Question 64
Some bacteria are decomposers. They break down food and change it. Usually this makes the food unpleasant, but sometimes it changes it to something that is good to eat.
One kind of bacterium changes milk to yoghurt. When the bacteria do this, they change sugar in the milk to acid. Many people like the sharp taste that the acid provides.
Sofia makes some yoghurt.
- She washes out a plastic container with boiling water.
- She lets the pot cool down, then puts some fresh milk into the container.
- She adds a small spoonful of yoghurt she bought.
- She covers the container with cling film.
- She puts the container in the refrigerator.
Sofia measures the pH of the milk before she puts it into the pot.
She measures it again after it had been in the pot for four days.
Suggest how the pH changes. Choose from:
**becomes higher becomes lower stays the same**
Explain your answer.
One kind of bacterium changes milk to yoghurt. When the bacteria do this, they change sugar in the milk to acid. Many people like the sharp taste that the acid provides.
Sofia makes some yoghurt.
- She washes out a plastic container with boiling water.
- She lets the pot cool down, then puts some fresh milk into the container.
- She adds a small spoonful of yoghurt she bought.
- She covers the container with cling film.
- She puts the container in the refrigerator.
Sofia measures the pH of the milk before she puts it into the pot.
She measures it again after it had been in the pot for four days.
Suggest how the pH changes. Choose from:
**becomes higher becomes lower stays the same**
Explain your answer.
