IGCSE Biology Excretion in humans topical questions

Name each part of the urinary system described.

1. (a)The organ that excretes urea and excess water and ions.[1]
2. (b)The tube carrying urine from a kidney to the bladder.[1]
3. (c)The organ that stores urine.[1]
4. (d)The tube that carries urine out of the body.[1]

Match each excretory product to where it leaves the body.

1. (a)Carbon dioxide[1]
2. (b)Urea[1]
3. (c)Excess water and ions[1]

Define deamination and state where it happens. (Extended)

1. (a)Define deamination.[1]
2. (b)Name the organ where it occurs.[1]

Urine travels from where it is made to the outside of the body through four structures.

1. (a)Write the letters in the order urine passes through them.[2]
2. (b)Name the process happening inside structure S that produces urine.[1]
3. (c)State the function of structure R.[1]
4. (d)State one way the body prevents the loss of structure S from stopping urine release entirely.[1]

A student labels a longitudinal section through a kidney.

1. (a)Name the outer and inner regions she should label. (Extended)[2]
2. (b)Name the microscopic units that make up these regions and state their function.[2]

Outline how the nephron produces urine. (Extended)

1. (a)Name the structure where blood is filtered and list what enters the filtrate.[2]
2. (b)State what is reabsorbed and in what quantities.[2]
3. (c)List the contents of the urine formed.[1]

A person with untreated kidney failure becomes increasingly ill.

1. (a)Explain why urea concentration rises in their blood. (Extended)[2]
2. (b)Explain why this is dangerous.[1]
3. (c)Describe how dialysis or a transplant solves the problem.[2]

A person’s daily water balance is shown in the table.

1. (a)Calculate the total water intake per day.[1]
2. (b)Calculate the total water loss per day.[1]
3. (c)Explain what the two totals show about the body’s water balance.[2]
4. (d)On a hot day, urine volume falls to 800 cm³ while sweat rises. Calculate the new urine figure as a percentage of the original urine output, and explain why the change happens.[2]

Two urine samples are tested. Sample X, from an athlete after a marathon, contains urea at 1.5 g per 100 cm³. Sample Y, from the same athlete at rest, contains urea at 0.15 g per 100 cm³. A third sample, Z from a hospital patient, contains both glucose and protein.

1. (a)Calculate how many times more concentrated the urea is in sample X than in sample Y.[1]
2. (b)Explain why the urea concentration is higher after the marathon.[2]
3. (c)Name the structure in the nephron whose damage would let protein appear in urine, and explain why.[2]
4. (d)Name the process that should have removed the glucose from the filtrate.[1]

In a healthy adult, the two kidneys filter about 125 cm³ of fluid per minute, but only about 1.5 cm³ per minute leaves as urine.

1. (a)Calculate the percentage of the filtrate that is reabsorbed. Show your working and give your answer to one decimal place.[2]
2. (b)Name the substance that makes up most of the reabsorbed volume.[1]
3. (c)Use the numbers to explain the difference between filtration and reabsorption.[2]
4. (d)Name the process by which the water is reabsorbed.[1]

Trace a molecule of urea from an excess amino acid to the outside world. (Extended)

1. (a)Describe how the urea molecule is formed, naming the organ and process.[2]
2. (b)Describe how it travels to and through the kidney.[3]
3. (c)Name the structures between the kidney and the outside.[1]

A test on two urine samples, P and Q, gives these results: P contains water, urea and ions; Q contains water, urea, ions and glucose. (Extended)

1. (a)Identify which sample is normal and explain why.[2]
2. (b)Explain why glucose should never reach the urine of a healthy person.[3]
3. (c)Explain one reason glucose could appear in urine.[2]

A student eats a meal containing far more protein than her body needs. (Supplement)

1. (a)Define deamination and state where it happens.[3]
2. (b)Explain why the body must deal with the excess amino acids.[1]
3. (c)Describe how the liver assimilates some of the amino acids from the meal.[1]
4. (d)Explain why the urea formed must be excreted promptly.[2]

The body excretes carbon dioxide and urea by different routes.

1. (a)Name the organ that excretes carbon dioxide and the process that removes it.[2]
2. (b)Explain why urea must be excreted by the kidneys rather than the lungs.[1]
3. (c)State two other adjustments the kidneys make to the blood besides removing urea.[2]
4. (d)Name the vessel that carries blood away from a kidney.[1]