IB Bio 2.5

Which enzyme is matched to its function?

• A.

• B.

• C.

• D.

Which statement applies to enzymes?

• A. Enzyme function depends on collisions between substrate and active sites.

• B. One active site typically binds to a broad range of substrates.

• C. The active site on the substrate is specific to one enzyme.

• D. When enzymes are immobilized, they stop working.

Three flasks were prepared for an analysis of the activity of amylase. At time zero, each of the substances indicated in the diagrams was added.

Which flask(s) could provide support for the hypothesis that heat denatures enzymes?

• A. Flasks I and II after 15 minutes

• B. Flasks II and III after 15 minutes

• C. Flasks I and III after 15 minutes

• D. Flask III at time zero and again after 15 minutes

In an experiment the effect of changing pH on an enzymatic reaction is tested. Which could be a dependent variable in this kind of experiment?

• A. Changing substrate concentration

• B. Rate of formation of product

• C. Variation in temperature

• D. Change in pH

The graph shows the effect of increasing the substrate concentration on the rate of an enzyme-catalysed reaction. What is occurring during the phase indicated by section Y of the graph?

• A. The active site of the enzyme is saturated

• B. The enzyme becomes denatured

• C. The substrate concentration has risen too high

• D. The optimum rate is reached

A fever in a normally healthy adult during an illness is not usually a problem and can be regarded as a defence mechanism. However, a fever higher than 41°C might be dangerous. What is the cause of the possible damage due to a high fever?

• A. Loss of body mass

• B. Muscle damage due to shivering

• C. Overactive metabolic enzymes

• D. Spread of infection

How can the activity of a human amylase enzyme be increased during a laboratory experiment?

• A. Adding sugar to the mixture

• B. Decreasing the pH from 7 to 3 C.

• C. Increasing the temperature from 20 °C to 37 °C

• D. Adding water to the mixture

In enzyme experiments, the rate of enzyme activity often gradually decreases. What is most likely to cause this decrease?

• A. The temperature decreasing

• B. The enzyme concentration decreasing

• C. The pH decreasing

• D. The substrate concentration decreasing

What contributes to the structure of an enzyme?

• A. Sequence of bases linked by hydrogen bonds

• B. Sequence of substrates linked by condensation reactions

• C. Sequence of amino acids linked by peptide bonds

• D. Sequence of polypeptides linked by hydrolysis reactions

The graph below shows the effect of substrate concentration on enzyme activity. What conclusion can be drawn about section X of the graph?

• A. The enzyme has started to denature and the reaction slows down

• B. The reaction has finished and the substrate has been used up

• C. The enzyme is saturated and is working at its maximum reaction rate

• D. Some of the enzyme has been consumed and the reaction has reached a plateau