<span>The lungs are the respiratory structure that controls breathing. They make up a substantial part of the respiratory system, along with the trachea, the ribs, the intercostal muscles and the diaphragm. Each lung contains small tubes called bronchioles which end in air sacs called alveoli.</span>
One of the signs that sleep is necessary is that all living creatures are harmed by lack of sleep. Correct answer: A Sleep serves important evolutionary functions for all animals, because sleep helps animals consolidate memories and learn. Animals sleep according to how much they eat – animals that eat food with a lower caloric density sleep less than others. However, lack of sleep and if the deprivation is long enough it can kill animals.
A. A UNIT OF ENERGY SUPPLIED BY FOOD.
A calorie is a unit of energy. Historically, scientists have defined "calorie" to mean a unit of energy or heat that could come from a variety of sources, such as coal or gas. In a nutritional sense, all types of food — whether they are fats, proteins, carbohydrates or sugars — are important sources of calories, which people need to live and function.
