In groups define/ discuss the
following words
•
•
•
•
Habitat
Population
Community
ecosystem
• Producers
• Primary consumers
• Secondary
consumers
• decomposers
Use the information below to draw a food web.
Along the shallow water close to our beaches, producers
such as brown algae, diatoms and dinoflagelates provide
food for limpets and copepods. These in turn are eaten by
carnivores such as starfish and arrowworms.
Energy Flow in
Ecosystems
1.1 Energy fixation
Before looking through this powerpoint,
Read: Pupil Monograph – Introduction and Page 1 –2
Scholar – 1.2 Energy Fixation
Learning Intentions
By the end of this section you will:
1. Understand what an autotrophs and heterotrophs.
2. Be able to explain the difference between Net Primary
Productivity and Gross Primary Productivity and be able
to do some calculations involving these.
3. Be able to define Biomass and describe how it is
measured.
4. Have learned which factors can affect productivity and
why the type of ecosystem will determine which factors
will be most important.
5. Understand the relationship between water depth and
photosynthetic production.
Photosynthesis = conversion of energy from
SOLAR
ENERGY
CHEMICAL
ENERGY (CHO)
• No ecosystem could exist without this
initial energy conversion
• This transformation is crucial to all life
Energy capture
SOLAR
ENERGY
Gross primary production
= the total energy captured by the plant
Producers
Some energy used by the plant for cell
processes
(15 - 70% depending on species)
Net primary production
= the energy available for the primary consumer
How to measure NPP?
• increase in dry mass (Biomass) per unit time
(because water
content varies)
(usually
a year)
• note NPP values from major ecosystems (p2 monograph)
Which is most productive?
Which is least productive?
Which is most significant globally?
Factors affecting primary productivity:-
• availability of nutrients
lack of nitrogen in tundra - slow rate of production
upwelling zones in coral reefs - high productivity
• light intensity
• temperature
• availability of water (rainfall!)
Energy Flow in an Ecosystem
OUTPUT:
INPUT:
HEAT, MOVEMENT,
ENERGY
SOLAR
ENERGY
Producers
(autotrophs)
Primary
Consumers
(heterotrophs)
Secondary
Consumers
(heterotrophs)
Decomposers
Notes and Questions
You may choose to make notes on what you have learned.
You may make notes on the reading, then the powerpoint
or you may like to combine to make 1 note. You may
choose NOT to make any notes on this. If you make any
notes PUT THEM IN YOUIR OWN WORDS. The learning
intentions should help guide you!
The questions and activities that follow are designed to
test your understanding and recall of the key facts and
ideas.
Questions
1. In your notes or on flash cards provide the
definitions for the following terms.
Secondary consumer
Heterotroph
Primary consumer
Producer
Gross primary production
Net primary production
Biomass
Autotroph (photoautotroph, chemoautotroph)
2. Circulation in Ecosystems Worksheet Q1-7
3. Scholar Pg 10 Q1-6