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

Q: Abnormally high activity or low activity of the parathyroid gland can cause disorders related to levels of what bone mineral? Choices: - potassium - collagen - magnesium - calcium A:
calcium

Q: Due to the __________ nature of the lipids that make up cell membranes, polar molecules (such as water) and ions cannot easily diffuse across the cell membrane. Choices: - hydrophylic - saturated - catalytic - hydrophobic A:
hydrophobic