Key concepts for Essay #1

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					          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.
Grading Rubric for Essay Prompt #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
                 Essay #2
           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.
Key for Essay #2 -Prop. of water
                                   Note: you will need to
                                   print this slide out to see
                                   the words better.
                      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.
           Grading Rubric for Essay #3
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
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
                 ESSAY #4
 Osmosis is a driving force for homeostasis in plant
 and animals. DEFINE osmosis and DISCUSS how the
 movement of water molecules regulates THREE of
 the following activities:
A. Water and solute transport
B. Solute concentration in the mammalian kidney
C. Stomatal opening in the leaves
D. Blood pressure in humans
**NOTE: Be sure to use your textbook to help you answer the
   three topics and include a drawing with key structures
   labeled.
 Grading Rubric for Essay #4
ESSAY #4-Grading Rubric
                ESSAY #5
 Enzymes 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 #5
•    Part a: (1 point for each of the following)
1.   Enzymes increase the rate of chemical reactions
2.   Enzymes bind to the substrate at the active site
3.   The enzymes and substrate bind through hydrogen bonding
4.   The substrate that binds to the enzyme is one of the
     reactants in the reaction
5.   The substrate is changed to products and consumed by the
     reaction
6.   The enzyme is not consumed by the reaction and can be
     used again
7.   The enzyme reduces the activation energy of the reaction
     causing the increase in reaction rate
8.   The enzyme is a protein with a complicated three
     dimensional shape
9.   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 following
1.   An increase in temp. causes substrate and enzyme
     molecules to move more rapidly
2.   The increased movement causes more collisions that
     increase the reaction rate
3.   Extreme temp. denature enzymes and slow reaction
4.   Competitive inhibitors are shaped similarly to the substrate
5.   Competitive inhibitors compete for the active site with the
     substrate, slowing the reaction rate
6.   Noncompetitive inhibitors bind to the site outside of the
     active site
7.   The non competitive inhibitors change the shape of the
     enzyme and its active site and slow the reaction
8.   Each enzyme operates most efficiently at an optimum pH
9.   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
                ESSAY # 6
• CELL RESPIRATION ESSAY 1993: Membranes
  are important structural features of cells.
• (a) Describe how membrane structure is
  related to the transport of materials across a
  membrane.
• (b) Describe the role of membranes in the
  synthesis of ATP in either respiration or
  photosynthesis.
                 Answer key to essay #6
•   PART A.

(6 Maximum) Membrane Structure
• __ Phospholipid structure - hydrophilic, hydrophobic, amphipathic
• __ Phospholipid bilayer / fluid mosaic description
• __ Proteins embedded in the membrane
• __ Sterols embedded in the membrane
• __ Well-labeled diagram may replace one of the above Membrane
     Transport

(3 Internal Maximum)
•    __ Use of the term "selectively permeable" or a good definition of selective
       permeability or an explanation of the role of phospholipids or proteins
       including nuclear pore proteins in determining selective permeability
•    __ Description of the effect of size, charge, polarity, lipid solubility on membrane
       permeability Mechanisms + description related to structure: membrane gradient
• __ Ion channel: transport as a mechanism for a change in permeability
• __ Facilitated diffusion: description (symport, antiport, uniport)
• __ Active transport: description
• __ Exocytosis, endocytosis, phagocytosis, pinocytosis: description (1 pt additional) A
       good example of one of the above mechanisms
• PART B. Role of the Membrane in the Production of ATP
  in Photosynthesis or Respiration

• (6 Maximum) Chemiosmosis:
__ Involved molecules are embedded in the
   membrane
__ Electron carriers are sequentially organized
__ The energy comes from the flow of electrons
__ H+ / Proton / pH gradient established
__ Movement through the membrane generates ATP
__ A specific protein makes ATP
• RESPIRATION
• __ Site is the mitochondrion
• __ Inner mitochondrial membrane
• __ Folded membrane present Cell membrane is involved in
      prokaryotes
• __ Correct direction of H+ flow

• PHOTOSYNTHESIS
• __ Site is the chloroplast
• __ Thylakoid / grana membranes (cristae) are involved in
      eukaryotes are involved in eukaryotes
• __ Folded membrane present __
• __ Thylakoid / grana membranes prokaryotes involved
• __ Correct direction of H+ flow
                       ESSAY #7
• 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 #7
•   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
           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
       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
             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
             FERMENTATION
Start 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-level
Start with pyruvate
• Function: recycling NADH
• Examples: Ethanol / Lactic Acid
• Details: Anaerobic, Regenerate oxidized
     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
            ESSAY #8
CELL QUESTION 1987:

 Discuss the process of cell division in
animals. Include a description of
mitosis and cytokinesis, and of the
other phases of the cell cyle. Do not
include meiosis.
ANSWER KEY
For Essay #8
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.
•   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 #9
GENETICS QUESTION: 1996
An organism is heterozygous at two genetic loci on different
chromosomes.

a) Explain how these alleles are transmitted by the process of mitosis
   to daughter cells.

b) Explain how these alleles are distributed by the process of meiosis to
   gametes.

c) Explain how the behavior of these two pairs of homologous
    chromosomes during meiosis provides the physical basis for
    Mendel's two laws of inheritance. Labeled diagrams that are
    explained in your answer may be useful.

				
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