The video explains how digestion converts large molecules into smaller ones for nutrient absorption. It covers chemical and mechanical digestion, focusing on enzymes as biological catalysts. Carbohydrates, proteins, and lipids are broken down by specific enzymes: carbohydrases, proteases, and lipases. The lock-key model illustrates enzyme specificity. Factors like temperature and pH affect enzyme activity. Metabolism, the sum of all chemical reactions in the body, relies on enzymes to proceed at life-sustaining rates.

What is the primary purpose of mechanical digestion?

• To eliminate waste from the body

• To absorb nutrients into the bloodstream

• To increase the surface area for chemical digestion

• To convert food into energy

Which enzyme is responsible for breaking down starch into glucose?

• Lactase

• Amylase

• Lipase

• Protease

What are proteins broken down into during digestion?

• Glycerol

• Simple sugars

• Fatty acids

• Amino acids

How does the lock and key model describe enzyme function?

• Molecules must fit into the enzyme's active site like a key in a lock

• Enzymes change shape to fit any molecule

• Enzymes work only at high temperatures

• Enzymes are destroyed after one use

What can cause an enzyme to change shape and become ineffective?

• Low oxygen levels

• Excessive water intake

• High or low pH levels

• Lack of sunlight

What is metabolism?

• The circulation of blood

• The breakdown of food in the stomach

• The process of breathing

• The sum of all chemical reactions in the body

Why are enzymes crucial for metabolism?

• They speed up chemical reactions necessary for life

• They slow down chemical reactions

• They transport nutrients in the blood

• They provide energy for the body