The Digestive System and Enzymes

TRUE or FALSE:

Enzymes speed up, or catalyze the rate of chemical reactions.

• FALSE

• TRUE

What is the enzyme which breaks down starch?

• lipase
• cellulase
• pepsin
• amylase

What is the enzyme which breaks down starch in the mouth?

• lipase
• cellulase
• pepsin
• amylase

Answer explanation

The first place where starch is broken down is in the mouth by salivary amylase. Remember the enzyme amylase will bind to the substrate starch.

Why doesn't the stomach digest itself with hydrochloric acid?

• It is lined with villi to protect the lining of the stomach

• the lining is covered with mucus to protect itself

• the stomach wall becomes immune to the strong acid over time

• the stomach walls are made of very thick skeletal muscle.

In the stomach pepsin breaks down proteins into ________

Answer explanation

The stomach contains gastric acid which is acidic with a pH of 2 but also contains an enzyme called pepsin which catalyses the breakdown of proteins into peptides.

___________ are enzymes that help break down fats.

• Lipase

• Amylase

• Papain

• Pepsin

In the small intestine peptides are broken down into

• amino acids
• nucleic acids
• sugars
• fatty acids

Maltase is the enzyme which breaks down maltose into

• lactose
• glucose
• sucrose
• fructose

What is the importance of the expanded surface area of the small intestine?

• Increased nutrient absorption

• Enhanced digestion process

• Improved blood circulation

• Better immune system function

What is the function of villi in the small intestine?

• Increase surface area for absorption

• Aid in digestion process

• Regulate blood flow

• Protect against infections