1. Flow of Energy
Unit 2

2. 7.5A: Photosynthesis
The word photosynthesis can be broken down to its Greek origin:
Synthesis “put together to form something new” and Photo “light.”
The most important aspect of photosynthesis is that radiant energy (from the sun) transforms into chemical energy.
The chemical energy is stored in the plant as sugar, or glucose, and is available as food.

3. Chloroplasts & Chlorophyll
Chloroplasts are the green organelles within plant cells where photosynthesis takes place, harnessing energy from sunlight to make sugars.
Chlorophyll is a green pigment found in all plants and algae that allows energy from sunlight to be transformed into chemical energy. (located inside the discs)

4. Partner discussion:
Explain what changes in the oxygen supply occur from early morning to noon on a sunny day in a pond where Anacharis (plant) is growing.
Early morning oxygen levels are low since photosynthesis does not happen at night. It is expected that oxygen levels increase throughout the day as sunshine provides energy. Oxygen levels peak in late afternoon and begin to decline as night falls. Oxygen consumers, such as fish will have an impact on oxygen levels.

5. Photosynthesis equation
A reactant is a substance that takes part in and undergoes a change during a reaction.
A product is a substance produced during a chemical reaction.
A chemical reaction is a process by which two or more chemical substances interact and are chemically changed, producing different chemical substances.
Reactants
Products

6. 7.5B: Cycling of matter
Interactions occur between matter and energy during the carbon, nitrogen, and water cycles.
Soil is a natural composting environment containing decomposers, such as bacteria and fungi, which break down or decay biomass.
This process produces thermal energy, releasing gases (such as carbon dioxide and nitrogen?, and simple molecules (such as water).
This matter is released back into the soil and atmosphere to be reused by producers to make food and to grow.

7. The Carbon cycle
Carbon is essential to life and cycles in many forms within living systems. Carbon dioxide in the atmosphere enters the leaves of plants and is used in the process of photosynthesis to make glucose. Some animals eat plants and thus carbon is cycled through the food web.

8. Partner discussion:
Describe how carbon is cycled through the biosphere. Your response should begin with carbon dioxide in the atmosphere and include the contribution of plants, animals, and decomposers.
photosynthesis removing CO2 from air, -plants fixing carbon in glucose, -animals consuming plants and acquiring carbon, and/or eating other animals, - respiration of animals releasing CO2, -further breakdown by decomposers, etc…

9. The nitrogen cycle
Nitrogen is an element essential to life. It is cycled from the atmosphere to living things and back into the atmosphere. Nitrogen in the atmosphere enters soil and is broken down by bacteria into a usable form that is absorbed by the roots of plants and enters the food web.

10. The Water cycle
Water is a simple molecule that is cycled throughout living systems and the atmosphere.

11. Partner discussion
Describe how nitrogen is cycled throughout living systems and the atmosphere. Your response should include the role of decomposers, producers, and consumers.
Nitrogen in atmosphere enters soil and is broken down by bacteria; this usable form of nitrogen is absorbed by plant roots; plants use nitrogen for growth and productivity; animals eat plants, thus ingesting nitrogen; dead animals and animal wastes are broken down by decomposers, allowing nitrogen to enter the soil and the atmosphere, etc…

12. 7.5C: Energy flow through living systems
Interactions that occur between matter and energy can be examined by using a variety of models. The flow of energy through living systems can be modeled as food chains, food webs, or energy pyramids.
Food chains diagram the transformation of energy is it flows from the sun to producers (plants) to primary consumers (herbivores), to secondary consumers (carnivores that eat herbivores) to tertiary consumers (carnivores that eat carnivores).

13. Food webs diagram the complex relationship of energy flow in an ecosystem containing a variety of producers and consumers.
Energy pyramids diagram the decreasing amount of available energy as it flows from one trophic level to the next. Energy transfer from one trophic level to the next is not efficient because some of the energy transforms into heat and is therefore unavailable to the next level on the pyramid.

14. Energy pyramid Tertiary Consumers (carnivores that eat carnivores)
heterotrophs
Secondary Consumers
(carnivores that eat herbivores)
heterotrophs
Primary Consumers (herbivores)
heterotrophs
Producers (plants)
autotrophs

15. Ten percent rule Only 10% of the energy transfers
from each Trophic level.
1 / 10 = 0.1%
10 / 10 = 1%
100 / 10 = 10%
100%

16. Partner discussion
What do you think is the value of showing the direction of energy flow in an energy pyramid?
Understanding the direction of energy flow in a food web helps us understand the interrelationships between the different organisms in the ecosystem.

17. Food chains A diagram of a marine food chain
is provided. Which of the organisms
in the food chain transforms energy
from the Sun into food?
Large Sharks
Marlin
Shrimp
Phytoplankton

18. Food webs A diagram of a prairie food web is provided.
A reduction in deer population will have the
effect in the amount of energy this ecosystem is
able to provide for which of the following
organisms?
Rabbit
Mountain lion
Mouse
Hawk

19. Food webs A diagram of a food web is provided.
Draw the arrows to show the direction
of the flow of energy. Provide three
examples of interactions where energy
flows from one organism to another.
Answers will vary- Deer to Mountain
Lion, Snake to Hawk, Cricket to Spider

20. Food webs
Use the following list of organisms to create a food chain diagram.
Hawk
Toad
Green plants
Snake
Be sure to include the original source of energy for all living things in your diagram. Then label each of the following: producer, primary consumer, secondary consumer, tertiary consumer