Weekly Essay Prompts by dffhrtcv3


									Weekly Essay Prompts

     Fall Semester
  Essay Prompt #1                            (Due Tues. 9/7)**
You must WRITE using a pen or pencil. A typed response will not be accepted.

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
b)for each property, describe one example of how the
  property affects the functioning of living organisms.

**Don’t Forget to Paste the Question on the 3rd page of
  your quad-ruled book and to have a BRAINSTORM
Essay #1 -Prop. of water

                           Note: you will need to
                           print this slide out to see
                           the words better.
Essay Prompt #2
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

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.
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
__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
__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.

__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)

__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
__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
                                           Levels of protein structure / zwitterion / as
__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 #3
 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
A. Water and solute transport (through plants)-Revised
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.
     ESSAY #3 – Grading Rubric
• Definition: (1 pt max)
• 1 pt. Definition of osmosis: the diffusion of water across a selectively
  permeable membrane.
• - High concentration of water to low concentration of water
• - High water potential to low water potential
• - Low water solute potential to high water solute potential
• 1 pt. Osmosis is maintained through the use of concentration gradients.

Part A: 1 pt. each (4 pt max; an be from root to stem category)-see Ch. 36
• Water enters the root hairs through osmosis
• Water moves through cells walls from one cell to another through the
• Water moves from one cell to another through the symplast.
• The endodermal calls allow water to enter the vascular cylinder (stele) but
  are selective
• A concentration gradient is maintained between the soil and the root
• Water is continuously moved out of the root by the xylem and by high
  solute concentration in the vascular cylinder
• Root pressure is an osmotic force that can force water u the xylem (not
  common – use of term guttation)
        ESSAY #3 – Grading Rubric (cont’d)
STEM (See C. 36)
• Capillary action is the rise of liquids in tubes
• Adhesion is the molecular attraction between unlike substances such as the
  water and the sides of the vascular cylinder
• Transpiration at the leaf causes a negative pressure to develop within the
  laves and xylem
• Cohesion between water molecules causes water to move up the xylem
• Bulk flow occurs at water molecules are lost from the leaf to transpiration
Part B: 1 pt. each (4 pt max)- See Ch. 44 (pgs. 931-938)
• site of osmosis is the nephron
• as salt moves from the filtrate to the interstitial fluid, water follows by
• interstitial fluid bathing the tubule is hyperosmotic to the filtrate in the
  descending loop of Henle
• ascending loop of the Henle reabsorbs NaCl without giving up water, making
  the filtrate dilute
• In the collecting duct the filtrate loses more and more water to the
  hyperosmotic interstitial fluid
• Antidiuretic hormone (ADH) increases the permeability of the epithelium to
• Water is absorbed in the nephron, reducing urine volume
         ESSAY #3 – Grading Rubric (cont’d)
Part C: 1 pt. each (4 pt max) – See Ch. 36 (Pgs. 749-751)
• Stomata are pores in a leaf
• When stomata are open water moves to the leaf
• Each stoma is surrounded by two guard cells
• When water enters a guard cell, the guard cell becomes turgid
• The turgidity of the guard cell causes an expansion or bulging of the cell
  creating an opening
• Stomatal opening is accompanied by a diffusion of K+. As K+ from
  surrounding cells enter the guard cell, a gradient is created, Water will then
  enter the guard cell (As K+ leaves, so does water)

Part D: 1 pt. each (4 pt max) – See
• when blood pressure drops the enzyme renin is secreted
• Angiotensinogen is converted to angiotensin
• Angiotensin stimulates the reabsorption of water, raising blood pressure
• Angiotensin constricts arterioles, raising blood pressure
• Aldosterone is secreted by the adrenal glands
• Aldosterone increases reabsorption of Na+ in the nephron’s distil tubule,
  increasing blood pressure and volume
• When blood pressure increases the release of renin is reduced
   ESSAY Prompt #4
 Enzymes are important biological
 molecules. They are one of the primary
 means of regulating chemical processes
 within cells.
A. Describe how enzymes affect chemical
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 #4
         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
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
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
9. pHs outside of that optimum can disrupt or denature
Part C (3pt max; 1 pt for each of the following)
1. Helicase causes the DNA double helix to
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
5. DNA polymerase proof-reads the new
   Other Information about Enzymes (2000 AP Question)
Enzyme question
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
    • Tertiary (and sometimes quarternary) structure determines function
    • Description of enzyme structure or function, e.g.
•   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 data
    Experimental design included sufficient range, varied the temp/pH of
    the reaction mix not the enzyme, what was measured, and how it was
    • 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 #5
• 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. Be sure to include all the
  intermediate molecules (# of carbons) as well as all of
  the products released. Also, indicate where all of the
  dehydrogenase & Kinase enzymes would be working.
  You may want to include labeled diagrams to support
  your answer
Answer Key to Essay #5:
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)
• 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
• 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)
EssayPrompt #6
 Discuss the process of cell division in
animals. Include a description of the entire cell
cycle and provide specific details of the key
events that occur in each of the phases. Do
not include meiosis. Be sure to include the
major proteins associated with the process of
cell division.
Answer Key/Grading Rubric for Essay #6
•    __ 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
• 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)
        (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. Explain how these controls prevent errors in
   inheritance and what happens when errors do
b. Discuss the key characteristics of Cancer and the
   genes commonly mutated that cause cancer to
c. Discuss how alleles are distributed by the process
   of meiosis to the gametes.
   Essay Prompt #7
No Rubric Available Yet. We
    might grade this one
  specifically in class!!! So
   make sure that you’ve
 included as much detail as
   possible to receive full
                                     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

**Answer the Questions on the Next Slide --------------
                 Essay Prompt #8 (cont’d)
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

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 of your 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 pts
   1 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 1.85
   1 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
   C) Maximum 4 pts
   1 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
           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
5-carbon sugar (ribose), a phosphate group, and a nitrogenous base.
       When a chromosome replicates, the two DNA strands unwind and
the hydrogen bonds between them are broken (Helicase). Single
stranded binding protein will stabilize and hold open the strands.
Topoisomerase will then cut each side of the replication fork alleviating
strain that reults from excessive coiling. Each strand serves as a
template for the synthesis of a complementary strand. Once the process
initiated (by RNA primase), DNA polymerase III adds the nucleotides to
each growing strand. One strand serves as the leading strand (made
continuously) and the other strand serves as the lagging strand (made
discontinuously). Each base matches the appropriate bases in the
template strand: they are complementary. DNA Polymerase I then will
replace the RNA nucleotides (Uracil-to-Thymine) that were laid down with
DNA nucleotides.
      Essay Prompt #9-Rubric (Key) Cont’d
      Once the complementary strands are formed, hydrogen
bonds form between the new base pairs, leaving two
identical copies of the original DNA molecules. The
process was determined by Meselson & Stahl to be
      A gene mutation is a change in the sequence of base
pairs in a DNA. It results from defects in the sequence of
bases. Mutations that involve a single base change in the
DNA sequence are called point mutations. Point mutations
fall into two general categories: base substitutions and
insertions/ deletions. A base substitution involves a single
DNA nucleotide replaced by another nucleotide. An
insertion or deletion occurs when a base pair is added or
removed from the DNA sequence. Any insertion or deletion
results in a frame shift when the mRNA is translating
resulting in a completely new unique protein formed. The
beginnings of possible adaptations and maybe an
advantage evolutionarily.
          Essay Prompt #10
  Describe the process of how genes are expressed
  (transcription & translation) in a eukaryotic cell. Be
  sure to include a discussion of how point mutations
  affect proper protein synthesis at the level of
  translation. You must mention all the key structures,
  molecules, and enzymes involved (ex. mRNA, tRNA,
  snRNA, RNA polymerase, aminoacyl-tRNA
  synthetase, ribosome & sites, TATA box, etc)

NOTE: Labeled drawings & diagrams may be useful in your
  response but you must draw them don’t cut & paste images

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