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

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Get ready for the OCR GCSE Biology exam with our comprehensive quiz, featuring flashcards and multiple choice questions. Understand the exam format, key topics, and effective study strategies to excel.

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What is the main role of veins in the circulatory system?

To carry oxygenated blood
To transport blood to the lungs for oxygenation
To carry blood to the heart
To distribute nutrients to the body

The correct answer is: To carry blood to the heart

Veins play a crucial role in the circulatory system by transporting blood back to the heart. This process is essential because the heart needs a continuous flow of blood to pump oxygenated blood to the rest of the body. Most veins carry deoxygenated blood, which has delivered its oxygen to body tissues and is now returning to the heart, primarily through the superior and inferior vena cavae. The other options address functions of different parts of the circulatory system. For example, arteries are responsible for carrying oxygenated blood away from the heart to tissues, while the lungs are connected to the pulmonary circulation, where blood is sent specifically to be oxygenated. Additionally, the distribution of nutrients occurs mainly through the capillary networks following arterial delivery, not directly through the function of veins. Thus, the primary and essential role of veins is to carry blood back to the heart, ensuring that the circulatory system continues to function effectively.