-Food Web vs. Food Chain (Food Web)
A series of what eats what in a food… * chain- one option
* web- many options
-Direction of Arrows/What Arrows Mean
* They point the way the energy is going
* Ex. Energy in deer is passed to wolf when deer is eaten
-Consumers vs. Producers
* Producer- organisms using sunlight to make energy
* Consumer- organisms eating plants/animals to receive energy from them
-Herbivores, Carnivores, Omnivores
* Herbivores- eat plants
Primary Consumers
* Omnivores- eat plants and meat
* Carnivores- eat meat
Secondary Consumers
-Reading a Food Web/Parts of a Food Web (Food Web)
Sun
Producers
Primary
Secondary
Tertiary
First
Second
Third
Fourth
Fifth (and usually last)
Energy
Energy
Energy
Energy
-Amount of Energy Lost/Passed on in Food Webs
* About 5% is lost, usually more
* Organisms use some of the energy that they receive, therefore, decreasing amount they have
* 100% to 95% to 80% to 72% to…
-Photosynthesis
******** Photosynthesis- how producers get the sun’s energy
-Role of Photosynthesis in Food Webs
* Producers turn the sunlight into energy or building materials through photosynthesis
* Organisms eat the producers and receive the energy/building materials that was in them
-Needs of Photosynthesis
* H₂O--- Water
* CO₂--- Carbon Dioxide
* Sunlight
-Products of Photosynthesis
1. H₂O molecule in plant from ground and leaf cells (minimal)
2. Energy from sunlight = Hs and O spilt (barrier broken)
3. O and another O combine to form O₂
4. O₂ leaves the leaf through microscopic holes called stomata
5. CO₂ (organisms on Earth) enters the leaf through the stomata
6. Energy from sunlight = C and O split from O
7. 2 Hs and O form H₂O. O and C form CO.
8. Any remaining Hs, Os, and Cs form a new molecule called glucose
-Inferences on What Happens When Parts of Food Webs are Damaged (RASE)
 There would be a chain effect:
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To what extent do living things depend on each other to survive?
Living things depend on each other to survive. In the world, the
different stages in which animals depend on each other to survive are
categorized into a food chain, web, or a tropic-level. Each and every one
of these graphs starts with the sun. Therefore the next step in a food
web, chain, or tropic-level (i.e. food web) is the second level. This level
consists of producers. These producers are really plants and plant-like
organisms that use photosynthesis to take the energy from the sun and
use it (Tropic). Producers depend on the sun to give them energy
(Energy Video) that they can use and produce through photosynthesis.
The third level of a food web has primary consumers. Primary
consumers are usually herbivores (i.e. plant-eaters) and omnivores (i.e.
plant and meat-eaters). Since all organisms need food to survive, most
have to eat other living things to do that (Food). The primary
consumers, then, have to eat producers in order to obtain energy and
other nutrients from the organisms (Energy Video). Primary consumers
eat producers, thus relying on producers to go through photosynthesis
and create energy for them. But primary consumers don’t get all of the
producer’s energy after eating it. About 10% of the energy that is
produced during photosynthesis is used in a plant’s system before a
primary consumer eats the producer. So since 10% of the energy was
used, that is a 10% less amount of
energy that’s passed onto a primary consumer (Tropic).
You’ve guessed it. Secondary consumers are found in the fourth level of the food web. These consumers are
omnivores and carnivores (i.e. meat-eaters). Secondary consumers eat the primary consumers to get energy and nutrients as
well (Tropic). So, producers are eaten by primary consumers that are eaten by secondary consumers [i.e. “anchovies, which are
secondary consumers, eat zooplankton, which are primary consumers, that eat phytoplankton, producers, that get energy from
the sun through photosynthesis” (Food)]. Secondary consumers depend on primary consumers to eat producers to get energy
that they can pass on in the food web. And now there is even less energy in the secondary consumer than there was in the
primary consumer because some of it was used.
Now we’re at the fifth level of a food web. Tertiary consumers eat secondary consumers (Energy Video). They receive
a very small amount of energy from the secondary consumers because most of it has been used. These tertiary consumers are
usually carnivores (Energy Video) and depend on secondary consumers for energy, no matter how little. The fifth level is usually
the last level of a food web because all of the energy is typically gone. But there are some exceptions, where the food web goes
on to a sixth or seventh level [i.e. “the sun has energy used by a single-celled algae, that is eaten by a zooplankton, which is
eaten by a anchovy, which is eaten by a salmon, which is eaten by a sea lion, which is eaten by an orca, which is eaten by a
white shark” (Tropic)]. And all of these organisms, up to the eighth level, depend on one another in order to survive.
This article distinctly shows how living things depend on each other to survive. A food web (shown on page 2) starts
out with the sun. A producer then takes energy from the sun using photosynthesis. A primary consumer eats the producer and
is eaten by a secondary consumer, which is eaten by a tertiary consumer, all the time having the amount of energy passed on
shrink. “… When you trace any food back to its source, it all starts with plants or plantlike organisms. Always,” (Food). And since
producers get energy from the sun… the real source of food is the sun!