Investigation 10 – Energy Dynamics
What factors govern energy capture, allocation, storage, and transfer
between producers and consumers in a terrestrial ecosystem?
Learning Objectives:
Materials and Equipment:
We will have two producers available: radish plants and the fast plants
What is your control?
Variables you could change: (they may call this improvements in the
question, that doesn’t mean something is wrong with their design) If you
need to change a variable, look at your supply list for ideas for
experimental design changes you could make. They will probably ask for
Environmental factors that could change things. pH or temperature.
We could easily use biomass gained by the larvae on brussel sprouts vs
radishes?
Background research you would do on this topic:
Sun light energy drives photosynthesis. Organic compounds create
biomass.
Gross productivity = total energy captured; Net productivity = net amount
captured and stored (after used for cellular processes)
Producers are the plants; Plants use biomass to run cellular processes or to
be stored. Producers consumed by consumer, powers the consumer.
This lab will be one producer with one consumer.
Experimental Design.
First copy this flow chart.
Your experiment will be designed to make the calculations needed for
the flowchart.
Our steps.
1. Plant radishes and fast plants.
2. Day 7 – get the biomass of the plants (not the water mass) of the
fast plants and radishes by removing 10 plants with roots. Wash off the soil,
blot dry, mass each in aluminum foil boat (tare the boat)
3. Dessication – put plants in drying oven at 100 C for 48 hours (Dr. Sowell
has this)
4. Get the dry mass of each plant. Make a table that looks similar to this:
Age
Plant
7 days
7 days
14 days
14 days
Fast Plant
Radish
Fast Plant
Radish
Wet
mass/10
plants
Dry
mass/10
plants
Percent
biomass
5. Care for plants
6. Day 14 – mass plants/repeat steps as day 7.
Energy
(g
biomass x
4.35
kcal/10
plants
Net primary
productivity
per day per
plant
Step 1: Make a model like above:
biomass
Kcal biomass -- energy/biomass kcal/resp
Plants
in larvae
kcal/waste
Step 2: Wet mass of a fresh brussel sprout. Peel back leaves. Place in
brassica barn on wet paper towel. Mass larvae as a group and divide per
individual.
Step 3: Day 3 mass the larvae, the brussel sprout left and mass the frass.
Be prepared to make a graph:.
THE GRAPHS/TABLES WILL LOOK LIKE/ or SHOULD LOOK LIKE THIS:
X axis – days
Y axis – grams biomass
Line for radishes
Line for brussel sprouts
Line for radish fed larvae
Line for brussel sprout fed larvae