Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
A balanced diet consists of seven main components: Carbohydrates (for energy), Proteins (for growth and repair), Fats (for insulation and energy storage), Vitamins, Minerals, Fibre, and Water ().
Carbohydrates are often stored as starch and broken down into simple sugars like Glucose () during digestion.
The digestive system is a long tube called the alimentary canal. It includes the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus.
Digestion occurs in two ways: Mechanical (physical breakdown by teeth and stomach churning) and Chemical (using enzymes and acids like ).
The stomach contains Hydrochloric Acid () which kills harmful bacteria and provides the optimum for protease enzymes to work.
The Small Intestine is where most chemical digestion is completed and where nutrients are absorbed into the bloodstream through tiny finger-like structures called villi.
The Large Intestine is primarily responsible for the absorption of Water () and the preparation of undigested waste (faeces) for egestion.
📐Formulae
💡Examples
Problem 1:
A student tests a piece of bread for starch. After adding iodine solution, it turns blue-black. If the student chews the bread for a long time, the iodine test no longer turns blue-black. Why?
Solution:
The enzyme Amylase in the saliva breaks down the starch into Glucose ().
Explanation:
Iodine only reacts with starch. Once Amylase converts starch into simple sugars, the starch is no longer present to react with the iodine.
Problem 2:
Calculate the total mass of macronutrients in a snack containing of carbohydrates, of protein, and of fat.
Solution:
Explanation:
To find the total mass of macronutrients, you sum the individual masses of the three energy-providing nutrient groups.
Problem 3:
What is the role of in the stomach?
Solution:
To provide an acidic environment () and kill pathogens.
Explanation:
The acid () helps denature proteins and creates the right conditions for the enzyme pepsin to start breaking down proteins into amino acids.