The correct answer is a dichotomous key. Basically, you use the key to decide what species an organism is by looking at what traits it has, and if it doesn't have some traits you can instantly rule out a large number of species which brings you closer to your answer of what the species is that you're looking at.
I believe that is ecology
Answer:
A = rough er
B = chloroplast
D = Cytoplasm
C = most likely a lysosome
E = cell wall
Answer:
Ralph is looking at a vein (likely a muscular vein).
Explanation:
Of all three great types of vessel present in vertebrates (arterial, venous, lymphatic), only veins and lymphatic vessels may normally contain valves. This is an essential feature of vessels which present low pressure flow, since it ensures that such flow is unidirectional.
Since blood cells are not typically found in lymphatic vessels, the vessel in question can be assumed to be a vein.
