Chapter 7

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. Note that you will lose points if you ask for hints or clues!



1. An is a substance that speeds up the rate of a biochemical reaction. All living make enzymes.

2. Large quantities of useful enzymes can be produced by culturing the that make them in industrial .

3. A is a cleansing agent such as washing powder. A detergent contains enzymes able to stains; a non-biological detergent does not contain enzymes.

4. Some people are to the enzyme in biological washing powders and develop skin rashes or . The enzymes are now in a harmless coating of wax to allow them to be handled safely.

5. Whereas non-biological washing powder only works well at temperatures (e.g. 900C), biological washing powder works well at temperatures (e.g. 400C) because the enzymes in it digest stains well at these lower temperatures.

6. A lower temperature wash saves and causes less to delicate fabrics.

7. Since less energy is needed for a lower temperature wash, the demand made on the stations that generate by burning fuel is reduced. Decreased combustion of fossil fuel cuts down the quantities of harmful gases such as dioxide released into the atmosphere. As a result of the environment is reduced.

8. Detergents contain chemicals called . If waste water containing phosphates is released into a river of loch, the phosphates may act as and encourage the growth of huge populations of .




9. When the algae die, they are decomposed by bacteria which increase in and use up the river’s supply. Lack of oxygen in the water results in the death of river animals such as . The detergent is therefore said to be (poisonous) to wildlife.

10. In some countries, phosphates are from use in detergents and replaced by other chemicals. A more effective method of controlling the phosphate content of water is to remove them at a works before the water is released into a local .