Question

A number of marine reptiles and birds have salt glands, which have a remarkable ability to concentrate salt solutions for excretion. These organs are used by these animals to remain in osmotic balance despite their hyperosmotic environment.
(Hint: You will need to look up the concentration of Na in sea water to know how much Na" the animal took in). (Group E)

a. How much water would it take to excrete, via the salt gland, a sodium load from ingesting 100 ml of sea water if the average sodium concentration of the salt glands's secretion is 600 mmoVL?

b. How much water would be needed to excrete the same sodium load if the average sodium concentration of the salt gland's secretion were only 300 mmol/L?

c. Which secretion is hyperosmotic to seawater?

d. What is necessary for salt glands to be advantageous for osmoregulation?

Answer 1

Answer:

A)100mL  B)50mL  C)The second option  D)Hypoosmotic Environment

Explanation:

The average Na concentration in the seas and oceans of the world is around 3,5% which mean that in 100 ml of sea water, there is around 3,5 grams of Na.

The weight of one mol of NaCl is 58,44 grams. For 3,5 grams of NaCl, we get 3,5/58,44 = 0,060 mol of NaCl which is 0,060x1000 = 60 mmol/100ml. According to this and the information given in the question about the secretion of the salt glands', if the average sodium concentration is 600mmol/L, we have 60*10 = 600mmol/L so it would take 100 mililiters of water to excrete.

If the average Na concentration of the salt gland's secretion were 300 mmol/L, only 50 mililiters of water would be needed to excrete the same sodium load.

The second option of secretion is hyperosmotic to seawater because the concentration is higher.

Osmoregulation is the process of balancing the amount of water and salt between the body of the organism and its surrounding environment. For salt glands to be advantageous for osmoregulation, they need to be in a hypoosmotic environment.

I hope this answer helps.