3-5~3-7

3-5What happens to energy in an ecosystem？

Energy flows through ecosystems in food chains and food webs.

◆Food chain食物鏈：將生物以掠食者與被食者的關係單向依序排列。

◆Food web食物網：由許多條單純的食物鏈相結成網，最後可把整個生物群集連在一起。

◆Biomass生物量：有機物-水的重量

◆Ecological efficiency生態效率：能量經過轉移後，真正可用的百分比。

◆每次能量轉移，剩下十分之一。

◆Pyramid of energy能量金字塔：由食物轉換為有效能量之效率非常有限，因此消費者如攝取高一層之生物為食，將增加消耗數倍食物之能量。

◆淨初級生產率(NPP)＝總初級生產率(GPP)－生物呼吸的能量消耗(R)

3-6What happens to matter in an ecosystem？

Matter cycles within ecosystems and in the biosphere.

◆Water cycles through the biosphere

◆Carbon cycles through the biosphere

◆Nitrogen cycles through the biosphere：bacteria in action

◆Phosphorus cycles through the biosphere.

3-7How do scientists study ecosystems？

◆Some scientists study nature directly.

◆Some scientists study ecosystems in laboratory.

◆Some scientists use models to simulate ecosystems.