BI 171 - Second Exam - 2008

Answer Key


Links connect to relevant parts of the online book.

Multiple Choice.

Place the letter of the choice that best answers the question on the line to the left.
Two Points Each. NOTE: "e" answers are never the correct answer.

___D___ 1.   Which are polymers?
                    a. Sugar and starch                     b. Sugar and lipid                     c. Lipid and protein
                    d. Protein and starch                                         e. Polly what-nows-?

                            ...long molecules of repeating units - sugars repeat in starches, amino acids in proteins.

___B___ 2.   Crossing the gap between nerve cells requires which proteins?
                    a. Enzymes and antibodies                     b. Neurotransmitters and receptors                    c. Antibodies and antigens
                    d. Antigens and receptors                                                            e. Logs and frogs

                            ...neurotransmitters cross the gap and attach to receptors on the other side to start up an impulse there.

___D___ 3.   The instability of radicals comes from what part of the atoms?
                    a. Protons                     b. Neutrons                     c. Inner electrons                    d. Outer electrons                     e. Their family situations

                            ...they have unfilled outer shells.

___C___ 4.   An R group is found in
                    a. Lipid molecules                     b. Sugar molecules                     c. Amino acids                    d. RNA                     e. Pirate molecules

                  's the part that varies among the different types.

___B___ 5.   Activators, enhancers, and promoters are functional parts of
                    a. Enzyme pathways                     b. Gene transcription                     c. Gene translation                     d. Evolutionary change
                                                                                e. A Broadway touring company

                            ...they help get the process started (although it's starting to look like D could be true, too, with changes in the
                                    processors maybe as important as changes in gene codes).

___A___ 6.   At a pH of 7,
                    a. H+ ions are about equal to OH- ions                                        b. H+ ions outnumber OH- ions
                    c. OH- ions outnumber H+ ions                                                  d. There are no ions
                                                e. Is there any way I can request a different question...?

                            ...that's why the pH is considered neutral.

___C___ 7.   Which is true?
                    a. Genes contain chromosomes which contain DNA                    b. DNA contain genes which contain chromosomes
                    c. Chromosomes contain genes which contain DNA                    d. Genes contain DNA which contains chromosomes
                                                        e. I knew I should have taken that basket-weaving class

                            ...this is very necessary basic knowledge.

___D___ 8.   Panspermia is a concept that applies to the
                    a. Reproduction of plants                     b. Reproduction of animals                    c. Expression of DNA
                    d. Beginnings of Life on Earth                                        e. Worst restaurant idea ever conceived

                   hypothesizes that Life started elsewhere and was somehow brought to Earth.

___A___ 9.   What would an unsaturated molecule have that a saturated one won't have?
                    a. Double bond                     b. Hydrogen bond                     c. Water                    d. Ions
                                                 e. Saturation, right-? Or, not saturation...

                            ...that's why it's not saturated:  it's got at least one extra "slot" for another atom.

___B___ 10.   Digestion of food will always involve
                    a. Acid-base reactions                     b. Hydrolysis                    c. ATP input                     d. Dehydration synthesis
                                                            e. Production of embarrassing gasses

                  's the breakdown reaction for organic molecules.

___A___ 11.   Which tends to come apart in water?
                    a. Ionic bonds                     b. Hydrogen Bonds                    c. Hydrophobic bonds                     d. Acidic bonds
                                                                    e. Someone who has just had their hair done

                            ...they get pried apart and held apart by the bipolar water molecules.

___D___ 12.   Histones are associated with
                    a. Protein synthesis                     b. Starch breakdown                    c. Enzyme function                     d. Chromosome structure
                                                            e. A big pile of rocks (or rocks with a drug problem)

                            ...they provide the "wrapping up" structure for the DNA.

___B___ 13.   Covalent bonds involve
                    a. Proton interactions                     b. Electron sharing                    c. Whole charge attractions
                    d. Partial charge attractions                                        e. Stuff I didn't learn

                            ...that's the definition.

___A___ 14.   Which would definitely be a protein?
                    a. Telomerase                     b. Glycogen                     c. Testosterone                    d. Galactose                     e. The one with the protein license

                            ...the "-ase" ending says it's an enzyme, which would be a protein.

___B___ 15.   The part of a protein that does some special function:
                    a. Functional group                     b. Domain                     c. Zone                    d. Locale                     e. Specialty spot

                            ...match term and definition.

___C___ 16.   Two molecules with different conformations would have
                    a. The same number of carbons, but differences in numbers of other atoms
                    b. The same atoms, and all bound to the same atoms, different 3 dimensionally
                    c. The same atoms, but bound to different atoms
                    d. Different distributions of charges
                    e. Probably have been raised Catholic-?

                            ...bonds can be rotated, producing different shapes to the molecules.

___D___ 17.   Telomeres
                    a. Attach to spindle fibers                    b. Are where a gene inventory can be found
                    c. Are made of RNA                           d. Cap the ends of chromosomes
                                        e. Are very nice little biological terms

                            ...they are the ends that take some work to copy properly.

___A___ 18.   Transfer RNA
                    a. Carries amino acids                    b. Moves from the nucleus to the ribosomes                    c. Moves from ribosomes to the nucleus
                    d. Connects chromosomes together                                        e. Helps you move credits to another college

                  's the small one that brings in the amino acids one-at-a-time to attach to a growing protein molecule in the ribosome.


Short Answer.

Pick NINE questions to answer in the spaces provided.
NOTE: if you answer MORE than nine, only the first nine will be corrected.
Four Points each. Partial credit is possible.

1.   What are the two distinct types of temporal isolation?

Niche, in the same ecosystem and sort of the same niche, but at a different time.

Reproductive, with a different breeding season.
2.   The three simplest hydrocarbons, according to their numbers of Carbons:
Methane Ethane Propane
3.   What single effect (other than extinction itself) has probably occurred in every major mass extinction event?

          ...a change that wipes out the active plants, cutting the food chain at the first link.

4.   What is a hydration shell?

          ...the sphere of water molecules that surround charged solute particles.

5.   Give two pairs of differences between



Loop 2-ended


Often with related / sequentially-used genes in sequence Genes usually spread around somewhat randomly
6.   What two elements, beside Carbon, Hydrogen, Nitrogen, and Oxygen, are common in biological molecules?
Phosphorus Sulfur
7.   What is a bottleneck effect?

          ...a population is almost wiped out, reduced to a small gene pool that then expands again.

8.   What would the stereospecificity of an enzyme determine?

          ...which particular substrates it would (and wouldn't) bind to.

9.   Plants produce starches for different reasons. Connect each reason to the stability of the bonds.
STABLE             Structure (cellulose).
STABLE                   Stored energy / sugars for growth.
10.  Give two organic functional groups by name, and then show their molecular arrangement.

Follow the Link on the number for the list.

11.   Exactly what sort of bad thing would happen without chaperonins?

 proteins would often fold into a non-functional conformation (chaperonins make sure they're the right shape).

12.   What are two features the first "living" molecular systems had to have?


Able to reproduce.
Able to evolve.  
13.  What are two features that would not have been there early, but which had to appear in "living systems" for them to be Life as we know it?
Protein-based chemistry. DNA coding.
14.   Ignore the specifics (don't name the molecules) - label with the general terms applied to any chemical reaction -

CO          +          H2O                  light       >           C6H12O6         +        O2

Reactant or Substrate                         Contributor                                                Products
---------------               ---------------               -----------------                  ----------------             -----------------

15.  Explain how genetic redundancy works in transcription.
          ...a base substitution in a codon will often code for the same or a similar amino acid.

Long Answer.

Select and answer completely any four of the following questions.
Note: if you answer more than four, only the first four will be corrected.
Seven Points Each. Partial credit is possible.

1.   Name and give a description of the four levels of protein structure.


Sequence of amino acids.


Local shaping patterns.


Overall 3-dimensional shape.


More than one protein strand in the functional protein.
2.   Using the numbers of bonds as a guide, fill in the symbols for either Carbon, Hydrogen, Nitrogen, or Oxygen.

NOT REALLY REPRODUCIBLE HERE.   Know how many bonds each has to fill in a given molecule.




3,   Name or describe four things that happen in Nature that are critically important to evolution, according to four different provisions of Hardy-Weinberg equilibrium.

Natural selection

Sexual selection


Migration / isolation
Size of population  

Column 2

How many
20 (Atomic number)
How many     
20 (Rounded-off weight, minus protons)

How      many                  
electrons?(Radical form)

20 - equals protons

ion form?
+2 , typical for Column 2
5. Put these in chronological order, according to the way current theories think they occurred - number from 1 (earliest) to 9 (latest).
2__    Evolution
             Life on
9__    Land
8__    Explosion
1__    Soup Forms
7__    Life
5__    Respiration
3__    (First Membranes)
6. For three different properties of water:
Property: How produced on molecular level:

Excellent solvent

Bipolar molecules surround and support dissolved particles


Bipolar molecules stick to other particles


Bipolar molecules stick to each other
Surface tension Bipolar molecules hold on to molecules at surface
Temperature stable Cohesion makes it harder to heat or cool volumes of water
Expands on freezing Repulsions of bipoles drive molecules apart as they freeze.
Ionizing Small proportion of molecules dissociate to H+ and OH- ions.
7.   For lipids - Basic molecular components

Glycerol and 3 fatty acids


2 Different Uses in Living Things

Water barrier

Longterm Energy storage
Hormones Insulation
8.   Given here is one side (strand) of DNA. Starting with this strand, and using the table attached to the back of the exam, show:

Strand T A C A G C C C C G C A T T G C T A G G G A T T

__A U G U C G G G G C G U A A C G A U C C C U A A  
Messenger RNA from 1st strand

(Start) Serine - Proline - Cysteine - Asparagine - Aspartate - Proline (Stop)
Amino Acid Sequence



Answer as many or as few as you wish. You can't lose points on the rest of the exam by getting these wrong. Partial credit is possible.

What unusual sort of isolation is often found in beetles? Three Points.

How are epigenetic factors Lamarckian? Three Points.

In what way is the old "photosynthesis problem" for Life origins uniformitarian? Three Points.

What is the likely evolutionary connection between the Snowball period and the Cambrian Explosion? Three Points.

Radioactive elements often turn into other elements. How do they do this? Three Points.

Carbon dating is pretty useless for things more than 60,000 years old. Why, exactly? Three Points.

When do local lakes stop "turning over"? Three Points.

What is it about our amino acids is really hard to explain? Three Points.

What two major medical research areas are specifically studying telomeres? Two Points Each.


How does an antibiotic treatment today give a person an antibiotic-resistant infection months from now? Four Points.

Why is prokaryote evolution so difficult to track? Three Points.




BI 171

Michael McDarby


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