IB DP Biology Topic 11: Animal physiology : 11.3 The kidney and osmoregulation HL Paper 1

Question

What is normally found in the urine of a healthy individual?

A Glucose

B Red blood cells

C Proteins

D Sodium ions

▶️Answer/Explanation

Ans: D

Normally, glucose, red blood cells, and proteins are not found in the urine of a healthy individual. Sodium ions are typically present in the urine of healthy individuals, but only in small amounts.Glucose is typically reabsorbed by the kidneys and returned to the bloodstream, so it is not normally present in the urine. Red blood cells and proteins are too large to pass through the filtration membrane of the kidneys, so they are also not normally present in the urine.

Therefore, the correct answer is D. Sodium ions.

 

Question

The graph shows the daily amount of the residue of a drug in the wastewater of a hospital.

What can be deduced from these data?

A. The drug is not fully reabsorbed by the proximal convoluted tubules.

B. The glomeruli are not permeable to the drug.

C. The collecting ducts reabsorb all of the drug.

D. The drug is catabolized by the liver

▶️Answer/Explanation

Markscheme

A

From the given data, it can be deduced that the drug is not fully reabsorbed by the proximal convoluted tubules.

The graph shows that the concentration of the drug in the wastewater decreases over time, which suggests that the drug is being excreted by the kidneys. However, if the drug were fully reabsorbed by the proximal convoluted tubules, the concentration of the drug in the urine would remain constant.

Therefore, the correct answer is A. The drug is not fully reabsorbed by the proximal convoluted tubules.

Question

The table shows solute concentrations in normal blood plasma and the fluid in one section of the nephron.

In which section of the nephron would you expect to fi nd these concentrations?

▶️Answer/Explanation

Markscheme

A

The Bowman’s capsule is the initial part of the nephron where the blood is filtered to form the glomerular filtrate. The solute concentrations in this filtrate are similar to those in blood plasma because the filtration process is non-selective and does not discriminate between small solutes and larger molecules like proteins and blood cells. Therefore, the correct answer to the question “In which section of the nephron would you expect to find these concentrations?” is the Bowman’s capsule.

Question

Which kidney adaptation would be expected in the desert kangaroo rat (Dipodomys deserti)?

A. Increased nephron density
B. Longer proximal convoluted tubule
C. Longer loop of Henle
D. Increased ADH receptors on the collecting duct

▶️Answer/Explanation

Markscheme

C

The desert kangaroo rat (Dipodomys deserti) is adapted to conserve water in a dry desert environment. One way this is achieved is by producing concentrated urine and minimizing water loss.

To produce concentrated urine, the mammalian kidney relies on the countercurrent multiplier system, which involves a long loop of Henle. Therefore, the kidney adaptation that would be expected in the desert kangaroo rat is a longer loop of Henle.

Therefore, the correct answer to the question “Which kidney adaptation would be expected in the desert kangaroo rat (Dipodomys deserti)?” is C. Longer loop of Henle.

Question

In which region of the kidney is the glomerulus found?
A. Cortex only
B. Medulla only
C. Cortex and medulla
D. Pelvis

▶️Answer/Explanation

Markscheme

A

The glomerulus is a network of capillaries that is part of the renal corpuscle, which is the initial part of the nephron where blood is filtered to form the glomerular filtrate.

The renal corpuscle is located in the cortex of the kidney. Therefore, the correct answer to the question “In which region of the kidney is the glomerulus found?” is A. Cortex only.

Question

The diagram shows a nephron from a human kidney. In what part of the nephron would most glucose be reabsorbed?

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▶️Answer/Explanation

Markscheme

A

The correct answer to the question “In what part of the nephron would most glucose be reabsorbed?” is A. Proximal convoluted tubule.

The proximal convoluted tubule is the first section of the renal tubule and is responsible for the reabsorption of the majority of glucose, amino acids, bicarbonate, and other solutes from the glomerular filtrate. The glucose is reabsorbed into the bloodstream by active transport mechanisms that utilize carrier proteins located on the apical and basolateral membranes of the tubule cells.

Therefore, the correct answer to the question is A. Proximal convoluted tubule.

Question

In the diagram of the nephron below, what structures are indicated by the letters Y and Z?

▶️Answer/Explanation

Markscheme

C

Y is Bowman’s capsule,-Bowman’s capsule is located at the beginning of the nephron in the kidney and is located in the cortex of the kidney. the cup-shaped structure at the beginning of the nephron in the kidney. It filters blood as it enters the nephron and is responsible for the first step in the process of urine formation.

Z is The distal convoluted tubule (DCT) is part of the nephron in the kidney that is responsible for the reabsorption of sodium, chloride, and calcium ions from the glomerular filtrate, as well as the secretion of hydrogen and potassium ions into the filtrate. It is located in the cortex of the kidney and plays a crucial role in regulating the pH and electrolyte balance of the body.The distal convoluted tubule (DCT) is located in the cortex of the kidney and is situated between the loop of Henle and the collecting duct system.

So the correct answer is C

Question

A person with failing kidneys is often treated with dialysis several times a week. This is done either by passing blood through a dialysis machine or by using the peritoneum, the lining of the abdomen, as shown in the diagram.

Dialysis fluid is similar to normal blood plasma. What would be in solution in the dialysis fluid?
A. Sugar, salts and urea

B. Salts and urea only

C. Sugar only

D. Sugar and salts only

▶️Answer/Explanation

Ans:D

The dialysis fluid is designed to mimic the composition of normal blood plasma as closely as possible. Blood plasma contains various substances including sugar, salts, and urea. During dialysis, the patient’s blood is passed through a semipermeable membrane that allows small molecules like urea, sugar, and salts to pass through while larger molecules like proteins and blood cells are retained. The dialysis fluid is designed to contain the same concentration of sugar, salts, and other substances as normal blood plasma, so that these substances can be removed from the patient’s blood and replaced with fresh ones. Therefore, the correct answer is A.

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