Enzymes

Question 1

True or false? Enzymes act as biological catalysts to speed up useful chemical reactions in the body.

Answer 1

True.

Question 2

What is the definition of a catalyst?

Answer 2

A catalyst is a substance which increases the speed of a reaction, without being changed or used up in the reaction

Question 3

Fill the gaps. Enzymes are all _____ and all _____ are made up of chains of _____ _____.

Answer 3

proteins, proteins, amino acids

Question 4

Give three purposes of proteins other than enzymes.

Answer 4

Act as structural components of tissues (e.g. muscles), hormones and antibodies.

Question 5

Explain the process of enzymes catalysing reactions.

Answer 5

Question 6

Why won’t enzymes work if the temperature is too hot?

Answer 6

If it gets too hot, some of the bonds holding the enzyme together break which destroys the enzyme’s special shape and it will no longer work. It is known as being ‘denatured’ when this happens.

Question 7

What temperature do enzymes in the human body work best at?

Answer 7

37°C, body temperature

Question 8

Why can pH affect enzymes?

Answer 8

If it is too high or too low, the pH interferes with the bonds holding the enzyme together. This changes the shape and denatures the enzyme and prevents it from working.

Question 9

True or false? pH 7 is the optimum pH for all enzymes.

Answer 9

False. It is often pH 7 that enzymes work best at however not all of them need this neutral pH. An example is pepsin which is an enzyme used to break down proteins in the stomach which works best at pH 2 meaning that it is suited to the conditions there.

Question 10

What do enzymes in digestion do? Give examples.

Answer 10

The digestive enzymes break down the big molecules in to the smaller ones. Starch, proteins and fats are big mollecules that can’t pass through the walls of the digestive system and so need to be broken down in to smaller ones like sugars, amino acids, glycerol and fatty acids.

Question 11

What does amylase do? Where is it made?

Answer 11

Question 12

What does protease do? Where is it made?

Answer 12

Question 13

What does lipase do? Where is it made?

Answer 13

Question 14

Where is bile produced, stored and released into?

Answer 14

• Produced in the liver
• Stored in the gall bladder
• Released into the small intestine

Question 15

What is the job of bile and why is it needed?

Answer 15

The hydrochloric acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly because these enzymes work best in alkaline conditions. Bile is alkaline and so neutralises the acid and makes the conditions alkaline.

It also emulsifies fats. It breaks the fats in to tiny droplets which gives a larger surface area for the lipase enzyme to work on and so results in digestion being faster.

Question 16

What happens at the salivary glands?

Answer 16

Amylase is produced and is found in the saliva.

Question 17

What happens in the liver?

Answer 17

Bile is produced.

Question 18

What happens in the gall bladder?

Answer 18

Bile is stored before it is released.

Question 19

What happens in the stomach?

Answer 19

The stomach pummels the food with its muscular walls and it produces the protease enzyme, pepsin. It also produces hydrochloric acid to kill bacteria and to give the right pH for the protease enzyme to work.

Question 20

What happens in the pancreas?

Answer 20

Protease, lipase and amylase enzymes are produced and released in to the small intestine.

Question 21

What happens in the large intestine?

Answer 21

Excess water is absorbed from the food.

Question 22

What happens in the small intestine?

Answer 22

Protease, amylase and lipase enzymes to complete digestion. The digested food is also absorbed out of the digestive system in to the blood.

Question 23

Why are enzymes used in biological detergents?

Answer 23

They are mainly made up of protein-digesting enzymes (protease) and fat-digesting enzymes (lipase). This means that because the enzymes break down animal and plant matter, they’re ideal for removing stains like food or blood.

Question 24

Explain how enzymes can be used to change foods. Three examples.

Answer 24

1. The proteins in some baby foods are ‘pre-digested’ using protease so that they are easier for babies to digest
2. Carbohydrase enzymes can be used to turn starch syrup into sugar syrup
3. Glucose syrup can be turned in to fructose syrup using an isomerase enzyme. Fructose is sweeter so you need less of it making it ideal for slimming foods.

Question 25

What are the advantages of using enzymes in industry?

Answer 25

1. They’re specific, so only catalyse the reaction you want them too
2. They work without the high temperatures and pressures so it saves energy and therfore money
3. Enzymes work for a long time so after the initial cost of buying them, you can continually use them
4. They are biodegradable and therefore cause less environmental pollution

Question 26

What are the diadvantages of using enzymes in industry?

Answer 26

1. Some people can develop allergies to the enzymes
2. Enzymes can be denatured by even a slight change in temperature. They’re also susceptible to poisons and changes in pH meaning conditions must be carefully and continuously controlled
3. Enzymes can be expensive to produce
4. Contamination of the enzyme can affect the reaction