IGCSE Biology Paper-1: Specimen Questions with Answers 145 - 145 of 208

Question 145




To get quick energy one should use


Choice (4)




Carbohydrates, proteins, and fats are digested in the intestine, where they are broken down into their basic units:

1. Carbohydrates into sugars

2. Proteins into amino acids

3. Fats into fatty acids and glycerol

  • Carbohydrates consist of various forms of sugar, such as glucose and sucrose (table sugar), are simple carbohydrates. They are small molecules, so they can be broken down and absorbed by the body quickly and are the quickest source of energy. They quickly increase the level of blood glucose (blood sugar). Fruits, dairy products, honey, and maple syrup contain large amounts of simple carbohydrates, which provide the sweet taste in most candies and cakes.
  • Proteins consist of units called amino acids, strung together in complex formations. Because proteins are complex molecules, the body takes longer to break them down. As a result, they are a much slower and longer-lasting source of energy than carbohydrates.
  • Fats are complex molecules composed of fatty acids and glycerol. The body needs fats for growth and energy. It also uses them to synthesize hormones and other substances needed for the body’s activities (such as prostaglandins). Fats are the slowest source of energy but the most energy-efficient form of food.