Final answer:
Reptilian nephrons lack a Loop of Henle, which is essential for concentrating urine more than their blood, as seen in mammals. The absence of this structure limits their ability to create a high osmotic gradient and thus produce highly concentrated urine.
Step-by-step explanation:
The nephrons in reptiles lack a Loop of Henle, which is crucial for concentrating urine. In mammals, the Loop of Henle allows for the production of urine that is more concentrated than their blood by reclaiming water and solutes from the urine. This structure extends into the medulla of the mammalian kidney, creating an osmotic gradient that facilitates water reabsorption from the collecting duct. Reptilian nephrons, by contrast, are not capable of creating such a high osmotic gradient due to the absence of an extensive Loop of Henle. As a result, reptiles cannot produce urine that is more concentrated than their blood, which is reflected in the physiology and adaptability of their renal system to different environmental conditions.
Furthermore, answering the question on which statement about the nephron is false, option a: 'The collecting duct empties into the distal convoluted tubule' is incorrect. The correct sequence is that the Loop of Henle empties into the distal convoluted tubule, and the collecting duct collects urine from multiple nephrons and transports it into the renal pelvis.