1. What are the two main resources the human gut provides that allow bacteria to thrive?
- A. Oxygen and water
- B. Food and physical space
- C. Light and carbon dioxide
- D. Acidity and enzymes
2. A scientist observes that a particular bacterial community inside a host is shrinking. Based on the provided information, what is a likely cause?
- A. The host started consuming a more nutrient-rich diet.
- B. The host's environment became warmer and more stable.
- C. The host's diet changed to provide fewer consumable nutrients.
- D. The host is providing a larger physical space for the bacteria.
3. In the relationship between a human and the bacteria in their gut, what term best describes the role of the human body?
- A. Predator
- B. Competitor
- C. Host
- D. Parasite
4. Based on the description of the gut environment, what general conditions are essential for a large community of bacteria to survive?
- A. A fluctuating temperature and a sporadic food supply.
- B. Complete darkness and a high-pressure environment.
- C. A sterile environment free from all other living organisms.
- D. A protected space and a consistent source of nutrients.
5. Which statement best describes how the human gut supports its bacterial community?
- A. It provides a safe habitat and a reliable food source.
- B. It attacks the bacteria with acids to make them stronger.
- C. It forces the bacteria to compete with each other for extremely scarce resources.
- D. It absorbs all nutrients before they can reach the bacteria.
6. How does the number of microbial cells in the human microbiome compare to the number of human cells in the body?
- A. The number of microbial cells is significantly smaller than the number of human cells.
- B. The number of microbial cells is roughly equal to the number of human cells.
- C. The microbial cells often outnumber the human cells by a large margin.
- D. A healthy body has no microbial cells, only human cells.
7. Based on the provided information, what is a key characteristic of the bacteria that are prevalent in the human microbiome?
- A. They are multicellular organisms.
- B. They are single-celled organisms.
- C. They are always larger than human cells.
- D. They exist only in the digestive tract.
8. A scientist is studying a healthy human's internal environment. What would be the most logical expectation regarding microorganisms?
- A. To find a sterile environment with no microorganisms present.
- B. To discover a vast and dense population dominated by bacteria.
- C. To find that human cells make up over 99% of all cells present.
- D. To observe that viruses are the most numerous type of organism by far.
9. The existence of a 100-trillion-organism microbiome directly challenges which of the following ideas?
- A. The theory of evolution.
- B. The germ theory of disease.
- C. The idea that the human body is a sterile entity.
- D. The principle that cells are the basic unit of life.
10. What is the best definition for the term "human microbiome"?
- A. The specific set of genes contained within human cells.
- B. A type of disease caused by an overgrowth of harmful bacteria.
- C. The collective community of all microorganisms living in and on the human body.
- D. The system in the body that fights off microbial infections.