13.1

Excretion in humans

Cambridge IGCSE Biology (0610)  · Unit 13: Excretion in humans  · 13 flashcards

Excretion in humans is topic 13.1 in the Cambridge IGCSE Biology (0610) syllabus , positioned in Unit 13 — Excretion in humans .  In one line: Excretion is the removal of metabolic waste products from the body. These waste products, such as urea and carbon dioxide, can be toxic if they accumulate. Examples of organs involved are the lungs and kidneys.

This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical). Past papers from 2022 to 2025 show this topic across 12 questions worth 160 marks (around 2.4% of all Biology marks in those years).

The deck below contains 13 flashcards — 1 definition, 3 key concepts, 4 process cards and 5 identification cards — covering the precise wording mark schemes reward.  Use the definition card to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.

Key definition

Excretion

Excretion is the removal of metabolic waste products from the body. These waste products, such as urea and carbon dioxide, can be toxic if they accumulate. Examples of organs involved are the lungs and kidneys.

What the Cambridge 0610 syllabus says

Official 2026-2028 spec

These are the exact learning objectives Cambridge sets for this topic. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks.

  1. State State that carbon dioxide is excreted through the lungs
  2. State State that the kidneys excrete urea and excess water and ions
  3. Identify Identify in diagrams and images the kidneys, ureters, bladder and urethra
  4. Identify Identify in diagrams and images the structure of the kidney, limited to the cortex and medulla Supplement
  5. Outline Outline the structure and function of a nephron and its associated blood vessels, limited to: (a) the role of the glomerulus in the filtration from the blood of water, glucose, urea and ions (b) the role of the nephron in the reabsorption of all of the glucose, some of the ions and most of the water back into the blood (c) the formation of urine containing urea, excess water and excess ions (details of these processes are not required) Supplement
  6. Describe Describe the role of the liver in the assimilation of amino acids by converting them to proteins Supplement
  7. State State that urea is formed in the liver from excess amino acids Supplement
  8. Describe Describe deamination as the removal of the nitrogen-containing part of amino acids to form urea Supplement
  9. Explain Explain the importance of excretion, limited to toxicity of urea Supplement
Definition Flip

What is excretion?

Answer Flip

Excretion is the removal of metabolic waste products from the body. These waste products, such as urea and carbon dioxide, can be toxic if they accumulate. Examples of organs involved are the lungs and kidneys.

Key Concept Flip

What waste product is excreted by the lungs?

Answer Flip

The lungs excrete carbon dioxide (CO2), a waste product of aerobic respiration. This is achieved through gas exchange in the alveoli during exhalation, where CO2 diffuses from the blood into the lungs and is expelled.

Example: when we breathe out.
Key Concept Flip

Which organ excretes urea, excess water, and ions?

Answer Flip

The kidneys are responsible for excreting urea, excess water, and excess ions from the body. They filter blood and produce urine containing these waste products.

Example: Kidney filter blood and make urine.
Key Concept Flip

Name the four main components of the urinary system.

Answer Flip

The urinary system consists of the kidneys, ureters, bladder, and urethra. The kidneys filter blood to produce urine, which travels through the ureters to the bladder for storage, and is then expelled through the urethra.

Example: Urine is made in the kidney.
Key Concept Flip

Name the two main regions of the kidney.

Answer Flip

The two main regions of the kidney are the cortex (outer region) and the medulla (inner region). These regions contain different structures and perform different functions in filtering blood and producing urine.

Example: Nephrons reside in both the cortex and the medulla.
Key Concept Flip

What is the functional unit of the kidney?

Answer Flip

The nephron is the functional unit of the kidney, responsible for filtering blood and forming urine. Each kidney contains millions of nephrons that work together to maintain homeostasis in the body.

Example: Nephrons are responsible for filtration and reabsorption.
Key Concept Flip

Outline the role of the glomerulus in urine formation.

Answer Flip

The glomerulus filters blood, allowing water, glucose, urea, and ions to pass into the nephron. This process is called ultrafiltration, and it separates small molecules from larger proteins and blood cells that remain in the blood.

Example: Ultrafiltration occurs at the glomerulus due to high pressure.
Key Concept Flip

Describe the role of the nephron tubule in reabsorption.

Answer Flip

The nephron tubule reabsorbs useful substances like glucose, some ions, and most of the water back into the blood. This process ensures that essential substances are not lost in the urine.

Example: All glucose is reabsorbed in a healthy individual.
Key Concept Flip

What is the final product formed by the nephron?

Answer Flip

The nephron forms urine, which contains urea (a waste product of protein metabolism), excess water, and excess ions. Urine is then transported to the bladder for storage before excretion.

Example: Urine production helps regulate blood volume and composition.
Key Concept Flip

What is the role of the liver in amino acid assimilation?

Answer Flip

The liver assimilates amino acids by converting them into proteins, which are essential for building and repairing tissues. It also plays a role in synthesizing enzymes and hormones.

Example: Albumin is a protein made by the liver from amino acids.
Key Concept Flip

Where is urea formed in the body?

Answer Flip

Urea is formed in the liver from excess amino acids. This process is a part of the urea cycle, which detoxifies ammonia produced during amino acid breakdown.

Example: The liver is a key organ in nitrogenous waste removal.
Key Concept Flip

What is deamination, and why is it important?

Answer Flip

Deamination is the removal of the nitrogen-containing part (amino group) of amino acids. This process forms ammonia, which is then converted to urea in the liver, thus reducing its toxicity.

Example: Deamination produces keto acids, which can be used in respiration.
Key Concept Flip

Why is excretion important for the human body?

Answer Flip

Excretion is important because urea is toxic and can damage cells if it accumulates in the body. Removing urea through urine helps maintain a stable internal environment and prevents harmful effects.

Example: Kidney failure can lead to urea buildup and death.

Review the material

Read revision notes with definitions, equations, and exam tips.

Read Notes

Test yourself

Practice with MCQ questions to check your understanding.

Take Biology Quiz
12.3 Anaerobic respiration 14.1 Coordination and response

Key Questions: Excretion in humans

What is excretion?

Excretion is the removal of metabolic waste products from the body. These waste products, such as urea and carbon dioxide, can be toxic if they accumulate. Examples of organs involved are the lungs and kidneys.

Tips to avoid common mistakes in Excretion in humans

Cambridge syllabus keywords to use in your answers

These are the official Cambridge 0610 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.

excretion kidney ureter bladder urethra urine nephron glomerulus Bowman's capsule tubule collecting duct filtration reabsorption urea water glucose dialysis kidney transplant ADH

Key terms covered in this Excretion in humans deck

Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.

Excretion

Related Biology guides

Long-read articles that go beyond the deck — cover the whole subject's common mistakes, high-yield content and revision pacing.

IGCSE Biology common mistakes

Where marks slip and how to avoid the most-common errors

IGCSE Biology high-yield questions

The 30+ definitions and processes that recur year after year

IGCSE Biology 2-week revision plan

Daily breakdown for the fortnight before exams

How to study this Excretion in humans deck

Start in Study Mode, attempt each card before flipping, then rate Hard, Okay or Easy. Cards you rate Hard come back within a day; cards you rate Easy push out to weeks. Your progress is saved in your browser, so come back daily for 5–10 minute reviews until every card reads Mastered.