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How to grade essaysUse 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 #1AP 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 #1
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 #1
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: CoenzymesProstaglandins: Neural modulatorsWaxes: 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 formedSubunit (monomer, building block) of
proteinLevels 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, myosinProtection - antibodies
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) a description of how you would set up and perform the experiment; (b) the results you would expect from your experiment; and (c) an explanation of those results based on the principles involved.
(Be sure to clearly state the principles addressed in your discussion.)
ESSAY Prompt #2
A. 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
Key to Essay #2
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
Key to Essay #2 continued
ESSAY Prompt #3Enzymes are important biological molecules. They are one of the primary means of regulating chemical processes within cells.
A. Describe how enzymes affect chemical reactions.
B. Describe environmental factors that affect enzyme action.
C. Describe how enzymes are important for the process of DNA replication. (see chapter 16)
**NOTE: Be sure to include the structure and what enzymes are composed in your answer.
Grading Rubric for Essay #3 Part a: (1 point for each of the following)1. Enzymes increase the rate of chemical reactions2. Enzymes bind to the substrate at the active site3. The enzymes and substrate bind through
hydrogen bonding4. The substrate that binds to the enzyme is one of
the reactants in the reaction5. The substrate is changed to products and
consumed by the reaction6. The enzyme is not consumed by the reaction and
can be used again7. The enzyme reduces the activation energy of the
reaction causing the increase in reaction rate8. The enzyme is a protein with a complicated three
dimensional shape9. The shape of the enzyme’s active site had to be
complementary to the substrate molecule
Part b (4 pt max-1 pt for each of the following1. An increase in temp. causes substrate and enzyme
molecules to move more rapidly2. The increased movement causes more collisions that
increase the reaction rate3. Extreme temp. denature enzymes and slow reaction4. Competitive inhibitors are shaped similarly to the
substrate5. Competitive inhibitors compete for the active site
with the substrate, slowing the reaction rate6. Noncompetitive inhibitors bind to the site outside of
the active site7. The non competitive inhibitors change the shape of
the enzyme and its active site and slow the reaction8. Each enzyme operates most efficiently at an
optimum pH9. pHs outside of that optimum can disrupt or denature
the enzyme
Part C (3pt max; 1 pt for each of the following)
1. Helicase causes the DNA double helix to unwind
2. DNA polymerase copies the exposed single strands of DNA
3. DNA polymerase can only add nucleotides to a free three prime side
4. DNA ligase seals Okazaki fragments together
5. DNA polymerase proof-reads the new strands
Other Information about EnzymesEnzyme 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.
Question I Part a. (maximum 6 points)
• Optimum temperature and pH concept [must include both temp and pH]
• Enzyme/Substrate Fit concept (function dependent on conformation complernentarity between enzyme and substrate)
• Tertiary (and sometimes quarternary) structure determines function
• Description of enzyme structure or function, e.g.
Structure Elegant description of primary to tertiary or primary to quarternary levels of structure Protein folding/coiIing Co-enzymes/co-factors Zymogens Allosteric effectors
Function Increases rate of reaction Increases proximity of reactants Decreases activation energy of the catalyzed reaction Decreases time to reach equilibrium Induced fit and/or orbital steering ("bond stress")
• Denaturation concept [temp and/or pH] linked to decreased enzyme activity (e.g. "denaturation" in context or unfolding or change in 3D shape. not "enzyme breaks down")
• How temperature affects conformation (increased temperature breaks specific bonds e.g. hydrogen, Van dcr Wuals, eljsrtllide bridges)
• How pH affects conformation (change in H concentration causes a change in specific bond interactions, e.g. hydrogen: ionic, R-group interactions)
• Kinetics (increased or decreased molecular movement ) linked to effect on enzyme activity due to increase or decrease in temperature up to the optimum.
Part b. (maximum 6 points)
Experimental design must be relevant to the data shown
• What is measured (e.g. product formed or substrate used)
• How is it measured (titration or spectrophotometry or color change or bubbles counted. etc.)
• The independent variable (temperature/pH) is manipulated to produce the results at least 3 data points are identified]
• The described experiment could produce these dataExperimental design included sufficient range, varied the temp/pH of the reaction mix not the enzyme, what was measured, and how it was measured)
• Held experimental factors constant (specified at least one)
• Specified a control group for comparison (no enzyme or boiled enzyme or no Substrate)
• Verified results (e.g. repeated trials: results represent an average)
• Hypothesis clearly related to experiment of choice, and clearly identified as a hypothesis can use the if/then... form.
Essay Prompt #4
AP BIO CELL RESPIRATION 1977 Explain how the molecular reactions of
cellular respiration transform the chemical bond energy of Krebs Cycle substrates into the more readily available bond energy of ATP. Include in your discussion the structure of the mitochondrion and show how it is important to the reactions of the Krebs Cycle and the Electron Transport Chain.
Answer Key to Essay #4:STANDARDS: 1/2 point for each of the following ___Krebs and ETS occur within mitochondria ___Krebs - enzymes freely present in matrix fluid ___ETS - respiratory chain (respiratory assembly) arranged in order
inner membrane of mitochondria (Diagram OK) ___more active cells - more respiratory assemblies & more cristae ___Aerobic - O2 necessary as final H acceptor (-> H2O) (most
eukaryotic cells all of the time) ___Glycolysis is 1st required (outside mitochondria) ___Glucose (6C) is broken down into 2 Pyruvic Acid (3C) molecules ___Phosphorylation must 1st occur ___Net production: 2 ATP & 2 NADH MITOCHONDRIA ___Pyruvic Acid & 2NADH enter mitochondria ___2 NADH will transfer H (electrons) into ETS ___yields 2 x 2 ATP = 4 ATP (some loss due to point of entry into ETS)
KREBS CYCLE SUBSTRATES ___2 Pyruvic Acid loses CO2 & H -> 2 NADH & combines w/CoA -> Acetyl CoA ___(2C) Acetyl CoA + (4C) Oxaloacetic Acid -> (6C) Citric Acid ___Citric Acid -> Isocitric Acid ___(6C) Isocitric Acid - DEHYDROGENATION & loss of CO2 -> (5C) Ketogluatric Acid NAD -> NADH ___(5 C) Ketoglutaric Acid - DEHYDROGENATION & loss of CO2 -> (4C) Succinic Acid NAD -> NADH ___(4C) Succinic Acid - DEHYDROGENATION -> (4C) Malic Acid FAD -> FADH2 ___(4C) Malic Acid - DEHYDROGENATION -> Oxaloacetic Acid NAD -> NADH ___specific mention of 2 x 3 NADH & 2 x 1 FADH2 produced during Krebs ___ATP (1) produced in Krebs
ETS RECEIVES THE FOLLOWING: NADH or FADH2 WHICH RESULTS IN ATP PRODUCTION
___Glycolysis -> 2 NADH x 2 ATP = 4 ___Pyruvic Acid -> Acetyl CoA + 2 NADH x 3 ATP = 6 ___Krebs -> 8 NADH (FADH2) x 3 ATP = 24 Total = 34 ___34 ATP gained through ETS ___Respiratory Assembly: CoQ, cytochromes b, c, a, a3 ___Ring Compounds w/Fe (porphyrin ring) ___Changing Oxidation states as "go down" assembly ___Fe III -> Fe II change ionic state as accept electrons ___Release energy in "packets" - small amounts sufficient to produce ATP (about 7 kcal/mole) ___Occurs at 3 places in the chain for each NADH, FADH2 ___mention of various hypotheses: Chemiosmotic, Conformational, Chemical Coupling ___O2 final acceptor ( -> H2O)
Essay Prompt #5 Ap Bio question 1995: Energy transfer occurs in all cellular
activities. For 3 of the following 5 processes involving energy transfer, explain how each functions in the cell and give an example. Explain how ATP is involved in each example you choose.
1. Cellular movement 2. Active transport 3. Synthesis of molecules 4. Chemiosmosis 5. Fermentation
KEY TO ESSAY #5
1 pt function of process 1 pt example 1 pt additional for detail 1 pt ATP involvement 4 pts = MAX/process ATP <====> ADP + Pi + Energy 1 pt
CELLULAR MOVEMENT
Function: Locomotion, Mitosis, Cytoplasmic Streaming, Muscle Contraction (sliding filaments)
Examples: Cilia, Flagella, Pseudopodia, Exocytosis, Endocytosis, Microfilaments, Spindle Fibers
Details: 9 + 2 Microtubules, Dynein, Actin-Myosin (Myosin heads), Kinesins
ATP Involvement: ATP used Motor molecules powered by ATP hydrolysis (Conformational change with ATP use)
ACTIVE TRANSPORT
Function: Concentration gradient low to high / Protein carrier w/use of ATP
Examples: Sodium/Potassium Pump, Other Transports Specified
Details: Protein carrier related to example
ATP Involvement: ATP used Conformational change with ATP use
SYNTHESIS OF MOLECULES Function: Small to Large / Monomer to Polymer Examples: Intermediates to Monosaccharides
to Polysaccharides Intermediates to Fatty Acids (Glycerol) to Lipids Intermediates to Amino Acids to Proteins Intermediates to Nucleotides to Nucleic Acids Intermediates to Vitamins
Details: Charging tRNA Reactions catalyzed by enzymes
ATP Involvment: ATP used ATP's energy stored in chemical bonds
CHEMIOSMOSIS
Function: Form electrochemical proton (H+) gradient
Examples: Mitochondria, Chloroplasts, Bacterial Cell Membrane
Details: Cristae, Thylakoids, Direction/ H+ vs e-
ATP Involvement: ATP formed Proton pump/gradient with ATP synthase yields ATP
FERMENTATIONStart with glucose Function: breakdown of organic compounds Examples: Ethanol / Lactic Acid Details Anaerobic, Less energy produced
Cytosolic process, Yeast, Muscle ATP Involvement: ATP used and formed
Substrate-levelStart with pyruvate Function: recycling NADH Examples: Ethanol / Lactic Acid Details: Anaerobic, Regenerate oxidized NAD,
Cytosolic process Yeast, Muscle ATP Involvement: (No direct involvement)
Makes ATP production Phosphorylation possible in glycolysis
OVERALL COMMENTARY ON QUESTION:
This question was a cell biology energetics question that required both breadth and depth of knowledge to answer the question successfully. Full credit could only be obtained by responding to three of the process examples listed in the question. Also, if more than three processes were discussed, readers were directed to grade the first three unless specifi indications directed one to be omitted. Each process had a four point maximum score. One point was available for description of the function of the process, which might also be a definition or description of a mechanism. One point came from an example in context with the process. One point was available for showing how ATP was involved in the process. For each of these points, it was possible to get an additional point for detail (elaboration). In addition, it was possible to obtain a point frordescription of the ATP <==> ADP cycle.
EssayPrompt #6
Discuss the process of cell division in animals. Include a description of mitosis and cytokinesis, and of the other phases of the cell cycle. Do not include meiosis. Be sure to be detailed in your response
PART I. DESCRIPTION OF MITOSIS IN ANIMAL CELLS: Max. = 7 points General __ division of nucleus __ daughter cells acquire the same number and kinds of chromosomes as in the mother cell __ process for growth or repair or asexual reproduction __ list phases in correct order (P,M,A.T)
Prophase (one point each / max. 2) __ centrioles move apart __ chromosomes condense __ nucleolus is no longer visible __ nuclear envelope disappears __ asters and spindle form Metaphase __ sister chromatids (chromosomes) are in a line at the midpoint of the spindle
Anaphase (one point each / max. 2) __ centromeres uncouple (split) __ chromosomes move to opposite poles __ microtubules involved in the push/pull movement
Telophase (one point each / max. 2) __ reverse of prophase __ nuclear envelope reforms __ nucleolus reappears __ chromosomes become diffuse __ spindle and aster disappear __ centrioles are replicated
Points less frequently mentioned: __ function of centrioles __ definition of kinetochores __ description of polar microtubules and kinetochore microtubules __ definition of chromatids
*In order to obtain a score of 10, there must be points in all three sections. If only two sections are written the maximum is 9.
Answer Key/Grading Rubric for Essay #6
PART II. CYTOKINESIS: __ division of cytoplasm __ formation of a cleavage furrow __ occurrence of cytokinesis in the cell cycle
Points less frequently mentioned:
__ function of cytokinesis
__ dense belt of actin and myosin microfilaments
__ purse-string mechanism
__ furrow occurs at location of equatorial plane
__ cytochalasin blocks activity of microfilaments (stops cytokinesis)
PART III. OTHER PHASES OF THE CELL CYCLE (INTERPHASE): General __ list G1, S, and G2 in correct order __ G1, S, and G2 are part of interphase __ chromosomes appear as a mass of chromatin material G1 __ synthesis of cell organelles or cell doubles in size __ restriction (decision) point or point of no return S __ synthesis or replication of DNA or DNA replication occurs during
interphase G2 __ synthesis of microtubular assembly, or prepare for mitosis
Points less frequently mentioned: __ description of nucleosomes __ times in each phase __ growth factors __ some cells do not go beyond G1 __ after cell passes "S", mitosis will usually continue __ colchicine prevents the formation of microtubules
Essay Prompt #7
The Cell Cycle functions in regulating information flow through organisms.
a. Discuss how alleles are distributed by the process of meiosis to the gametes.
b. Explain how the cell cycle is controlled.
c. Explain how these controls prevent errors in inheritance.
Note: It is important t answer all three parts (a-c) and to include all of the key proteins and concepts discussed in class. ie. Cyclin, MPF, three checkpoints, p53 genes, tumor suprerssor genes, etc.
Essay Prompt #7 Grading Rubric
Essay Prompt #8 Read the following question and on a separate sheet op paper give your answer in an ESSAY FORM. Outline
alone is not acceptable. Labeled diagrams may be used to supplement discussion, but in no case will a diagram alone suffice. It is important that your read each question completely before you begin to write.
In Fruit flies, the phenotype for eye color is determined by a certain locus. E indicates the dominant allele and e indicates the recessive allele. The cross between a male wild-type fruit fly and female white-eyed fly produced the following offspring:
Wild-type Wild-type White-eyed White eyed Brown eyed Male Female Male Female Female F1 0 45 55 0 1
The wild-type and white-eyed individuals from F1 generation were then crossed to produce the following offspring:
Wild-type Wild-type White-eyed White eyed Brown eyed Male Female Male Female Female F2 23 31 22 24 1
1. Determine the genotype of the original parents (P generation) and explain your reasoning. You may use Punnett squares to enhance your description, but the results from the Punnett squares must be discussed in your answer.
2. Use a Chi-squared test on the F2 generation data to analyze your prediction of the parental genotypes.
Show all your work and explain the importance of your final answer. BE sure to write the Chi-Square
formula next to your work. The brown-eyed female in the F1 generation resulted from a mutational change.
Explain what a mutation is, and discuss two types of mutations that might have produced the brown-eyed female in the F1 generation.
**Note: Your response to these three questions will be a major part ofyour grade for this lab. Therefore, be thorough and complete in your response
ESSAY Prompt #8: Rubric (Key) A) maximum 4 pts
1 pt Genotypes of the parents (words or symbols) XEY (or X+Y) and XeXe
1 pt Discuss/show how these resulted in this F1 (may be annotated Punnett) 1 pt Explain that it is a sex-linked (X-linked) gene (not just the word) 1 pt How you know which type is dominant 1 pt F2 results (may be annotated Punnett square) B) Maximum 4 pts1 pt Correct F2 hypothesis (1:1:1:1 or 25/genotype)1 pt Show work (components): o e o-e (o-e)2 (o-e)2/e (or correct numbers (4/25 of
36/25 + 1/25 + 9/25 = 50/25 = 2; or at least the last term)1 pt Sum; correct chi-square result ~ 2.0 or 1.851 pt degrees of freedom = 3 (critical value is 7.82)1 pt correct interpretation of chi-square in terms of p
p = probability that the difference between the observed and the expected value is due to chance alone. This p value shows we accept our hypothesis. The null hypothesis is supported in this case. (alternative: 2 X2 tests of white vs. red males and white vs. red females.
C) Maximum 4 pts1 pt Explain what a mutation is: (heritable) change in the DNA (code)1-2 pts Discuss 2 types of mutations
May be: point mutation, frameshift (deletion/duplication), insertion, transposition, break, inversion within gene, base substitution, nonsense/stop, missense)May NOT be: chromosomal aberration, nondisjunction, silent/neutral, transcription or translation or processing error
1 pt Molecular or biochemical elaboration beyond the explanation required
Essay Prompt #9
Describe the chemical nature of genes. (a) Discuss the replication process of DNA naming all of the steps and key enzymes involved. (b) Name TWO types of gene mutations that occur during replication.
Essay Prompt #9-Rubric (Key)A gene is a hereditary unit located at a specific locus along a
chromosome. Genes are made up of DNA, and DNA is made up of repeating subunits of nucleotides. A nucleotide consists of three parts: a five-carbon sugar, a phosphate group, and a nitrogenous base.
When a chromosome replicates, the two DNA strands unwind and the hydrogen bonds between them are broken. Each strand serves as a template for the synthesis of a complementary strand. Once the process is initiated by an RNA primer), DNA polymerase adds nucleotides to each growing strand. One strand serves as the leading strand (it is made continuously) and the other serves as the lagging strand (it is made discontinuously). Each base matches the appropriate bases in the template strand; they are complementary. Once the complementary strands are formed, hydrogen bonds form between the new base pairs, leaving two identical copies of the original DNA molecule.