$1\mathrm{.}1.$ The difference between human engineered systems and natural systems $($like an ecosystem$)$ is

that human made systems tend to perform more consistently than natural systems.

that natural systems are simpler than human designed ones

that natural systems are often much more complex than human designed systems.

no difference, they are the same

$22\mathrm{.}5$ points

$1\mathrm{.}2.$ All natural systems have been understood as products of what?

natural selection

long periods of time

primary productivity

optimization to achieve maximal productivity

$3$

$2\mathrm{.}5$ points

$1\mathrm{.}3.$ Ecosystem are systems $...$

that always include many species