* not completed

. Which of these statements about geological weathering to produce soils is/are true? (Please select all that apply)

During weathering, carbonate rocks generate acidity in the soil correct incorrect

Hydrolysis reactions on some igneous rocks lead to formation of clay minerals correct incorrect

Pressure release due to erosion of rocks leads to horizontal fracturing of the rocks correct incorrect

Under reducing conditions, iron(III) oxides can be solubilized correct incorrect

Lichens on the surface of rocks enhance weathering due to the acidity they release correct incorrect

* not completed

. Which of these statements about organic matter and soil formation is/are true? (Please select all that apply)

Carbohydrates and lignin are the two major components of plant material correct incorrect

The surface layers of forest soils are generally high in organic matter correct incorrect

Humus (humin, humic and fulvic acids) is the final product of organic matter decomposition in soils correct incorrect

Typical soil organic matter concentrations in agricultural soils are in the range 1 to 5% correct incorrect

Simple sugars and starches in soil can decompose in a matter of days correct incorrect

* not completed

. Which of these statements about geological weathering to produce soils is/are true? (Please select all that apply)

The solubility of non-redox elements may be affected by redox behaviour of elements like iron correct incorrect

Changes in interlayer ions in 2:1 clay minerals can cause changes in the physical properties of these minerals correct incorrect

Hydrolysis reactions of primary silicates involves release of hydronium ions into the solution correct incorrect

Fulvic acid can bind to metals through carbonyl and carboxyl functional groups correct incorrect

Lichen on the surface of rocks protects them from being weathered correct incorrect

* not completed

. Which of the following statements correctly describe aspects of organic matter degradation in soils? (Please select all that apply)

The half-life of lignin from plant material in soil is typically measured in 10s or 100s of days correct incorrect

Heterotrophic organisms incorporate carbon compounds into their own biomass correct incorrect

Forest soils typically have a lower organic matter content than well-tended agricultural soils correct incorrect

The C:N ratio of organic residues in soil increases as degradation continues correct incorrect

Humus is the final product resulting from degradation of plant material in soil correct incorrect

* not completed

. Which of the following statements correctly describe aspects of organic matter degradation in soils?  (Please select all that apply)

Organic matter in forest soils decomposes more rapidly after the forest has been cleared correct incorrect

Most of the carbohydrate found in plant tissues is in the form of cellulose, hemicellulose, and some starch correct incorrect

The mineral content of plant dry matter left on soil surfaces can contribute to soil fertility correct incorrect

When a supply of fresh organic matter is added to soil, the microbial population is temporarily supressed correct incorrect

Either the degradative pathway or the synthetic pathway can be used to explain the formation of humic material from fresh organic matter in soil correct incorrect

* not completed

. Which of the following influence the processes and the rate of soil formation? (Please select all that apply)

Human activities correct incorrect

The climate correct incorrect

The nature of the bedrock in the area correct incorrect

The local topography correct incorrect

Type and amount of vegetation in the area correct incorrect

* not completed

. Which of the following soil-related processes contribute to removal of carbon dioxide from the atmosphere? Please select all that apply.

Microbial oxidation of soil organic matter correct incorrect

Respiration by plants growing in a field correct incorrect

A forest fire correct incorrect

Rapid growth in a temperate rain forest correct incorrect

Chemical weathering of limestone correct incorrect

* not completed

. Which of the following statements about nitrogen is/are true? Please select all that apply.

Mature yellow grass shoots have a C:N ratio of 0.25 correct incorrect

Fresh plant material has a C:N ratio between 12 and 120 correct incorrect

Soil microorganisms incorporate nitrogen into their bodies as proteins and structural materials correct incorrect

The OM:N ratio in humic materials is around 20:1 correct incorrect

High %N content of materials indicates there will be a high C:N ratio correct incorrect

* not completed

. Which of the following statements about carbon/carbon dioxide sequestration is/are true? (Please select all that apply)

Annually, anthropogenic processes release 8.5 Gt of carbon dioxide into the atmosphere correct incorrect

The oceans are responsible for sequestering 27% of the anthropogenic carbon released annually correct incorrect

Terrestrial systems are responsible for sequestering 52% of the 56% of the anthropogenically released carbon correct incorrect

43% of anthropogenically released carbon stays in the atmosphere correct incorrect

Reforestation practices account for 20% of the total biomass in a forest system correct incorrect

* not completed

. Which of the following statements about redox reactions is/are true? (Please select all that apply)

An increase in the oxidation state of an element disturbs the charge balance of a mineral correct incorrect

Reduction of iron in the primary mineral biotite produces the 2:1 layer clay mineral vermiculite correct incorrect

Oxidizable elements in low oxidation states may be susceptible to oxidation when exposed to the atmosphere correct incorrect

Redox is an important process involved in chemical weathering correct incorrect

In soil chemistry, due to its abundance, iron is the only important element when considering redox processes correct incorrect