1. Essay prompt Week #1
Discuss the web of life in a biological community. Your essay should focus on energy flow, conversion, and loss in food chains, including the concepts of trophic levels and pyramids.

2. Key for Essay #1 Structural hierarchy Define community
Producer’s-consumers; provide examples
10% loss at every level; explain why
Energy is lost in a system
Explain plant photosynthesis
Need to eat at the carnivore level and cellular respiration
Explain detritovore
Define food chain and food web; provide sample diagrams
Discuss/diagram energy pyramid, biomass pyramid; biomagnification pyramid
Bonus: discuss exceptions inverted pyramid

3. Essay #2
AP BIO QUESTION 1996
The unique properties (characteristics) of water make life possible on Earth. Select three properties of water and
for each property, identify and define the property and explain it in terms of the physical/chemical nature of water.
for each property, describe one example of how the property affects the functioning of living organisms.

4. Key for Essay #2 -Prop. of water
Note: you will need to print this slide out to see the words better.

5. that makes possible the building of a variety of biological molecules.
ESSAY #3
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. 5

6. KEY TO ESSAY #3 6

7. A. CHARACTERISTICS OF CARBON ATOMS: (Max of 4 points)
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 7

8. 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. 8

9. 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 9

10. __Recognizing cysteine's role in disulfide bond formation
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 10

11. ESSAY QUESTION #4
CELL QUESTION 1992:
A laboratory assistant prepared solutions of 0.8 M, 0.6 M, 0.4 M, and 0.2 M sucrose, but forgot to label them. After realizing the error, the assistant randomly labeled the flasks containing these four unknown solutions as flask A, flask B, flask C, and flask D.
Design an experiment, based on the principles of diffusion and osmosis, that the assistant could use to determine which of the flasks contains each of the four unknown solutions. Include in your answer
a description of how you would set up and perform the experiment;
the results you would expect from your experiment; and
an explanation of those results based on the principles involved.
(Be sure to clearly state the principles addressed in your discussion.)

12. Key to Essay #4 (hydrostatic/turgor pressure) in analysis of results
EXPERIMENTAL SET-UP (1 point each)
___ 1. Experiment based on concentration gradient
___ 2. Experiment based on semipermeable membrane (dialysis tubing, thistle
tubes, plant or animal cells)
___ *3. Experimental set-up (design) adequate to produce measurable results
___ *4. (2 max) Experimental variables are eliminated (mass, volume, time,
temperature, tissue type, etc.)
___ *5. Experimental set-up is exemplary (must include semipermeable
membrane)
B. RESULTS ( 1 point each)
___ *1. Describes a measurable change
___ *2. Correctly correlates the observed changes with molarities of unknowns
C. APPLICATION OF PRINCIPLES TO RESULTS (1 point each)
___ *1. Correctly applies principles of diffusion and osmosis in the interpretation
of results (a correct analysis)
___ 2. Demonstrates an understanding of the concept of water potential
(hydrostatic/turgor pressure) in analysis of results

13. Key to Essay #4 continued
D. PRINCIPLES (1 point each)
___ 1. Demonstrates an understanding, or gives a correct definition of diffusion
___ 2. Demonstrates an understanding, or gives a correct definition of osmosis **
(must include both water and semipermeable membrane)
___ 3. Demonstrates an understanding, or gives a correct definition of selective
permeability
___ 4. Describes how solute size and/or molar concentration (hypertonic/hypotonic)
affects the process of diffusion through a membrane
_______________________ Max possible = 14 * No points if the lab will not work. **Osmosis: the diffusion of water through a selectively (semi)permeable membrane in the following directions: -from higher water potential toward lower water potential -from hypotonic (hypoosmotic) solution toward hypertonic (hyperosmotic) solution -from higher water concentration toward lower water concentration -from lower solute concentration toward higher solute concentration -from region of lower osmotic pressure toward regions of higher osmotic pressure -from region of higher osmotic potential toward region of lower osmotic potential

14. ESSAY #5 Enzyme question QUESTION I-2000
1. The effects of pH and temperature were studied for an enzyme-catalyzed reaction. The following results were obtained.
a) How do (1) temperature and (2) pH affect the activity of this enzyme? In your answer, include a discussion of the relationship between the structure and the function of this enzyme, as well as a discussion of how structure and function of enzymes are affected by temperature and pH. b) Describe a controlled experiment that could have produced the data shown for either temperature or pH. Be sure to state the hypothesis that was tested here.