10 Blood is filtered in the kidney - Edexcel - GCSE Biology - Question 10 - 2023 - Paper 2
Question 10
10 Blood is filtered in the kidney.
Figure 17 shows the diameter of some molecules found in human blood.
| molecule | diameter in nanometres (nm) |
|----------|----... show full transcript
Worked Solution & Example Answer:10 Blood is filtered in the kidney - Edexcel - GCSE Biology - Question 10 - 2023 - Paper 2
Step 1
Which part of the nephron is the site of ultrafiltration?
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Answer
The site of ultrafiltration in the nephron is the glomerulus (Option C). The glomerulus is a network of capillaries where blood pressure forces water, ions, and small molecules out of the blood and into the Bowman's capsule.
Step 2
Explain why protein is not usually found in urine.
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Answer
Proteins are typically not found in urine due to their large size compared to the glomerular filtration barrier, which selectively allows smaller molecules and water to pass while retaining larger molecules like proteins. Additionally, healthy kidneys reabsorb small amounts of proteins in the renal tubules during urine formation, ensuring only minimal amounts, if any, are present in the urine.
