Question 1

Which of the following best describes the process illustrated in the first image, where water moves across a selectively permeable membrane from the hypoosmotic side to the hyperosmotic side?

Accepted Answer

Osmosis

Question 2

A marine jellyfish is shown in the second image. Which osmoregulatory strategy does it most likely use?

Accepted Answer

Osmoconformation, matching body fluid osmolarity to seawater

Question 3

Based on the third image, which of the following is a key adaptation of freshwater fish for osmoregulation?

Accepted Answer

Excreting large amounts of dilute urine to remove excess water

Question 4

The fourth image shows a saltwater fish. Which of the following statements best explains how it maintains osmotic balance?

Accepted Answer

It drinks seawater and actively excretes excess salts through its gills.

Question 5

Anhydrobiosis, as depicted in the fifth and sixth images, is an adaptation that allows some animals to:

Accepted Answer

Enter a dormant state and survive extreme dehydration by losing almost all body water

Question 6

Which of the following best describes the trade-off between ammonia, urea, and uric acid as nitrogenous wastes, as shown in the eighth and ninth images?

Accepted Answer

Urea is less toxic than ammonia and requires less water for excretion, but is more energetically costly to produce.

Question 7

Which step in the excretory process, as shown in the tenth image, is responsible for selectively reclaiming valuable solutes and water from the filtrate?

Accepted Answer

Reabsorption

Question 8

In the nephron, as illustrated in the eleventh and twelfth images, which segment is primarily responsible for the reabsorption of water due to its permeability to water but not to salts?

Accepted Answer

Descending limb of the loop of Henle

Question 9

Which hormone, as shown in the thirteenth image, increases the permeability of the collecting duct to water, thereby concentrating urine?

Accepted Answer

Antidiuretic hormone (ADH)

Question 10

A patient is suffering from low blood pressure. According to the fourteenth image, which hormonal system is activated to restore blood pressure, and what is one of its effects?

Accepted Answer

RAAS (renin-angiotensin-aldosterone system); causes arteriole constriction and increased Na$$^+$$ reabsorption

Question 11

Which of the following equations best represents the osmotic movement of water across a membrane, as shown in the first image?

Accepted Answer

$$J_w = L_p (\Delta P - \sigma \Delta \pi)$$

Question 12

A freshwater fish is transferred to a tank with water of higher osmolarity than its body fluids. Predict what will happen to the fish if it cannot adjust its osmoregulatory mechanisms.

Accepted Answer

It will lose water by osmosis and risk dehydration.

Question 13

Which of the following is a correct sequence of filtrate flow through the nephron?

Accepted Answer

Bowman's capsule → proximal tubule → loop of Henle → distal tubule → collecting duct

Question 14

Which of the following adaptations would you expect to find in a desert mammal's kidney compared to a mammal living in a moist environment?

Accepted Answer

Longer loops of Henle to maximize water reabsorption

Question 15

Which of the following best explains why uric acid is the primary nitrogenous waste in birds and many reptiles?

Accepted Answer

It is non-toxic and can be excreted as a solid with minimal water loss.

Question 16

If a person is dehydrated, which of the following changes would you expect in their urine and hormone levels?

Accepted Answer

Urine becomes more concentrated; ADH levels increase

Question 17

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

Accepted Answer

Production of red blood cells

Question 18

A mutation causes the collecting duct to become impermeable to water, regardless of ADH levels. What would be the most likely consequence?

Accepted Answer

The person would produce very dilute urine, even when dehydrated.

Question 19

Which of the following best describes the role of the vasa recta in the kidney?

Accepted Answer

It maintains the osmotic gradient in the medulla by acting as a countercurrent exchanger.

Osmoregulation and Excretion in Animals

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