This exam tips covers Exam Tips: Water Regulation within Water Regulation for GCSE Biology. Topic 7: Water Regulation It is section 12 of 12 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Exam Tips: Water Regulation
Always name the source of ADH: Many students write "the kidneys release ADH." This is wrong — ADH is produced in the hypothalamus and released by the pituitary gland. The kidneys are the target organ, not the source.
Use "permeability" precisely: ADH increases the permeability of the collecting duct to water. Avoid saying ADH "opens channels" or "makes the kidney work harder" — use the specific word permeability.
Negative feedback direction: Always state what the original change was AND how the response reverses it. E.g., "Blood water concentration falls, ADH is released, water is reabsorbed, blood water concentration rises back to normal."
Dialysis vs transplant questions: Give a balanced comparison with specific named advantages AND disadvantages for each. Vague answers (e.g., "dialysis is worse") score zero. Use the words: lifestyle, rejection, immunosuppressants, donor shortage.
Osmosis link: When explaining water movement in the kidney, say water moves by osmosis along a concentration gradient. This earns an extra mark in extended response questions.
Practice questions for Water Regulation
Where does the filtration of blood take place in the kidney?
Describe the process of selective reabsorption in the kidney and explain why it is important.