Lampreys Completely Lack Parathyroid Glands

question 79

Multiple Choice

Lampreys completely lack parathyroid glands.Suggest why these glands may be important for other vertebrates,but not for jawless fish.

• A)Because they are parasitic,lampreys get plenty of calcium from their hosts.
• B)Living in the ocean,they are surrounded by large amounts of sodium,chloride,and magnesium ions.
• C)Jawless fish employ a different system than other vertebrates to regulate blood sugar.
• D)Since they have a cartilaginous skeleton but not true bone,they have less need to regulate calcium levels.

---

Definitions:

Galactose

A simple sugar that is a component of lactose, found in milk and dairy products.

Pepsinogen

An inactive precursor of pepsin, secreted by stomach lining cells, which is activated by stomach acid into the enzyme pepsin.

Salivary Glands

Exocrine glands in the mouth that produce saliva, which begins the process of digestion and helps maintain oral hygiene.

Mesentery Proper

A fold of the peritoneum connecting the intestines to the posterior abdominal wall, providing support and containing blood vessels.