Q: Which of the following equations correctly represents osmolarity?

$$\text{Osmolarity} = \frac{\text{moles of solute}}{\text{liters of solution}}$$

Question 1

Which of the following best explains why marine bony fishes must drink seawater and excrete concentrated salt through their gills?

Accepted Answer

They are hypoosmotic to seawater and lose water by osmosis.

Question 2

A freshwater fish is placed in a tank of seawater. Predict what will happen to its cells and explain why, using the concept of osmolarity.

Accepted Answer

Water will move out of the fish's cells, causing them to shrink, because the fish is hypoosmotic to seawater.

Question 3

Which adaptation allows desert mammals to conserve water most efficiently?

Accepted Answer

Long loops of Henle in their nephrons

Question 4

What is the primary function of the transport epithelia in the nasal salt gland of marine birds?

Accepted Answer

To secrete excess sodium chloride from the blood

Question 5

Which of the following best describes the process of osmosis?

Accepted Answer

Water moves from regions of low solute concentration to high solute concentration across a selectively permeable membrane.

Question 6

Which excretory system is correctly matched with the animal group in which it is found?

Accepted Answer

Malpighian tubules – insects

Question 7

A patient is severely dehydrated. Which hormone would you expect to be elevated in their blood, and what effect would it have on the kidneys?

Accepted Answer

Antidiuretic hormone (ADH); increases water reabsorption in the collecting ducts

Question 8

Which of the following equations correctly represents osmolarity?

Accepted Answer

$$	ext{Osmolarity} = \frac{	ext{moles of solute}}{	ext{liters of solution}}$$

Question 9

Which of the following is a key difference between ammonia, urea, and uric acid as nitrogenous wastes?

Accepted Answer

Uric acid requires the least water for excretion.

Question 10

Which step in the nephron is primarily responsible for the reabsorption of water via aquaporins, and what is the result for the filtrate?

Accepted Answer

Descending limb of the loop of Henle; filtrate becomes more concentrated

Question 11

A salmon migrates from the ocean to a freshwater river to spawn. Which osmoregulatory change must occur for the salmon to survive in freshwater?

Accepted Answer

Decrease drinking of water and excrete large amounts of dilute urine

Question 12

Which of the following best describes the function of the countercurrent multiplier system in the loop of Henle?

Accepted Answer

It maintains a high salt concentration in the kidney medulla, enabling water reabsorption and hyperosmotic urine.

Question 13

Which of the following scenarios would most likely trigger the release of atrial natriuretic peptide (ANP)?

Accepted Answer

An increase in blood volume and pressure

Question 14

Which excretory adaptation allows insects to conserve water most efficiently in terrestrial environments?

Accepted Answer

Malpighian tubules

Question 15

A person with a mutation that prevents the insertion of aquaporin channels into the collecting duct cell membranes would most likely experience which of the following?

Accepted Answer

Production of large volumes of dilute urine

Question 16

Which of the following best explains how anhydrobiosis enables tardigrades to survive extreme dehydration?

Accepted Answer

They lose almost all body water and enter a dormant state until water is available again.

Question 17

Which of the following is the correct sequence of steps in urine formation in vertebrate kidneys?

Accepted Answer

Filtration → Reabsorption → Secretion → Excretion

Question 18

Which of the following would most likely occur if the renin-angiotensin-aldosterone system (RAAS) is activated?

Accepted Answer

Increased sodium and water reabsorption, leading to increased blood pressure

Question 19

Which of the following best describes the role of osmoreceptors in the hypothalamus?

Accepted Answer

They monitor blood osmolarity and regulate ADH release.

Osmoregulation and Excretion in Animals: Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards