HardBiologyHigh School (9–10)GeneralLife Processes › Transport in Living OrganismsHuman Body › Circulatory SystemConceptualBoard ExamA-LevelIB
A fish has a heart with two chambers, and its blood passes through the heart only once in each…
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A fish has a heart with two chambers, and its blood passes through the heart only once in each round. A sparrow has a heart with four chambers and a double circulation. Give two reasons why the sparrow needs the double circulation, and say why the fish can manage without it.
Need a reminder? The key ideaShow
The heart has four chambers. The right side receives blood with little oxygen from the body and pumps it to the lungs. The left side receives oxygen-rich blood from the lungs and pumps it to the body. Valves stop backflow. In double circulation, the blood passes through the heart twice in each round of the body.
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The sparrow's needs. A sparrow keeps its body warm and flies, so it uses a lot of energy. Its cells need a large, steady supply of oxygen.
Step 2. What double circulation gives. The septum keeps oxygen-rich blood apart from used blood, so only oxygen-rich blood goes to the body. The left ventricle also gives it a second, strong push, so it reaches the body under high pressure.
Step 3. The fish. A fish takes its body temperature from the water, so it needs less energy. Blood with a single push through the gills is enough for its needs.
Answer: The sparrow needs a lot of energy to keep warm and to fly, so it needs blood that is fully rich in oxygen and under high pressure. A fish needs less energy, so a single circulation is enough.
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