1. Food provides our bodies with the substances needed for growth, health, and energy. We obtain food from both animal sources like meat and milk, and plant sources like fruits and vegetables.
2. Food is classified into five groups - grains, vegetables, fruits, milk, and meat/fish/beans - which provide us with energy, vitamins, minerals, calcium, and proteins respectively. A balanced diet incorporates foods from all groups.
3. The amount of food needed depends on age and activity level. The digestive system breaks down food through a multi-step process involving the mouth, esophagus, stomach, and intestines to extract nutrients for the body and eliminate waste.