Biology Energy Transfer Unit

What is the Biosphere? The biosphere is the part of the Earth's surface and atmosphere that contains life.

Ecosystems The biosphere is made of ecosystems. An ecosystem is all of the living and nonliving things in a specific area.

Ecosystems Have Two Parts Abiotic – All of the nonliving things in an ecosystem. Rocks, water, climate, elevation, ect...

Ecosystem Parts Continued Biotic – All of the living things in an ecosystem. Plants, animals, fungi, protozoans, algae and bacteria.

Community All of the living things in a defined area. Ex: All forms of life in this room.

Population All members of a species found in a defined area. Ex: All of the opposums in Somerset County

Species A group of organisms that look similar and are able to produce fertile offspring.

Habitat The place where an organism lives.

Niche The role an organism plays in its environment. Organisms can be generalists or specialists.

Generalists Species with broad niches. They can tolerate a wide range of conditions. Ex: Gray Squirrels

Specialists Species with narrow niches. They have very specific habitat requirements. Ex: Kirtland's Warbler

How do Organisms Deal with Unfavorable Conditions? Dormancy – Organisms enter a state of reduced activity. Migration – Organisms move to areas with favorable conditions

*Important Fact* “Energy enters the biosphere via sunlight and chemicals.” PDE Big Idea 7A

Producers or Autotrophs Organisms that use light or chemicals to produce their own energy. Use photosynthesis or chemosynthesis

Consumers or Heterotrophs Organisms that must eat in order to gain energy.

*Important Fact* “Animals are important energy consumers obtaining their energy by assembling and recombining fats, carbohydrates and proteins from plants and/or other animals passing through the food web.” PDE Big Idea 7C

Herbivores Organisms that eat producers.

Carnivores Organisms that eat other consumers.

Omnivores Organisms that eat both producers and consumers.

Detritivores Organisms that eat the “garbage” of an ecosystem. Dead organisms, wastes or fallen leaves

Decomposers Special detritivores that break down dead matter and return nutrients into the ecosystem. Ex: Bacteria and Fungus

*Important Fact* “Some bacteria and fungi are known as decomposers using dead and decaying organisms as an energy source.” PDE Big Idea 7D

Trophic Levels An organism’s position in a sequence of energy transfers.

Trophic Level Limitations Only about 10% of the energy available at any one level passes on to the next level. This limits the number of levels.

Food Chain Food chains trace the transfer of energy through an ecosystem. They are simple, linear diagrams showing who eats who in an ecosystem.

Sample Food Chain

Food Web A complex, branching diagram showing who eats who in an ecosystem. They show how different food chains are intertwined.

Sample Food Web

Bioaccumulation Toxins introduced to an ecosystem accumulate in greater concentrations at the upper trophic levels.

*Important Fact* “Food webs consist of intertwined food chains.” PDE Big Idea 7B

*Important Fact* “As matter and energy flow through the many cycles of food chains, chemical assembly and recombination conserves matter and dissipates energy as heat.” PDE Big Idea 7E

Laws of Thermodynamics Matter and energy are neither created nor destroyed. They simply change form.

Photosynthesis H2O + CO2 + Light  C6H12O6 + O2 Light energy is absorbed by special electrons in chlorophyll. Electrons begin to move through the plant (electrical energy). The electrons and their energy are put into the glucose molecule (chemical energy). So, tracing the energy transformation… Light  Electrical  Chemical

Chloroplasts Stroma - the protein rich fluid that fills in the spaces around the grana Thylakoids – the part of the chloroplast that contains chlorophyll Grana – stacks of thylakoids

The Light Dependent Reactions

Light Independent Reactions AKA the Calvin Cycle Discovered by Melvin Calvin and others He discovered how products from the light dependent reactions were used to make glucose

Cellular Respiration The production of ATP from glucose. It can happen one of two ways: Aerobic Respiration – Uses oxygen to produce ATP (very efficient) Anaerobic Respiration – Does not use oxygen to produce ATP (very inefficient)

Stages of Respiration Aerobic Begins with glycolysis Second step is called the Krebs Cycle (named for Hans Krebs) Anaerobic Begins with glycolysis Second step is either lactic acid fermentation or alcoholic fermentation

Glycolysis Literally means breaking glucose (glyco=“glucose” in Latin) (lysis=“to break” in Latin) It is always the first step in respiration

Products: - 2 Pyruvic acids - 4 ATP’s (gained 2 ATP’s) - 2 NADH’s

Aerobic Cellular Respiration C6H12O6 + O2  H2O + CO2 + ATP Also known as the Krebs Cycle Discovered by Hans Krebs in 1957

Products: - 4 NADH’s -1 ATP - 1 FADH2 - BUT there are 2 pyruvic acids … so - 8 NADH’s - 2 ATP’s - 2 FADH2’s

Wrapping Up Aerobic Respiration The products of glycolysis and the Krebs cycle get added together Glycolysis made 2 ATP’s and 2 NADH’s Krebs Cycle made 2 ATP’s, 8 NADH’s and 2 FADH2’s So, the overall products of both processes are 4 ATP’s, 10 NADH’s and 2 FADH2’s

Finally! After the Krebs Cycle, NADH and FADH2 enter and electron transport chain, undergo chemical reactions and get converted into ATP Each NADH will make 3 ATP Each FADH2 will make 2 ATP

Total ATP Products ATP’s Made 4 ATP 10 NADH 2 FADH2 4 ATP 30 ATP

Anaerobic Respiration Makes no additional ATP It just regenerates more NAD+ for glycolysis

Lactic Acid Fermentation

Alcoholic Fermentation

Locations Photosynthesis takes place in the chloroplasts Light Dependent Reactions – thylakoids Light Independent – stroma Glycolysis – cytoplasm Krebs Cycle – mitochondria Fermentation – cytoplasm