BISC 102 – Final exam (
/100 marks) – Fall 2022
This document is intended to help TA markers develop their marking schemes. On an exam like this I
aim for - short answers that require little writing, and that are reasonably clear in what is ‘correct’.
- about 40% ‘factoid’ questions (section A)
- about 30% ‘concept questions’ (section B)
- about 30% ‘synthesis questions (section C)
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SECTION A (40 marks in total)
A1.
Darwin’s theory of evolution is actually comprised of five distinct parts.
List them in a few words each: (5 points total)
In your slides
A2.
Summarize the whole theory in 3 words. (1 point) Lecture slides
A3.
Some of the Forest Walk Assignments submitted a picture of the female reproductive
structure of the red alder Alnus rubra, a locally abundant angiosperm species. These do look
like the ‘pine’ cones produced by gymnosperms and asked for in the assignment, but they
are actually a modified fruit. Are the ‘cones’ of red alders and conifer ‘pinecones’
homologous structures? (YES or NO). (1 point) NO
Give the evolutionary term for their resemblance. (1 point) HOMOPLASY SLIDE
A phylogenetic tree that grouped plants with ‘cones’ into a single taxon would nowadays be
considered wrong. What kind of phylogenetic error would this be? (1 point)
PARAPHYLETIC SLIDE
A4.
You drive across Canada, heading to Nova Scotia. Name 4 major biomes you would pass
through along the way. (4 points)
TEMPERATE CONIFEROUS FOREST
TEMPERATE GRASSLAND
TEMPERATE FOREST
BOREAL FOREST
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A5.
Three domains are currently recognized on Earth. Name them. (2 points)
BACTERIA (P)
ARCHAEA (P)
EUKARYA (E)
Identify each as prokaryotic (P) or eukaryotic (E). (1 point)
Circle those domains that have a nucleus. (1 point).
Draw a basic phylogenetic tree in the space below (ignore the endosymbiotic events)
showing their relationships (1 point), indicating with an arrow where chemiosmosis is
thought to have evolved. (1 point)
A6.
Approximately how long ago did the oxygen level of the atmosphere begin to rise? Express
your answer in ‘billion years ago’, or bya. (1 point) 2bya
What evidence supports this estimate? (1 point) RUST DEPOSITS IN ROCKS, or BANDED
IRON FORMATIONS
What is the source of all this oxygen? (1 point)
PHOTOSYNTHESIS
A7.
Name four different compounds from which
various taxa obtain the high energy electrons
used by electron transport chains. (1/2 point
each) See image
A8.
Name four different possible electron
acceptors to which electron transport chains
give electrons drained of their potential
energy. (1/2 point each) See image
A9.
What compound donates the electrons used in oxygenic photosynthesis? (1 point)
WATER
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A10.
How is the potential energy of the electrons in question A9 boosted before they enter an
electron transport chain? (1 point) FULL ANSWER IS ENERGY FROM PHOTONS CAPTURED
BY A PIGMENT MOLECULE IS TRANFERRED TO ELECTRONS IN PHOTOSYSTEM I or II.
A11.
We studied two organelles that are the (modified) descendants of prokaryotes that evolved
to live inside another prokaryotic cell. This union made possible the evolution of
eukaryotes. Name these organelles. (1/2 point each)
MITOCHONDRIA CHLOROPLAST
Name the ancestral prokaryotic kingdom of each. (1/2 point each)
SLIDE #18 PROTEOBACTERIA CYANOBACTERIA
A12.
Name the brief haploid phase of the human life cycle. (1 point) GAMETES
A13.
Name the brief diploid phase of a fungal life cycle. (1 point) ZYGOTE
A14.
Your girlfriend dumped you after last summer’s vacation in the Rocky Mountains,
giving as her reason that you just don’t respect the cartilaginous fishes. You tearfully
explain that you now realize that sharks didn’t evolve 730 mya (as you thought), but 650
mya. Instead of the happy make-up you had hoped for she snorts in disgust, turns on her
heel, and walks away. Why? (1 point)
Some version of SHARKS COULDN’T HAVE EVOLVED BEFORE THE CAMBRIAN EXPLOSION
Admittedly, you don’t understand why this is so important to her. Perhaps - as she has
sometimes said - you just don’t get her after all. Might BISC 102 have helped prevent
this heartache? (YES or NO; 0 points for this – it’s your opinion) ANY ANSWER FINE
A15.
A16.
How many cells is the body of an adult Caenorhabditis elegans built from? (1 point)
1031
Who invented the Drake equation? What does the Drake equation analyze? (1 point each)
DRAKE; How many detectable alien societies exist in our galaxy?
A17.
True or false? Worms are less evolved than humans. (1 point) FALSE
A18.
The ‘central dogma’ of molecular biology is: DNA makes mRNA which makes proteins.
Name the process that connects DNA and mRNA
Where does this take place?
Name the process that connects mRNA and proteins
Name the structure on which proteins are assembled
A19.
(0.5 point): TRANSCRIPTION
(0.5 point): NUCLEUS
(0.5 point):TRANSLATION
(0.5 point): RIBOSOME
Name the ship on which Charles Darwin made his famous voyage. (1 point)
HMS BEAGLE, or THE BEAGLE or just BEAGLE
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SECTION B (30 points in total)
B1.
There is no ‘why’ in stellar evolution. Explain. (2 points) Stars have an ‘evolution’ (the
‘main sequence’ arises as a result), but there is no descent with modification by selection,
and hence no questions about ‘why’
B2.
The town of Osoyoos in British Columbia lies ~300 km east of Vancouver. Driving there
requires a (beautiful!) trip of about 4h, during which you cross the Cascade Mountains.
Which biome would you expect to find at Osoyoos. (1 point). DESERT
Explain in basic climate terms how this comes about. (3 points)
MOISTURE-LADEN AIR MOVES EASTWARD FROM THE PACIFIC
FORCED UPWARD BY THE CASCADE MTNS, SO COOLS AND DROPS ITS MOISTURE
DESCENDS ON THE EAST SIDE OF CASCADES, AND WARMS
THIS DRY WARM AIR TAKES UP AVAILABLE MOISTURE CREATING A DESERT
B3.
We studied reproduction by the small old world passerine Parus major, a close relative of
our ‘chickadee’ (Parus atricapillus). Name the genus of these two species. (1 point)
Parus
It was shown in lecture that clutch size (the number of eggs laid in a nest) affects the
number of young that survive. Explain the underlying trade-off. (2 points).
MORE EGGS INCREASES THE NUMBER OF YOUNG, BUT EACH HAS SMALLER BODY
WEIGHT WHICH LOWERS SURVIVAL CHANCES
It was shown in lecture that the birth weight of human babies varies (from ~1 – 5 Kg), and
that those at the extremes of this distribution of survive less well than medium birthweight babies. Do you think a basic component of human reproduction like completed
family size evolved by natural selection? Or are the reasons instead cultural and religious?
Could both play a role? If so, how? (2 points). Question B4 might help you here).
COMLETED FAMILY SIZE SUBJECT TO NATURAL SELECTION, BUT THE MECHANISMS OF
CULTURE AND RELIGION ALSO PLAY A ROLE AS PROXIMATE FACTORS.
B4. You are driving to Nova Scotia (see Question A4) one summer with some friends. One hot day
in Saskatchewan you see many pelicans soaring on a thermal high above the lake where they
breed. (These flights are called ‘boils’. Pelicans often do this when thermals are strong, as on
hot days.) One friend says “I bet those birds are doing that because it’s energetically cheap,
and predators can’t get them up there.” Your other friend snorts out his Tim Horton’s doubledouble in derision (it seems he has stopped at every Tim’s along the route – there are many
of them) and says “Are you kidding! Those birds aren’t thinking about predators or
calculating energy intake, they’re just having fun!” The heat, too much coffee, and roadweariness combine to escalate the argument and the fun of the trip is threatened. As the only
one who has taken BISC 102 you have to step in to save the day. What do you say? (2 points)
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ESCAPING PREDATORS IS AN ULTIMATE EFFECT, HAVING FUN IS A MECHANISM. THESE
ARE COMPLEMENTARY AND NOT COMPETING EXPLANATIONS. BOTH COULD PLAY A
ROLE.
B5.
Mid-term II asked about sword ferns (Polystichum munitum) - an abundant plant in local
forests (many of you included photos this species in your Forest Walk Assignment). The
question read An individual fern has the genotype AaBb. These genes influence the height
(the gene with alleles A and a) and width (the gene with alleles B and b) of the leaves. You
were asked about the genotypes of the spores it produces, and the genotypes of its
descendent gametophytes.
You were then asked: The sword fern [in the question above] is a member of a population of
sword ferns all of whom have the genotype AaBb. Assuming that the genes are on different
chromosomes, what are the genotypes of the sporophytes that result after mating?
For this questions give the ratio of phenotypes among the sporophytes that result after
mating. Assume that dominance is incomplete. Use the following phenotype names:
Allele A is tall; Allele a is short; call the heterozygote ‘medium’;
Allele B is broad; Allele b is narrow; call the heterozygote ‘stout’. (4 points)
TALL
TALL
TALL
MEDIUM
MEDIUM
MEDIUM
SHORT
SHORT
SHORT
BROAD
STOUT
THIN
BROAD
STOUT
THIN
BROAD
STOUT
THIN
1/16
2/16
1/16
2/16
4/16
2/16
1/16
2/16
1/16
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B6.
B7.
B8.
Explain why the level of atmospheric carbon dioxide fell rapidly during the
Carboniferous period. (2 points)
MUCH COAL, OIL AND NATURAL GAS WAS FORMED DURING THIS PERIOD FROM CO2 AND
BURIED. THE FACT THAT IT WAS BURIED MEANS THAT IT COULD NOT BE OXIDIZED AND
RETURNED TO THE ATMOSPHERE. BE GENEROUS WITH THIS ONE IF THEY’RE EVEN
CLOSE.
A human body contains approximately equal numbers of prokaryotic and eukaryotic cells.
Estimate the proportion of the total cell volume that is prokaryotic, and explain the steps
taken in making this estimate. (2 points)
EUKARYOTIC CELLS ~1000 TIMES THE VOLUME OF A PROKARYOTIC CELL, SO 0.999 OF
TOTAL CELL VOLUME IS EUKARYOTIC IF NUMBERS ARE THE SAME.
In a population of sea cucumbers at Hardy-Weinberg equilibrium, the following genotype
frequencies were measured: MM = 0.64; Mm = 0.32.
What must the frequency of mm be? (1 point) MUST BE 1 – 0.64 – 0.32 = 0.04
MM = 0.64; Mm = 0.32.
What is the allele frequency of M? (1 point) 0.8
What is the allele frequency of m? (1 point) 0.2
What will be the frequency of genotypes in the next generation? (2 points)
AT EQUILIBRIUM SO MM = 0.64; Mm = 0.32; mm = 0.04
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B9.
The diagram below is a generalized representation of alternating generations.
Label each arrow as either ‘mitosis’; ‘meiosis’; or ‘syngamy’.
(1.5 points)
Label each circle (or group of circles) as either ‘zygote’; ‘spore’; ‘gametes’; ‘sporophyte’; or
‘gametophyte’. (2 points)
Indicate whether each circle (or group of circles) is haploid (n) or diploid (2n). (1/2 point)
ZYGOTE 2N
SPOROPHYTE 2N
MITOSIS
MEIOSIS
SYNGAMY
SPORES N
GAMETES N
GAMETOPHYTE N
MITOSIS
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MITOSIS
SECTION C (30 points)
C1.
‘Keeling’s curve’ (shown below) is named after Charles Keeling, an atmospheric scientist
who initiated the study of atmospheric carbon dioxide levels. Which two of the planet’s
biomes do you think is most responsible for the annual cycle (the zigzag) in Keeling’s
curve (1 point)? Explain how this happens (1 point).
ANY 2 OF TEMPERATE FOREST, TEMPERATE CONIFEROUS FOREST, BOREAL
FOREST,TEMERATE DECIDUOUS FOREST
GROWTH IN THE SPRING REMOVES CO2 FROM ATMOSPHERE
DECOMPOSITION OF (UNBURIED) BIOMASS IN THE FALL PUTS IT BACK
C2.
To run its energy metabolism a cell needs:
1.
2.
3.
4.
5.
A continuous supply of carbon (and other elements) to synthesize new organic molecules;
A supply of free energy to drive metabolic biochemistry;
Catalysts, else reactions are too slow and undirected;
Elimination of waste products, so that reactions proceed in the correct direction;
Compartments, to keep the inside and outside separate.
Explain how alkaline hydrothermal vents meet each of these requirements (4 points).
•
•
•
•
Warm water rich in carbon compounds flows through the vent, supplying nutrients and
removing waste
The pores were lined with a frothy foam with metal ions which could catalyze reactions.
The chambers and pores were alkaline, while the early ocean was acidic.
The thin mineral walls allow movement of electrons and protons, with the strong acid –
alkaline gradient providing a potential difference not unlike that in basic metabolism.
•
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C3.
Write out the logistic equation (1 point).
Draw a graph in the space below of the curve described by this equation, label the axes, and
indicate the carrying capacity K (1 point). Indicate (e.g. with an arrow) where the increase
in numbers is maximal. (1 point).
MAXIMUM POINT IS HALFWAY BETWEEN 0 AND K
C4.
The following is a basic life table.
x
l (x)
m(x)
l(x) * m(x)
0
1
2
3
4
1.000
0.500
0.250
0.125
0.000
0
1
2
4
/
0
0.5
0.50
0.50
0
What do x, l(x), m(x), and l(x)* m(x) represent, in words? (2 points)
x IS AGE
l(x) IS PROPORTION STILL ALIVE AT AGE X
,m(x) IS THE NUMBER OF (FEMALE) OFFSPRING AT AGE X
l(x)* m(x) IS REPRODUCIVE VALUE
Complete the table, filling in the m(x) column so that the reproductive value at each age is
0.5. (2 points). Note that this is impossible at age 4, as none are still alive.
What is the finite rate of growth (λ)? (1 point) 1.5
Assume that the population at year t is 100.
What will be the population size in year t+1?
= 1.5 * 100 = 150
Year t+2? (2 points)
= 1.5 * 150 = 225
Calculate the ‘environmental resistance to growth’ term in year 2, assuming K = 450.
Show your work. (2 points)
ENV RESISTANCE = (N-K)/K , SO (225 – 450)/450 = 0.5
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C5.
The image below displays the global carbon ‘budget’ (i.e. sources and sinks of carbon and
the flow between them). According to this estimate from the 1990s, what is the annual
net addition of carbon to the atmosphere? Show your work. (1 point)
= 6.3 + 1.6 – 3.0 – 1.5 = 3.4
In what units is this measured? (1 point) GIGATONNES OF CARBON PER YEAR
About how large is this increase in percentage terms? Show your calculation. (1 point)
A NET ADDITION OF 3.4 GIGATONNES TO A STORE OF 778 = 3.4/778 = 0.44%
Express the increase in parts per million of carbon dioxide? Question C1 will help.
Show your calculation. (1 point)
ACCORDING TO C4 THERE WERE ABOUT 350 – 360 PPM CO2 DURING THE 1990S,
MAKING 0.44% ABOUT 1.5 ppm.
Does this match the rate of increase shown in question C1? How does this show? (1 point)
THE MATCH IS PRETTY CLOSE. SEEN IN THE INCREASE OF HEIGHT IN SUCCESSIVE ZAGS.
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C6.
The graph below was shown in lecture. It displays the annual change in population (in
millions) for different countries.
Suggest the proximate reason for the rapid fall of the annual change in population after ~1990 (in
China) and ~2000 (in India). (2 points)
RAPID ECONOMIC GROWTH
Why are the age structures of Africa and Europe so different? (2 points)
EUROPE UNDERWENT ECONOMIC DEVELOPMENT STARTING ~1750, AND IS NOW MUCH
WEALTHIER THAN AFRICA. AGE STRUCTURE CHANGED AS FAMILY SIZE WAS REDUCED,
BECOMING A ‘COLUMN’ RATHER THAN A PYRAMID.
How is it that much of the world’s population increase for the next century will occur in Africa? (2
points)
THE AGE STRUCTURE SHOWS THAT MOST PEOPLE ARE LESS THAN 20 I.E. PRE-REPRODUCTIVE.
THE RATE OF POPULATION GROWTH CANNOT FALL RAPIDLY BECAUSE THESE PEOPLE WILL
HAVE CHILDREN.
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BONUS QUESTION
The graph in question C6 shows indicates the introduction of China’s one-child policy in 1980. This
was intended to curb the country's population growth, but evidently led to the opposite outcome.
On what basis do I make this claim? (1 point)
THE ANNUAL CHANGE IN POPULATION SIZE WENT UP RATHER THAN DOWN.
Estimate by about how many years this policy set back the intended result. (1 point)
It took about 10 years for the annual change in population size to fall back to the level it had in
1980. It could also be argued that it took much longer for the annual change to fall to the level that
it would have reached had its fall not been interrupted in 1980.
Estimate how much larger the population became before it began to decline than would have been
the case had it continued on its trajectory prior to the introduction of this policy (1 point).
The annual population increase went from ~14million in 1980 to ~20million in 1990. Therefore,
the average annual increase went from 0.6 million in 1981, to 1.2 million in 1981 …….. Complete
this series to 1990 and you get more than 33 million.
The comparison could instead be made with what would have happened had the annual increase
continued to fall at the same rate before 1980. This would give a much larger number.
The architects of this policy should perhaps have taken a BISC 102. With the benefit of hindsight,
can you suggest a reason for this perverse policy outcome! (1 point)
People adjusted their planning once they knew or suspected that they would be allowed to have
only a single child. Presumably they advanced the timing of the first birth, thinking that the policy
might be suspended later. Or if they lost a child they would have time for another.
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