[Campbell Biology P.961] According to the 'Mutualistic Adaptations' section, which of the fo... | Practice Question

According to the 'Mutualistic Adaptations' section, which of the following is a direct benefit provided by intestinal bacteria to the human host?

  • A: Production of essential vitamins like vitamin K, biotin, and folic acid, which are absorbed into the blood.
  • B: Reducing the size of the human stomach to improve nutrient absorption efficiency.
  • C: Causing gastric ulcers by near-complete elimination of all stomach bacterial species.
  • D: Facilitating the rapid ingestion of large prey like gazelles.

Explanation

The 'Mutualistic Adaptations' section explicitly states: 'For example, some intestinal bacteria produce vitamins, such as vitamin K, biotin, and folic acid, which are absorbed into the blood, supplementing our dietary intake.' It also mentions their role in regulating the immune system and providing a stable host environment, but vitamin production is a key direct benefit listed.