Metabolic Water

Metabolic water is also known as water of oxidation. This is the water that is formed as an electron moves down the electron transport chain and combines with oxygen and a hydrogen proton. Metabolic water can be a significant source of water for animals that live in area where water is limited. Some desert rodents, marsupials, and sheep and camels in the winter, do not need to drink water. When kangaroo rats were fed dry grains at humidities above 10% relative humidity, and no water, they exhibited no negative water balance. Grains are typically rich in lipids. A gram of fat will release 1.07 g of water. A gram of carbohydrate or protein will release less water, 0.556 and 0.396 g water, respectively.

• Why would fat release more water, even more than the original weight of the food, than carbohydrates and proteins?
• Would the kangaroo rats have a negative water balance if they were fed grass instead of grain?
• Why was it important to conduct the feeding experiment at a relative humidity above 10 percent?
• What is relative humidity?
• My father used to say that a camel stores water in its hump, but this is not true. What did he mean by this statement?
• Why don't chickens need water when they are developing but tadpoles do?
• If I fed the kangaroo rat a high protein diet and no water, I would place the animal in double jeopardy. Why?
• If I fed a white rat and a kangaroo rat a high fat diet, the white rat would eventually die from water loss. Why?

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