BIOL 1120 Lecture Notes - Lecture 24: Eutrophication, Garter Snake, Water Cycle

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31 May 2016
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Chapter 57: Dynamics of Ecosystems
I. The Nature of Ecosystems
A. Overview of the Participants
1. Regions on the earth function as systems running on energy from the sun processed through various organisms.
2. _____________ are autotrophs that can capture sunlight energy and incorporate it into organic compounds.
3. __________________ are heterotrophs that feed on tissues of other organisms.
a. _____________ (primary consumer) eat plants.
b. _____________ (secondary consumer) eat animals.
c. _____________ (primary or secondary consumer) eat a variety of organisms.
4. _____________ (scavengers) feed on partly decomposed particles of organic matter (detritus).
a. ___________________
i. Vultures
i. Ravens and crows
ii. Hyenas
b. ___________________
i. Earthworms
ii. Fly maggots
iii. Beetles
5. _____________ are also heterotrophs and include fungi and bacteria that extract energy from the remains or products of
organisms.
5. An ______________ is a complex of organisms interacting with one another and with the physical environment (2
principles):
a. ________________________________ (Fig. 57.10, p. 1217).
b. ________________________________.
B. Food Chains and Food Webs
1. ____________ are a simple linear sequence of who eats whom.
2. ___________ are interconnected food chains in which the same food resource is often part of more than one food chain.
VIII. Energy Flow Through an Ecosystem
A. Trophic levels (Fig. 57.8, p. 1215)
1. ______________ (feeding levels) are a hierarchy of energy transfers.
a. Level 1 (closest to the energy source) consists of producers.
b. Level 2 comprises herbivores.
c. Levels 3 and above are carnivores.
d. Decomposers feed on organisms from all levels.
2. In a simple food chain (for example: grass  cutworm  garter snake  plover  hawk) the energy initially captured by
the producers passes through no more than four or five trophic levels.
B. Primary Productivity
1. ___________________________ is the total rate of photosynthesis for the ecosystem during a specified interval.
2. ___________________________ is the rate of energy storage in plant tissues in excess of the rate of respiration by the
plants themselves.
C. Energy/Biomass Pyramids
1. Trophic structure can be diagrammed as a pyramid in which producers form a base for successive tiers of
consumers above them.
2. Pyramids can be of 2 basic types:
a. A __________________ makes provision for differences in size of organisms by using the weight of
the members in each trophic level (Fig.57.13b. p. 1219).
b. An _________________ reflects trophic structure most accurately because it is based on energy losses
at each level (Fig. 57.13a, p. 1219).
D. Biological Magnification in Food Webs
1. DDT, which was an effective chemical to kill mosquitoes, accumulates in fatty tissues and results in
__________________ and unexpected non-target effects.
2. Even though DDT has been banned since the 1970s, the chemical is very persistent in certain sections of the
environment, namely sediments.
IX. Nutrient Cycles
A. __________________ (a.k.a. water cycle) (Fig. 57.2, p. 1209)
1. Water is moved or stored by evaporation, precipitation, retention, and transportation.
2. Water moves other nutrients in or out of ecosystems.
a. Watershed funnels rain or snow into a single river.
b. Nutrients are absorbed by plants to prevent their loss by leaching.
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