is needed to determine if speciation has occurred? the figure shows two populations of squirrels separated by a geographic barrier. examine the two squirrel populations in the accompanying figure. the populations are separated by a geographic barrier. if after a long period of time the two species are no longer separated, what evidence is needed to determine if speciation has occurred? the figure shows two populations of squirrels separated by a geographic barrier. polyploidy is creating new species. the two populations are not interbreeding freely. hybrid offspring of the two populations begin to appear. one species will increase into a population size twice as large as the other species.

Drag each label to the correct location on the table. each label can be used more than once. decide whether each statement describes saturated fat, unsaturated fat, or both saturated and unsaturated fats.

Which of the following statements about archaea and bacteria is true? a. neither is single-celled. b. they both have nuclear membranes. c. neither reproduces by binary fission. d. they both lack a nuclear membrane.