SC 139 - Second Exam 2004

SC 139 - Second Exam 2004

Answer Key

MULTIPLE CHOICE.

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 is the proper definition of sexual reproduction?

                    a. Offspring are a product of two parents
                    b. Male and female get together and produce offspring
___C___      c. Offspring are a genetic mix of two sources
                    d. All of these are equally good
                    e. The approach widely preferred by surveys

...remember that it does not require either genders or two parents.

2. Evolution rates should be both gradual and punctuated because they should follow the rate of

___A___      a. Environmental change                     b. Mutations
                    c. Allele frequency change                  d. Genetic drift
                                   e. Hmmm...um, the stock market?

...environments can change slowly (gradual), but they can also change fast
and stay unchanged for long periods (punctuated).

3. In most land plants, individuals are both male and female, a condition that can be called

___C___ a. Asexual b. Dioecious c. Monoecious
d. Ambisexual e. Highly confusing on Valentine’s Day

...connect the term to the definition.

4. Type species or ecospecies occupy

___D___      a. The same group in a classification system
                    b. Different niches in a single ecosystem
                    c. Spots on a single food chain
                    d. The same niche in different ecosystems
                    e. Only the cheapest ecosystems, which makes them cranky

...same job, different places.

5. The organic materials in primordial soup came from

___C___ a. Plants b. Animals c. Space dust
d. Bacteria e. The Chowder Family

...the material that formed the Earth and dissolved into the forming oceans.

6. Which fits best with current theories about Earth’s earliest life?

___A___      a. Some of the earliest cell forms are still around today
                    b. The first molecule systems were probably pure protein
                    c. Protocells probably formed in the ocean depths
                    d. All of these are equally likely
                    e. The real estate prices were really low then

...some of the first cells were probably similar to Archaea.

7. Which system was not possible before photosynthesis became widespread?

___C___      a. Digestion                                         b. Reproduction
                    c. Aerobic respiration                          d. Evolution
                                e. The Dewey Decimal System

...it requires available oxygen, which wouldn't have been around before
lots of photosynthesis happened.

8. Which describes the eventual fate of a small group split off from a large population?

___C___      a. Genetic drift                                 b. Adaptive radiation
                    c. Founder effect                             d. Isolation matrix
                                        e. Ah, who needs ‘em anyway?

...the small group is the "founder."

9. Stromatolites are

___C___      a. Chromosome structures                     b. Rock formations
                    c. Extremely old fossils                         d. Dominant genes
                                    e. The diet version of something-or-other

...the remains of bacterial clumps that hang together by secreting minerals.

10. Linkage between genes refers to their

___D___      a. Making proteins used in the same processes
                    b. Similarities when compared between related organisms
                    c. Codes and the proteins made from the codes
                    d. Being together on the same chromosomes
                    e. Being front-page material on the Enquirer

...connect the term to the definition.

11. Panspermia is an idea that connects

___C___      a. Reproduction & gender                 b. Evolution & isolation
                    c. Meteors & Life                             d. Alleles & traits
                    e. My mind to an extremely weird food preparation

...it's the "Life was carried in from Elsewhere" theory.

12. When DNA is used as a molecular clock, the "ticks" of the clock are

___A___      a. Mutations                     b. Direct products of radioactive decay
                    c. New species                 d. Brand new protein products
                                        e. We have ticks on our DNA???

...they make DNA on different-but-related branches accumulate little
differences over time.

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 are two examples of different types of memes?
*Anything that can be passed on that's not* genetic -**		Could be learning, territory, placement, lots of different things.
2. What two pre-existing systems might have combined to produce the first photosynthesis system?
Chemosynthesis (making fuel using simple energy sources)		Light detection (to find hydrothermal vents)
3. Mutation effects - put these in order from most to least likely: bad, good, neutral.
Neutral - most mutations produce no or almost no effect at all	Bad - if there is an effect, it's likely to screw up a working system		Good - only rarely will a change produce a better system or a good new ability
4. For asexual reproduction -
BASIC Offspring are genetic DEFINITION - copies of "parent"		ADVANTAGE Actually makes OVER copies SEXUAL - (sexual doesn't)
5. For a high chromosome number -
ADVANTAGE Produces more variety in offspring		DISADVANTAGE Mistakes during cell divisions more likely
6. For sexual reproduction - Ooops! Kind of asked again elsewhere.
BASIC Offspring are genetic DEFINITION - mix from 2 sources		ADVANTAGE Produces more OVER variety in offspring ASEXUAL - (less vulnerable to change)
7. Two different energy sources or types that might have been used by the first living systems -
Heat Lightning		Ultraviolet

8. What two specific advantages do asexual reproducers get from producing large numbers of offspring (it increases survival chances, but why?)
Spreads them out (more likely changes won't catch all of them)	Can produce advantageous differences by mutation (the odds are bad, though, and only work with lots of chances)
9. Define alternations of generations (but don’t use any of those words in the definition). ...A life cycle that always has both an asexual and a sexual phase.
10. Although they wouldn’t have needed them at first, what are two features that the Earth’s first living systems eventually had to develop?
They had to be able to make decent copies of themselves	They had to be able to evolve (they went on to be "our" kind of Life)
11. When an allele appears to be dominant, what is *actually* going on? (What’s the biological process that makes an allele dominant?) ...the coded protein has a very powerful effect, strong enough to cover up the effect from a recessive allele's coded protein.
12. Briefly explain the "plant problem" that slowed down First Life Theory before the heterotroph hypothesis. ...since modern life depends on photosynthesis, it was thought that the first life had to be plants, which are very complex - too complex to easily explain as the first forms.
13. What are two different ways that molecules undergoing chemical evolution might gain a competitive advantage over other molecules?
- It could "grab" raw materials better / quicker. - It could tear apart other molecules for raw materials. - It could resist being torn up itself.	- It could assemble copies faster. - It could make more copies that were good copies. - It could cooperate with other molecules better, producing a more efficient system.
14. Briefly describe how one of the two types of genetic redundancy works. ...changes in DNA sequences often have no effect on the coded protein. ...during meiosis, chromosomes can pick up extra copies of genes - originals continue to do their original jobs, while extras can mutate to do something else.

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.

1. How do the basic sex cells differ? Give three sets of differences.
SPERM	EGG CELLS
Smaller	Larger (contain food for next generation)
Produced in much greater numbers	Fewer made
Able to somehow get to egg cell	Must be reached by sperm

2. What are four different circumstances that are thought to lead to mass extinctions?
Supervolcanoes	Ice Ages
Asteroid / comet impacts	Continental Drift Connections (Invasions)

3. What are *four different* conditions that a population must have for the Hardy-Weinberg Law** to apply to it?
It's large	No mutations occurring
No migration in or out	Mating in it is random
No Natural Selection is occurring

4. Briefly describe the two different methods for figuring out how old a fossil is.

Knowing how old the layer it's in is (by comparing layers from around the world) & adding up the depths

Looking for radioactive materials and their breakdown products - the ratio will tell you how long since either the organism died or the layer formed.

5. Describe (*don’t* just give a simple label!) four different isolating situations that can lead to the evolution of new species from the same starting group.
Geographic - physical separation by things like water bodies, mountain ranges, deserts, etc. (Any examples from this are still all one type)	Habitat / Niches - split groups stay in same place, adapt to different jobs in same environment
Time-based - organisms move from day-to-night or some such, or reproductive periods occur at different times	Behavioral - mating behaviors change between groups.
Mechanical - maters become physically incompatable	Chemical - females reject males' sperm, pollen, or embryoes

6. For the very first "living" systems, what basic requirements have to be met - what sort of features should the systems have to be considered "living"? Also kind of asked already (that's a mistake).

Need to be self-constructing

Need to be able to reproduce

Need to be able to evolve

NO KEY FOR 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.

What is the Nemesis theory of mass extinctions? Three Points.

Why is disease not a major factor in producing mass extinctions? Three Points.

Briefly explain how low chromosome numbers may sometimes produce offspring similar to what asexual reproduction would produce. Five Points.

Why is mitochondrial DNA more useful to evolutionary studies than "regular" DNA from a nucleus? Four Points.

What type of researchers were Hardy & Weinberg? Three Points.

Although he got some credit for evolution theory, Alfred Russel Wallace really is considered the originator of what science specialty? Three Points.

What material, still found today, might have given the first living systems a place to organize on? Three Points.

What feature in the fossil record indicates when photosynthesis became common on the Earth? Three Points.

Michael McDarby.

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