A geologist is studying an ancient stack of rock layers. Most of the layers contain fossils of shallow marine creatures (clams, corals,
etc.), suggesting the layers formed in a shallow ocean environment. But at the top of the stack, there is a layer that could only have
been deposited by a river.
What does this change in rock layers tell the geologist about Earth's history in the area where these layers formed? (Assume the
layers have not changed position since they formed.)

Name the plastid and pigment likely to be found in the cells of (a) petals of sunflower (b) ripe tomato.

What was dr. willem johan kolff’s first step in using the scientific process to invent the hemodialysis machine? he built the machine and tried it with various patients, collecting data about its effectiveness. when a patient’s kidneys failed, he wondered if it would be possible to perform kidney functions with an external machine. he researched and collected data about numerous patients who exhibited symptoms of kidney failure. he drew conclusions from studies of various symptoms of kidney failure, and drew a design for the ideal external blood-processing machine.

Which best describes the digestive system of arthropods? a incomplete, two openings b complete, one opening c two-way, one opening d one-way, two openings