The demand curve is a graphical representation of the relationship between the price of a product and the quantity of that product that consumers are willing to buy at that price. It is a fundamental concept in economics and is used to analyze the behavior of consumers in the market.

Here are some potential questions you may encounter on a junior certificate business test about the demand curve:

1. Define the demand curve.
2. Explain the law of demand and its relationship to the demand curve.
3. Draw a demand curve for a product and label the axes.
4. What factors can cause a shift in the demand curve?
5. Describe the difference between a movement along the demand curve and a shift in the demand curve.
6. How does a change in price affect the quantity demanded along the demand curve?
7. What is the relationship between price elasticity of demand and the slope of the demand curve?
8. How does income affect the demand curve for normal goods and inferior goods?
9. Explain the concept of substitute goods and how they affect the demand curve.
10. Give an example of a non-price factor that can cause a shift in the demand curve for a specific product.

These questions will test your understanding of the demand curve and its implications for consumer behavior in the market. Make sure to study the concepts thoroughly and practice drawing and interpreting demand curves to prepare for the test.