Final answer:
Super-tasters have increased density of fungiform papillae, which means they have more taste buds and are more sensitive to tastes like bitterness.
Step-by-step explanation:
The physiological/anatomical quality that makes some people super-tasters is a) Increased fungiform papillae density. Gustatory receptor cells located within the taste buds on the papillae are responsible for the transduction of taste stimuli. These cells are sensitive to the chemicals in foods and release neurotransmitters based on the concentration of these chemicals, which then activate sensory neurons in various cranial nerves leading to the brain. Super-tasters have a higher density of fungiform papillae on their tongues, and hence more taste buds, making them more sensitive to certain tastes, such as bitterness.