LS1.5 Protein Quiz

Enzymes catalyze chemical reactions. How do enzymes work?

• They speed up chemical reactions by lowering the activation energy

• They slow down chemical reactions by lowering the activation energy

• The speed up chemical reactions by increasing the activation energy

• They slow down chemical reactions by lowering the activation energy

Enzymes are specific to their substrate because...

• the density of the enzyme matches the density of the substrate

• They are made of the same substance

• The structure of the enzymes active site matches the structure of the substrate.

If the pH where the enzyme is functioning changes from the usual pH of 2 to a pH of 10, what would happen?

• The enzyme would become less functional as it would change shape.

• The enzyme would become more functional as enzymes work better in a higher pH.

• This would have no effect on the enzyme pH does not impact enzyme function.

Enzymes work by...

• Increasing activation energy

• Lowering activation energy

• slowing down chemical reactions

A scientist exposed seeds to different temperatures and the rate of germination differed.

What is the most likely explanation of this?

• cellulose needs a certain temperature to operate

• Glucose breakdown is affected by specific temperatures

• Enzyme activities differ at different temperatures.

An enzyme that typically works at a pH of 10 is placed in lemon juice (which has a very low pH). Would this enzyme still operate at the same rate?

• No, adding lemon juice changes the pH, therefore enzyme activity would decrease.

• Yes, enzymes are not effected by pH levels.

• No, enzymes are not effected by pH levels.

• Yes, adding lemon juice changes the pH, therefore enzyme activity would decrease.

When cutting an apple, enzymes are released that cause the apple to turn brown. Adding lemon juice helps prevent this browning from occurring. What is a possible explanation for this?

• adding lemon juice causes the temperature to drop, which slows the enzymes down

• adding lemon juice causes the pH to drop, which slows the enzyme down

• adding lemon juice causes the pH to drop, which speeds the enzyme up