IB Biology HL C1.1 Enzymes and metabolism Question Bank

Common bottlenose dolphins, Tursiops truncatus, are marine mammals of temperate and tropical oceans throughout the world, where they feed on fish, squid and crustaceans.

Research has been carried out on a population of these dolphins in Sarasota Bay, Florida. The table shows the mean sea surface temperature in Sarasota Bay and catch per unit effort (CPUE) in winter and summer. A large CPUE indicates it would take little effort for the dolphin to catch a lot of prey.

Diabetes in Youth is a study that examined diabetes (type I and type II) among children and adolescents in the United States. The graphs show the rate per year of new cases of type I and type II diabetes among young people (aged less than 20 years) by ethnicity between 2002-2005.

Peroxidase enzyme (HRP) in horseradish (Armoracia rusticana) plants is used to break down hydrogen peroxide into water and oxygen. The extracted enzyme also has industrial uses when immobilized in ferrosoferric oxide $\left(\mathrm{Fe}_{3} \mathrm{O}_{4}\right)$ and embedded in a polymer matrix. The graph shows the relative activity of HRP in both its free and immobilized forms at different temperatures. The results are a mean of three trials.

The rate of hydrolysis of fish proteins using the enzymes papain and pancreatin was monitored using the apparatus shown. The pH decreased with the progress of hydrolysis, so alkali in the burette was added as necessary in order for the hydrolysis to proceed at constant pH . The rate of protein hydrolysis was measured as the amount of alkali added. Measurements were taken at constant conditions of temperature and pH for two enzyme concentrations, 1 % and 0.1 %.

Lactase enzyme from the fungus Aspergillus oryzae was immobilized on two different support materials, chitin and chitosan. The activity of the immobilized enzyme was measured at $55^{\circ} \mathrm{C}, \mathrm{pH} 4$ and $200 \mathrm{gdm}^{-3}$ of lactose at increasing masses of enzyme per kilogram of either chitin or chitosan as a support.

The graph shows enzyme activity of immobilized lactase at increasing masses of enzyme per mass of support.

Urease is an enzyme found in soybeans (Glycine max) that catalyses the hydrolysis of urea into ammonia and carbon dioxide. The reaction can be summarized as shown.

In order to investigate the effect of temperature on the activity of urease, a student placed 0.50 g samples of urease powder into 10.0 ml of 1.0 % aqueous urea solutions in five separate test tubes. Each test tube was held at a different temperature and the change in pH in the samples was measured after 20 minutes. Ammonia is a weak base and its formation causes the pH of the reaction mixture to increase. The results are summarized in the table.

Lipase was extracted from the fungus Aspergillus niger and used to hydrolyse one of its substrates. This was repeated for an immobilized form of lipase. The graph shows how the enzyme activity varied at different pH and temperature levels.

Cholinergic synapses use acetylcholine as their neurotransmitter. They are widespread in the body, passing on signals to muscle cells. These synapses are affected by neonicotinoid pesticides.

The diagrams, which are not drawn to scale, show the synapse between two neurons and a detail of the synaptic cleft.

Egg white or albumin solutions can be used in enzyme activity experiments. The influence of different ions on the activity of a peptidase was determined at $55^{\circ} \mathrm{C}$ and at pH 6.5 . The concentration of each ion studied was the same.

A study investigated the effect of pretreating egg white proteins with ultrasound on how they were digested by enzymes. A series of 10 % egg white solutions were exposed to ultrasound waves. Enzymatic hydrolysis of the egg whites with and without ultrasound pretreatment was then carried out using the enzyme alcalase in optimum conditions.