SCI 135 - Fourth Exam Fall 2019
Answer Key


On the line to the left, place the letter of the choice that best answers the question.

Three Points Each.               NOTE:  "e" answers are never the correct answer.


                        1.  Which type of cells are most at risk for becoming cancerous?

___B___                    a.  Very metabolically active

                                    b.  Ones that normally divide

                                    c.  Cells that were made long ago

                                    d.  Cells that normally can crawl

                                    e.  Cells that secretly hate their lives

            's hard to make non-dividing cells divide out of control.


                        2.  Plants depend upon symbionts to supply them with

___D___                    a.  Carbon dioxide                            b.  Light

                                    c.  Minerals                                       d.  Nitrates

                                                    e.  Most of their “Likes”

                      ...they need them to make amino acids and proteins, but can't use
                                      the Nitrogen in the air directly.


3.  What fuses during fusion?

___C___                    a.  Chromosomes                  b.  Genes                    c.  Haploid nuclei

           d.  Diploid nuclei                             e.  Can these fuses burn out?

                      ...sperm and egg cell nuclei, each with just one set of chromosomes.


                        4.  Researchers connect problems with breeding cheetahs to a lack of
                                                genetic diversity – they think that cheetahs almost went

                                                extinct during the last major ice age.  What effect is

                                                at play here?

___B___                    a.    Genetic drift                               b.  Bottleneck effect

                                    c.    Founder effect                           d.  Residual reduction

                                                                        e.    Irony

                      ...the population "pinched down" to a very limited gene pool that gave rise
                                 to today's population allele ratios.


5.  Enzymes are affected by temperature because temperature

___D___                    a.  Changes how electrons move in the molecules

b.  Can break the membrane

c.  Disrupts the enzyme’s DNA

d.  Moves and shakes the molecules

                                    e.  Sneaks up behind the enzymes and frightens them

             can "tighten up" active sites when cooled or make it hard for them
                                       to keep the right shape when heated.


                        6.   Which would have started as ectoderm?

___A___                    a.  Brain                                 b.  Intestine

                                    c.  Muscles                             d.  Lungs

                                                e.  Isn’t that an acne cream? 

                      ...ectoderm gives rise to the nervous system.


                        7.   Protocells probably got started from

___B___                    a.  Hydrothermal vents

                                    b.  Surface oils and stormy conditions

                                    c.  The Snowball Period

                                    d.  Aerobic respiration

                                    e.  Satellite telephones 

            's about the first membrane-like "bubbles."


8.  When the leaves turn to bright colors in the fall, what are those colors?

___D___                    a.  Degraded chlorophyll                b.  Cellulose              c.  Glucose

                                    d.  Carotenoids                                 e.  Nature’s makeover 

                      ...they've been there all along, hidden under all of the now-degraded chlorophyll.


9.   When a protein denatures, it

___B___                    a.  Attaches to a substrate                           b.  Changes shape

c.  Comes apart into amino acids               d.   Shifts to a new function

                                               e.  Gets really self-conscious and quiet 

                      ...that's all you need for it to lose its function ("nature").


10.  Plants use glucose for

___C___                    a.  Feeding animals

b.  Energy storage and reproduction

c.  Energy storage and structure

d.  Reproduction and structure

                                    e.  Whatever they want - plants are evil that way 

            , the same way everything uses it, but also linked together
                                         into structural starches.


11.  Oxygen debt typically happens in

___A___                    a.  Muscles under high demand      b.  Plants in intense light

c.  Respiratory surfaces                      d.  Brain cells

                                    e.  Banks that really want you to pay them back 

                      ...they can get a small amount of ATP running the anaerobic stage by itself.


 12.  What are coupled in coupled reactions?

___D___                    a.  Enzymes & substrates                b.  Enzymes & coenzymes

c.  Enzymes & cofactors                d.  Exergonic & endergonic

e.  The reactions with deep, abiding respect for each other

                                                                        ...or the hot ones...

             and energy-needing.


SHORT ANSWER.   Answer any eight of the following questions for 4 Points Each.

            Note:  if you answer more than eight, only the first eight will be corrected.

            You can get partial credit on these answers.


1.  What happens to the alleles in a population as that population evolves in changing conditions?

Alleles that are useful get more common (their holders are more likely to survive to reproduce and pass them on), those that are harmful in the new condition get less common (their holders don't survive to reproduce and pass them on). 



2.  For older plant growth lights -

Why are      Purple is higher frequency

they               and supplies more energy

purple?         to the plants per watt.

Why are     Plants reflect green,

they not      they can't use it.



3.  How does end-product inhibition work?


 The final product in a pathway can attach loosely to the first enzymes of the pathway and inhibit them.  As product builds up, the path slows down.



4.  When ATP gets used, what are the products?





5.  What are two different things that happen during a normal meiosis that do not happen during mitosis?


Homologous chromosomes

get pulled in next to each other

during prophase


Crossing over - pieces swapped

between paired



6.  The first pre-living molecular systems needed to have what two abilities?

 Ability to self-organize

Ability to reproduce

Ability to evolve 




7.  What are two different abilities that cancer cells typically activate after they have become cancerous?


 Oxygen debt or blood-vessel recruitment



Crawling with pseudopods

Immune system evasion


8.  What are the basic levels, in order, of the energy pathway through food chains?







9.   What exactly is activation energy?


The energy needed to get a chemical reaction started.



10.  What sort of role in cell chemistry is generally played by minerals?


They help to move electrons around.



11.  For either of the first 2 Laws of Thermodynamics -

Number or  1 - Conservation

Name            2 -Entropy


Description-  1 - Energy can't be created or destroyed, just changed.

   2 - Energy is lost as heat at any transfer. 



12.  In order for the Hardy-Weinberg Rule to work, what are two things that should not happen to an allele?


Natural Selection

Sexual Selection




13.  What are the three basic types of nitrogenous wastes?




Uric Acid 


14.  What are two different abilities that early Life needed eventually, but not right away?



Protein-Based Chemistry

DNA-based coding system 


15.  What are Hox genes?


 Genes that set basic layout as an embryo develops.


16.  Glucose is mostly made by what two different processes?






LONG ANSWER.  Answer any four of the following questions for Eight Points Each.

Note:  if you answer more than four, only the first four will be corrected.

            You can get partial credit on these answers.

3.  At the points labeled with the stars, attach the appropriate labels from this list:
Violet. X-Ray. InfraRed. Red. Blue. Ultraviolet.
         High Frequency       \           Visible Range          /            Low Frequency        
          High Energy                    Um, visible-?                        Low Energy
       *                           *   /   *       *                        *   \   *
 X-Ray           Ultraviolet    Violet   Blue                Red    InfraRed



2.  Describe (don’t just give a term) four different types of reproductive isolation.
Features of environment physically separate groups.
Subgroups start to serve different roles in ecosystem.
Subgroup reproduces at different time.
Subgroup develops different reproductive preferences.
Subgroups lose ability to copulate with each other.
Subgroup becomes incompatible.
(Chemical / Immunological)



3.  Below is a graph showing how enzyme activity, measured through the rate of the reaction catalyzed by the enzyme, reacts to changes in pH (NOT temperature!).  Fill in:  A)  The name given to the pH where the graph peaks; B) Why the graph peaks there;  C) and D) What’s happening to the enzyme molecules as the rate drops off (C) below the peak; and (D) above the peak.



                                                                      *   A Optimum
                                                                  *                *
                                                              *                        *
Reaction        Too much H+         C    *                             *   D  Too much OH-
Rate                                                 *                                   * 
                                                       *                                       *
                                                  *                                                    *
                                         *                                                                       *
                          *****                                                                                         ******
                                                                          B   Enzymes at proper shapes 

                                                                    pH ---->



4.  Briefly describe the three different ways that enzyme inhibitors can work. Inhibitor molecule attaches in active site
so substrate can't
Inhibitor molecule attaches near active site and
 blocks substrate from getting into it
Inhibitor attaches to enzyme and changes its shape,
changes active site so substrate doesn't fit there




5.  Give the names and something that happens in the three stages of aerobic respiration.





Glucose broken apart in "half"

2 ATPs -2 in, 4 out.


 Krebs Cycle



 Carbon dioxide produced.

Many electrons generated.


 Electron Transport Chain



 Many ATPs produced.


6.  What are four different ways that anaerobic organisms impact humans?
Produce ethyl alcohol for beverages Produce gases for rising dough
Produces flavors in dairy products like cheeses Causes milk to go sour
Can cause some diseases Symbionts help protect us and do some digestive functions


7.  For the main photosynthesis reactions:
Name Light-Dependent Reaction Light-Independent Reaction
Exact Materials or Energy Used
Water (supplies Hydrogen)
Carbon Dioxide
Exact Materials Produced
(using Hydrogen-carried electrons)
Oxygen (from water)
(Carbon dioxides stuck together using ATP Energy)



BONUS QUESTIONS.  Answer as many as you are able.  Wrong answers will not result in points being lost from the main exam.   You can get partial credit on these answers.


Hardy and Weinberg -  what was their general specialty?  Three Points.



Briefly explain how mistakes during meiosis can add to genetic information.  Three Points.



Why do polar bodies exist?  Three Points.



When human embryos become “hollow balls,” what shape are they really (Three Points), and why that shape?  Three Points.



Hybrid vigor was first discovered in the relationship between what two diseases?  Four Points.


How does convergent evolution show up in advanced cancers?  Three Points.



People complain that cancer chemotherapy is poison.  Why does it pretty much have to be?  Three Points.



Although Splenda is a sugar molecule, it has no calories.  Why?  Three Points.



What is weird about the definition of a vitamin?  Three Points.



What is a Calorie?  Three Points.



What is panspermia?  Three Points.



What “retunes” the energy in reradiation?  Three Points.




SCI 135 

Michael McDarby