Final answer:
It is true that sweetness can be enhanced by adding small amounts of salt, bitterness, or sourness, due to the complex interplay of taste receptors on the tongue.
Step-by-step explanation:
The statement that sweetness can be enhanced by adding a small amount of salt, bitterness, or sourness is true. The five primary tastes detected by humans are sweet, sour, bitter, salty, and umami. These tastes can be combined to create more complex flavors. For instance, the addition of salt can bring out deeper flavors in food, even enhancing sweetness because it suppresses bitterness and balances flavors overall.
Similarly, the addition of a sour element can help to brighten a dish and make sweet flavors stand out. Sourness and bitterness in the right proportions can also add depth and contrast to sweet flavors, making a dish more palatable. The ability to taste these flavors is due to the activation of receptors on the tongue, often involving G protein-coupled receptors, which trigger different responses for different tastes.