The Kidneys and Excretion
The kidneys filter the blood to remove urea and excess water and salts, forming urine.
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The kidneys filter the blood to remove urea and excess water and salts, forming urine.
- Nephrons are the filtering units
- Urea is made in the liver
- Kidney machines perform dialysis
🧠 Quick quiz
Three questions. Score 2 or more to complete the topic.
What is The Kidneys and Excretion?
Within Biology, which covers cells, the human body, genetics, evolution, plants and ecosystems: the science of living things, this topic explains The Kidneys and Excretion. Biology topics show how living things work, from the cell up to whole ecosystems, with models you can explore step by step.
Check that you can explain The Kidneys and Excretion in your own words and give one example from everyday life. If you can do that, you have understood the core idea.
Understanding The Kidneys and Excretion helps you explain how living things stay alive and respond to their surroundings, which is central to biology exams.
The Kidneys and Excretion in detail
The kidneys filter blood to remove urea, excess water and salts and produce urine. Urea, made in the liver from excess amino acids, is poisonous in high concentrations. Blood enters the kidney, and in each nephron, high pressure forces small molecules out of the blood into the tubule (filtration).
Useful substances such as all of the glucose, some salts and water are reabsorbed. The amount of water reabsorbed is controlled by ADH, a hormone from the pituitary, which maintains the water balance. If the kidneys fail, dialysis or a transplant is needed. Dialysis machines filter blood across a partially permeable membrane.
How the interactive helps you understand The Kidneys and Excretion
Watch the cell model in the interactive. Use any sliders or buttons it offers to change the values and see how the cell model responds.
Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of The Kidneys and Excretion.
Real-life uses and examples
- Structure a longer answer about The Kidneys and Excretion by moving from definition to example to consequence.
- Explain how The Kidneys and Excretion helps a living thing stay alive, using a plant or animal example.
- Connect The Kidneys and Excretion to health, food and medicine in everyday life.
Common mistakes to avoid
- Listing the steps of a process without saying how one step causes the next.
- Using everyday words, such as “energy” or “bad”, without their scientific meaning.
- Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.
Frequently asked questions about The Kidneys and Excretion
What is The Kidneys and Excretion?
The kidneys filter the blood to remove urea and excess water and salts, forming urine.
What are the most important points about The Kidneys and Excretion?
The main points are: Nephrons are the filtering units; Urea is made in the liver; Kidney machines perform dialysis.
Why is The Kidneys and Excretion useful?
Understanding The Kidneys and Excretion helps you explain how living things stay alive and respond to their surroundings, which is central to biology exams.
How can I practise The Kidneys and Excretion?
Open the interactive at the top of this page and change the controls one at a time. Predict the result before each change, then take the three-question quiz. A score of two or more marks the topic as complete on this device.
Which topics are related to The Kidneys and Excretion?
Related topics in Biology include Muscles and Movement, Pregnancy and Development, Cell Division: Meiosis.