A haversian canal is a(n) Select one:
O A. fiber in dense bone
O B. meshwork in spongy bone
O C. depression on the surface of a bone
O D. channel in dense bone

The study of interaction between living organisms and their enviroment is called (a) phytogeography (b) ecology (c) phytosociology (d) ecosystem

An easy way to calculate the amount of energy available at each level is to what?

The table shows dates and appearance of index fossils. which rock layers can be dated most precisely? a) a layer containing both a fossil 4 and a fossil 3 b) a layer containing both a fossil 2 and a fossil 3 c) a layer containing both a fossil 1 and a fossil 4 d) a layer containing both a fossil 1 and a fossil 2