Question

What do the arrows in a food chain represent?

Answer 1

Hint: A food chain represents the flow of energy and matter in the form of food, from prey to predator. The arrows in a food chain demonstrate this flow.

Complete answer:
In a basic food chain, marine for example, organisms like seaweed and phytoplankton occupy the first trophic level, followed by small fishes and zooplanktons in the second and so on. This transition from one trophic level to another is shown by the help of an arrow. The arrow is not added to point at a relationship between the prey and predator, its purpose is entirely different.
The arrow always points to the higher trophic level, that is from the prey to the predator and this indicates the flow of energy in the form of food.
Energy from one trophic level to another is not completely transferred. A major part of it is lost in the form of heat. Food produced by an autotrophic organism is stored in their body as biomass, when an animal consumes this organism, only $10\%$ of total food consumed is stored in the herbivore as biomass. This pattern continues till the top of the food chain with the flow of energy, in short every trophic level only stores $10\%$ of what it consumes.

Note:
Food chains are linear chains which suggest a unidirectional flow of energy, although in reality energy transfer is much more complex than a linear chain. A more practical representation of energy flow through food is done by a food web, which is a web of many interconnected food chains.