Exam Questions

1)      List and describe all six possible soil horizons.

Answer:

-The O layer is made up of undecomposed and decomposed organic material and humus.

-The A layer contains a high proportion of organic matter and is a leached mineral horizon.

-The E layer is lightly colored and is the zone of maximum leaching

-The B layer is the maximum zone of accumulation of weathering products like clay, silicate, and carbonates

-The C layer is relatively unaltered and is made of unconsolidated parent material

-The R layer is considered the hard bedrock layer

2)      Briefly explain the differences between C3, C4, and CAM plants and give some examples of each.

Answer:

-C3 plants have 2 molecules of three-carbon acid as the initial products of Carbon fixation. Most land plants are C3 plants. Examples: wheat, cotton, most trees

-C4 plants have a 2 stage strategy that keeps CO2 high and O2 low in chloroplast in order to maintain a vigorous Calvin cycle. This strategy uses malic acid and has a stage in the mesophyll cell and a stage in a bundle sheath cell. These plants can handle hot, dry conditions. Examples: Sugar cane, corn, crabgrass

-CAM plants are similar to C4 plants but their 2 stages are done at different times of the day. At night, the stomata open and malic acid is created and stored. During the day, the stomata are closed and the malic acid is used in the Calvin cycle. Examples: cacti, orchids, pineapple

3)      List the 4 dominating ecological processes in the dynamics of a system and determine which parts of the following situation fall under which ecological process:

A deer hunting plan has been put into place to control the density of the deer population in the state. The deer population eventually drops to an alarmingly low level. A change is made to the deer hunting plan to limit harvesting of the deer. The deer population begins to rise again.

Answer: The 4 processes are rapid growth, conservation, release, and reorganization. The deer hunting plan being put into place is the “rapid growth” stage. The population dropping to a low level is the “conservation” stage. The change made to the hunting plan is the “release” stage. The population growing in response is the “reorganization” stage.