Exam 20: Nutrient Cycles

The metabolic process of denitrification

Lignin is a complex polymer of methoxylated ________ compounds and is present in ________.

Coccolithophores and foraminiferans both use ________ to form their exoskeletons.

Mercury has both organic and inorganic forms that are neurotoxic.

In the oceans,sulfur exists primarily as ________,and in rocks and sediments sulfur occurs mostly as ________ and ________.

When carbon is limiting in a system,sulfate reducers often predominate the system when sufficient sulfate ions are present for reduction.

Nitrification and anammox both

Draw a microbial-based nitrogen cycle.In the open ocean there is plenty of sunlight and carbon dioxide for primary production,yet photosynthesis is limited in the open ocean compared to other aquatic environments.What limits photosynthesis in the open ocean?

Carbon dioxide is the only greenhouse gas produced by anthropogenic activities.

The mercury in fish is normally in the form of elemental mercury (Hg⁰).

Which is the MOST toxic form of mercury?

Which organisms form the foundation of the carbon cycle?

Which iron species is produced primarily from iron smelting and rarely is produced by microbial-mediated processes?

Humic acids are difficult to degrade,and therefore they usually remain in a system for several decades.

How are the Ca cycle and the C cycle linked in marine environments? How will increased carbon dioxide from anthropogenic activity affect the Ca and C cycling in marine environments?

Methanogens,among other compounds,use alcohols and fatty acids to synthesize methane gas in anoxic environments.

The two main biological activities in the Ca and Si cycles are the biosynthesis of shells and exoskeletal material as well as the mineralization of these materials in sediments.

Which of the following is a sulfide?

The primary energy source for termites comes from

Syntrophic organisms cannot grow fermentatively without a hydrogen-consuming partner organism.