Answer:
The sentences can be completed as follows:
The enzyme lactase breaks down the sugar lactose.
If the body doesn’t produce much of this enzyme, people have what’s called lactose intolerance.
During the chemical reaction the enzyme doesn’t get used up, but gets reused.
Enzymes are substances that speed up chemical reactions which are also known as catalysts.
Explanation:
Enzymes can be described as molecules which act as biological catalysts i.e they are involved in speeding up a chemical reaction. The enzymes do not get used up in a chemical reaction and hence, they can be reused.
Lactase is an enzyme which helps in breaking down the sugar lactose which is commonly found in the milk. If enough lactase is not produced by a person's body, then he/she becomes unable to digest the sugar lactose. Such a condition is known as lactose intolerance.
