Q.Bile juice contains no digestive enzymes, yet it is important for digestion. Why?

Step 1. Recall bile's composition: bile contains bile pigments (bilirubin and biliverdin, from haemoglobin breakdown), bile salts, cholesterol and phospholipids, but genuinely contains no digestive enzymes.

Step 2. Recall the emulsification role: bile salts reduce the surface tension of large fat droplets and break them into many small globules — this emulsification greatly increases the total surface area of fat exposed to lipase, since enzymes can only act at a substrate's surface.

Step 3. Recall the enzyme-activation role: bile also directly activates lipase enzymes, meaning fat digestion would proceed far less efficiently in bile's absence, even though bile is not itself doing the hydrolysing. …

Separate bile's composition (pigments, salts, cholesterol, no enzymes) from its physiological actions (emulsification, lipase activ …

• Assuming that because bile is 'important for digestion', it must itself contain a digestive enzyme. …