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High fructose syrup is used to sweeten diet food and drink because it is much sweeter than other sugars, so less of it is required. This means fewer calories for the same sweetness.

Unit 2 - Enzymes

This GCSE Biology quiz tests your knowledge of enzymes, the biological catalysts that speed up reactions in digestion, respiration and other life processes inside cells.

Explore the Topic →

(quiz starts below)

Fascinating Fact:

Digestive enzymes such as amylase, protease, and lipase break down large food molecules into smaller, soluble ones that can be absorbed.

In GCSE Biology, enzymes are studied as protein molecules that control the speed of chemical reactions in cells. You learn how temperature, pH and substrate concentration affect enzyme activity, and why enzymes are essential for digestion and metabolism.

Key Terms

Enzyme: A protein that acts as a biological catalyst, speeding up chemical reactions without being used up.
Active site: The specific part of an enzyme where the substrate fits and the reaction takes place.
Substrate: The molecule that an enzyme acts on to form products in a reaction.

Frequently Asked Questions (Click to see answers)

What are enzymes in GCSE Biology?

In GCSE Biology, enzymes are described as protein molecules that act as biological catalysts. They speed up chemical reactions inside cells, such as digestion and respiration, without being used up.

How does temperature affect enzyme activity?

As temperature increases, enzyme activity usually increases until it reaches an optimum temperature. Above this, the enzyme’s shape can change and it becomes denatured, so the reaction slows or stops.

Why are enzymes important in the human digestive system?

Enzymes in the digestive system break large, insoluble food molecules into smaller, soluble ones. This allows nutrients like sugars, amino acids and fatty acids to be absorbed into the bloodstream.

Try These Related Quizzes

1 .

Which enzyme is used in industry to convert starch to glucose?

Protease

Lipase

Carbohydrase

Isomerase

Other examples include the use of the enzyme rennin to make cheeses and esterases that break down certain chemical bonds in glues and adhesives during the recycling of paper

2 .

Enzymes are which type of molecule?

Fat

Starch

Protein

Amino acid

They are very complex molecules

3 .

Which enzyme converts fats into 3 fatty acids and glycerol?

Amylase

Protease

Lipase

DNA polymerase

When you see a bioligical word that starts with 'lip' or 'lipo' it will usually indicate something to do with fats

4 .

The shape of an enzyme will change if which of the following is increased?

Temperature

Concentration

Time

Pressure

The temperature at which the enzyme works best is called the optimum temperature. For most human enzymes, this is body temperature, 37 degrees C. As the temperature increases above the optimum, the enzyme changes shape due to bonds breaking which hold the shape. The enzyme can no longer work so enzyme activity is reduced

5 .

Protease enzymes are located in which organ?

Mouth

Oesophagus

Stomach

Colon

Protease enzymes are also located in the small intestine. The stomach protease works best at pH 2 and the one in the small intestine works best at pH 8

6 .

Isomerase enzyme is used in industry for making high fructose syrup from which of the following?

Sucrose

Glucose

Maltose

Starch

High fructose syrup is used to sweeten diet foods because it is much sweeter than other sugars, so less of it is required. This means fewer calories for the same sweetness

7 .

Which enzyme converts starch into sugars in the mouth and small intestine?

Protease

Lipase

Isomerase

Amylase

Enzyme names usually end with 'ase'

8 .

Protease enzymes break down proteins into what?

Fatty acids

Amino acids

Carboxylic acids

Hydrochloric acid

These can then be re-assembled by other enzymes into new, different protein molecules exactly where they are needed

9 .

Which word describes the change of shape when an enzyme is heated to high temperatures?

Denatured

Destroyed

Killed

Damaged

Some students believe that enzymes are 'killed' by heat and extremes of pH. They are not - enzymes can't be killed as they were never alive! Denatured is the correct word to use in exams

10 .

Which of the following emulsifies fats so they can be further digested by the enzyme lipase?

Hydrochloric acid

Mucus

Bile

Saliva

Bile is made in the liver and stored in the gallbladder. It is released into the digestive system through the bile duct

You can find more about this topic by visiting BBC Bitesize - Enzymes

Author: Donna Davidson (GCSE Biology Teacher & Examiner, Quiz Writer)