Answer:
Lichens are not parasitic when they grow on trees, they just use the tree bark as a home. They enrich the soil by trapping water, dust and silt. When lichens die they contribute organic matter to the soil, improving the soil so that other plants can grow there.
They must be non-toxic ie not chemicals that could poison the customers because of the potential risk of contaminating things which can come into contact with the food like say cutting boards, dishes, utensils, pots, pans and any other similar items.
ocean - Large bodies of water.
current flowing towards equator carry cold water from poles
current flowing towards away from equator carry warm water from poles
Example - Humidity
The products and reactants of each cycle are connected. reactants of photosynthesis (6O2 and C6H12O6) are recycled as products in cellular respiration which produces 6H2O 6CO2 and energy to fuel photosynthesis