Get Started…  Volunteer needed to pass out any papers in the “out-bin”  Materials Specialists – Get a stapler and scissors for your group.  Everyone needs to staple the macromolecule chart into their journal.  Take a sheet of energy diagrams from the frog and cut out each diagram. (Do not staple these in your journal yet.)  Take an “I can…” sheet from the frog. Your test is tentatively scheduled for next Thursday.

BIO SCAN:  Below is a closed system in which seeds have germinated and are growing into plants. As these plants photosynthesize they are transforming CO 2 and H 2 O into sugar. Does the amount of energy of the container and its contents remain the same? Explain your answer.

BIO SCAN: Answer  Energy enters the biological system as light energy, is transformed into chemical energy during photosynthesis and respiration, and ultimately is converted to heat energy. This energy is dissipated, meaning it is lost to the system as heat; once it is lost it cannot be recycled.  Law of Conservation of Energy  Energy cannot be created or destroyed, only transformed.  Energy In = Energy Out

Energy Diagrams  Show the difference in energy from the beginning of a reaction to the end of the reaction. OR  Show the difference in energy between the reactants and the products.  HEAT OF THE REACTION – the difference in Energy

Heat of Reaction Exothermic Reaction  When the energy of the products is lower than the energy of the reactants, the products form through the release of heat energy.  Negative Heat of Reaction Endothermic Reaction  When the energy of the products is higher than the energy of the reactants, the products form through the input of heat energy.  Positive Heat of Reaction

Combustion of Hydrogen Watch the video clip of the combustion of hydrogen  What evidence do we have that this was combustion and not just a popping balloon?  flame  What evidence did you have that the combustion of hydrogen was an EXOTHERMIC reaction (Energy Releasing)?  Heat/flame  Once you get a fuel to start burning, do you need to do anything to keep it burning?  More fuel Click on the picture below the watch the video.

Energy Diagram for the Combustion of Hydrogen 1. Is energy stored or released in reaction 1?  Released 2. Look at reaction one. Does the energy in the system increase or decrease going from reactants or products?  Decrease 3. Explain what diagram one tells you about the energy stored in the reactants compared to the products.  More energy stored in the reactants than the products. 2 H 2 + O 2 2 H 2 O Heat of Reaction kcal/mol Reaction 1: 2 H 2 + O 2  2H 2 O

Electrolysis of Water Watch the video clip of the electrolysis of water.  Was the decomposition of water endothermic or exothermic?  endothermic  If you unplug the battery, do you still observe hydrogen and oxygen bubbles from forming?  No, there is no longer an input of energy. Click on the picture below the watch the video.

Energy Diagram for the Electrolysis of Water 1. How is the decomposition of water related to the combustion of hydrogen?  It is the reverse reaction 2. Is energy stored or released in reaction 2?  Stored 3. Does the stored energy increase or decrease going from reactants or products?  Increase 4. Explain what the diagram tells you about the energy stored in the reactants compared to the products.  More energy stored in the products than in the reactants.

The overall change in the amount of energy (kcal/mol) given in both diagrams in the Heat of the Reaction.  Why is heat of reaction. positive (+) in one reaction and negative (-) in the other?  Rxn 1 releases energy, Rxn 2 absorbs energy.  Compare the heat of reaction between reaction 1 and reaction 2. Does this support or refute the law of conservation of energy?  Support, they are the exact opposite of each other. Energy In = Energy Out  Which reaction “releases” energy? Where does the energy “go?”  Rxn 1 releases energy. The energy is given off to the surroundings.

Activation Energy  Activation Energy is the spark that provides the energy to start the reaction  Activation Energy Animation Activation Energy Animation

Enzymes  Enzymes speed up reactions by lower ing the activation energy.

Assignment  Answer questions 5 – 8 in your journal.  Glue the appropriate diagram next to each set of questions in your journal.

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Enzyme Tutorial  Complete the enzyme tutorial online.  Go to the “Links” tab on the class website. In “Biology 3 – Metabolism” view the link titled, “Enzyme Tutorial. If the link does not work you can access the animation directly at: s/Enzyme%20activity.html

Activation EnergyActive SiteProducts EnzymesSubstrateReactants Review Key Terms The “ingredients” needed to start a chemical reaction. The amount of energy required to initiate (start) a reaction The site on the enzyme that connects to the substrate The “results” of a chemical reaction. Proteins that lower the activation energy required to initiate a biochemical reaction in living things. The molecule that an enzyme acts upon.

Exit Assessment  Endothermic or Exothermic?  AE = kcal/mol  HR = kcal/mol

Exit Assessment  Endothermic or Exothermic?  AE = kcal/mol  HR = kcal/mol