Ralph is looking at a blood vessel under a microscope as part of his study about the cardiovascular system. he notices that the vessel contains blood and has valves. determine the blood vessel being observed.

The seed coat's most important function is to provide a) a nonstressful environment for the megasporangium. b) the means for dispersal. c) dormancy. d) a nutrient supply for the embryo. e) desiccation resistance.

What was the land like over 500 million years ago? what was under the sea?

What can be said about farmers in highly developed countries? a) they have little or no negative impact on the environment. b) they practice subsistence agriculture. c) they are able to incorporate polyculture into their farming practices. d) they utilize organic farming techniques on a regular basis. e) they rely on large amounts of energy from fossil fuels.