Download Name: BIOS E

Name: __________________________________
BIOS E-1b
EXAM 1
Research has shown that students who write a self-affirming statement before beginning an exam
do better on that exam. If you would like, please feel free to take a minute before this exam
begins to write something positive about yourself. It doesn’t have to be something courserelated (though “I will rock the crossbridge cycle” has a certain ring to it). This is entirely
optional, and your response (or non-response) will not have any effect on the grading of your
exam.
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You will have 2 hours to complete this exam.
For multiple-choice questions, select the best answer.
For short answer questions, the space provided is meant to be sufficient for your
answer, so be concise.
If you need more space to work, you can use the back of the preceding page.
If you finish early, quietly bring your exam to the front of the room and leave.
Please stay seated during the last 10 minutes of the exam, so that all students
may have quiet to finish.
1-35. _______ / 101
40.
_______ / 9
36.
_______ / 18
41.
_______ / 12
37.
_______ / 5
42.
_______ / 10
38.
_______ / 14
43.
_______ / 9
39.
_______ / 8
44.
_______ / 14
Total:
____________/200 points
Multiple choice answers are worth +3 points each, with +1 partial credit where indicated.
1. Which of the following was not synthesized by the original Miller–Urey experiments
(performed without the gasses that would have been released by volcanic eruptions)?
a. Many of the naturally occurring amino acids
b. Small carbon sugars
c. Adenine and thymine
d. Ribose
e. Uracil
2. Because fatty acids are amphipathic, with hydrophobic tails, they
a. form bilayers in water with tails facing inward in the membrane.
b. form bilayers in water with tails facing outward from the membrane.
c. catalyze the synthesis of proteins.
d. catalyze the synthesis of nucleic acids.
e. enable cellular reproduction.
3. The ultimate origin of genetic variation in a population is
a. genetic drift.
b. mutation.
c. natural selection.
d. a founder effect.
e. nonrandom mating.
4. The similarities in the wings of bats and birds as adaptations for powered flight evolved
through
a. divergent evolution.
b. convergent evolution.
c. evolutionary reversal.
d. evolutionary divergence.
e. ancestral inheritance.
5. Which of the following statements about genetic drift as an evolutionary factor is true?
a. It is more potent in a population with small numbers than in a population with large numbers.
b. It is responsible for selection against deleterious mutations.
c. It is connected to the movements of alleles between populations of a single species.
d. Its strength is proportional to the size of a population: the larger the population, the greater the
force.
e. Both a and b
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6. In a population at Hardy-Weinberg equilibrium, two alleles are possible at a particular locus:
A and a. The frequency of aa homozygotes is 0.09. What is the frequency of the A allele?
a. 0.03
b. 0.3
c. 0.49
d. 0.7
e. 0.81
7. Below are data from a population over five generations; 100 individuals were analyzed from
each generation. The locus being studied contributes to the size of an individual: AA individuals
tend to be largest, Aa individuals are of intermediate size, and aa individuals are the smallest.
What type of selection does this population appear to be under?
Generation
# of AA individuals
# of Aa individuals
# of aa individuals
1
31
45
24
2
25
46
29
3
20
48
32
4
15
51
34
5
10
53
37
a. Stabilizing selection
b. Disruptive selection
c. Directional selection to be larger
d. Directional selection to be smaller
e. Cannot tell from the information given
8. Different species of fruit flies occupy each of the islands in the Hawaiian island chain, a group
of volcanic islands that formed one after the other. After each new island was formed, fruit flies
from existing islands colonized it and subsequently diverged. When flies from different species
are allowed to mate in the lab, the offspring that are produced die early in development. This is
an example of
a. allopatric speciation with gamete incompatibility
b. allopatric speciation with hybrid inviability
c. allopatric speciation with hybrid infertility
d. sympatric speciation with gamete incompatibility
e. sympatric speciation with hybrid inviability
f. sympatric speciation with hybrid infertility
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9. If the per capita birth rate is 0.07 and the death rate is 0.14, then the per capita rate of increase
in a population (assuming that there is no immigration or emigration) is
a. -2
b. -0.07
c. 0.07
d. 0.0098
e. 2
10. Which of the following would be most likely to produce a regular dispersion pattern of a
population in the environment?
a. Availability of water
b. Competition for sunlight
c. Dispersion of seeds by wind
d. Predation
e. Mutualism
11. Five species of ants can be found on aspen sunflowers (Helianthella quinquenervis), which
live in wet mountain meadows of the Rocky Mountains. The aspen sunflowers provide nectar to
the ants in special structures called extrafloral nectaries. The ants, in turn, protect the sunflowers
from other insects. This is an example of
a. defensive mutualism
b. dispersive mutualism
c. herbivory
d. commensalism
e. amensalism
12. In the Sierra Nevada Mountains of California there are many populations of the checkerspot
butterfly Euphydryas editha. You notice that females of one population lay their eggs near the
tip of a plant’s stem (population A). Females of another population in the same area lay their
eggs at the base of the stem on a different type of plant (population B). The young hatch out as
caterpillars; they live on the host plant and eat its leaves.
What direct advantage does laying their eggs on different plants give these two populations?
a. reduced competition through resource partitioning
b. reduced competition through sharing a common resource
c. increased speciation rate through resource partitioning
d. decreased speciation rate through resource partitioning
e. a larger niche in their natural environment
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13. In a pond, tadpoles eat algae and fish eat the tadpoles. Above the pond, grasshoppers eat
grass and, at night, are preyed upon by bats. Other bats eat the fish that eat the tadpoles. In this
community, the fish are
a. parasites.
b. predators.
c. prey.
d. both parasites and prey.
e. both predators and prey. +1 partial credit for either b or c
14. In the late 1960’s, Robert Paine conducted landmark studies on diversity in the rocky
intertidal zone comparing the species diversity in control plots with diversity in experimental
plots from which he removed the top predator, sea stars. After 5 years, 15 species of intertidal
invertebrates lived in the control plots, while the experimental plots were dominated by only two
species, one mussel and one barnacle. Why did species diversity most likely remain high in the
presence of a predator?
a. The sea star kept the mussel and barnacle populations low enough to prevent
competitive exclusion from occurring.
b. The sea star kept the mussel and barnacles from developing a mutualistic relationship. That, in
turn, kept their populations low.
c. The mussel and the barnacle parasitized the sea star, keeping populations low enough to
prevent competitive exclusion from occurring.
d. The sea star developed a mutalistic relationship with the mussel and barnacle, keeping their
populations low and preventing competitive exclusion from happening.
e. None of the above is likely to apply.
15. Suppose that frog embryos were genetically manipulated so that the epidermal (skin) cells
express both E-cadherin and N-cadherin on their cell surface. The neuronal tissue and epidermal
tissues are collected from the embryos and treated such that the cells separate from each other,
then are allowed to re-assemble. Which of the following results would you expect from this
experiment?
a. The modified epidermal cells would adhere to each other and to neuronal cells.
b. The genetically modified epidermal cells would adhere to neuronal cells and would no longer
adhere to epidermal cells.
c. The epidermal cells would adhere to each other, and not to the neuronal cells, because they
would still be epidermal cells regardless of the presence of an additional cell adhesion protein on
their surface.
d. More information is necessary to make a prediction about the result of this experiment.
e. None of the above is correct.
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16. One function of adipose tissue is to
a. provide thermoregulation.
b. detect odors.
c. transmit electrical signals to the central nervous system.
d. provide support against gravity.
e. transport oxygen.
17. Smooth muscle differs from both cardiac and skeletal muscle in that
a. it can act as a pacemaker for rhythmic contractions.
b. its contractions are not due to interactions between neighboring microfilaments.
c. its neighboring cells are electrically connected by gap junctions.
d. its neighboring cells are tightly coupled by intercalated discs.
e. its contraction can be stimulated by stretching.
18. Glial cells are
a. gland cells in the digestive tract that secrete digestive juices.
b. neurons that generate electrical signals.
c. cells in the nervous system that provide support functions for neurons.
d. part of ductless glands that secrete hormones.
e. skeletal muscle cells that contract to generate a force.
19. The alveoli in the lungs contain simple squamous epithelial cells. These cells are particularly
well suited to function in the alveoli, as they are optimized for
a. protection.
b. diffusion.
c. elasticity.
d. strength.
e. structural support.
20. Which of the following statements about the molecular arrangement of actin and myosin in
myofibrils is false?
a. A thin filament consists of actin, tropomyosin, and troponin.
b. Two chains of actin monomers are twisted into a helix.
c. Two strands of tropomyosin lie in the grooves of the actin.
d. Troponin forms the head of the myosin molecule.
e. The myosin heads have ATPase activity and interact with the actin.
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21. In most humans, the primary determinant regarding the proportion of fast- and slow-twitch
fibers in skeletal muscle is
a. diet.
b. exercise.
c. genetic heritage.
d. age.
e. None of the above
22. Bricklayers periodically need to carry heavy stacks of bricks from their truck to the work site,
and they are quickly fatigued by this activity. An examination of the muscles used to perform
this work would reveal
a. substantial fuel reserves.
b. low levels of ATPase activity.
c. an abundance of blood vessels.
d. relatively few mitochondria.
e. relatively high amounts of myoglobin.
23. The role of cartilage in the human skeleton is to
a. provide stiffness and resiliency to the surface of joints.
b. add stiffness to structures such as the nose.
c. provide a reservoir of calcium.
d. Both a and b +1 partial credit for either a or b
e. All of the above
24. Which of the following statements about the long bones in a human skeleton is false?
a. Ossification starts at the center of developing long bones.
b. Elongation occurs at epiphyseal plates.
c. Secondary sites of ossification occur at the ends of developing long bones.
d. They are first laid down as cartilage.
e. They form on a scaffold of connective tissue membrane.
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25. Use the diagram on the right for reference. If an engineer
designed a skeletal muscle lever system for maximum force,
Origin
a. the insertion point for the muscle would be close to the joint and
Muscle
the load would be far from the joint.
Joint
Insertion
b. the origin of the muscle would be close to the joint and the load
would be far from the joint.
Load
c. the insertion point for the muscle would be far from the joint
and the load would be close to the insertion point.
d. the muscle would have longer tendons
e. more information is needed to answer this question.
For each of the following statements, indicate if it is true or false. If the statement is false, cross
out and change up to three words it to make it true. You cannot simply add or remove the word
“not.” +2 for “True,” if false, +1 for “False,” and +2 for a valid correction (others may be
possible)
26.
True
False
Experiments by Louis Pasteur disproved the hypothesis that
life could spontaneously arise.
27.
True
False
In the origin of life on earth, an advantage that DNA has
over RNA is its greater catalytic activity.
RNA, DNA
28.
True
False
Predation is an example of a density-independent factor
that affects population dynamics. dependent
29.
True
False
Semelparous organisms can have many offspring of
different ages. Interoparous (or change to “same age”)
30.
True
False
In neurons, dendrites receive signals.
31.
True
False
Peripheral nerves consist of several different tissues.
32.
True
False
Vascularization is an important process in the development
of cartilage. bone
33.
True
False
Ball-and-socket joints allow motion in a single plane. hinge
Could also be corrected to maximum range of motion
34.
True
False
The jaw is an example of a hinge joint.
35.
True
False
Pivot joints are optimized for maximum range of motion.
ball-and-socket; could also be corrected to rotational
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36.
(18 points) For each of the following structures or substances, describe its key
characteristics and function, and identify the tissue type with which its function is
especially closely associated. If indicated, also identify one key protein or other
molecular component of the structure or substance.
Tight
junctions
Key characteristics and function:
Found around the periphery of cells, forms a very tight, continuous seal or
gasket to prevent leakage of fluids from one side of the cell layer to the other.
Provides an impermeable barrier that prevents the movement of molecules
from one side of the cell layer to the other. +2 total, +1 for function, +1 for
structure
Tissue type:
Epithelium +1 (+0.5 for an example
instead of tissue type)
Desmosomes Key characteristics and function:
Form very strong focal adhesions between cells to prevent tissue from
tearing/cells from separating under stress. Designed to resist shearing and
maintain cell adhesion. +2 total, +1 for function, +1 for structure
Tissue type:
Protein/other component:
Epithelium +1 (+0.5 for an example
Cadherins +1
instead of tissue type)
Gap
Key characteristics and function:
junctions
Allow direct transmission of ions and other small molecules from one cell to
another, facilitating rapid communication. Are pores that directly connect cells
to each other. +2 total, +1 for function, +1 for acknowledging the directness of
the connection
Tissue type: +1 for one:
Protein/other component:
Cardiac muscle, epithelium (+0.5 for
Connexin +1
an example instead of tissue type)
Ground
Key characteristics and function:
substance
The extracellular matrix of connective tissue; may take different forms
depending on the tissue and be liquid (blood), gel-like, or hard +2 total, +1 for
extracellular nature, +1 for various forms
Tissue type:
Protein/other component: +1 for one:
Connective tissue +1 (+0.5 for an
GAGs, hyaluronic acid, proteoglycans
example instead of tissue type)
Elastin
Key characteristics and function:
Provides stretch and resiliency, found in extracellular matrix +2 total, +1.5 for
function, +0.5 for extracellular
Tissue type: +1 for one (+0.5 for an
example instead of tissue type)
Elastic cartilage, cartilage,
Loose connective tissue, elastic tissue
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37.
(5 points) One theory for life’s origins on earth is panspermia. Briefly explain this
theory, and describe one piece of evidence in support of it.
Panspermia refers to the idea that life travels around the universe (+3 for explanation
of panspermia) in galactic dust and meteors, and that life on earth could have
therefore originated elsewhere in the universe. Organic compounds found on the
Murchinson meteorite and in galactic dust provide support for this hypothesis. (+2 for
a valid piece of evidence)
38.
(14 points) Below is a list of several of the key characteristics of life.
A.
Circle those that were exhibited by the early proto-cells, and for each that you chose,
briefly explain how proto-cells accomplished it.
Compartmentalization (+1)
+2 for explanation:
Proto-cells had membranes separating the internal from external environment (+1).
These membranes were made of fatty acids. (+1)
Response to the environment (+1)
Regulation and homeostasis (+1)
Reproduction (+1)
+3 for explanation
Proto-cells could increase in size by adding new fatty acids to their membranes using
basic physical properties. These membranes could separate into two cells also using
basic physical and chemical properties.
Proto-cells used ribozymes to facilitate chemical reactions such as RNA replication,
allowing them to duplicate their genetic material.
Evolution (+1 for correct decision)
+2 for explanation
RNA replication was not foolproof, so variation could arise from new mutations. In
addition, splicing/recombination could generate additional diversity.
B.
Briefly explain how montmorillonite clay can facilitate one of the characteristics that you
circled above.
Montmorillonite clay can facilitate fatty acid synthesis and vesicle formation, as well as
RNA replication It attracts the precursors to the surface, and orients them properly for
bond formation. (+2 for one of these)
10
39.
(8 points) For each of the following subcellular structures, identify if it is thought to have
arisen by endosymbiosis, membrane invagination, or neither.
+2 each
Nucleus
Endosymbiosis
Membrane invagination
Neither
40.
A.
+3
B.
Mitochondria
Endosymbiosis
Membrane invagination
Neither
Ribosomes
Endosymbiosis
Membrane invagination
Neither
Endoplasmic
reticulum
Endosymbiosis
Membrane invagination
Neither
(9 points) The phylogenetic tree on
the right shows the relationships
between several groups of
mammals. Answer the questions
that follow based on the tree.
Whales
Circle the point on the tree
corresponding to the last common
ancestor of bats and pangolins.
Perissodactyls
Hippos
Pigs
Carnivores
Pangolins
Which is more closely related to
bats: (a) shrews or (b) hippos?
Briefly explain your reasoning.
Bats
Shrews
Bats are more closely related to hippos
(+1); they share a more recent common
ancestor (+2)
Rats
Rabbits
C.
Lemurs
Which is more closely related to
pigs: (a) perissodactyls or (b)
pangolins? Briefly explain your
reasoning.
Tree shrews
Monkeys
Pigs are equally related to perissodactyls
Sloths
and pangolins (+1); their last common ancestor occurs at the same time (+2)
Armadillos
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Tenrec
Elephant shrews
41.
(12 points) Below are listed several pieces of evidence that support the theory of
evolution by natural selection.
A.
For each piece of evidence, determine whether or not Darwin used it to formulate his
hypothesis of evolution by means of natural selection.
+1.5 each correct
Biogeography
Yes
No
Fossil record
Yes
No
Molecular homology
Yes
No
Tiktaalik roseae
Yes
No
B.
For two of the pieces of evidence listed above, briefly explain how it supports the theory
of evolution by natural selection. Your explanation can include an example, if it helps to
illustrate your point, and you can use evidence that Darwin did and/or did not have access
to.
+3 for each of two valid explanations:
Biogeography: species in close geographic proximity are more closely related to each
other than species that have similar features in distant parts of the world
Fossil record: intermediate forms can be identified that bridge older and newer species
Molecular homology: related species share common genes/DNA sequences, more
closely related species’ genomes are more similar
Tiktaalic roseae represents a possible transitional form between aquatic and land
animals, with features common to both
42.
(10 points) In a mark-recapture study, you perform four rounds of collecting, and observe
the following numbers of individuals each time:
Round of capture
Captured for the first time
Recaptured
1
64
Not applicable
2
61
16
3
58
11
4
55
4
A.
Based on captures 1 and 2, estimate the size of the population. Show your work.
= 64 x 77 / 16 = 308 (+3, +2 partial credit if use 64x61/16)
12
B.
Data from your third and fourth captures make you suspect that your mark-recapture
method may be flawed. Based on the data from all four captures, do you think that you
would have overestimated or underestimated the size of the population after the first
capture and recapture (rounds 1 and 2)? Briefly explain your reasoning.
Overestimated (+1); it looks like the recaptures are going down/are not a true
representation of the fraction captured. This means that the denominator is artificially
deflated, and population size inflated (+3 for explanation).
C.
Given the data, what is one possible flaw in your mark-recapture method that would
produce this outcome?
+3 for an answer consistent with the response to C above
Individuals learn to avoid traps or marked individuals are at an increased risk of
predation.
43.
(9 points) Some populations are r-selected, while others are K-selected. For the situation
described below, determine if the population is more likely r-selected or K-selected, and
identify a key piece of evidence that allowed you to come to this conclusion.
A.
Giant pandas live for about 20 years in the wild in the moist bamboo forests of
southwestern China. Beginning at about age 6, a female can give birth about every two
years. One or two tiny offspring are born per successful mating, and usually only one will
be tended by the female over the first 18 months of its life.
K-selected (+1); They reproduce at a relatively old age, produce few offspring, and
exhibit high parental care (+2 for a piece of evidence)
B.
If you introduce an exploitative competitor to the panda population, how would this most
likely affect the size of the population? Briefly explain why, including in your answer a
definition of exploitation competition and how it differs from interference competition.
The population would decrease (+2 for effect on population size) as fewer resources
would be available to support the members of the population because the exploitative
competitor would be using that resource (+2 for a statement about reduced resource
availability), though they would not be directly interfering with the panda’s access to it
(+2 for a distinction between exploitation and interference competition)
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44.
(14 points) You treat skeletal muscle cells with a drug that inhibits the re-uptake of Ca2+
into the sarcoplasmic reticulum after it has been released.
A.
What would the effect of this drug treatment on muscle function be? Briefly explain your
reasoning.
+3 points: Muscles would remain contracted (+1) – removal of Ca2+ is required for
troponin to allow tropomyosin to re-cover the actin binding sites on myosin, as when
troponin binds to Ca2+, it causes tropomyosin to shift off of the actin binding sites (+2
for explanation).
B.
At the molecular level (not the physiological level), which of the following mutations
would you expect to have the same effect as your drug? Briefly explain your reasoning.
A.
B.
C.
D.
A mutation that prevents troponin from binding to actin.
A mutation that prevents tropomyosin from binding to myosin.
A mutation that prevents tropomyosin from binding to actin
A mutation that prevents myosin from binding to actin
+4 points: C (+2), as this would allow myosin to bind all the time, similar to the Ca2+
excess from part (A) (+2 for explanation)
C.
A colleague of yours has identified a drug that they think will affect muscle function in a
similar way to the one that you used above. Their drug prevents ATP hydrolysis in
muscle cells. With your knowledge of muscle function, you realize that, depending on
what protein their drug inhibits, they may be right – or they may be wrong. Identify two
proteins that are involved in muscle function that both hydrolyze ATP, and explain how
inhibiting ATP hydrolysis in each would specifically affect contraction, including where
in the cross-bridge cycle the muscle would become “stuck,” if applicable.
+7 points
The Ca2+ “pump” required to get calcium back into the SR could be inhibited (+1) this would have the same effect as the other drug, in that Ca2+ levels would remain high
in the cytoplasm, since it wouldn’t return to the SR (+1). The fiber would remain
contracted (+1).
The other option is that myosin would be unable to hydrolyze ATP (+1), so that it
would be stuck “un-cocked” (+1) and unbound to actin (+1). This would have the
opposite effect – the muscle would be unable to contract, rather than continuously
contracting (+1).
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