 Biotic and Abiotic  All things on Earth fall into one of two categories:   Biotic: alive Abiotic: not, and never has been, alive

 Thought Question 1  Identify five biotic and five abiotic factors in Edgard.

 Carbon  Carbon can make long molecular chains and rings  It circulates through the biosphere

 Carbon Dioxide  All CO2 is circulated throughout all Earth spheres constantly

 Thought Question 2  About how much of the Earth’s atmosphere is CO 2 ?

 The Carbon Cycle  Enters the atmosphere through:  Cellular respiration    Decomposition of plants Eruption of volcanoes Human actions, 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 picture.

 Thought Question 3  Why are scientists concerned about rising levels of atmospheric carbon dioxide?

 Solar energy and the water cycle  Also referred to as the hydrologic cycle  It’s driven by the sun’s energy and temperature differences on Earth

 The Nitrogen Cycle  Essential component of DNA, RNA and proteins  78% of our atmosphere is gaseous nitrogen, but most organisms cannot use it in this form

 Fixing nitrogen step 1  Lightning (5-8%)

 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 nitrogen-fixing bacteria.  Most live in the roots of plants called legumes, like soybeans, clover, alfalfa.

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 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 using manure.

 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

 Recall Question  In which organelle does most cellular respiration take place?  Which kingdoms are able to do this (and what word do we use to describe it)?

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 Trophic levels  Who’s eating who

 Thought Question 7  Explain why the Sun is the ultimate source of an opossum’s energy?

 Producers  The basis of any ecosystem  They make their own food through photosynthesis

 Primary consumers  Just eat the producers

 Secondary consumers  Animals that eat primary consumers

 Tertiary consumers  Animals that eat both primary and secondary consumers

 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 direction.

 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 trophic level immediately above it.

 Depicted in a

trophic

pyramid.

 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 available to…  …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.

  Food webs  A food web is a model that shows energy flow in an ecosystem.

Keys:  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 disappear. Describe at least 2 effects that the worm’s disappearance would have on other populations.

 Exit Ticket  Watch the video and complete the trophic levels pyramid with the animals you see.