How to grade essays Use a highlighter to mark all the statements that are in your essay that are on the rubric (give yourself points according to the guidelines of the rubric) Use a red pen to write in the concepts you missed in the section of the essay where that concept should have been covered. At the top of the page, put the score you received and circle it in pen. Voila! Done!

Essay Prompt #1 AP BIO QUESTION 1996 The unique properties (characteristics) of water make life possible on Earth. Select three properties of water and a) for each property, identify and define the property and explain it in terms of the physical/chemical nature of water. b) for each property, describe one example of how the property affects the functioning of living organisms.

Note: you will need to print this slide out to see the words better. Key for Essay #1 -Prop. of water

AP BIO QUESTION 1991: Carbon is a very important element in living systems. a. Describe the various characteristics of the carbon atom that makes possible the building of a variety of biological molecules. b. Explain how reactions involving carbon-containing compounds can contribute to the greenhouse effect. c. The following structures are examples of two different categories of biological compounds. Describe how each category of compounds is important to the structure and function of living systems. Essay Prompt #2

STANDARDS: A. CHARACTERISTICS OF CARBON ATOMS:(Max of 4 points) __Ready availability, abundance __Atom small in size, outer (valence) electrons close to nucleus, so forms stable (strong) bonds __4 electrons in a valence-capacity of 8, forms 4 bonds to 4 other atoms __Forms covalent bonds __Can bond to other carbon atoms, no upper limit to size of carbon compounds __Bond angles form tetrahedron, resulting in 3-D structures, chains, rings, not just planar __Can form multiple C-C, C=C, C=C bonds __Can form isomers, different structures - same number and kind of atoms __Functional groups/combine with a variety of other elements __BONUS POINT: if get 3 above - Uniqueness, only Carbon has all of these characteristics KEY TO ESSAY #2

B. REACTIONS CONTRIBUTING TO GREENHOUSE EFFEC (Max of 4 points) __Overview: Increase in gas concentration (CO2, CO, CFC) causes greenhouse effect __CO & CO2 from respiration and combustion, or volatilization of limestone __CH4 from correct source - livestock, microbes, landfills, swamps, oil wells, etc. __CFCs from industrial activities, refrigerants, plastic foam, etc. PHYSICAL MECHANISMS OF HEATING: __Ozone destruction / more energy (UV) gets in __Trapping of Energy - "Blanket" traps heat or Reflection of Sun's Energy (technically incorrect but common use in texts) __Good technical description of absorption, reradiation and wavelength shift leading to production or long wave infrared absorbed by greenhouse gases __Concept of sinks: CO2 removal by photosynthesis, CaCO3 formation, soluble in oceans, etc. CO2 addition by forest destruction, industry, etc.

C. BIOLOGICAL MOLECULES:(Max of 5 points) (Cannot get 10 points for this question without mentioning both category I and II) CATEGORY I: __Identification of molecule / category:Phospholipid, phosphoglyceride, fat, lipid, phosphatidylethanolamine / polypeptide. __Characteristics of molecule:Hydrophobic/hydrophilic, polar/nonpolar, amphipathic, or non-water soluble, high E bonds, sat/unsat C-C bonds. __Structural uses of molecule:membrane, lipid bilayer, fluid mosaic. __Functions of molecule (for example): (2 Max)Phospholipids: Regulation of membrane permeability, fluidity Fats: Structural, insulation, energy storage, water-proofing Steroids/Sterols: Hormonal, membrane fluidity Cholesterol:Animal membranes Fat soluble Vitamins:Coenzymes Prostaglandins:Neural modulators Waxes:Water-proofing

CATEGORY II: __Identification of molecule / category:Amino acid / protein / cysteine __Recognizing cysteine's role in disulfide bond formation __Characteristics of molecule:Side chains variable Peptide bonds may be formed Subunit (monomer, building block) of protein Levels of protein structure / zwitterion / as buffers __Structural roles:Keratin, collagen, cytoskeletal (tubulin, actin), etc. __Functional roles:Enzymatic - speed reactions (2 Max)(pepsin, glucose oxidase, etc.) Transport (Hb, Myb, permeases, HDL/LDL) Regulatory (oligopeptides, ex. hypothalamic releasing factors, insulin, glucagon, etc.) Contractile - actin, myosin Protection - antibodies