Transcript Standard 13

Standard 13
Lesson 1
Food Chain- a succession of organisms in an
ecological community that constitutes a
continuation of food energy from one
organism to another as each consumes a
lower member and in turn is preyed upon by
a higher member.
Lesson 1
Food chains are also called trophic social networks which
describe the eating relationships between species in an
ecosystem. Organisms are connected to the organisms they
consume by lines representing the direction of organism or
energy transfer. It also shows how the energy from the
producer is transferred to the consumer. Most of the times a
food chain refers to a graph where only connections are
recorded, and a food network or ecosystem network refers to
a network where the connections are given weights
representing the quantity of nutrients or energy being
transferred. Trophic levels may contain either a single
species or a group of species that are presumed to share both
predators and prey. They usually start with a plant and
end up with a carnivore.
Lesson 1
The food chain consists of four main parts:
• The Sun: which provides the energy for everything on the
planet.
• Producers: these include all the green plants. These are also
known as autotrophs every, since they make their own food.
Ultimately, organisms is dependent on plants for oxygen
and food.
• Consumers: in short, consumers are every organism that
eats something else. They in herbivores, carnivores,
parasites, and decomposers.
• Decomposers: these are mainly bacteria and fungi that
convert dead matter into gases such as carbon and nitrogen
to be released into the air, soil, and water. Fungi, and other
organisms that break down dead organic matter are known
as saprophytes.
Lesson 1
The bottom layer of the energy pyramid has
plants and other producers. The middle layer
has herbivores. They eat plants and other
producers. The top layer has types of
carnivores. They eat the herbivores and
maybe some other carnivores. In a healthy
ecosystem, there are lots of producers, and
some herbivores but not many carnivores.
Lesson 2
Energy Pyramid- a pyramid showing the
energy flow in an ecosystem.
Example of an
energy pyramid
Lesson 2
For the ecosystem to function energy must be
available and it must be transferred. Why?
Because of the First and Second Laws of
Thermodynamics. The First Law states that
energy can neither be created or destroyed,
but can be converted to one form to another.
The Second Law states that everything is
running downhill or, more formally,
everything in the universe is going from a
more organized state to a less organized one.
Lesson 3
FOOD WEBS - is a model that shows all the
possible feeding relationships between
organisms living in an ecosystem.
Lesson 3
• food webs are more accurate models than food chains.
• A food web is actually several food chains joined together,
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Because most organisms depend on more than one species
for food
Food chains are overly simplistic as representatives of what
typically happens in nature
The food chain shows only one pathway of energy and
material transfer.
The food web is divided into two broad categories: the
grazing web, which typically begins with green plants,
algae, or photosynthesizing plankton, and the detrital web,
which begins with organic debris
These webs are made up of individual food chains. In a
grazing web, materials typically pass from plants to plant
eaters (herbivores) to flesh eaters (carnivores). In a detrital
web, materials pass from plant and animal matter to
LESSON 3
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Generally, many interconnections exist within food webs
Food webs shows how energy and material flow through a community of species as a result
of these feeding relationships connected by lines or arrows called "links", and the species
are sometimes referred to as "nodes" in food web diagrams
The pioneering animal ecologist.
Typically, species are Charles Elton (1927) introduced the concept of the food web (which
he called food cycle) to general ecological science.
The herbivores are usually preyed upon by carnivores, which get the energy of the sunlight
at third-hand, and these which has no enemies, and which forms, as it were, a terminus on
this food cycle. There are, in fact again may be preyed upon by other carnivores, and so
on, until we reach an animal, chains of animals linked together by food, and all
dependent in the long run upon plants. We refer to these as 'food-chains', and to all the
food chains in a community as the 'food-cycle.'"
A food web differs from a food chain in that the latter shows only a portion of the food web
involving a simple, linear series of species connected by feeding link
A food web aims to depict a more complete picture of the feeding relationships,
and can be considered a bundle of many interconnected food chains occurring
within the community
Lesson 3
Examples of food web charts.
Questions
Question 1:
What is a food chain?
Answer
A succession of organisms in an ecological
community that constitutes a continuation
of food energy from one organism to another
as each consumes a lower member and in
turn is preyed upon by a higher member.
Question 2
What is the difference between a food chain
and a food web?
Answer
A food web differs from a food chain in that
the latter shows only a portion of the food web
involving a simple linear series of species
connected by feeding link
Question 3
What do food webs do?
Answer
Food webs shows how energy and material
flow through a community of species as a
result of these feeding relationships
connected by lines or arrows called links.
Question 4
What is another name for the food chain?
Answer
Trophic Social Networks
Question 5
What does a food chain show?
Answer
The food chain shows only one path way of
energy and material transfer.
Question 6
What is an energy pyramid?
Answer
An energy pyramid is a pyramid showing
the energy flow in an ecosystem.
Question #7
What do food chains refer to?
Answer
They usually refer to graphs.
Question #8
What does the food chain consist of?
Answer
The main parts of the food chain are the sun,
producers, consumers, and decomposers.
Question #9
What do the lines on the food chain represent?
Answer
The direction of organisms or energy transfer.
Question #10
What do food webs show?
Answer
A food web shows how energy and material
flow through a community.
Question #11
What are the two categories that food webs are
categorized into?
Answer
The two categories that food webs are
classified in is the grazing web and the
detrital web.