Consider the purchase of a specific bottle of soft drink at a convenience/corner store. describe the various stages in the (of what happens in its) supply chain and the different flows involved?

First, we have to know that the supply chain's stages include first, the customers and he is the main controller of the supply chain. Then, retailers, distributors (who fill the stock of the retailers and at the end the manufacturer's companies.

So when the customer starts to buy the product this represents the final stage of delivering the product to the end of the supply chain and the beginning of collecting information regarding the customer purchase.

When the customer purchases the product, the money and the information will move towards the retailer.
The retailer requests a new order to fill his stock again from the distributor and that makes money and information move towards the distributor.
The distributor requests a new order from the manufacturer's companies so, the money and the information move towards the manufacturer's companies and shipping companies.
So the Customer's purchase is the most powerful stage in the supply chain.