Nutrition & Energy Flow

Chapter 2, Section 2

Think, Pair, Share 1. Describe at least 4 relationships between these organisms in an ecosystem?

How Organisms Obtain Energy

• The Sun is the ultimate source of energy for life.

Producers

• Photosynthetic Autotrophs– Use light energy to make glucose

Consumers• Heterotrophs

– Herbivores = feed only on plants

– Carnivores = eat other heterotrophs

– Scavengers = eat dead animals

– Omnivores = eat both animal and plant materials

– Decomposers = break down and release nutrient from dead organisms

Flow of Matter and Energy in Ecosystems

• Models to show how energy moves through an ecosystem– Food Chains– Food Webs– Ecological Pyramids

Food Chain Ex: berries mice snake eagle

Arrows show transfer and direction of energy flow– A portion of energy is given off as heat at each

transfer– Amount of energy in final transfer is only a fraction

of what was at the first transfer

Think, Pair, Share

2. Does all the energy from every plant on the planet get used by herbivores? Explain

• Trophic Levels = Each organism represents a feeding step in the movement of energy

Food Web• Shows all possible feeding relationships at each trophic

level in a community

Think, Pair, Share

3. List all the secondary consumers in the web below and list how they fit that description.

Ecological Pyramids

• Base always represents 1st trophic level

• Higher trophic levels are layered on top of one another

• Pyramid of Energy = Energy decreases with each trophic level moving up– Total energy transfer from one trophic level to

the next is only about 10% (90% is lost)

10% Rule – only 10% of the energy makes its way to the trophic level above it.

Think, Pair, Share

4. Explain where you think 90% of the energy goes.

• Pyramid of Biomass = Less living material as you move up trophic levels

Cycles in Nature

• Matter moves through the trophic levels of an ecosystem.

• Energy can be lost through heat; Matter is not gained or lost, it is recycled.

• Ex: Water Cycle, Carbon Cycle, Nitrogen Cycle, Phosphorous Cycle

Water Cycle

• Water present 3 billion years ago is still present today

• It’s been recycled between land, ocean and atmosphere– Evaporation (water gas)– Condensation (clouds)– Precipitation (rain)

The Carbon CyclePutting Carbon in the Ground:• Plants use CO2 to create carbon compounds

(sugar) for growth and energy• Consumers eat plants and/or other animals to

get carbon compounds for growth and energy• Plants and animals die, carbon is returned to the

ground where fossil fuels can form

Putting Carbon in the Atmosphere:• CO2 gets released during cell respiration• CO2 released when burning fossil fuels

The Nitrogen Cycle

• See figure 2.19 on page 56

The Phosphorous Cycle

• See figure 2.20 on page 57

Practice• Why is a pyramid a good shape to

represent how matter and energy transfer in an ecosystem? Why not use a circle or a square?

• According to the Law of Conservation, matter can neither be created nor destroyed. Make a relationship between this statement and the recycling of carbon in an ecosystem. (Hint: All life on this planet is carbon based. What happens to a tree that dies & falls in a forest? Who benefits from the dead tree?)