Excretion in Humans
Each subtopic includes About section, revision page link, 10 preview questions, and practice CTAs.
Structure and function of kidneys
SubtopicStructure and function of kidneys under Excretion in Humans for Grade 12 IGCSE.
Preview questions (no answers)
- 1.
Which of the following describes the shape of a human kidney?
A.Sphere
B.Bean-shaped
C.Tube-shaped
D.Flat disk
- 2.
In which part of the kidney is the renal pelvis located?
A.The outermost layer
B.The innermost central region
C.Wrapped around the cortex
D.Inside the glomerulus
- 3.
What is the effect of alcohol on ADH production?
A.It increases ADH production
B.It suppresses ADH production
C.It has no effect
D.It turns ADH into insulin
- 4.
Which statement about the renal vein is correct?
A.It carries blood with high urea content
B.It carries blood with low oxygen content
C.It carries blood to the kidney
D.It carries urine to the bladder
- 5.
Which of the following would NOT be expected in the urine of a healthy person?
A.Water
B.Sodium chloride
C.Red blood cells
D.Urea
- 6.
What happens to the water potential of the blood if the kidneys reabsorb more water?
A.It increases (becomes less negative)
B.It decreases (becomes more negative)
C.It stays the same
D.It becomes zero
- 7.
What is the primary nitrogenous waste product excreted by humans?
A.Uric acid
B.Ammonia
C.Urea
D.Nitrate
- 8.
What is the final destination of the 'reabsorbed' substances after they leave the nephron tubules?
A.The peritubular capillaries (network of blood vessels surrounding the nephron).
B.The renal pelvis for temporary storage before entering the ureter.
C.The lymphatic system for filtration before returning to the heart.
D.The lumen of the collecting duct to be transported to the bladder.
- 9.
A patient with uncontrolled Diabetes Mellitus has glucose in their urine. Why does this cause the patient to produce a larger volume of urine (polyuria)?
A.The glucose in the filtrate lowers its water potential, reducing the osmotic reabsorption of water.
B.Glucose directly inhibits the release of ADH from the pituitary gland.
C.The kidneys must filter more water to help the glucose dissolve in the filtrate.
D.The presence of glucose causes the afferent arteriole to dilate, increasing GFR.
- 10.
Which of the following best describes 'selective reabsorption'?
A.The recovery of useful substances from the filtrate into the blood via active transport and osmosis.
B.The movement of all small molecules from the blood into the Bowman's capsule under pressure.
C.The transport of toxic wastes from the blood into the distal convoluted tubule.
D.The process of concentrating urine within the bladder before excretion.
Download the worksheet for Excretion in Humans - Structure and function of kidneys to practice offline. It includes additional chapter-level practice questions.
Urea formation and dialysis
SubtopicUrea formation and dialysis under Excretion in Humans for Grade 12 IGCSE.
Preview questions (no answers)
- 1.
Which component of the blood carries the highest percentage of urea to the dialysis machine?
A.Platelets
B.Red blood cells
C.White blood cells
D.Plasma
- 2.
Urea is synthesized in the liver from and which other molecule?
A.Oxygen
B.Ammonia
C.Glucose
D.Hemoglobin
- 3.
If a blood test shows a very high level of urea, which organ's function is a doctor likely to investigate first?
A.The lungs
B.The kidneys
C.The heart
D.The brain
- 4.
Which property of urea allows it to be easily transported by the blood and excreted by the kidneys?
A.It is highly soluble in water
B.It is a solid at body temperature
C.It is very large and heavy
D.It is insoluble in water
- 5.
Why is dialysis typically required several times a week for several hours each session?
A.Urea is produced continuously by the liver and builds up in the blood
B.The dialysis machine works very quickly and needs rest
C.The body needs time to make more dialysis fluid
D.The patient needs to absorb glucose from the fluid for the whole week
- 6.
What physical principle drives the movement of urea out of the blood in a dialysis machine?
A.A difference in hydrostatic pressure
B.A difference in solute concentration
C.The presence of specific carrier proteins
D.The movement of water by osmosis
- 7.
Which of the following would be found in the blood entering a kidney but should be absent or in very low concentration in the urine of a healthy person?
A.Urea
B.Water
C.Glucose
D.Sodium ions
- 8.
Which of the following describes the 'counter-current' flow in a dialysis machine correctly?
A.Blood and dialysis fluid flow in opposite directions to maintain a concentration gradient across the entire length of the membrane.
B.The blood flows faster than the dialysis fluid to create a vacuum that pulls urea through the membrane.
C.The dialysis fluid flows in pulses to mimic the heartbeat of the patient.
D.Warm fluid flows one way and cool blood flows the other to ensure heat is exchanged.
- 9.
The deamination reaction can be summarized as: Amino acid + + Keto acid + . What happens if the keto acid is NOT used for respiration?
A.It is converted into fats or glycogen for storage in the liver.
B.It is excreted by the kidneys in the same ratio as urea.
C.It is converted back into an amino acid by adding a sulfate group.
D.It accumulates in the blood, causing the to drop significantly.
- 10.
How is the concentration of urea in the blood of a patient on dialysis related to the time since their last treatment?
A.It increases linearly as the liver continues to produce urea from dietary and body proteins.
B.It decreases because the body starts excreting urea through sweat and breath.
C.It stays constant because the liver stops deamination when the kidneys fail.
D.It fluctuates based on the amount of water the person drinks, regardless of protein intake.
Download the worksheet for Excretion in Humans - Urea formation and dialysis to practice offline. It includes additional chapter-level practice questions.