SCI 135 - Fourth Exam Spring 2012

Answer Key


Links connect to relevant parts of the online book.





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.   The main effect of the Snowball period was

___B___                    a.  Extinction cleared the way for new forms

                                 b.  Greatly increased competition

                                 c.  Cold was favored by new species

                                 d.  Ice moved species around

                                 e.  Many many snowmen


                            ...the livable space on the frozen Earth became very limited, increasing competition for every




                        2.   End-product inhibition should always involve

___D___                    a.  Protein production & ATP                    

    b.  Direct inhibition and ADP

                                 c.  Temperature and pH effects

                                 d.  Metabolic pathways & indirect inhibition

                                 e.  Inhibition, and some sort of product…at the end…


                            ...the end is the end of a pathway, and the eventual product wouldn't attach to the first enzyme's

                                active site, but somewhere else to turn it off.



                        3.   The particular step that produces a zygote

___B___                    a.  Embryogenesis                b.  Fusion                               c.  Oogenesis

             d.  Organogenesis                 e.  Zygotogenesis


                            ...the sperm cell nucleus (haploid) fuses with the egg cell nucleus (haploid) to produce the

                                    diploid zygote cell. 



                        4.   What works by lowering activation energy?

___C___                    a.    ATP                                 b.   DNA                                 c.  Enzymes

                                d.   Heat                                   e.   How about lowering expectations?


                            ...that's how they get the reactions to happen faster.



                        5.   Evolution actually changes the population of

___D___                    a.  Species                             b.  Enzymes                           c.  Families

                                d.  Alleles                               e.  Ames, Iowa (but that’s a secret)


                            ...what changes over time is the gene pool, all of the alleles in the population.



                        6.   As pH varies from optimal, enzymes lose efficiency from

                                 a.  Ion effects on hydrogen bonds               b.  Disconnection of ATP

___A___                    c.  Lack of respiration                                d.  Inhibition

                                    e.  They just don’t care as much as when they started


                            ...enzymes get a lot of shape from those weak charge attractions, which can be

                                disrupted with a change of H+ or OH- around the molecules.



                        7.   A sedimentary layer of rust is evidence of

___D___                    a.  An asteroid impact                                     b.  A volcanic eruption

                                 c.  An ice age                                                 d.  Photosynthesis

                                                            e.  Lack of rustproofing


                            ...all of the iron that could dissolve in the oceans without oxygen combined with
                                the photosynthetically-produced oxygen, making rust that settled to the bottom.



                        8.   Reradiation involves

___A___                    a.  Changes in frequency                 b.  Jumping of electrons

                       c.  Changes in wavelength               d.  All of these

                                                e.  Mutational vomiting


                   frequency goes in, but another comes out.



                        9.   Coenzymes are

___B___                    a.  Always vitamins                                  b.  Sometimes vitamins

             c.  Always cofactors                                 d.  Sometimes cofactors

                                    e.  Always annoying


                             ...if humans can't make them, but need to get them in their diet, the coenzymes are




                        10.  Virtually every mass extinction has as an early step

___C___                    a.  Widespread disease                    b.  Huge drop in temperature

                       c.  Loss of plant life                         d.  Asteroid impact

                                                e.  Nobody shows up for work


                   can be cold or lack of light that takes out most of the plants, but loss of the first step

                                of the food chain is important.



                        11.  Coupled in coupled reactions:

___B___                    a.  Enzymes & genes            b.  Exergonic & endergonic

                                c.  Inflow & outflow             d.  Electrons & protons

                                                            e.   Stupidity & violence


                            ...the exergonic release energy used by the endergonic.



                        12.   Which process makes a lot of ATP?

___B___                    a.  Any metabolic pathway                 b.  Electron transport chain

                                 c.  Krebs cycle                                  d.  DNA synthesis

                                                            e.  The ATP-making process


                            ...whether in aerobic respiration or photosynthesis, it is the most productive step.






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 is the founder effect? happens when a small group, with a unique gene pool, splits off from a bigger group, becomes isolated, and that small gene pool is the starting point for what becomes a big group elsewhere.

2.   What are two different things that happen during glycolysis?

Glucose is broken in "half."

4 ATP are made.

2 ATP are invested.
3.    Show the three steps, in order, of organisms types in any food chain.
Producers Consumers Decomposers
4.     What are two different types of molecules that have specificity?


5.   The two likeliest staging areas for the movement of Life onto the Land -
Tidal Pools Inland fresh water systems
6.   What two different tissues can go into oxygen debt?
Muscles Cancer / tumor cells
7.   Land plants could not exist without their symbiotic partners -


type of             Fungi or Bacteria


What do

they do                Produce nitrate from nitrogen

for the plants?                    in the air.

8.   Briefly explain how the second law of thermodynamics applies to a food chain.


       ...every transfer of material through the food chain loses some of the energy in that food, as the system loses order. 

9.   Two different nitrogenous waste products -


Uric Acid

10.  Explain how hybrid vigor works.


      ...a "bad" allele can, when matched with a "good" allele, produce an advantage over 2 "goods" or 2 "bads."

11.  What are two different types of isolation that can happen to groups sharing the same space / ecosystem?  Just a name is fine.
Niche (different jobs or times)

Temporal (different reproductive times)

Mechanical (incompatible reproductive parts)

Chemical (prevents successful reproduction)

12.  Chemosynthesis was discovered at hydrothermal vents.  Where were the vents?

 the bottom of the ocean, where new ocean floor is made between moving continents.


13.  What happens during differentiation?


       ...cells in embryos begin to use different genes and do different jobs.

14.   The two major different uses for carotenoids -
Capture light frequencies for photosynthesis Color flowers and fruits

15.  Why is RNA thought to have been part of the first “living” molecular complexes?


      ... it can do some protein (enzyme) functions and some DNA (coding) functions, and it's still working in between those functions.

16.   What is panspermia?


       ...the idea that Life began somewhere else and was carried to Earth on early meteors.


17.  Two features the very first “living” systems had to have -
Had to use and transform energy.

Had to be able to build internal order.

Had to be able to reproduce.

Had to be able to evolve.

18.  Two features those living systems would not have had at first, but had to have eventually -

Protein-based chemistry.

DNA-based coding.




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.


1.   According to the Hardy-Weinberg rules, what has to be true about a population for there to be NO change in allele frequencies over time?
No Natural Selection No Sexual Selection
No Mutation No Migration of subgroups in or out
Population must be huge  
2.   Answer the questions on the graph for the relationship between enzyme activity and temperature.   A.  Why is the rate dropping off here (the downslope after the peak)?  B.  What is this point called (Where the peak lines up with the temperature axis)?  C.  Why is the rate rising here (the upslope heading toward the peak)?

A - As temperature rises, more and more enzymes shake open (denature) and aren't working.

B - Optimum or optimal temperature.

C - Molecules move faster as temperature rises (and enzymes get "looser," quicker to grab substrate and release product)

3.   For the main photosynthesis reactions:
Name Exact Materials or Energy Used Exact Materials Produced
Water, Light Oxygen, ATP
ATP, Carbon Dioxide Glucose

4.   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            

                                *                                         *   /      *          *                                       *        \    *

                                   X-Ray                   Ultraviolet      /   Violet      Blue                                 Red     \    Infrared

5.   For each step in the theoretical development of Life on Earth, put them in chronological order, from earliest to latest, 1 - 8 in the boxes to the left.
8 Movement onto Land 4 Photosynthesis 7


















6.  What are four different ways that anaerobic organisms impact humans? 
Alcohol production Spoilage, especially milk
Rising dough Dairy product production (cheeses, yogurt)
Intestinal symbionts Diseases
7.   Plants have nutrient needs besides the materials directly needed for photosynthesis.  Give two different nutrients they need, and for each, tell how the plants use that nutrient. 
Nutrient How that nutrient is used
Nitrates Used in protein production
Phosphates Used in ATP
Minerals Important as cofactors





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.


Why do we know bizarre physical attributes of beetles?  Three Points.



What species have gone through a bottleneck?  Three Points each.



Which processes are like parking a car in a garage?  Three Points.



Why would the product of a metabolic pathway have to be a part of a multiple gene trait?  Three Points.




What sorts of materials often produce irreversible enzyme inhibition?  Three Points.



The optimal temperature of what human process is about 93o F?  Three Points.



What ability is often found in cofactors and coenzymes that enzymes generally lack?  Three Points.



What’s the relationship between a calorie and a Calorie?  Three Points.




Why are most religion-based explanations for the beginnings of Life rejected by biologists?  Three Points.




What does the moon Titan have to do with primordial soup?  Three Points.





Michael McDarby.

SCI 135

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