Biotic and Abiotic
All things on Earth fall into one of two categories:
Abiotic: not, and never has been, alive
Thought Question 1
Identify five biotic and five abiotic factors in Edgard.
Carbon can make long molecular chains and rings
It circulates through the biosphere
All CO2 is circulated throughout all Earth spheres
Thought Question 2
About how much of the Earth’s atmosphere is CO2?
The Carbon Cycle
like burning fossil
fuels (coal, gas, oil)
Carbon Cycle continued
Carbon is removed from the atmosphere by:
Plants and bacteria “fix” it into sugar molecules
Thought Question Picture
Draw a picture of diagram of the carbon cycle on
your own paper. Be sure to label each part of your
Thought Question 3
Why are scientists concerned about rising levels of
atmospheric carbon dioxide?
Solar energy and the
Also referred to as the hydrologic cycle
It’s driven by the sun’s energy and temperature
differences on Earth
The Nitrogen Cycle
DNA, RNA and
78% of our
use it in this form
Fixing nitrogen step 1
Thought Question 5
Imagine the beginning of life on Earth. How
important would lightning’s fixation of nitrogen
have been at that time as compared with today?
Fixing nitrogen step 2
The rest of the usable nitrogen is produced by
Most live in the roots of plants called legumes, like
soybeans, clover, alfalfa.
Fixing nitrogen step 3
Organisms cycle nitrogen through their bodies.
Animals expel it with urine, where is comprises part
of ammonia and some proteins.
Fungi and bacteria degrade it so it stays in the soil
and plants can use it, called denitrification.
Nitrogen fixation step 4
Humans can also fix it directly from the atmosphere
Thought Question 6
The nitrogen cycle includes nitrogen-fixing bacteria,
plants and animals that use nitrogen compounds;
human industrial processes; and bacteria and fungi
that convert nitrogenous compounds back into
ammonia. Which of these could be eliminated
without totally disrupting the nitrogen cycle?
Explain your answer.
Where does energy come from?
Photosynthesis and cellular respiration
In which organelle does most cellular respiration
Which kingdoms are able to do this (and what word
do we use to describe it)?
Who’s eating who
Thought Question 7
Explain why the Sun is the ultimate source of an
The basis of any
They make their own
Just eat the producers
Animals that eat
Animals that eat both
primary and secondary
Thought Question 8
Think of a grassland ecosystem. Name one example
of a producer, a primary consumer, and a secondary
consumer in that ecosystem.
The movement of energy
Matter moves in
cycles, but energy
moves up the trophic
pyramid in one
It also drains as it
moves from life form
to life form.
The 10% rule
Only about 10%
of the energy
that enters a
trophic level is
available to the
Depicted in a
Thought Question 9
Suppose that a field of blackberries absorbs
400,000,000 kJ of sunlight. According to the ten
percent rule, how much of the original energy is
…mice that eat the berries?
…snakes that eat the mice?
… owls that eat the snakes?
Thought Question 10
Explain why a grassland can sustain many more
mice than snakes.
A food web is a
model that shows
energy flow in an
Arrows points from
an organism to
what eats it
It shows that energy
is moving from one
thing to whatever
it’s pointing at
Thought Question 11
Suppose that the
worms in this
ecosystem were to
Describe at least 2
effects that the
would have on
Watch the video and complete the trophic levels
pyramid with the animals you see.