Q: What type of structure between the esophagus and the stomach normally opens only when a bolus arrives? A:
OPTIONS:
- larynx
- intestine
- gland
- sphincter

Answer: sphincter

Q: What did rockets help launch into space during their beginning? A:
OPTIONS:
- rovers
- shuttles
- sensors
- satellites

Answer: satellites

Q: Metabolism is controlled by regulation of what? A:
OPTIONS:
- sequence activity
- nucleus activity
- cell activity
- enzyme activity

Answer:
enzyme activity