What is the purpose of having a water-tight covering?

Which best explains how this maneuver unblock a person's airway?

Which statement describes an endocrine function rather than an exocrine function? a. salivary glands release saliva into the mouth. b. sweat glands release sweat onto the skin c. the pineal gland releases melatonin into the blood. d. esophageal glands release mucus into the esophagus.

Describe how alleles and genes are related