HEL A trophic pyramid describes the flow of energy in an ecosystem. Producers are at the base of the pyramid, and tertiary consumers are at the top of the pyramid. Where is the population the largest?

a
In the middle.
b
At the bottom.
c
It depends on the ecosystem.
d
At the top.

What was piaget's explanation as to why preschool-age children in the preoperational stage make errors on tasks requiring conservation? a) preschool children's tendency toward centration prevents them from focusing on other relevant features of a situation b) preschool children have not yet developed numerical understanding; therefore, different amounts are meaningless c) preschool children's neural-visual network is not fully matured d) preschool children have not lived long enough and accrued enough experience to know the difference between quantities