Matter is recycled within and between ecosystems through closed loops called biogeochemical cycles. How is this unlike how energy is passed through ecosystems?

Energy flows in a one-way direction i.e. unidirectional flow

Explanation:

Matter and energy both pass through an ecosystem as organisms feed on one another. However, as rightly emphasized in this question, matter in form of elements such as water, nitrogen, phosphorus etc. moves in different directions and is recycled within and between ecosystems through closed loops called biogeochemical cycles.

Contrarily to how matter is recycled in an ecosystem i.e. within and between, ENERGY only flows in one direction. Energy enters an ecosystem in form of light (sun) and is passed down from one trophic level to another starting from the producers. This unidirectional pattern of energy flow differentiates energy flow from matter recycling.

heat a spark and oxygen

the answer is:

carbon dioxide