Science (086) — AI-generated practice question

Birds and mammals are warm-blooded (homeothermic) — they constantly use energy to maintain a stable body temperature regardless of the environment. This means they have high energy needs and require a highly efficient, continuous oxygen supply. A four-chambered heart completely separates oxygenated and deoxygenated blood, ensuring only pure oxygenated blood is pumped to body tissues, supporting their high metabolic rate.

Amphibians and many reptiles are cold-blooded (poikilothermic) — their body temperature depends on the environment, so they have lower energy needs. A three-chambered heart with some mixing of blood is sufficient for their slower metabolism. Hence, the incomplete separation is tolerated without significant harm.

Source: Chapter 5, Section 5.4.1 — Transportation in Human Beings

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• The examiner expects you to link heart structure → energy needs → body temperature regulation. This is the core logic.
• Key terms to use: warm-blooded/homeothermic, cold-blooded/poikilothermic, oxygenated/deoxygenated, efficient oxygen supply, high/low metabolic rate.
• The textbook explicitly states: "This is useful in animals that have high energy needs, such as birds and mammals, which constantly use energy to maintain their body temperature." Quote or paraphrase this reasoning directly — examiners reward it.
• Do not describe the chambers of the heart in detail unless asked; focus on why the separation matters.