Question 1

Refer to the diagram showing net water flow across a selectively permeable membrane. If the solute concentration on the hyperosmotic side is doubled, what will happen to the net water flow?

Accepted Answer

Net water flow will increase toward the hyperosmotic side due to a greater osmotic gradient.

Question 2

Which equation best describes the relationship between osmotic pressure ($$\Pi$$), solute concentration ($$C$$), and temperature ($$T) in a $$solution?

Accepted Answer

$$\Pi = iRT C$$

Question 3

A marine invertebrate is placed in a tank with seawater. Its body fluids are isoosmotic with the environment. What term best describes this organism?

Accepted Answer

Osmoconformer

Question 4

Freshwater fish must actively uptake ions from their environment. Which process explains why they need to do this?

Accepted Answer

They lose ions by diffusion to the environment.

Question 5

Which adaptation allows some terrestrial animals to survive extreme dehydration by entering a dormant state?

Accepted Answer

Anhydrobiosis

Question 6

Which nitrogenous waste is most energetically expensive to produce but requires the least water for excretion?

Accepted Answer

Uric acid ($$\mathrm{C_5H_4N_4O_3})$$

Question 7

Which step in the nephron is responsible for selectively reclaiming valuable solutes and water from the filtrate?

Accepted Answer

Reabsorption

Question 8

A patient has high blood osmolarity. Which hormone will be released to increase water reabsorption in the kidneys?

Accepted Answer

Antidiuretic hormone (ADH)

Question 9

Which part of the nephron is permeable to water but not to salts, allowing for concentration of the filtrate?

Accepted Answer

Descending loop of Henle

Question 10

If a mammal consumes a diet high in protein, which nitrogenous waste will increase in production, and what is the chemical equation for its synthesis from ammonia and carbon dioxide?

Accepted Answer

Urea; $$\mathrm{2NH_3 + CO_2$ \rightarrow CO(NH_2$)_2 + H_2O}$$

Question 11

Which process in the nephron involves the active addition of wastes and toxins to the filtrate?

Accepted Answer

Secretion

Question 12

A saltwater fish is placed in freshwater. What is the most likely physiological consequence?

Accepted Answer

It will gain water by osmosis and risk cell swelling.

Question 13

Which equation best represents the osmotic movement of water across a membrane?

Accepted Answer

$$J = -P (C_1$ - C_2$)$$

Question 14

Which structure in the nephron is responsible for creating the osmolarity gradient necessary for water reabsorption?

Accepted Answer

Loop of Henle

Question 15

Which hormone system is activated when blood pressure drops, leading to increased sodium and water reabsorption?

Accepted Answer

Renin-angiotensin-aldosterone system (RAAS)

Question 16

Which of the following is a trade-off for terrestrial animals in converting ammonia to uric acid?

Accepted Answer

Lower toxicity and higher energy cost

Question 17

Which term describes an organism that can tolerate a wide range of environmental salinities?

Accepted Answer

Euryhaline

Question 18

In the collecting duct, which substance diffuses out to contribute to the high osmolarity of the inner medulla?

Accepted Answer

Urea

Question 19

Which of the following would result in the production of the most concentrated urine?

Accepted Answer

Low water intake and high salt intake

Question 20

Which of the following is NOT a function of the mammalian kidney?

Accepted Answer

Production of glucose from amino acids

Osmoregulation and Excretion in Animals

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