Matter and Energy in Ecosystems

All things on Earth fall into one of two

categories: Biotic: alive Abiotic: not, and never has been, alive

Biotic and Abiotic Factors

Identify five biotic and five abiotic factors in

Edgard.

Thought Question 1

Carbon can make long molecular chains and

rings It circulates through the biosphere

Carbon

All CO2 is circulated throughout all Earth

spheres constantly

Carbon Dioxide

About how much of the Earth’s atmosphere is

CO2?

Thought Question 2

Enters the

atmosphere through: Cellular respiration Decomposition of

plants Eruption of

volcanoes Human actions,

like burning fossil fuels (coal, gas, oil)

The Carbon Cycle

Carbon is removed from the atmosphere by:

Plants and bacteria “fix” it into sugar molecules

Carbon Cycle continued

Draw a picture of diagram of the carbon cycle

on your own paper. Be sure to label each part of your picture.

Thought Question Picture

Why are scientists concerned about rising

levels of atmospheric carbon dioxide?

Thought Question 3

Also referred to as the hydrologic cycle It’s driven by the sun’s energy and

temperature differences on Earth

Solar energy and the water cycle

Essential

component of DNA, RNA and proteins

78% of our atmosphere is gaseous nitrogen, but most organisms cannot use it in this form

The Nitrogen Cycle

Lightning (5-8%)

Fixing nitrogen step 1

Imagine the beginning of life on Earth. How

important would lightning’s fixation of nitrogen have been at that time as compared with today?

Thought Question 5

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.

Fixing nitrogen step 2

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.

Fixing nitrogen step 3

Humans can also fix it directly from the

atmosphere using manure.

Nitrogen fixation step 4

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.

Thought Question 6

Photosynthesis and cellular respiration

Where does energy come from?

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)?

Recall Question

Who’s eating who

Trophic levels

Explain why the Sun is the ultimate source of

an opossum’s energy?

Thought Question 7

The basis of any

ecosystem They make their own

food through photosynthesis

Producers

Just eat the producers

Primary consumers

Animals that eat

primary consumers

Secondary consumers

Animals that eat both

primary and secondary consumers

Tertiary consumers

Think of a grassland ecosystem. Name one

example of a producer, a primary consumer, and a secondary consumer in that ecosystem.

Thought Question 8

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 movement of energy

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.

The 10% rule

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 9

Explain why a grassland can sustain many

more mice than snakes.

Thought Question 10

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

Food webs

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.

Thought Question 11

Watch the video and complete the trophic

levels pyramid with the animals you see.

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