Year 12s: what will be the first way you research your future options? >>

biology one mark question help

Hi can some help me answer this question pls

Phenolphthalein is an indicator that is pink in alkaline solutions.
When the pH drops below pH 8.3 phenolphthalein goes colourless. When phenolphthalein is added to milk it turns pink.
Suggest why, when lipase is added to a milk solution containing phenolphthalein, a colour change from pink to colourless is observed. (1 mark)

Reply 1

Glow72778826

When lipase breaks down the lipids (fats) in the milk, the pH of the milk decreases so it turns colourless

Reply 2

Fa.ara

Original post by Glow72778826

When lipase breaks down the lipids (fats) in the milk, the pH of the milk decreases so it turns colourless

thnx

Reply 3

Glow72778826

Your welcome! I’ve recently just learnt about the decay practical in Biology so I managed to remember the answer 😅

Reply 4

Hufflepuffle17

It goes colourless because of lipase breaking down the milk and making it less alkaline than before

Reply 5

khanj471.202

Here, an alkaline solution of milk, lipase and phenolphthalein will change from pink to colourless as the fat in milk is broken down to form fatty acids (and glycerol) thus reducing the pH to below 8.3. The time taken for this reaction to occur is affected by temperature.