Question 1

Which of the following best explains why marine bony fishes must drink large amounts of seawater?

Accepted Answer

They are hypoosmotic to their environment and lose water by osmosis.

Question 2

Which nitrogenous waste product is most energetically expensive to produce but allows for the greatest conservation of water?

Accepted Answer

Uric acid

Question 3

A freshwater fish is transferred to a saltwater environment. Which physiological change is most likely to occur?

Accepted Answer

It will lose water by osmosis and must drink seawater to compensate.

Question 4

Which of the following correctly matches the excretory structure with the organism in which it is found?

Accepted Answer

Malpighian tubules – insect

Question 5

Which process in the nephron is responsible for reclaiming valuable solutes from the filtrate?

Accepted Answer

Reabsorption

Question 6

What is the primary function of the descending limb of the Loop of Henle?

Accepted Answer

Reabsorption of water through aquaporin channels

Question 7

Which hormone increases the permeability of the collecting duct to water, thereby reducing urine volume?

Accepted Answer

Antidiuretic hormone (ADH)

Question 8

A patient with diabetes insipidus produces large volumes of dilute urine. Which of the following best explains this symptom?

Accepted Answer

Lack of ADH or nonfunctional aquaporin channels

Question 9

Which of the following equations correctly represents the deamination of an amino acid, a process that produces ammonia?

Accepted Answer

$$\mathrm{R-CH(NH_2$)-COOH + H_2O \rightarrow R-CO-COOH + NH_3$}$$

Question 10

Which adaptation is most important for desert mammals to conserve water?

Accepted Answer

Long Loop of Henle

Question 11

Which of the following best describes the role of aldosterone in the kidney?

Accepted Answer

It increases sodium reabsorption in the distal tubule, raising blood pressure.

Question 12

Which of the following is a correct sequence of events in the renin-angiotensin-aldosterone system (RAAS) in response to low blood pressure?

Accepted Answer

Renin converts angiotensinogen to angiotensin I, which is then converted to angiotensin II, stimulating aldosterone release.

Question 13

Which of the following best explains why birds excrete uric acid instead of urea or ammonia?

Accepted Answer

Uric acid is less toxic and can be excreted with minimal water loss.

Question 14

A marine bird uses specialized nasal glands to excrete excess salt. What type of tissue is primarily responsible for this function?

Accepted Answer

Transport epithelium

Question 15

Which of the following would most likely occur if a mutation caused the loss of aquaporin channels in the collecting duct?

Accepted Answer

Decreased water reabsorption and large volumes of dilute urine

Question 16

Which of the following best describes the difference between osmoconformers and osmoregulators?

Accepted Answer

Osmoconformers match their internal osmolarity to their environment, while osmoregulators expend energy to maintain a constant internal environment.

Question 17

Which of the following is a direct effect of ADH (antidiuretic hormone) on the nephron?

Accepted Answer

Increases the number of aquaporin channels in the collecting duct

Question 18

Which of the following best explains why untreated diabetes mellitus can lead to increased urination and dehydration?

Accepted Answer

Glucose in the filtrate is not reabsorbed, increasing osmotic pressure and preventing water reabsorption.

Question 19

Which of the following is a correct description of the function of metanephridia in earthworms?

Accepted Answer

They collect coelomic fluid and produce dilute urine for excretion.

LECTURE 20: Excretory System and Osmoregulation in Animals

Study Guide - Practice Questions