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!

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What is the primary function of thyroxine?

To regulate blood sugar levels
To regulate metabolic rate
To stimulate growth hormone production
To control blood pressure

The correct answer is: To regulate metabolic rate

Thyroxine, also known as T4, is a hormone produced by the thyroid gland that plays a crucial role in regulating the body's metabolic rate. By increasing the metabolism, thyroxine affects how our bodies utilize energy from the food we consume. This hormone influences the rate at which cells convert oxygen and calories into energy, thereby impacting various physiological processes such as heart rate, temperature regulation, and overall energy levels. While it is important for growth, the primary function of thyroxine is specifically tied to metabolism rather than directly stimulating growth hormone production or regulating blood sugar levels and blood pressure. These other functions are managed by different hormones and systems within the body.