(a) Describe the induced-fit hypothesis of enzyme action. (b) Many marine organisms can become attached to hard surfaces such as rocks or the surfaces of ships. These organisms are known as fouling organisms. The larva of the acorn barnacle, Amphibalanus amphitrite, is an example of a fouling organism. One of these barnacle larvae is shown in Fig. 3.1. The larvae of A. amphitrite use a protein to attach themselves to the surfaces of ships. It is expensive to remove fouling organisms from ships. Scientists have developed substances to prevent the attachment of larvae. However, some of these substances are toxic and have been responsible for a decrease in marine biodiversity. Scientists investigated the effect of using an immobilised protease, subtilisin A, to prevent the attachment of the larvae of A. amphitrite to surfaces. The scientists used 4 different concentrations of subtilisin A which had been immobilised onto the surface of a polymer film. As a control they used denatured subtilisin A immobilised onto the surface of the same polymer. Glass slides were also used as a control. The larvae were released into 6 tanks of artificial sea water: • 4 tanks, each with a polymer surface and a different concentration of immobilised subtilisin A • 1 tank with a polymer surface and denatured immobilised subtilisin A • 1 tank with glass slides instead of a polymer surface. The number of larvae that attached to the different surfaces in the tanks was counted after 24 hours and again after 48 hours. The number of larvae attached in each tank was expressed as the percentage of the total number of larvae released in each tank. The results are shown in Fig. 3.2.