Primary and Secondary Productivity
Worksheet
Primary Productivity
Tracking Energy
Smart businesses do careful accounting of their daily profits and expenses. In a similar way,
we can track the amount of energy moving through trophic levels of a biological system to
determine its overall prod...
Smart businesses do careful accounting of their daily profits and expenses. In a similar way,
we can track the amount of energy moving through trophic levels of a biological system to
determine its overall productivity. There are many energy “transactions” to keep track of
and account for when trying to calculate productivity. Producers capture light energy and
convert it into chemical energy, stored in macromolecules such as glucose, which have
mass. To measure the energy in biological systems, the potential energy of these molecules
must be measured indirectly as “biomass.” A consumer eats producers, and this biomass is
either stored as chemical energy, used as kinetic energy for movement, converted to cellular
energy to power cell processes and growth, or energy is lost as heat. According to the
second law of thermodynamics, when light energy is converted to chemical energy in
photosynthesis or transferred from a producer to its consumer, some energy will always be
lost as heat during each transfer.
Tracking Energy Reflection Questions
1. Describe one way you could keep track of energy use and transfer in a biological system.
- Producers capture light energy and convert it into chemical energy stored in energy-rich
molecules. These molecules have mass, so the energy in biological systems can be
indirectly measured by mass, biomass.
2. Identify the possible inputs and outputs of mass and energy between the sun and a
producer.
- Plants harvest their energy from the sun during photosynthesis. This energy can then be
passed from one organism to another in the food chain. The organism that obtains energy
from sunlight is called the producer.
3. Draw a simple diagram showing the inputs and outputs you identified in question 2.
This study source was downloaded by 100000850872992 from CourseHero.com on 06-08-2023 07:30:47 GMT -05:00
For this part of the lab activity, go to "Part 1: Primary Production” tab in the lesson. Read lab
scenario on the pansy garden investigation and use the data to calculate net primary productivity.
Estimating Net Primary Productivity (NPP)
Use the data in Table 1 to calculate Net Primary Productivity (NPP). Record your answers to the
reflection questions in Table 2.
Table 2
Time Mean Mean Dry Percent Percent Average Net
Wet Biomass(g) Biomass Water Energy Productivity
Mass (g) from per day/per
Biomass plant
per plant
(kcal)
2 Weeks 18.8 4.1 21.8% 78.2% 17.84kcal 1.27
4 Weeks 37.53 8.16 21.8% 78.2% 35.525kcal 1.27
This study source was downloaded by 100000850872992 from CourseHero.com on 06-08-2023 07:30:47 GMT -05:00
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