GCSE Unit 2 AQA Biology - The Digestive Systems What it is, the process, enzymes

1. The Digestive
System

2. What Is Digestion?
Digestion is the breakdown of large
molecules into smaller, soluble
molecules that can be absorbed into
the blood/body. Digestion happens
inside the gut, and relies on
enzymes.

3. The Journey Of Digestion
Stop 1: The Mouth
Stop 2: The Pharynx and Esophagus
Stop 3: The Stomach and Small Intestine
Stop 4: The Colon, Rectum, and Anus

4. Organs
Involved
A diagram
displaying the
name and
uses of
organs
throughout
the digestive
systems

5. Enzymes
What are they?
 Enzymes are biological catalysts. There are optimum temperatures
and pH values at which their activity is greatest. Enzymes are also
proteins, and usually denatured above about 45ºC.
 Enzymes are important in respiration. Aerobic respiration releases
energy from glucose.
Why are they important?
 Enzymes are a crucial part of digestion, without them there would
be nothing to break down the carbohydrates, proteins and fats.

7. Different Enzymes
Enzyme Where Produced
(In The Gut)
Reaction
Catalysed
Function
Amylase Salivary glands,
pancreas, small
intestine
Starch →
sugars
Amylase catalyses the breakdown
of starch into sugars in the mouth
and small intestine.
Protease Stomach,
pancreas, small
intestine
Proteins →
amino acids
Proteases catalyse the breakdown
of proteins into amino acids in the
stomach and small intestine.
Lipase Pancreas, small
intestine
Lipids → fatty
acids + glycerol
Lipases catalyse the breakdown of
fats and oils into fatty acids and
glycerol in the small intestine.