Q1. Humans excrete their excess nitrogenous wastes as
Correct Answer: (d)
Humans are ureotelic organisms, meaning they convert toxic ammonia into urea in the liver. Urea is less toxic and can be safely transported in the blood and excreted by the kidneys.
Q2. A shark’s blood is isotonic to the surrounding seawater because of the reabsorption of ____ in its blood.
Correct Answer: (c)
Sharks retain high concentrations of urea in their blood. This raises the osmolarity of their body fluids, making them isotonic with seawater and preventing excessive water loss by osmosis.
Q3. An osmoregulator would maintain its internal fluids at a concentration that is ____ relative to its surroundings.
Correct Answer: (d)
Osmoregulators actively control their internal osmotic concentration and may maintain body fluids that are hypertonic, hypotonic, or isotonic relative to the external environment, depending on ecological conditions.
Q4. Diuretics are drugs that can be used to treat high blood pressure by increasing urinary output. Possible mechanisms of action in the kidney include
Correct Answer: (b)
Many diuretics work by inhibiting NaCl reabsorption in the loop of Henle or proximal tubule. Reduced salt reabsorption decreases water reabsorption, leading to increased urine output and lowered blood pressure.
Q5. Suppose that your research mentor has decided to do a project on the filtering capabilities of Malpighian tubules. Which of the following creatures will you be spending your summer studying?
Correct Answer: (a)
Malpighian tubules are the primary excretory structures found in insects. Ants, being insects, possess Malpighian tubules, whereas birds, mammals, and earthworms use different excretory mechanisms.
Q6. An important function of the excretory system is to eliminate excess nitrogen produced by metabolic processes. Which of the following organisms is most efficient at packaging nitrogen for excretion?
Correct Answer: (c)
Iguanas excrete nitrogen primarily as uric acid, which is relatively non-toxic and requires very little water for elimination. This makes uric acid the most efficient form of nitrogen packaging among the options given.
Q7. Which of the following is NOT an ion homeostatically maintained in vertebrates?
Correct Answer: (d)
Vertebrates tightly regulate essential ions such as sodium (Na⁺), chloride (Cl⁻), and calcium (Ca²⁺) because they are critical for nerve conduction, muscle contraction, and cellular functions. Fluoride (Fl⁻) is not an essential ion that is homeostatically regulated by vertebrate excretory systems.
Q8. In comparing invertebrate and vertebrate excretory systems, you conclude that
Correct Answer: (d)
Vertebrate excretory systems involve filtration of blood followed by selective reabsorption of water and ions. Many invertebrate systems rely primarily on secretion rather than filtration, making option (d) correct.
Q9. Which of the following is a function of the kidneys?
Correct Answer: (d)
Kidneys perform multiple vital roles including removal of metabolic wastes, regulation of water balance, and maintenance of electrolyte (salt) levels. Therefore, all listed functions are correct.
Q10. You and your study partner want to draw the pathway that controls the reabsorption of sodium ions when blood pressure falls. Which of the following is the correct sequence of events? 1. Aldosterone is released. 2. Kidney tubules reabsorb Na+. 3. Renin is released. 4. Juxtaglomerular apparatus recognizes a drop in blood pressure. 5. Angiotensin II is produced.
Correct Answer: (c)
A drop in blood pressure is detected by the juxtaglomerular apparatus (4), which releases renin (3). Renin leads to the production of angiotensin II (5), which stimulates aldosterone release (1). Aldosterone then increases Na⁺ reabsorption in kidney tubules (2).
Q11. A viral infection that specifically interferes with the reabsorption of ions from the glomerular filtrate would attack cells located in the
Correct Answer: (c)
Reabsorption of ions from the filtrate occurs mainly along the renal tubules, particularly the proximal convoluted tubule, loop of Henle, and distal convoluted tubule.
Q12. You are studying renal function in different species of mammals found in very different environments. The desert species would be expected to have
Correct Answer: (b)
Desert mammals must conserve water efficiently. Longer loops of Henle create a stronger osmotic gradient in the kidney medulla, allowing greater water reabsorption and the production of highly concentrated urine.
Q13. Caffeine inhibits the secretion of ADH. Prior to an exam, you have a large coffee. During the exam, you can expect
Correct Answer: (b)
ADH normally increases water reabsorption in the collecting duct. By inhibiting ADH, caffeine reduces water permeability of the collecting duct, resulting in less water reabsorption and increased urine production.
Continue in App
For the best quiz experience and detailed performance analytics, download the Master Biology App.