Excretory System

1. What is the direct effect of Aldosterone on the nephron?

It converts Angiotensin I into the active Angiotensin II.
It increases the glomerular filtration rate (GFR) by dilating the efferent arteriole.
It upregulates the production of Na+ pumps to increase sodium reabsorption.
It inhibits the release of ADH from the posterior pituitary.

2. In the Renin-Angiotensin-Aldosterone System (RAAS), which enzyme is responsible for converting Angiotensin I into the potent vasoconstrictor Angiotensin II?

Aldosterone synthase
Angiotensin converting enzyme (ACE)
Renin
Antidiuretic hormone (ADH)

3. Which of the following describes a ‘symporter’?

A protein that uses ATP to pump a single ion against its concentration gradient.
A cotransporter that moves two substances in opposite directions.
A channel that allows ions to flow down their electrochemical gradient without energy.
A cotransporter that moves two different substances in the same direction across the membrane.

4. In a hyperosmotic environment, how does the solute concentration of the environment compare to the internal osmolarity of an animal?

The environment has a higher solute concentration than the animal.
The environment has a lower solute concentration than the animal.
The solute concentrations of the environment and the animal are equal.
The environment contains no solutes, while the animal contains many.

5. Which structure contains the ‘Macula densa’ cells that monitor filtrate flow and composition?

Proximal convoluted tubule
Collecting duct
Loop of Henle
Distal convoluted tubule

6. Which of the following best describes the function of juxtamedullary nephrons compared to cortical nephrons?

They possess long loops of Henle that extend deep into the medulla to establish osmotic gradients.
Their renal corpuscles are located in the outer portion of the renal cortex.
They lack a vasa recta, relying instead on peritubular capillaries for reabsorption.
They are the most abundant type of nephron in the human kidney, making up 85% of the total.

7. Urine leaves the kidney through which structure to reach the bladder?

Renal vein
Urethra
Major calyx
Ureter

8. According to the principles of diffusion, in which direction do solutes move across a selectively permeable membrane?

Solutes move in the same direction as the net flow of water.
Solutes only move if ATP is present to provide energy.
From areas of higher concentration to areas of lower concentration.
From areas of lower concentration to areas of higher concentration.

9. Which of the following is an effect of Angiotensin II?

Increased excretion of Na+ in the urine
Inhibition of the adrenal cortex
Decreased heart rate
Systemic vasoconstriction

10. How does Antidiuretic Hormone (ADH) increase the reabsorption of water in the collecting duct?

By triggering the insertion of aquaporins into the apical membrane.
By decreasing the osmolarity of the interstitial fluid in the renal medulla.
By constricting the afferent arteriole to reduce filtrate volume.
By actively pumping Na+ out of the filtrate to create a stronger gradient.

11. What is the primary role of the proximal convoluted tubule (PCT)?

Massive, unregulated reabsorption of water, ions, and nutrients.
Filtering blood based on the size of the solute.
Final adjustment of urine concentration via ADH.
Creating the high osmotic gradient in the renal medulla.

12. Which mechanism of transport moves ions against an electrochemical gradient using energy?

Facilitated diffusion via a channel protein.
Direct diffusion through the lipid bilayer.
Osmosis across a semi-permeable membrane.
Active transport via a pump.

13. In the process of secondary active transport, such as a symporter, what provides the energy to move a solute against its gradient?

The physical pressure of blood in the capillaries.
The direct hydrolysis of ATP at the symporter site.
The electrochemical gradient of a different ion, like Na+.
The kinetic energy of water molecules moving via osmosis.

14. Which nitrogenous waste product is the most toxic and requires the greatest volume of water for safe excretion?

Uric acid
Ammonia (NH3)
Amino acids
Urea

15. Which of these is NOT a function of the renal system?

Removal of metabolic nitrogenous wastes from the blood.
Digestion of complex proteins into amino acids.
Maintenance of osmotic balance in the body fluids.
Regulation of blood pressure via the RAAS pathway.

16. Which of the following nitrogenous waste products is the least toxic and can be excreted with very little water loss?

Urea
Uric acid
Amino groups (−NH2)
Ammonia (NH3)

17. Which of the following describes the thick ascending limb of the loop of Henle?

Permeable to water and passively allows Na+ to enter.
Impermeable to water and actively transports Na+ and Cl− out.
The site where ADH inserts aquaporins.
The location where the majority of glucose is reabsorbed.

18. The filtration membrane in the renal corpuscle consists of three layers. Which of the following is the correct order of these layers from the blood side to the filtrate side?

Parietal layer, basement membrane, visceral layer.
Podocytes, basement membrane, fenestrated endothelium.
Fenestrated endothelium, capillary basement membrane, epithelial cells (podocytes).
Macula densa, granular cells, mesangial cells.

19. Why is the loop of Henle considered a ‘countercurrent’ system?

Because it causes water and electrolytes to move in opposite directions.
Because it pumps Na+ and Cl− in opposite directions across the tubule wall.
Because the blood in the vasa recta flows in the same direction as the filtrate in the tubule.
Because fluid flows in opposite directions in the two parallel limbs of the loop.

20. In insect excretion, what is the primary mechanism by which water enters the Malpighian tubules?

Water is directly pumped into the tubules by ATP-dependent water pumps.
Water follows an osmotic gradient created by the active transport of ions.
Water enters through non-selective pores driven by blood pressure.
Water is actively transported via symporters along with glucose.

21. What happens to the volume of the filtrate as it travels through the proximal convoluted tubule?

It increases as urea and other wastes are actively secreted.
It remains constant because only solutes are reabsorbed at this stage.
It decreases significantly due to the reabsorption of water and solutes.
It decreases only when ADH levels are high.

22. Which region of the adrenal gland is responsible for secreting Aldosterone?

Zona glomerulosa
Zona reticularis
Zona fasciculata
Adrenal medulla

23. In the Formation of the filtrate, which statement is true regarding selectivity?

Filtrate formation is not particularly selective, whereas reabsorption is highly selective.
Both filtrate formation and reabsorption are equally non-selective processes.
Reabsorption is primarily regulated by physical pressure rather than biological signals.
Filtration selectively chooses which toxins to remove from the blood.

24. Which part of the insect excretory system is responsible for the highly selective reabsorption of electrolytes and water under osmotic stress?

Midgut
Hindgut
Hemolymph
Malpighian tubules

25. Which region of the kidney contains the renal corpuscles and proximal convoluted tubules?

Renal Pelvis
Renal Papilla
Inner Medulla
Cortex

26. What is the net effect of Angiotensin II on the cardiovascular system and kidneys?

Systemic vasoconstriction and increased aldosterone release.
Increased excretion of sodium in the distal tubule.
Decreased heart rate to compensate for high blood pressure.
Vasodilation and inhibition of ADH secretion.

27. True or False: The human kidney can produce urine that is more concentrated than the blood plasma.

True
False

28. Which structure in the human urinary system is responsible for carrying urine from the kidneys to the bladder?

Renal vein
Renal papilla
Ureter
Urethra

29. In the countercurrent multiplier system, what is the role of urea in the inner medulla?

It is actively transported into the descending limb to increase filtrate pressure.
It is the main solute used by the vasa recta to transport oxygen.
It contributes to the high osmolarity of the interstitial fluid to help concentrate urine.
It acts as a buffer to maintain the pH of the medullary blood supply.

30. In a hyposmotic environment, an animal faces which primary osmoregulatory challenge?

Losing water to the environment and gaining too many salts.
Gaining too much water and losing essential electrolytes.
Inability to produce metabolic water through cellular respiration.
Maintaining a body temperature higher than the surrounding water.

31. What is the primary difference between cortical nephrons and juxtamedullary nephrons?

Cortical nephrons are located entirely within the renal medulla.
Juxtamedullary nephrons have much longer loops of Henle that extend deep into the medulla.
Cortical nephrons are the only ones that possess a renal corpuscle.
Juxtamedullary nephrons lack a proximal convoluted tubule

32. What is the result of the ‘non-selective’ formation of filtrate in insects?

The filtrate is instantly converted into uric acid crystals.
Large proteins are effectively pumped into the tubules to be broken down.
Only nitrogenous wastes are allowed to enter the Malpighian tubules.
Most small molecules in the hemolymph, including nutrients and waste, enter the tubules.

33. Which statement regarding the vasa recta is correct?

It surrounds the proximal convoluted tubules of cortical nephrons.
It consists of long, straight capillaries that parallel the loop of Henle in juxtamedullary nephrons.
It is the site where primary filtration of the blood occurs.
It carries blood directly from the renal artery to the afferent arteriole.

34. Based on the filtration equation, how does an increase in the osmotic pressure caused by proteins in the capillary (π capillary) affect the net filtration rate?

It decreases the filtration rate by opposing the outward movement of fluid.
It decreases physical pressure (P capillary) within the glomerulus.
It increases the filtration rate by drawing more fluid into Bowman's capsule.
It has no effect because filtration is only driven by physical pressure (P).

35. How do terrestrial animals like tortoises gain ‘metabolic water’?

Through the active transport of water vapor in the lungs.
By absorbing humidity through specialized pores in their shell.
As a byproduct of cellular respiration during the breakdown of food.
By converting NH3 into urea, which releases water molecules.

36. What happens to the osmolarity of the filtrate as it travels through the ascending limb of the loop of Henle?

It decreases because solutes are removed while the limb remains impermeable to water.
It increases because water is reabsorbed into the hyperosmotic medulla.
It increases due to the active secretion of urea into the tubule lumen.
It remains isotonic to the blood plasma throughout the entire limb.

37. Which component of the filtration membrane acts as a coarse filter to exclude blood cells and large proteins?

Bowman's capsule epithelium
The afferent arteriole
Glomerular capillary pores (fenestrations)
The loop of Henle

38. Which arteriole has a smaller diameter, creating the high pressure needed for glomerular filtration?

Peritubular capillary
Afferent arteriole
Renal artery
Efferent arteriole

39. Which of the following is a key difference between passive transport and active transport in the nephron?

Passive transport only involves the movement of water, while active transport only involves ions.
Active transport requires energy in the form of ATP to move molecules against a gradient.
Passive transport requires specialized membrane proteins called 'pumps'.
Active transport always moves substances from the interstitium into the tubule (secretion).

40. In the human nephron, what is the osmolarity of the filtrate when it reaches the bottom of the loop of Henle in the inner medulla?

1200 mOsm/L
100 mOsm/L
600 mOsm/L
300 mOsm/L

41. What is the role of the ‘Basolateral membrane’ in the reabsorption process within the nephron or hindgut?

It is the layer of cells that produces the mucus to protect the kidney.
It acts as a physical gate that opens only when blood pressure is too high.
It contains the transporters, like Na+/K+ -ATPase, that move solutes from the cell into the interstitial fluid/blood.
It faces the lumen and is the first barrier for solutes entering the cell from the filtrate.

42. What are the two primary ways electrolytes are lost from the body of a tortoise?

Metabolic water production and eating
Breathing and evaporation
Urine and feces
Drinking and active transport

43. Which segment of the loop of Henle is permeable to water but nearly impermeable to solutes?

Thin ascending limb
Thick ascending limb
Descending limb
Proximal convoluted tubule

44. In the context of the renal corpuscle, which variable represents the osmotic pressure exerted specifically by proteins within the blood plasma?

π interstitial
π capillary
P capillary
P interstitial

45. What is the functional significance of the ‘filtrate’ produced in the renal corpuscle compared to the ‘final urine’?

The filtrate is much more concentrated than the final urine.
The filtrate is non-selective and contains many useful nutrients that must be reabsorbed later.
The filtrate contains large proteins and blood cells that are removed in the proximal tubule.
The filtrate is produced by active transport, while urine is formed by passive diffusion.

46. What is the primary function of the vasa recta in the kidney?

To store urine before it enters the collecting duct.
To filter blood into Bowman's capsule.
To maintain the medullary osmotic gradient through countercurrent exchange.
To actively pump NaCl into the inner medulla.

47. Which component of the juxtaglomerular apparatus (JGA) acts specifically as a baroreceptor to sense changes in blood pressure and secrete renin?

Macula densa cells
Mesangial cells
Granular cells
Podocytes

48. Where is the Macula Densa located?

Inside the lumen of the glomerular capillaries.
The beginning of the distal convoluted tubule where it contacts the renal corpuscle.
The tip of the medullary pyramids (renal papilla).
The inner lining of the Bowman's capsule.

49. How does Antidiuretic Hormone (ADH) increase water reabsorption in the collecting duct?

It constricts the afferent arteriole to reduce filtration.
It increases the active transport of Na+ out of the filtrate.
It triggers the insertion of aquaporins into the apical membrane.
It decreases the osmolarity of the medullary interstitial fluid.

50. An animal excreting nitrogenous waste as uric acid is likely adapting to which specific environmental pressure?

The need for rapid metabolic turnover
Extreme water scarcity
High availability of fresh water
Living in a strictly marine environment

51. Which structure connects the distal convoluted tubule to the collecting duct?

Loop of Henle
Afferent arteriole
Connecting tubule
Renal papilla

52. Which enzyme is released by the juxtaglomerular cells in response to a drop in blood pressure?

Aldosterone
Angiotensin Converting Enzyme (ACE)
Renin
Angiotensinogen

53. What is the primary mechanism by which water is reabsorbed in the descending limb of the loop of Henle?

Secondary active transport via sodium symporters
Active transport via H2O pumps
Facilitated diffusion against a concentration gradient
Passive osmosis following an osmotic gradient

54. What would be the effect of a significant decrease in the concentration of plasma proteins (e.g., due to liver failure) on glomerular filtration?

The physical hydrostatic pressure (P capillary) would double to compensate.
Filtration would stop entirely due to lack of osmotic pull.
Glomerular filtration rate would decrease.
Glomerular filtration rate would increase.