The food web above represents feeding relationships in a biological community near a deep-sea hydrothermal vent. Hydrothermal ve
nts are geysers on the seafloor that gush super-heated, mineralrich water. The seawater surrounding hydrothermal vents typically contains carbon dioxide (CO2), molecular hydrogen (H2), hydrogen sulfide (H2S), and methane (CH4). Sunlight, however, fails to reach the seafloor where deep-sea hydrothermal vents are located. As part of an investigation, researchers collected living specimens from an area near a deep-sea hydrothermal vent. Mussels in the collection were found to be dependent on molecular hydrogen in seawater. Also, the researchers discovered multiple species of bacteria living in the gills of the mussels. Mussels use gills for filter-feeding and gas exchange with the surrounding seawater. On the basis of their experimental results, the researchers hypothesized that some bacteria living in the gills of the mussels are capable of chemosynthesis. Which of the following best explains how biological communities near deep-sea hydrothermal vents can exist in a habitat lacking sunlight?
a) Environmental conditions on some distant planets resemble those experienced by organisms
living near hydrothermal vents.
b) Heterotrophs metabolize carbon-containing compounds produced by the photosynthetic
organisms that live on the seafloor.
c) Some organisms rely on energy captured from inorganic compounds to drive basic biological processes.
d) Some organisms that can tolerate high temperatures are single celled, whereas others are multicellular.
Answer: c) Some organisms rely on energy captured from inorganic compounds to drive basic biological processes.
Explanation:
Deep-sea hydrothermal vents are hot spots of geothermal water. The organisms living in deep-sea vents cannot obtain energy from sunlight. They are dependent on chemosynthesis, which involves the utilization of inorganic substances to produce organic substances, which allows their survival and act as a source of energy. In the given situation, bacteria present on the surface of mussels are capable of chemosynthesis also the mussels are dependent upon inorganic hydrogen in seawater. Thus chemosynthesis supports the survival of organisms living in the deep sea vents.
