Tasmanian Devils put on Endangered
Species List
(May 19 2008)
Video Clip from
National Geographic
Energy Movement
in
Ecosystems
Base of all food chains?
Source of energy for all
organisms?
What is meant by the albedo of a surface?
What happens to the amount of available energy every time
you go up a level in the food chain?
Why do we see
colors?
Light is a form of energy. What we perceive as
visible light is really a narrow range of energy
wavelengths which includes radio waves,
microwaves, x-rays, etc.
Wavelength and
Frequency
Energy can be thought of as travelling in waves.
The distance between two wave crests is called the
wavelength.
The number of waves that pass a point in a given
time is called the frequency, and is measured in
hertz (waves per second).
Wavelength and
Frequency
You can see that shorter wavelengths will result in
higher frequency...if the waves are spaced closer
together, more crests will pass a point per second.
Visible Light Spectrum - Colors by
Wavelength
We perceive color when light enters our eyes,
triggering a signal to be sent to our brain. The
wavelength of the light determines how our brain
interprets the signal, which determines the color we
see.
How Our Eyes Perceive
Color
Wavelength and
Frequency
The greater the frequency, the greater the energy
contained by the wave. Energy made up of shorter
wavelengths tends to penetrate deeper than energy
with longer wavelengths.
This is why, for example, things seem to take on a
bluish color when you go underwater...the blue end
of the visible light spectrum is made up of the
shortest wavelengths, and therefor blue light has the
greatest frequency, or highest energy. Blue light is
able to penetrate deeper underwater, while reds,
oranges, yellows, and greens are absorbed by the
water.
At 90 feet deep, this sea turtle and the
surrounding coral reef appears blue.
Reminder to include sources on posters.
Be careful of your sources...Wikipedia is fine, but be
sure to check any facts you find there with other
sources...it can be a good starting point, but don't
automatically believe what you find on the site...it is
too easy to be altered.
Also, evaluate any other sites you use carefully...
For example: View website on facts about Beluga
whales
Trophic Levels
Classify the organisms in this
food chain as a producer, or as a
consumer
Grasshopp
er Eats
Grass
Consumers can also be classified
by their specific level in the food
chain as primary, secondary,
tertiary, quaternary, etc.
Grasshopp
er Eats
Grass
Review Homework (from Monday)
Read Section 1.10
Complete Questions 1-3 on page 33)
1)
Why is sunlight important for the
biosphere?
(first of all, what is the biosphere?)
2)
Make a pie graph showing what happens
to the energy from the Sun that penetrates
into Earth's atmosphere.
Label each
piece of the pie.
44%
30%
Heats
atmosphe Reflected
by clouds
re
and25% or
Heats and
surface
surface
evaporates
water
0.023%
Photosynthe
sis
1%
Generates
*Notice that the percentages
wind
don't equal exactly
100%; this is because some of
3)
In your own words, describe the Albedo
effect.
If you were building a doghouse in the
desert, what color would you make it?
With a partner, read Question #4 on page 33.
Try to answer A, C, and D.
(a)
Write a hypothesis to explain why
temperatures became lower after
an eruption?
(c)
Predict which was the largest eruption.
(d)
Predict what would happen to
temperatures if volcanic activity
stopped.
Homework
Read (pages 34-37) in Section 1.11
(stop at the end of the section titled
"Limits on Energy Transfers and the Number of Trophic
Levels"
Complete Questions 1-4, 7, and 8 on page 39)
1.
In your own words, explain what is meant
by the term "trophic level".
2.
Why are producer organisms called
"autotrophs"?
3.
How does a heterotroph differ from
an autotroph?
4.
What type of food would be consumed by
a secondary consumer?
Explain your answer.
7.
Explain why an Arctic ecosystem would
be more fragile than a southern forest
ecosystem?
8.
In your own words, explain the first and
second laws of thermodynamics.
Another way to classify organisms is by
Trophic level.
First Trophic
Level:
Second Trophic
Level:
Third (and higher)
Trophic Levels:
Some organisms routinely occupy multiple trophic
levels;
what types would you expect these to be?
The organism in an ecosystem that has nothing above it
in the food chain is called the:
1)
2)
If a rabbit eats the grass, much of the energy contained in the
grass is used by the rabbit for maintaining its own life
systems...so not all of this energy is available to a wolf that
eats the rabbit. Also, the wolf doesn’t consume ALL of the
matter in the rabbit...some is left for the decoposers to take
care of.
The result of this is that every time energy is transferred
up a level in the food chain, there is a total energy
loss...in other words, there is less total energy available
for the organism at the higher level.
The exact amount varies, but in general you can estimate
that only about 5-10% of the total energy at one trophic
level will actually be available to the next level. (This
amount varies greatly, but about 10% is a good enough
approximation for our purposes.
A simple way to think of this rule goes something like this:
*It takes 10 kilogram of plant material to grow 1
kilogram of herbivore.
*In the same way, it takes 10 kilograms of herbivore
to grow 1 kilogram of carnivore.
This also explains why young animals need to eat
more than adult animals relative to their body size...the
adults aren't increasing their size, they only have to
maintain their size, and get enough energy and nutrients to
run their systems, maintain and repair their cells.
Carrying Capacity:
The maximum sustainable (long-term)
population which can be supported by
existing resources in an ecosystem.
Limiting Factor:
Anything which acts to lower (or limit)
the growth of a population.
What might be some examples of limiting factors?
Several population studies have found a relationship
between predator and prey populations, such as the lynx
and snowshoe hare, where both populations cycle
through periods of highs and lows.
Can you explain the fluctuations?
Three Ways to Graph Energy in an Ecosystem
1)
Pyramid of
energy
2)
Pyramid of
numbers
3)
Pyramid of
biomass
Turn to page 85, and read Question #16.
In your groups, discuss answers to A, B, C, and D.
Review answers with the class.
Homework Questions to Discuss
Questions 9-11 and 14 on page 39
Questions #1 and 2 on page 44
Questions 7 (b and c only) and 9 on page 46
9)
Explain why only 10% of the energy
available in a plant is transferred to
the primary consumer.
10)
Using the example of a cat and a mouse,
explain the factors that account for the
loss of energy in the transfer from mouse
to cat.
11)
What data would you need to collect to
create an ecological pyramid of numbers?
14)
Figure 11 shows pyramids of biomass and
numbers for a deciduous forest.
Explain why the two are different.
Pyramid
of
numbers
Pyramid
of biomass
Page 45
1)
In your own words, define the term
"ecological niche".
2)
Give examples illustrating the problems
that can be created when a new species is
introduced into an ecosystem.
Page 46
7, b)
Use figure 2 to predict an ecological
pyramid of numbers using the organisms
shown.
7, c)
Predict an ecological pyramid of energy.
9)
System
Indicate whether each of the four
ecosystems listed in Table 1 can be
sustained. A check indicates the type
of organism is present. Defend your
answers.
Autotrophs
Decomposers
A
B
C
D
Heterotrophs