Download SA #5 -- Energy and Nutrient Assimilation

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SA #5 -- Energy and Nutrient Assimilation
Part #1 Autotrophs
Overview:
In SA #4, we emphasized that life on Earth depends on a continuous supply of solar
energy which interacts with the planet’s atmosphere, land, and oceans in such a way
as to produce global climatic patterns and local microclimate differences. In this
assignment, divided over two lectures, we will examine two major groups of
organisms based upon how they assimilate energy and nutrients (raw materials).
Assimilation refers to the capture and metabolic conversion of energy and nutrients
into the constituents of cellular structure necessary for growth. The two groups are
the autotrophs (including photosynthesizers, and chemosynthesizers) to be
considered in SA #5-Part 1, and the heterotrophs, in Part 2.
Reading:
SA #5, Part #1 – Molles Chapter 6, pages 144-150; 155-157; 161-164
Study
The approach of SA #5 is to bring you through a series of topical studies
Questions: referenced to specific pages in your Molles text in support of each topic. Use word
processor or hand-written notes to record your personal responses for each topic.
A. Concept #1:
1.
Organisms may be classified according to their trophic niche, or the source of
energy they utilize, whether light, organic molecules, or inorganic molecules.
Develop an outline, concept map, or table which arranges the following trophic categories
into a correct hierarchy of groups and subgroups. Briefly define the source of energy used
by the principal trophic categories (e.g. attach an extra ‘bubble’ in the concept map):
autotroph
heterotroph
chemosynthetic autotroph
photosynthetic autotroph
2.
herbivore
carnivore
detritivore
decomposer
C3 autotrophs
C4 autotrophs
Crassulacean acid metabolism plants
What is the nature of the relationship between supposed evolutionary advancement in the
major taxonomic kingdoms and trophic diversity. What does this suggest, particularly
about the most “simple” and “primitive” species in Kingdoms Bacteria and Archaea?
B. Photosynthetic autotrophs have adaptations that favor fitness in acquiring photosynthetically
active radiation (PAR) under various environmental conditions that influence energy and
nutrient acquisition in a given microclimate or region. [pages 146-150]
3.
Path and reduction (attenuation) of PAR by the stratification of a biotic community:
a. Approximately what percentage of total solar radiation incident upon the top of a
forest canopy would register on a quantum sensor positioned at that level?
b. Approximately what percentage of the incident radiation incident upon the quantum
sensor as in (a.. top of canopy) would be available to a plant on the forest floor?
c. What processes are involved in causing attenuation (reduction) of light energy
between the top of the canopy (a.) and the ground surface (b.)?
5.2
4.
Use the energy flow diagram below for a typical green leaf to answer the following:
a.
b.
c.
5.
Use your knowledge of the global energy flow diagram for Earth in SA #4 to discuss
the processes involved in energy exchange between leaf and environment.
Consult Chapter 18 (introductory paragraphs) to define gross primary production, or
GPP. Distinguish GPP from net primary production (NPP).
How will reflection [R] and transmission [T] influence net radiation [Q] and GPP?
Distinguish the three photosynthetic pathways; namely, C3, C4, and CAM; and then,
a. Answer Molles’ Review Question #2.
b. Answer Molles’ Review Question #3.
C. Chemosynthetic autotrophs are microbes that have the capacity to convert inorganic nutrients
to organic compounds by oxidative reactions involving inorganic molecules such as sulfides
and ammonium rather than relying upon photosynthetic light reactions. [pages 154-157]
6.
Compare the energy deriving reactions of photosynthetic bacteria and plants with that of
chemosynthetic bacteria in ocean-floor geothermal communities with respect to:
a. Primary source of energy
b. Source, destination, and electromotive force for electrons during ATP production
7.
How do nitrifying bacteria in soils compare to sulfur oxidizers in undersea communities?
D. Concept #2: Energy Limitation – The rate at which organisms can take in energy is limited.
[pages 157;161-164]
8.
Learn to sketch a photosynthetic response curve, point out the portion of the curve in
which PAR is limiting and the portion in which photosynthesis is light saturated. Then
answer:
a. How does the photosynthetic response curve for a shade adapted plant species differ
from that of a plant species adapted to high solar radiation?
b. How might the light harvesting antenna pigment system of chloroplasts of shadeadapted species differ from those of high-light adapted species?
c. Why do photosynthetic response curves for C4 plant species have a much higher Isat?
9.
How does “Optimal Foraging Theory” account for certain plant species that adjust root:
shoot biomass ratio in response to (a) low light microclimates, (b) nutrient-poor soils?
General Ecology
BIO 2600
LECTURE-DISCUSSION FEEDBACK FORM
Names (Contributing Cooperative Group Members): __________________________________________
_____________________________________________________________________________________
Lab Sec (circle one) W
R
F
Date:
INSTRUCTIONS: Please print and keep this form in a convenient place in your Ecology notebook
(“journal”). On certain occasions during the semester, you may be asked individually, or in
cooperation with other members of your cooperative learning group, to respond to one or more
questions of the type given below. As with Quizzes, you must be in attendance to sign your name in
the space above. For group feedback, one form will be requested per group.
Example Questions:
A. In one or two sentences, state your understanding or current position regarding an issue or concept we
have been discussing. (Group Response or Individual)
B. What is the most significant thing you have learned from General Ecology so far?
C. What specific aspects of the BIO 2600 lectures have been most helpful to you? Most challenging?