Testing for biological molecules — practice question

In ecosystem studies, food chains and food webs are drawn. Read the passage below about trophic relationships on one of the Galapagos Islands. Marine iguanas eat kelp, which grows attached to rocks in shallow waters. Kelp is a photosynthetic organism. Farther inland, xerophytes are grazed by land iguanas. Many herbivorous insects, including numerous species of short-horned grasshoppers, feed on the xerophytes. An examination of the gut contents of lava lizards shows that these insects are prey for the lizards. The lizards are then preyed upon by Galapagos snakes. The snakes also hunt grasshoppers and newly hatched iguanas. The Galapagos hawk has a varied diet and captures animals such as Galapagos snakes, short-horned grasshoppers, small lava lizards and newly hatched iguanas.