Please take out your Chapter 3 Reading
Assignment

Module 6:
1. A 2. D 3. A 4. C 5. B 6. E
Module 7:
1. D 2. B 3. C 4. A 5. E 6. D 7. C
Module 8:
1. B 2. C 3. D 4. E 5. C

6.
7.
8.
9.
1.
2.
3.
4.
5.
D
D
E
A
B
C
D
A
B
10. E
11. E
12. B
13. C
14. A
15. A
16. B
17. E
18. B

Section 3.1

Levels of Organization
 Living things can be studied at many levels:
 In Ecology, we will study everything above individuals
Biosphere
Biomes
Ecosystems
Communities
Populations
Individuals
Cells/
Tissues

Levels of Organization
 Biosphere: Our earth!
 Biome: areas of biosphere that have similar climate, plants, and animals
 Ecosystem: collection of living and non-living things that make up an environment
Biosphere
Desert
Biome
Old Growth Forest
Ecosystem

Levels of Organization
 Community: populations of different species living together (ex: humans and bacteria living together)
 Population: group of one species living together
 Species: a group of organisms that can only breed with each other
Community of macaws, grasses, insects…
Population of prairie dogs
(a species)

What do Ecosystems Need?
 For ecosystems to thrive, its members need
energy and matter
 Matter = liquid, solid, and gas ‘stuff’
 Energy moves in a one-way flow, while matter recycles.
 Today’s focus = energy

 The sun provides the initial energy for ecosystems
 Plants harvest sunlight and turn light energy into chemical energy (glucose)
 This is called photosynthesis
 CO2 + H2O + light glucose + O2
 In an ecosystem, we call plants producers

 Chemical energy (glucose) stored in plants is passed on to herbivores, which eat the plants
 Chemical energy in herbivores (protein, fat, sugar) is passed on to carnivores, which eat the herbivores
 This forms a food chain/web.

 Carnivores eat animals
 Herbivores eat plants
 Omnivores eat both

ENERGY ALWAYS FLOWS THE SAME
WAY THROUGH AN ECOSYSTEM:
Sun Producers Consumers
Energy does not recycle. It is lost as heat when organisms burn it off!

How is the chemical energy used?
 Plants AND consumers use the energy in sugar for cellular respiration .
Glucose + O2
CO2 + H2O + ATP
 It’s converted to a smaller, more useable molecule called ATP, which is converted to kinetic energy.

 Plants are called producers, and also autotrophs
 Autotroph = makes own food using sunlight
 First level consumers eat producers
 Second level consumers eat first level consumers, and so on
 Consumers are also called heterotrophs
(get food/energy from outside source)

 Detritivores (mites, snails, and worms) feed on dead matter
 Decomposers (bacteria and fungi) break down dead matter

 Watch the Planet Earth video clip
 Make a food web on your whiteboard
 Label producers (P), 1 st , 2 nd , 3 rd level consumers, detritivores, decomposers (inferred)
 Put a star next to heterotrophs

 Each step along a food chain or web is called a trophic level
 Producers are the first trophic level
 Consumers make up the second, third, and higher trophic levels
 Trophic levels are the order in which energy is eaten
Label your whiteboard organisms with trophic levels!

 The energy that producers and consumers can possibly make and pass on can be represented in an energy pyramid
 Because producers photosynthesize and are numerous, they are on the bottom of the pyramid

Measures of Energy in Ecosystems
 Gross Primary Productivity (GPP) = total solar energy captured by plants (ONLY
ABOUT 1%)
 Net Primary Productivity (NPP) = total energy captured minus the energy used by producers for their own respiration (what’s left over for consumers!)
NPP = GPP – Respiration by Producers

 A forest has an NPP of 1.4 kg C/m 2 /year and the rate of cellular respiration is 2.4 kg
C/m 2 /year. What is the GPP?
NPP = GPP – Respiration
1.4 = GPP – 2.4
GPP = 1.4 + 2.4 = 3.8 kilograms of Carbon per square meter per year

 Proportion of energy that is passed between trophic levels, after cellular respiration
 10% on average!

10%

? Cal
? Cal
? Cal
1000 Cal

1 Cal
10 Cal
100 Cal
1000 Cal

 Let’s try it out the 10% rule for ourselves!

Data from Energy Bucks
Amount of Energy taken in:
1275 Grasses
Final Amount of
Energy Available:
242
Crickets 159
Frogs
Hawks
TOTAL
63
18
482
Which number is NPP? GPP? How could we find total respiration?

Biomass= total mass of living matter in an area
At which level is the most biomass located?

100 grams
 Same as pyramid of energy
 More mass in bottom trophic levels
200 grams
600 grams
1000 grams

 Time to add consumers to your ecosystem!
 Do steps 15-17
 We already collected baseline readings, so we will take our next set of data next week
 Record what you add/subtract in your data table

 Energy Flow in an Ecosystem Worksheet and 1 st current event due next time.
 Take retakes by Friday at 2pm.