AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
Mammals and birds are warm-blooded animals that constantly use energy to maintain their body temperature. This means they have high energy needs and require a highly efficient supply of oxygen to the body. If oxygenated and deoxygenated blood were to mix, the efficiency of oxygen supply would decrease. Separating the two types of blood ensures oxygen-rich blood is pumped to the body without dilution, meeting their high energy demands.
Source: Life Processes, Section 5.4.1
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The examiner expects two linked points: (1) mammals and birds are warm-blooded with high energy needs (to maintain body temperature), and (2) separation prevents mixing, allowing highly efficient oxygen supply. Avoid just saying "mixing is bad" — you must connect it to the reason why these animals specifically need it (warm-blooded/high energy). The textbook phrase "highly efficient supply of oxygen" is worth using directly.