Exam 22: Decomposition and Nutrient Cycling

In open-water ecosystems,turnover prevents the movement of nutrients between the bottom and surface layers.

Bacteria and fungi have higher C:N ratios than most of the plant litter they consume.

Given that mass loss is expressed as a negative exponential function (original mass remaining = e-kt),how much mass would be left after 20 weeks given a decomposition coefficient k = 0.0167 in units of proportion mass loss per week?

Soil organic matter contains recalcitrant compounds that are of low quality and contain little energy for decomposers.

The breakdown of chemical bonds that were formed during the construction of plant and animal tissues is called ________.

The rate of decomposition is greatest in

Coastal zones of contact between freshwater from streams and rivers and saltwater from the ocean are called

As decomposition proceeds,which molecule is lost to the atmosphere?

The incorporation of mineral nutrients into an organic form is called ________.

In a process known as the ________,the rise and fall of water depth with tidal cycles bring nutrients into coastal marshes from coastal ocean waters.

Bacteria,fungi,and animals are all important in decomposition.

Litter degrades into a dark brown or black homogeneous organic matter known as ________.

The microbial loop results from

Nitrogen fertilizers used for crops represent the main source of pollution in the ocean.

The rate of decomposition is faster for proteins,simple sugars,cellulose,and hemicellulose than it is for lignin.

Bacteria and fungi secrete ________ into plant and animal tissues to break down the complex organic compounds.

In salt marshes,only a small portion of primary production is consumed by herbivores.

In open-water systems such as lakes and oceans,decomposition occurs mostly in the surface layer.

In an estuary,the zone of maximum vertical difference in density of water layers is called the

Which of the following breaks down the slowest during decomposition?