Enzymes #1

Enzymes are capable of increasing the rate of a chemical reaction within a living cell. Enzymes accomplish this through which of the following means?

• reducing the number of products

• reducing the activation energy

• increasing the temperature of the cell

• increasing the concentration of reactants

Answer explanation

Activation energy is the energy the reaction needs to get going. Usually it is quite high, and that is why some reactions take a very long time to get going if they get going at all.

Enzymes LOWER the ACTIVATION ENERGY of a reaction, hence speeding it up!

Tags

NGSS.HS-PS1-5

The graph shows how enzymes affect reactions in cells. Which statement best summarizes the information shown in the graph?

• Enzymes increase the energy of the reactants.

• Enzymes decrease the energy level of the products.

• Enzyme decrease the activation energy of the reaction.

• Enzymes reverse the direction of the reaction.

Answer explanation

The graph clearly shows the reaction goes quicker when the enzyme is present and the activation energy is lowered.

Tags

NGSS.HS-PS1-4

Which of the following conclusions can be drawn from this graph?

• The optimum pH of the enzyme is 6.6.

• The optimum pH of the enzyme is 5.8

• The enzyme’s activity increases as pH increases 5.0 to 9.0

• The enzyme’s activity is greater around pH of 8.0 .

Answer explanation

Remember, OPTIMUM is the usually the highest point on the graph and shows the 'best' value.

Which statement best describes the enzyme represented in the graphs below?

• This enzyme works best at a temperature of 35°C and a pH of 8

• This enzyme works best at a temperature of 50°C and a pH of 12

• Temperature and pH have no influence on the activity of this enzyme

• This enzyme works best at a temperature above 50°C and a pH above 12

Answer explanation

For this question you are looking for TWO OPTIMUM values, one for temperature and one for pH.

Which of these is NOT true.

• Enzymes can denature (change shape) when the temperature gets too high.

• Enzymes can only be used once in a chemical reaction.

• Enzymes can denature when the pH changes.

• Enzymes speed up chemical reactions.

Answer explanation

Enzymes are proteins so they can denature just like any other protein. However, enzymes are not used up or changed during the reaction, so they can be used over and over again.

Tags

NGSS.HS-PS1-5

NGSS.HS-PS1-2

When the temperature or pH causes the enzyme to change so it no longer works, this is called ....

• Allosteric inhibition

• Substrate concentration

• Denaturation

• Active Site transference

Which substrate would this enzyme catalyze?

• Δ

• σ

• ∅

• Π

Answer explanation

It's all about the shape of the active site and the substrate 'fitting' together.

Letter D is the .....

• active site

• enzyme

• substrate

• products

Answer explanation

The enzyme is the 'facilitator' of the reaction.

Letter C is the.....

• active site

• enzymes

• substrate

• products

Answer explanation

The area of the enzyme where the substrate 'slots in' is called the active site.

Tags

NGSS.HS-LS1-7

Letter B is the.....

• active site

• enzyme

• substrate

• products

Answer explanation

Substrate is a fancy biological name for reactant(s).

Tags

NGSS.HS-LS1-7