STEP-BY-STEP ANSWER:
Step 1: Recognize the key social constructs in the South, such as a culture of honor, strict gender roles, and racial ideologies.
Step 2: Explain how these constructs created a justification system for the institution of slavery.
Step 3: Illustrate how the values and beliefs upheld the proslavery agenda, making it appear socially and morally acceptable.
Step 4: Connect this social acceptance to the sustained economic practices on plantations, including the use of slave labor.
Final Answer: The social and cultural structures of the South, emphasizing honor, strict gender roles, and racial hierarchies, reinforced the economic model based on slavery by justifying its practices and supporting an expansionist, proslavery agenda.