Question 1

Which of the following statements best explains why hemoglobin is more effective than myoglobin at delivering oxygen to tissues during exercise?

Accepted Answer

Hemoglobin exhibits cooperative binding, allowing it to release more O$$_2 as $$tissue PO$$_2$$ drops, while myoglobin does not.

Question 2

A patient is exposed to carbon monoxide (CO). Which of the following best describes the effect of CO on oxygen transport in the blood?

Accepted Answer

CO binds to hemoglobin with much higher affinity than O$$_2$$, forming carboxyhemoglobin and preventing O$$_2$$ transport.

Question 3

During intense exercise, the pH of blood decreases due to increased CO$$_2$$ production. According to the Bohr effect, what happens to the oxygen-hemoglobin dissociation curve?

Accepted Answer

The curve shifts to the right, indicating decreased affinity of hemoglobin for O$$_2.$$

Question 4

Which of the following adaptations allows diving mammals, such as Weddell seals, to remain underwater for extended periods?

Accepted Answer

High concentrations of myoglobin in muscles to store O$$_2.$$

Question 5

Which of the following best describes the function of aquaporins in kidney collecting duct cells?

Accepted Answer

They facilitate rapid water reabsorption by allowing water to move through the cell membrane.

Question 6

A marine bony fish is placed in freshwater. Which of the following physiological challenges will it most likely face?

Accepted Answer

It will gain water by osmosis and lose salts by diffusion.

Question 7

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

Accepted Answer

Ammonia is highly toxic and requires large amounts of water for excretion, while uric acid is less toxic and excreted as a semi-solid paste.

Question 8

Which of the following best explains why the loop of Henle is longer in mammals that live in arid environments?

Accepted Answer

A longer loop of Henle allows for greater reabsorption of water, producing more concentrated urine.

Question 9

Which of the following equations correctly represents the conversion of CO$$_2 to $$bicarbonate in red blood cells?

Accepted Answer

$$\mathrm{CO_2$ + H_2O \rightarrow H_2CO_3 \rightarrow $$HCO_3$$^- + H^+}$$

Question 10

Which of the following best describes the role of the renin-angiotensin-aldosterone system (RAAS) in regulating blood pressure?

Accepted Answer

RAAS increases blood pressure by promoting reabsorption of Na$$^+$$ and water in the kidneys.

Question 11

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

Accepted Answer

Increased insertion of aquaporin channels in the collecting duct, leading to increased water reabsorption.

Question 12

Which of the following best explains why ice fish can survive in frigid Antarctic waters without hemoglobin?

Accepted Answer

O$$_2$$ solubility is higher in cold water, and ice fish have large hearts and extensive capillary networks to compensate.

Question 13

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

Accepted Answer

It creates a gradient of increasing osmolarity in the medulla, allowing for water reabsorption from the collecting duct.

Question 14

Which of the following is a function of the transport epithelia in the nasal glands of marine birds?

Accepted Answer

Removal of excess sodium chloride from the blood.

Question 15

Which of the following best describes the process of osmosis?

Accepted Answer

The movement of water across a selectively permeable membrane from a region of low solute concentration to high solute concentration.

Question 16

Which of the following is a correct sequence of events in the excretory process of a mammalian nephron?

Accepted Answer

Filtration → Reabsorption → Secretion → Excretion

Question 17

Which of the following best explains why 2,3-BPG (bisphosphoglycerate) decreases the affinity of hemoglobin for oxygen?

Accepted Answer

2,3-BPG binds to deoxyhemoglobin, stabilizing the T state and promoting O$$_2$$ release.

Question 18

A freshwater fish is transferred to a saltwater environment. Which of the following physiological responses is most likely to occur?

Accepted Answer

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

Question 19

Which of the following best describes the effect of atrial natriuretic peptide (ANP) on kidney function?

Accepted Answer

ANP opposes the action of RAAS and ADH, promoting excretion of Na$$^+$$ and water to decrease blood volume.

lecture 4 Respiration and Excretion: Mechanisms and Adaptations in Animals

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