Enzymes 5 Quiz IGCSE Bio

What is the main reason enzymes are important to living cells?

• To carry out chemical reactions

• To speed up non-useful reactions

• To damage cells

• To increase temperature

Answer explanation

Enzymes are important to living cells because they carry out chemical reactions, facilitating essential processes for cell function and metabolism.

What is a catalyst?

• A substance that decreases the speed of a chemical reaction

• A substance that is harmful to living organisms

• A substance that increases the speed of a chemical reaction without being changed

• A substance that is used up in the process of a chemical reaction

Answer explanation

A catalyst is a substance that increases the speed of a chemical reaction without being changed, allowing the reaction to occur faster.

What are enzymes made of?

• Large proteins

• Small lipids

• Carbohydrates

• Nucleic acids

Answer explanation

Enzymes are made of large proteins, which are complex molecules made up of amino acids. These proteins serve as biological catalysts in various biochemical reactions.

What is the unique part of an enzyme that is complementary to the substrates of a reaction?

• Inactive site

• Active site

• Passive site

• Reactive site

Answer explanation

The unique part of an enzyme that is complementary to the substrates of a reaction is called the active site.

What happens if the substrate doesn't fit the active site of an enzyme?

• The enzyme will be used up

• The enzyme will change shape

• The reaction will be catalyzed faster

• The reaction won't be catalyzed

Answer explanation

If the substrate doesn't fit the active site of an enzyme, the reaction won't be catalyzed as the enzyme cannot bind to the substrate.

What is the lock and key model of enzyme action based on?

• Substrates not fitting into the active site

• Enzymes being used up

• Enzymes not changing shape

• Substrates fitting perfectly into the active site

Answer explanation

The lock and key model of enzyme action is based on substrates fitting perfectly into the active site.

What is the induced fit model of enzyme action compared to?

• Putting your hand into a plastic glove

• Putting your hand into a rubber glove

• Putting your hand into a metal glove

• Putting your hand into a glass glove

Answer explanation

The induced fit model of enzyme action is compared to putting your hand into a rubber glove, where the glove adjusts to fit your hand, similar to how the enzyme changes shape to fit the substrate.

What is the key role of enzymes in chemical reactions?

• To change the process

• To slow down the process

• To speed up the process

• To stop the process

Answer explanation

Enzymes play a key role in chemical reactions by speeding up the process, allowing reactions to occur more quickly.

What is the main difference between the lock and key model and the induced fit model?

• Enzymes being faster in lock and key model

• Enzymes being used up in lock and key model

• Enzymes not changing shape in lock and key model

• Enzymes changing shape in induced fit model

Answer explanation

Enzymes changing shape in induced fit model

What is the active site of an enzyme?

• A part of the enzyme that is reactive

• A part of the enzyme that is passive

• A part of the enzyme that is inactive

• A part of the enzyme with a unique shape complementary to substrates

Answer explanation

The active site of an enzyme is a part of the enzyme with a unique shape complementary to substrates, allowing for specific interactions and catalysis.