Enzyme Function and Activity Quiz

A student is planning an investigation into the effects of substrate concentration on enzyme activity. Which of the following is an important consideration for their experimental design?

• Using only one substrate concentration

• Keeping all other variables constant except substrate concentration

• Changing the enzyme concentration for each trial

• Ignoring the temperature of the reaction

Which statement best describes the process shown in the diagram?

• It is a linear pathway with only one enzyme

• It is a cyclic pathway that produces glucose

• It is a series of enzyme-controlled reactions that convert ammonia to urea

• It is a process that breaks down urea into ammonia

Who proposed the lock and key model for enzyme action?

• Albert Einstein

• Emil Fischer

• Louis Pasteur

• Gregor Mendel

Why are cyclical biochemical pathways important in living organisms?

• They only occur in plants

• They allow the regeneration of compounds needed for the pathway to continue

• They are not involved in energy production

• They only involve one chemical reaction

According to the lock and key model, what determines the specificity of an enzyme for its substrate?

• The enzyme’s color

• The enzyme’s size

• The shape of the enzyme’s active site

• The temperature of the reaction

Why does the rate of enzyme-catalysed reactions increase as temperature rises (up to an optimal point)?

• Enzymes become larger

• Increased kinetic energy leads to more collisions and chemical reactions

• Enzymes are denatured

• Substrate concentration decreases

What happens to the rate of reaction if the enzyme is denatured?

• It increases rapidly

• It remains unchanged

• It drops to zero

• It doubles

What is the typical optimum temperature for many enzymes in the human body?

• 20°C

• 40°C

• 70°C

• 5°C

Which enzyme has an optimum pH of about 2?

• Trypsin

• Amylase

• Pepsin

• Lipase

Why do changes in pH affect enzyme activity?

• They change the enzyme's primary structure.

• They alter the charged groups on amino acids, affecting the tertiary structure.

• They increase the enzyme's temperature.

• They add more substrate to the reaction.