OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

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Prepare for the OCR GCSE Biology Exam with detailed quizzes, flashcards, and explanations. Enhance your understanding of biology concepts and get exam-ready today!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

What role does the brain play in urine concentration regulation?

It produces urine directly
It measures blood sugar levels
It monitors blood water content and signals the pituitary gland
It filters waste from the blood

The correct answer is: It monitors blood water content and signals the pituitary gland

The brain plays a crucial role in regulating urine concentration through the monitoring of blood water content. Specifically, the hypothalamus, a part of the brain, detects changes in the osmolarity of the blood. When the body is dehydrated, the osmolarity increases, signaling the brain to respond appropriately. In this case, the hypothalamus stimulates the posterior pituitary gland to release antidiuretic hormone (ADH). This hormone acts on the kidneys, promoting the reabsorption of water, which concentrates the urine and helps to conserve water in the body. The other choices reflect functions that do not accurately describe the brain's role in urine concentration. While the brain is involved in sensory processing and functions, it does not directly produce urine, measure blood sugar levels, or filter waste from the blood. These processes are managed by the kidneys and other systems in the body, highlighting the specific and essential role the brain plays in regulating water balance through hormonal signaling.