Explain the shape of a normal demand curve

• the income effect causes demand for a product to fall when price rises, because it becomes less affordable (1)
• The substitution effect causes consumers to switch to cheaper substitutes as price rises (1)
• The Law of Diminishing Marginal Utility states that as more of a good is consumed, the marginal utility gained from the consumption of an additional unit decreases (1).
• A consumer will only demand additional units if price is lowered (1), this is because the lower price reflects the lower satisfaction gained from consuming one more unit of the product (1)

(From Higher Economics 2023 Q3 (b))