LO 3.36: The student is able to describe a model that expresses the key elements of signal transduction
pathways by which a signal is converted to a cellular response.
SP 1.5: The student can re-express key elements of natural phenomena across multiple representations in the
domain.
Explanation: There are three main stages of cell signaling. These stages are reception, transduction, and response.
In reception, a chemical signal acts as a ligand and binds to a receptor. These receptors may include G-proteinlinked receptors, receptor Tyrosine Kinases, Ion Channel receptors, and intracellular receptors. The binding of the
signal molecule will in some way change the shape of the receptor. This is what begins the transduction stage. In
transduction, kinases add a phosphate group to relay proteins. This activates second messengers such as cAMP to
pass along the signal. This then leads to the final stage, response. The response is always specific to the signal
molecule that started this process. The most common examples of a response are the transcription of a gene into
mRNA and also the translation of mRNA into a protein that has a specific function.
M.C. Question: Which of the following about receptor
Tyrosine Kinases is false?
A) They can trigger more than one signal transduction
pathway at once.
B) They are involved in cell reproduction.
C) The receptor is a dimer before the signal molecule
binds.
D) The receptor has two binding sites.
E) The receptor attaches phosphates to tyrosines.
Learning Log/FRQ style question: Compare and contrast
the differences between membrane-bound receptors and
intracellular receptors.
Answer Key- LO 3.36
Which of the following about receptor Tyrosine Kinases is false?
A) They can trigger more than one signal transduction pathway at once.
B) They are involved in cell reproduction.
C) The receptor is a dimer before the signal molecule binds.
D) The receptor has two binding sites.
E) The receptor attaches phosphates to tyrosines.
Compare and contrast the differences between membrane-bound receptors and intracellular receptors.
Membrane-bound receptors are located in the plasma membrane of a cell. Their ligands are water
soluble and are too large to pass through the membrane without any assistance. These include G-proteinlinked receptors, receptor tyrosine kinases, and ion channel receptors. Once the signal molecule binds to the
receptor, it causes a transduction pathway which leads to a specific cellular response. On the other hand,
intracellular receptors are located either in the cytoplasm or in the nucleus. The signal must be able to freely
pass through the plasma membrane in order to be able to bind to this type of receptor. This may either be due
to the signal molecule being very small in size or to it being hydrophobic. Most molecules that bind to
intracellular receptors are hydrophobic steroid hormones. When the signal molecule binds to the receptor, it
stimulates the transcription of the gene into mRNA which is then translated into a specific protein.
LO 1.29: The student is able to describe the reasons for revisions of scientific hypotheses on the
origin of life on Earth.
SP 6.3: The student can articulate the reasons that scientific explanations and theories are refined
or replaced.
•
Explanation: Scientific hypotheses are revised when new evidence arises that changes previous thoughts. Primitive Earth was very
different than the Earth known today. There was little oxygen, but much more water, carbon monoxide, carbon dioxide, and ammonia.
There was a lot of lightning, volcanic activity, UV radiation, and meteorite bombardments. In the 1920s, Oparin and Haldane hypothesized
that early Earth was a reducing (electron adding) environment, in which organic compounds were formed by inorganic compounds. The
energy for these reactions would have been powered by lightning and UV radiation. Haldane proposed that early oceans were solutions of
organic molecules, “primitive soup”, from which life arose. In 1953, the Miller-Urey experiment tested Oparin and Haldane’s hypothesis.
They created lab conditions comparable to those that existed on early Earth, and is shown in the figure below. This experiment yielded all
20 amino acids, several sugars, purines and pyrimidines, ATP (when phosphate is added), and all monomers. Many labs have since
repeated this experiment using different recipes for atmosphere, and organic molecules were also produced in some of those. Sydney Fox
then expounded on the previous hypotheses, and to show how these monomers connected to make polymers, dripped monomers on hot
sand, clay, or rocks. This created proteinoids -polypeptides created by abiotic means. The next step is protobionts, which are abiotically
produced molecules surrounded by a membrane. They are primitive cells with imprecise reproduction and a simple metabolism.
•
Multiple Choice Question:
•
•
•
•
•
•
In which of these cases would organic molecules most likely
NOT be created in a Miller-Urey type experiment?
A) There was high levels of UV radiation
B) produced in something similar to the “primitive soup”
C) the environment was not reducing
D) methane was present
•
FRQ:
•
•
•
•
Describe in detail the Miller-Urey experiment. Then,
discuss how this experiment, and the Fox experiment, fit into
the timeline of the origin of life from inorganic molecules to
protobionts.
Answer Key- LO 1.29
•
•
In which of these cases would organic molecules most likely NOT be
created in a Miller-Urey type experiment?
•
•
A) There was high levels of UV radiation
B) produced in something similar to the “primitive soup”
•
C) the environment was not reducing
•
D) methane was present
•
Describe in detail the Miller-Urey experiment. Then, discuss how this experiment, and the
Fox experiment, fit into the timeline of the origin of life from inorganic molecules to
protobionts.
•
The first stage of the Miller-Urey experiment, water was heated and the vapor traveled upward. There, it
came in contact with hydrogen gas, methane, and ammonia, and was shocked by electrodes. Then, it
condensed and cooled. The now cooled water containing the organic molecules was then sampled for a
chemical analysis. This experiment simulates the conditions scientists postulate existed on early Earth
and demonstrate how organic molecules were made from inorganic molecules. The ammonia, methane,
and hydrogen gas in the atmosphere and in the “primitive soup” oceans would have come in contact
with the lightning, simulated by the electrodes, combining to make organic molecules. Next, these
monomers would have combined to make polymers by interacting, as Fox hypothesized and tested, on
hot sand, clay, or rocks, to make proteinoids. After, theses proteinoids combined to create protobionts
which were the first primitive cells.
LO 1.27 The student is able to describe a scientific hypothesis about the origin of life on Earth.
SP 1.2 The student can describe representations and models of natural or man-made phenomena and systems in the
domain
Explanation: It is believed that the origin of life on Earth began through simple cells that were created though four main
stages: 1)The abiotic synthesis of small organic molecules 2) The joining of these monomers into polymers 3) The
packaging of these molecules into protobionts 4) The origin of self replicating molecules. The first atmosphere of Earth
was thick with water vapor, nitrogen, carbon dioxide, methane, ammonia, and hydrogen. Abiotic synthesis of organic
molecules was facilitated by the reducing environment of early earth, mixed with organic molecule solution from the
oceans and charged by lightning or UV radiation. This theory was tested by Miller and Urey who simulated the former
conditions in the lab and indeed synthesized organic molecules, such as amino acids and nucleotides. These monomers
are then abiotically joined into polymers through dripping amino acids onto hot clay, sand, or rock. The polymers
formed spontaneously and of their own accord, with each polymer being original. These macromolecules (proteins and
nucleic acids)could now serve as weak catalysts for reactions. The macromolecules aggregated and were surrounded by
a membrane-like structure. These were known as protobionts which performed some of the properties of life such as
reproduction, metabolism, and maintaining an internal chemical environment different from its surroundings.
Protobionts used molecules around them and synthesized some until they were replaced by organisms that produced
all needed compounds from the environment. Diversification occurred and led to autotrophs and heterotrophs which
were the first prokaryotes. Endosymbiosis followed, in which the prokaryotes, chloroplasts and mitochondria, were
ingested by a larger cell, resulting in interdependence and the creation of a single organism which would be the
eukaryotic cell.
MC: Which of the following are regarded as essential to the origins of life
i. the biotic synthesis of polymers
ii. The maintained internal chemical state of protobionts
iii. Endosymbiosis of chloroplast/mitochondria and a host cell
a) i b) ii c) iii d) i and iii e) ii and iii
FRQ: Use three of the four following
terms to identify and explain a
scientific hypothesis regarding the
origins of life on Earth.
i) polymers
ii) protobionts
iii) Endosymbiosis
iv)lightning/UV radiation
Answer Key
MC: Which of the following are regarded as essential to the origins of life
i. the biotic synthesis of polymers
ii. The maintained internal chemical state of protobionts
iii. Endosymbiosis of chloroplast/mitochondria and a host cell
a) i b) ii c) iii d) i and iii e) ii and iii
FRQ: Use three of the four following terms to identify and explain a scientific hypothesis regarding the origins
of life on Earth.
i) polymers
ii) protobionts
iii) Endosymbiosis
iv)lightning/UV radiation
In early Earth, monomers were synthesized abiotically from gasses in the atmosphere such as
hydrogen, methane, and ammonium along with energy from lightening/UV radiation. Polymers
were created by monomers being dropped onto hot clay, sand, or rock and spontaneously forming
into macromolecules such as proteins or nucleic acids. The macromolecules would join together
with a membranous structure surrounding, making them into protobionts. Protobionts were key as
not only could they reproduce and metabolize, but they could maintain their own internal chemical
balance that was different from the rest of the environment. Protobionts led to diversification and
the first prokaryotes, which became essential to endosymbiosis as chloroplasts and mitochondria
were enveloped by a host cell and became integrated into it, resulting in a eukaryotic structure.
LO 2.19 The student is able to make predictions about how positive feedback mechanisms amplify activities and
processes in organisms based on scientific theories and models.
SP 6.4 The student can make claims and predictions about natural phenomena based on scientific theories and
models.
Explanation: Positive feedback mechanisms amplify responses in biological organisms, and moving farther away from
the target set point. Some common examples of positive feedback would be with labor in childbirth, ripening of
fruits, and lactation in animals. In childbirth, the pressure that is caused by the baby’s head against receptors near the
opening of the uterus stimulates uterine contractions. These cause greater pressure against the opening, which
increases the contractions, and this causes more pressure. With positive feedback, it completes childbirth. With
lactation in mammals, the suckling on the mothers breasts produces prolactin, which leads to milk production. More
suckling leads to more prolactin which leads to more to milk production which then leads to more lactation. This is
one of few examples of positive feedback since the product which is milk leads to more suckling which leads to more
lactation. Positive feedback can cause instability in an environment.
M.C. Question: Which of the following statements is an example of
positive feedback?
A)When humans body temperature drops too low, the body shivers
to bring it back up
B)Predator-prey relationships – if the number of prey decreases, the
predator will starve
C)Blood clotting – when the vessel is injured, platelets cling to the
injured site and release chemicals to attract more platelets. The
platelets continue to come until a clot is formed
D)Blood sugar regulation in humans. When it rises, insulin sends a
signal to the liver to store the glucose
Learning Log/FRQ-style Question: What is the difference between
positive feedback and negative feedback? Give an example of each.
Identify which is more common, positive feedback or negative
feedback?
ANSWER KEY - LO 2.19
Which of the following statements is an example of positive feedback?
A)When humans body temperature drops too low, the body shivers to bring it back up
B)Predator-prey relationships – if the number of prey decreases, the predator will starve
C)Blood clotting – when the vessel is injured, platelets cling to the injured site and release chemicals
to attract more platelets. The platelets continue to come until a clot is formed
D)Blood sugar regulation in humans. When it rises, insulin sends a signal to the liver to store the
glucose
What is the difference between positive feedback and negative feedback? Give an example of each.
Identify which is more common, positive feedback or negative feedback?
Positive feedback is when the rate of a process increases as the amount of product increases.
Negative feedback is the opposite, and is when the rate of the process decreases as the amount of
product increases. In negative feedback, the output reduces the effect of the stimulus while in
positive feedback the output enhances the stimulus. An example of negative feedback would be
sweating. When our body temperature gets too high, negative feedback works to try and stop the
temperature from increasing, thus we start sweating. An example of positive feedback would be
during childbirth when the body releases the hormone oxytocin to speed up contractions. This
increase in the hormone causes there to be more contractions which then causes more oxytocin to be
released and this goes on until the baby is born and positive feedback is stopped. Out of the two,
negative feedback is more common.
LO4.9: The student is able to predict the effects of a change in a component(s) of a biological system on the
functionality of an organism(s).
SP6.4: The student can make claims and predictions about natural phenomena based on scientific theories
and models.
Explanation: Biological systems, like the Endocrine system contain many components that aid in the function of
the system. For example, the hypothalamus plays an important role in the system by receiving
information from nerves throughout the body and from other parts of the brain and initiates endocrine
signals appropriate to conditions. The hypothalamus contains neurosecretory cells that store and regulate
hormonal secretions in the pituitary gland. The posterior pituitary gland is an extension of the
hypothalamus. Specific neurosecretory cells make the ADH hormone which increases water retention and
decreases urine volume. The neurosecretory cells also make oxytocin which forces target cells in the
uterine muscles to contract during childbirth. If a change in secretion of ADH occurs, then water retention
would potentionally decrease and cause an increase of urine volume. Using the idea of the role of the
posterior pituitary gland, it is easily able to lead to predictions of the role of the anterior pituitary gland.
M.C Question:
Which of the following would most likely occur due to the inhibition of the
thyroid glands?
A) An Increase in blood glucose
Hypothalamus
B) Lack of regulation of T3 and T4 secretion
C) Retention of sodium ions and water by kidneys
Neurosecretory
D) Build up of proteins and fats leading to decreased blood glucose
cells of the
Axon
FRQ:
hypothalamus
Choose one of the biological systems listed below and
Posterior
list the components and function of the system.
pituitary
Anter
i.
Endocrine
pituita
ii.
Nervous
iii. Respiratory
HORMONE ADH
Oxytocin
Explain the effects of inhibition of one of the components in the system
TARGETKidney tubulesMammary glands,
mentioned above.
uterine muscles
Answer Key-LO 4.9
Which of the following would most likely occur due to the inhibition of the
thyroid glands?
A) An Increase in blood glucose
B) Lack of regulation of T3 and T4 secretion
C) Retention of sodium ions and water by kidneys
D) Build up of proteins and fats leading to decreased blood glucose
Choose one of the biological systems listed below and
list the components and function of the system.
i.
Endocrine
ii.
Nervous
iii. Respiratory
Explain the effects of inhibition of one of the components in the system
mentioned above.
The central nervous system is made up of the brain and spinal cord. The peripheral nervous
system is made up of the nerve fibers that branch off from the spinal cord and extend to all
parts of the body, including the neck and arms, torso, legs, skeletal muscles and internal
organs. The brain sends messages through the body to control the movement of the
muscles and the function of internal organs. The messenger of the nervous system are
neurons. Neurons communicate with each other using axons and dendrites. When a neuron
receives a message from another neuron, it sends a signal down the length of its axon. At the
end of the axon, the electrical signal is converted into a chemical signal, and the axon
releases messengers called neurotransmitters. The neurotransmitters are released into the
between the end of an axon and the tip of a dendrite from another neuron, a synapse.
If the neurons were inhibited, then the brain would not be able to send messages through the
rest of the body to send signals to create movements and functions of other parts of the
body and internal organs.
LO 4.23: The student is able to construct explanations of the influence of environmental factors on the phenotype of an
organism.
SP 6.2: The student can construct explanations of phenomena based on evidence produced through scientific practices.
Explanation:
The interactions between diverse environment conditions, multiple genetic loci and possible phenotypic expression is
unpredictable and therefore a constant topic of study for scientists. The use of microarray analysis allows for the examination of
thousands of genes, in differing environmental conditions, at once in order to better understand the relationship between phenotype and
the environment. There are an endless amount of environmental factors that can alter an organism’s phenotype including:
temperature, diet, and light cycles. The ability for phenotype to be altered by environmental changes is referred to as phenotypic
plasticity. This is what allows organisms to cope with their environment and what increases their chances of survival. The higher the
phenotypic plasticity, the greater the organism’s ability to adapt and survive in changing environments. Variations in an organism’s habitat
can also trigger modes of natural selection such as directional, disruptive, and stabilizing. Directional selection occurs when an
environment is unlike the organism’s original habitat, shifting the entire makeup of the population so that the individuals with the favored
characteristic will survive and produce offspring. Disruptive selection is when conditions favor organisms on both extremes of a
phenotypic range. And stabilizing selection favors intermediate variants in the population, maintaining a specific phenotype’s average
success. The shift in favored phenotypic expression among populations creates a higher rate of reproductive success for those organisms
and thus increases the rate of survival.
M.C. Question: Which of the following does not represent an environmental factor that could alter an organism’s phenotype?
a) Temperature
b) Soil Acidity
c) Meiosis
d) Predation
FRQ Question:
1a) Choose two of the following factors to evaluate the correlation
between an organism’s phenotype and the environment.
I. Temperature
II. pH
III. Diet
Answer Key (L.O. 4.23)
M.C. Question: Which of the following does not represent an environmental factor that could alter an
organism’s phenotype?
a) Temperature- This may change the thickness of an organism’s coat to protect against environmental
conditions
b) Soil Acidity- The color of flowers changes due to the soil’s properties
c) Meiosis- Sexual reproduction does not involve an organism’s outside environment
d) Predation- Organisms may be forced to develop protection or camouflage against predators in their
environment
FRQ Question:
1) Choose two of the following factors to evaluate the correlation
between an organism’s phenotype and the environment.
I. Temperature
II. pH
III. Diet
FRQ Response:
In the case of the arctic fox, the environment’s temperature effects the color of the fox’s coat. The summer
months produce a brown coat for the fox, and the winter season causes the coat to turn white. These changes
allow for the fox to survive more successfully by its ability to blend in with its surroundings. The acidity of soil
has a similar color-changing effect for some flowers. Hydrangeas, for instance, will bloom blue flowers with a
lower pH balance in the soil; however, if the soil is more neutral a pink color will appear. These two shifting
environmental conditions happen to change the color of the organisms- targeting that specific phenotypic
characteristic in the two individuals.
LO 2.14:The student is able to use representations and models to describe differences in prokaryotic and eukaryotic cells.
SP 1.4: The students can use representations and models to analyze situations or solve problems qualitatively and
quantitatively.
Explanation: Prokaryotic and eukaryotic cells, while both contain the materials necessary for life, are different in many aspects. One noticeable
difference is that eukaryotic cells are bigger than prokaryotic cells. Eukaryotic cells contain many “organelles,” organized membrane-bound
structures that help the cell function by performing specific tasks, within them, while prokaryotic cells lack these, usually containing DNA and a
protein making structure called ribosomes. Actually, both eukaryotic and prokaryotic cells contain ribosomes, but eukaryotic cells have bigger
ribosomes than prokaryotic cells do. As previously mentioned, eukaryotic cells contain organelles that help them function. The presence of these
organelles help the eukaryotic cell perform more specific tasks that help the whole cell function more efficiently than a prokaryotic cell, which
lacks these organelles. The most important organelle within a eukaryotic cell is the Nucleus, which helps to protect the DNA and control the rest
of the cell. Since prokaryotic cells don’t have membrane-bound organelles, which includes the nucleus, their DNA is floating around the
cytoplasm, the gel like substance that fills both prokaryotic and eukaryotic cells. Speaking of DNA, prokaryotic and eukaryotic cells contain
differing DNA structures. In eukaryotic cells, there are multiple “chromosomes,” which are tightly compacted strings of linear DNA, contained in
the nucleus. In prokaryotes, on the other hand, there is one, circular, piece of DNA. Since the DNA in prokaryotic and eukaryotic cells are stored
differently, they also undergo different types of DNA replication. In prokaryotic cells, the reading of the DNA, called transcription, and the making
of new DNA from that reading, called translation, are performed simultaneously in the cytoplasm. However, in eukaryotic cells, transcription and
translation occur in separate places. Transcription happens in the Nucleus, where the DNA is stored. Then, the reading of the DNA, called RNA,
goes into the cytoplasm, where the RNA is read and converted into new DNA that complements the original DNA.
M.C. Question: Prokaryotic and eukaryotic cells both contain materials necessary for life. However, there are some key differences between the
two. Which of the following are considered differences between prokaryotic and eukaryotic cells?
I. Eukaryotic cells contain circular DNA, while prokaryotic cells contain linear DNA
II. Prokaryotic cells are smaller than eukaryotic cells
III. Prokaryotic cells have bigger ribosomes than eukaryotic cells
A) I only
B) II only
C) I and II only
D) I, II, and III
Learning Log/FRQ-Style Question: Suppose that a scientist has two slides prepared
for observation under the microscope. One slide contains a prokaryotic cell, and the
other contains a eukaryotic cell. However, the scientist forgot to label the slides,
and now he can’t remember which is which. Shown below are pictures of the two
slides.
a)Describe three differences between prokaryotic and eukaryotic cells
b) Label the two slides as either prokaryotic or eukaryotic, and give at least two
observations that led to your decision.
Pictures for FRQ Question
Slide A
Slide B
Answer Key – LO 2.14
M.C. Question: Prokaryotic and eukaryotic cells both contain materials necessary for life. However, there are some
key differences between the two. Which of the following are considered differences between prokaryotic and
eukaryotic cells?
I. Eukaryotic cells contain circular DNA, while prokaryotic cells contain linear DNA
II. Prokaryotic cells are smaller than eukaryotic cells
III. Prokaryotic cells have bigger ribosomes than eukaryotic cells
A) I only
B) II only
C) I and II only
D) I, II, and III
Learning Log/FRQ-Style Question: Suppose that a scientist has two slides prepared for observation under the
microscope. One slide contains a prokaryotic cell, and the other contains a eukaryotic cell. However, the scientist
forgot to label the slides, and now he can’t remember which is which. Shown below are pictures of the two slides.
a) Describe three differences between prokaryotic and eukaryotic cells
b) Label the two slides as either prokaryotic or eukaryotic, and Label the two slides as either prokaryotic or
eukaryotic, and give at least two observations that led to your decision.
a) One difference between prokaryotic and eukaryotic cells are the size. Eukaryotic cells are bigger than
prokaryotic cells are. This size difference is due to the fact that eukaryotic cells contain more than
prokaryotic cells do. These contents are another difference between the two types of cells. Eukaryotic cells
contains membrane-bound organelles, which are specialized structures that perform specialized functions
within the cell and help the cell to function more efficiently. Prokaryotic cells do not contain these
organelles. The third difference is the DNA within the two types of cells. In prokaryotic cells, the DNA is
unbound, while in eukaryotic cells have a special organelle called the nucleus that functions as storage
facility for the DNA, as well as the control center for the rest of the cell that the DNA functions from.
b) Slide A is the eukaryotic cell and Slide B is the prokaryotic cell. Slide A is the eukaryotic cell because it
contains organelles, and the DNA is bound within a nucleus. Slide B is the prokaryotic cell because the DNA is
unbound, and there are no organelles present.
LO 2.29: The student can create representations and models to describe immune system responses.
SP 1.1: The student can create representations and models of natural or man-made phenomena and systems in the domain.
SP 1.2: The student can describe representations and models of natural or man-made phenomena and systems in the domain.
Explanation: One of the many systems in our body is the immune system, a three level system of defense against pathogens such as
viruses, bacteria, fungi, protists and other foreign/harmful substances that may enter our body. The body has two categories of
immune defense: innate immunity, which is short term and attacks a broad range of antigens, and acquired immunity, which is long
term and antigen-specific. Within the first line of defense there are external modes of defense such as barriers and traps as well as
internal modes of defense such as unfavorable pH and lysosome enzymes. The second line of defense, though it doesn’t
“remember” the pathogen, effectively rids the body of the harmful substances. Phagocytic white blood cells called leukocytes ingest
pathogens and digest them with the help of lysosomes. The third line of defense, called acquired immunity, utilizes B cells and T
cells (lymphocytes) and antibodies to attack and remember pathogens. When a pathogen gets past the first and second lines of
defense, phagocytes engulf the pathogen and present MHC proteins on the outer surface of the cell membrane specific to the
pathogen. Helper T cells then recognize the MHC proteins and “alert” the rest of the immune system by releasing cytokines.
Cytotoxic T cells attack the Antigen presenting cell (APC) by releasing perforin into the cell causing it to undergo apoptosis while
memory T cells are produced. Cytokines also signal fro plasma B cells and memory B cells. Plasma cells immediately produce
antibodies as a rapid response. Memory B cells continually circulate in the body and provide long term immunity. All three of these
lines of defense are necessary to quickly remove antigens from the body and prevent future attacks.
MC Question: Which of the following statements concerning innate immunity is not true?
A) The pH of stomach acid causes pathogens to denature
B) Anitbodies received from breast feeding are part of innate
immunity
C) Innate immunity comes from structures we’re born with
D) Sneezing and coughing are modes of elimination
FRQ Question: What is the difference between innate and
acquired immunity? Give examples of both. Active and passive
immunity? Give examples of both.
Answer Key LO 2.29
MC Question: Which of the following statements concerning innate immunity is not true?
A) The pH of stomach acid causes pathogens to denature
B) Anitbodies received from breast feeding are part of innate immunity
C) Innate immunity comes from structures we’re born with
D) Sneezing and coughing are modes of elimination
FRQ Question: What is the difference between innate and acquired immunity? Give examples of both. Active and
passive immunity? Give examples of both. How do these differences affect the body in short term and long term
circumstances?
Innate immunity is comprised of the first two lines of defense and has only short term results. These modes of
defense, including the skin and mucous membranes as well as leukocytes and natural killer cells, attack a very broad
spectrum of antigens and rid the body of them very quickly. Acquired immunity is the third line of defense and
allows the body to “remember” and recognize antigens it has already fought off. This line of defense attacks the
antigen and produces memory T cells to prevent further attacks. Cytotoxic T cells and antigen presenting cells (APCs)
are both part of this line of defense. Acquired immunity has two types of defense. Active defense is when antibodies
and memory T cells are produced through the forming of an APC when the body is attacked by a certain antigen.
Passive defense is when the body is not infected with the antigen but receives the antibodies from an outside source
such as vaccinations or breast feeding.
LO 2.38: The student is able to analyze data to support the claim that responses to
information and communication of information affect natural selection.
SP 5.1: The student can analyze data to identify patterns or relationships.
Explanation: Natural selection (reproduction of the fittest) is a response to things like environmental changes and
mutations in specific members of a population. Plants are the best example for this LO. If the entire plant isn’t exposed
to the same kind of light all around and for the same amount of time, then some leaves will grow larger and survive
longer than the smaller leaves because they have a larger surface area to do photosynthesis (they can absorb more
light than the smaller leaves). We can observe this with a graph showing the results of having a plant exposed to
different wavelengths of light and their resulting light absorption (the higher the light absorption, the higher the
photosynthetic rate). In this well-known experiment by Thomas Engelmann, it was proven that photosynthesis
happens best under blue-purple light and red-orange light. This is because oxygen-using bacteria will migrate to places
where a lot of oxygen is released because of photosynthesis. We have to know how to analyze the graph to reach
these conclusions. By observing that the white line is the highest around 400-425 nm and 650-675 nm, we can come
to a conclusion that the chlorophyll absorption spectrum of visible light is the most efficient under blue-purple and redorange light. This supports the LO because the data analyzed proves that a response to information (wavelength)
affects natural selection (the plants exposed to the more efficient wavelength will do photosynthesis faster and more
efficiently and thus survive longer).
M.C. Question: According to the graph on the right, chlorophyll absorbs the most light under
which wavelength(s) of light?
A) 500 nm
B) 700 nm
C) 425 nm
D) 675 nm
E) Both C and D
Learning Log/FRQ-style Question: A researcher is doing an
experiment on algae to see what kind of wavelength of light
encourages photosynthesis the most efficiently. She grows algae in
front of a prism of light to expose different areas to different
wavelengths. Using the graph on the right to help you, predict
what the her results will be, and explain why the results are the
way they are.
ANSWER KEY – LO 2.38
According to the graph on the right, chlorophyll absorbs the most light under which
wavelength(s) of light?
A) 500 nm
B) 700 nm
C) 425 nm
D) 675 nm
E) Both C and D (correct answer)
A researcher is doing an experiment on algae to see what kind of wavelength of light
encourages photosynthesis the most efficiently. She grows algae in front of a prism of light to
expose different areas to different wavelengths. Using the graph on the right to help you, predict
what her results will be, and explain why the results are the way they are.
The scientist will reach the results that chlorophyll will absorb
light the best, and therefore do photosynthesis the most
efficiently, under the purple-blue light (425 nm). This is
because this wavelength of light can release lots of oxygen
during photosynthesis (because the absorption is so high), so
the oxygen-using bacteria will travel to the area that has the
most oxygen to use. Algae will grow the best and the fastest
under this light. On the flip side, the algae under the green
light (525 nm) will hardly grow at all. Chlorophyll can’t absorb
green light, which is why leaves (or algae in this case) appear
to be green in the first place. Since the chlorophyll can’t
absorb the green light, there’s no starting place for
photosynthesis and it just won’t happen.
LO 3.21- The Student can use representations to describe how gene regulation influences cell products and functions.
SP 1.4 The student can use representations and models to analyze situations or solve problems qualitatively and quantitatively.
Explanation- Brain and kidney cells each contain DNA but their functions are vastly different. This is due to gene regulation, which turns “on”
and “off” certain genes, this effects the expression of the genes in the cell and influences the cell products and the overall function of the
cell. Gene regulation happens at many different levels, for example the DNA level or the RNA level. At the DNA level, for example, there is
DNA methylation, which is a turn of switch that puts caps on sections of DNA with methyl groups and Histone acetylation, which is an on
switch that unwinds DNA for easier translation. At the RNA level there is the activation of transcription with proximal and distal control
elements and enhancers and silencers. All the regulators at the RNA level effect transcription. In eukaryotes, the control of transcription
depends on the binding of activators to DNA control elements. For example before the start of transcription an activator protein binds to the
distal control element which forms a enhancer (activator). The a DNA-bending protein then bends the DNA and helps it connect to general
transcription factors at the TATA/Promoter region of the strand. This will eventually initiate RNA synthesis. The different combinations of
control elements affects what genes are expressed on the strand of new RNA. After the mRNA is processed and is translated by a ribosome
the protein is formed it will be sent off to do work. These different gene regulators, regulate what genes are expressed which when translated
makes many different kind of proteins. This allows brain cells and kidney cells, which both contain the same genome, to have very different
functions and produce different things that the body needs. For example a kidney cell will the enzyme Calcitriol, while the brain cell will
produce neurotransmitters.
M.C. Question – Which of the following regulator of gene expression occurs at the DNA level?
A) DNA methylation turns off a switch for sections of RNA and puts caps on the RNA with methyl groups which is a key process in
regulation of gene expression.
B) Proximal and distal elements bind upstream from the promoter, effect the gene expression.
C) DNA creates a protein that is degraded because it is tagged by ubiquiden to be engulfed by Protosomes.
D) Enzymes called histone acetelyation, acetylate lysine amino acids on histone proteins by transferring an acetyl group from acetyl CoA to
form N-acetyl lysine as a important part of gene expression.
Learning Log/FRQ Style Questions
Both liver cells and lens cells have the genes to make the
proteins albumin and crystallin, but only liver cells make albumin (a blood
protein) and only lens cells make crystallin. This is possible through
transcription factors. Describe the process and influence of activator and
repressor proteins on the DNA which allows for liver and lens cells to make
different proteins.
M.C. Question Answer – Which of the following regulator of gene expression occurs at the DNA level?
A) DNA methylation turns off a switch for sections of RNA and puts caps on the RNA with methyle groups which is a key
process in regulation of gene expression.
B) Proximal and distal elements bind upstream from the promoter, effect the gene expression.
C) DNA creates a protein that is degraded because it is tagged by ubiquiden to be engulfed by Protosomes.
D) Enzymes called histone acetelyation, acetylate lysine amino acids on histone proteins by transferring an acetyl group
from acetyl CoA to form N-acetyl lysine as a important part of gene expression.
Learning Log/FRQ Style Questions- Answer
Both liver cells and lens cells have the genes to make the
proteins albumin and crystallin, but only liver cells make albumin (a
blood protein) and only lens cells make crystallin. This is possible
through transcription factors. Describe the process and influence of
activator and repressor proteins on the DNA which allows for liver and
lens cells to make different proteins.
Transcription factors allow for gene’s to express different
traits. Enhancers, or activators proteins, bind to distal control
elements which form an enhancer on the DNA. This enhancer
has three binding sites. Then a DNA bending protein brings the
bound activators closer to the promoter. The activators then
bind to general transcription factors and mediator proteins
which affect transcription initiation at the promoter site. The
promoter site includes the TATA box. The liver cell and lens
cells have different types of activators and repressors which
allows for creation of two very different proteins. These
proteins allow for different cell functions.
By: Gracie Nicklas-Morris
LO 2.32: The student is able to use a graph or diagram to analyze situations or solve problems that
involve timing and coordination of events necessary for normal development in on organism.
SP 1.4: The student can use representations and models to analyze situations or solve problems
qualitatively and quantitatively.
Explanation: Fruit flies, for example, are good model organisms because they share key developmental life
cycle events with humans. Their egg cells develop within the female ovaries, surrounded by ovarian cells
called nurse cells and follicle cells. The egg cell is able to develop and is fertilized within the mother and then
laid. The first ten mitotic divisions have 2 notable features: they consist of S and M phases, with no growth,
so the amount of cytoplasm does not change, and cytokinesis does not occur, so the embryo is one of big
multinucleate cells. At the tenth nuclear division, the nuclei begin to migrate, forming and early blastula-like
stage called blastoderm. At division 13, plasma membranes finally partition the nuclei into separate cells. A
centrally placed yolk nourishes the embryo, and the egg shell continues to protect it. Clearly visible segments
of the embryo form. Then, some cells move to new positions, and organs form. The fly may now develop into
its adult form.
M.C. Question: The criteria for a good model organism for studying
development would probably include all of the following except:
A- observable embryonic development
B- short generation time
C- a relatively small genome
D- preexisting knowledge of the organism’s life history
E- a rare pattern of development when compared to most organisms
Learning Log/FRQ-style Question:
The DNA sequences called homeoboxes,
which help homeotic genes in animals direct development,
are common to flies and mice. Given this similarity, explain
why these animals are so different.
ANSWER KEY – LO 2.32
M.C. Question:
The answer is E- a rare pattern of development
when compared to most organisms.
Learning Log/FRQ Style Question:
Homeotic genes differ in their homeotic
sequences, which determine their interactions with
other transcription factors and which genes are regulated
by the homeotic genes. These interactions differ in the two
organisms, as do the expression patters of the homeotic
genes. The expression patterns are regulated on the DNA
level by DNA methylation and histone acetylation. DNA
methylation turns off a gene by capping it with a methyl
group. Histone acetylation attaches actely groups (-COCH3)
to positively charged lysines in histone tails. When histone
tails are acetylated, their positive charges are neutralized and
they no longer bind to neighboring nucleosomes. This
“unwinds” DNA for an easy transcription.
LO 1.16: The student is able to justify the scientific claim that organisms share many conserved core processes and features that evolved
and are widely distributed among organisms today.
SP 6.1: The student can justify claims with evidence.
Explanation: All life on Earth is related and can be traced back through lines of descent to a common ancestor. Organisms inherit traits from
their parents, and their parents from their parents. The traits are and have been passed down through the genes over and over with occasional
mutations, allowing for extreme differences and similarities between the ancestor and current organisms. All organisms have DNA and/or RNA,
a universal genetic code with which they carry their genetic information and pass it on through transcription, translation, and replication.
Major features of the genetic code, such as the nucleotide bases A, T/U, C, and G, are shared by all modern living systems. Metabolic
pathways, as well, are conserved across all domains of life; for example, glycolysis of respiration is performed by all organisms and structural
evidence supports the relatedness of all eukaryotes. Lost and acquired traits can be represented in phylogenetic trees, branching diagrams that
graphically model evolutionary history based on similarities and differences in genetic and physical characteristics.
M.C. Question: Based on information provided in the diagram directly below,
which two organisms are most closely related to one another?
A) Chordata and Anthropoda
B) Tardigrada and Nematoda
C) Kinorhyncha and Annelidia
D) Mollusca and Entoprocta
Learning Log/FRQ-style Question: Compare and contrast a basic
eukaryotic cell and a basic prokaryotic cell. Identify similar
processes and features and explain why they can be present in the
different types of cells.
Answer Key – LO 1.16
Based on information provided in the diagram directly below, which two organisms are most closely related to one another?
A) Chordata and Anthropoda
B) Tardigrada and Nematoda
C) Kinorhyncha and Annelidia
D) Mollusca and Entoprocta
Learning Log/FRQ-style Question: Compare and contrast a basic eukaryotic
cell and a basic prokaryotic cell. Identify similar processes and features and
explain why they can be present in the different types of cells.
A cell is the basic unit of life as according to cell theory and all cells are either eukaryotic or prokaryotic. Prokaryotic cells are cells
lacking a membrane-bound nucleus or any other membrane-bound organelles. Prokaryotes generally always have a cell wall and
are unicellular organisms. Eukaryotic cells are cells that contain a nucleus and membrane-bound organelles. All multicellular
organisms, such as plants, animals, and fungi, are eukaryotes, though eukaryotes can also include unicellular organisms as well,
such as protozoa. Eukaryotes and prokaryotes both have DNA as their genetic material and are both membrane bound, though
eukaryotes contain their DNA in the nucleus where prokaryotes have DNA that floats freely around the cell. Eukaryotic DNA is
much more complex than prokaryotic DNA and therefore much more extensive. The two cells reproduce in different ways, the
prokaryotes dividing asexually by binary fission, or simple cell division, and eukaryotes dividing by mitosis and can also do sexual
reproduction. Eukaryotes originally came from prokaryotes in a process called endosymbiosis. A large prokaryote engulfed a much
smaller aerobically respiring one through endocytosis. Because of this, both cells are similar in their metabolisms and in the way
they produce energy. Eukaryotes are generally about ten times larger than prokaryotes and have organelles, such as mitochondria,
that produce energy for them that have evolved from the engulfed from the smaller aerobic prokaryote.
LO 1.24: The student is able to describe speciation in an isolated population and connect it to change in gene frequency, change in environment,
natural selection and/or genetic drift.
SP 7.2: The student can connect concepts in and across domain(s) to generalize or extrapolate in and/or across enduring understanding and/or big
ideas
Explanation: An isolated population will often reach the state of equilibrium, where evolution is not occurring. This will only happen if the
population is also large, if no mutations occur, if all mating is random, and if no natural selection is present. If any of these requirements are not
met, the population will change through a microevolution. Small populations are more susceptible to random changes and can easily result in
genetic drift, where the changes develop into a major alteration in the population. For example, one of the most common types of genetic drift is
the bottleneck effect, where a small population's gene pool is affected by a disaster (the random change), and the remaining population must
inbreed to repopulate. Another method of change in gene frequency is gene flow, where emigration and/or immigration involves in the gain or
loss of alleles and the remaining population undergoes a microevolution since it was so longer isolated. Mutations often result in a favorable trait
being developed, which would help a mutated individual and the individual would outcompete others in the population. Natural selection will
allow the mutant to survive and successfully reproduce, passing on its favorable trait(s). The allelic frequency of this gene will increase, because
it is recognized as favorable, and in time the majority of the population will have evolved (sometimes to a new species) to have this gene.
M.C. Question: Which of the following would result in the greatest change in an
isolated population of humans?
A) a large number of babies were recently born into the population
B) a widespread disease struck the population
C) a major earthquake occurred
D) many species of birds were hunted
FRQ Question: Suppose an island population is cut off from the mainland. The
island is prone to widely varying weather which can include raging storms ,
unbearable heat, and the occasional bout of snow if it gets cold enough.
• Explain what effect that weather has on the population size. Hypothesize what
could happen to the population’s gene pool and allelic frequency if it were to
hail for an entire year.
• Hypothesize what could happen if an invading species entered the isolated
population. Include an immediate effect and a long-term effect.
An example graph of competition for food
ANSWER KEY– LO 1.24
Which of the following would result in the greatest change in a population of humans that is in equilibrium?
A) a large number of babies were recently born into the population; this would just add to the population size, and it is assumed that the death
rate will counter the birth rate.
B) a widespread disease struck the population; one of the most common disadvantages to a dense population is the easy spread of disease,
which regulates the large populations back below carrying capacity (understanding of a population in equilibrium is required to infer that the
population in question is in fact a large population).
C) an earthquake occurred; while it could possibly result in many deaths, it is not a major earthquake, and its effect would most likely be an
immediate and then a short-term one.
D) many species of birds were hunted; though excessive hunting could lead to threatening of species, this answer only says that many different
species were hunted, so the hunting of birds really only mimics predators preying on birds, which is normal.
Suppose an island population is cut off from the mainland. The island is prone to widely varying weather which can include raging storms,
unbearable heat, and the occasional bout of snow if it gets cold enough.
a) Hypothesize what could happen to the population’s gene pool and allelic frequency if it were to hail for an entire year.
b) Hypothesize what could happen if an invading species entered the isolated population. Include an immediate effect and a long-term effect.
Exposure to extremely cold weather can kill just about any land animal that has not adapted to it. Considering how the weather is kn
fluctuate in the population, it is logical to assume that the organisms have adapted to rapidly changing weather, but they are unfamiliar with
a sustained climate. Due to this, the isolated population will be likely to suffer many deaths from lack of food, overexposure to cold, etc. After
many organisms have died, the remaining population will be forced to repopulate. At this point, the gene pool has been drastically reduced by
the loss of victims of the hail season. The repopulation will show a bottleneck effect, and the small gene pool will force the population to begin
inbreeding, and the specific alleles that the remaining individuals have will become very prominent in the population (since those alleles are the
only ones left).
An immediate effect of the presence of an invading species is that it would be likely to compete with an indigenous species, or it cou
a new niche in the population and not have to compete with another species. However, should the invading species compete with the indigenous
species, the invading one could easily win if it has a favorable trait from outside the isolated population’s gene pool. Should this be the case, the
two species would continuously compete until eventually the invading species outcompetes the indigenous species. The long-term effect here
is that the indigenous species was replaced and it either migrated elsewhere or became extinct.
a) LO 3.35 The student is able to create representation(s) that depict how cell-to-cell communication occurs by direct contact or from a distance through
chemical signaling.
[See SP 1.1]
b) SP 1.1 The student can create representations and models of natural or man-made
phenomena and systems in the domain
c) Explanation:
Cell signaling can be divided into two subcategories. Paracrine signaling is from one cell to another in close range. It is a signal that is
secreted into the extracellular fluid by a nearby cell and causes a differentiation of cells in close range after reception of the recognized signal. An
example of paracrine signaling occurs during embryonic development. In developing embryos, stem cells are differentiated through this process. The
forth cell of the embryo releases a signal to tell the half of cell three closest to cell four to activate the genes responsible for intestinal cells.
Endocrine signaling is long distance signaling involving hormones and steroids. There are three stages: 1) Reception- ligand (signal
molecule) binds to a receptor protein that causes a transduction pathway. 2) Transduction- conversion of the received signal to a specific cellular
response. According to the science practice 1.1, a model of how transduction occurs in the 4 types of transduction pathways is necessary. 3) Responsecell responds to signal. There are 4 different types of endocrine receptors: 1) Intracellular receptors- steroid hormone receptors. These receptors are
found within the cytoplasm. Small polar substances, like steroids, can pass easily through the cell membrane. This creates a more direct transcriptional
change. 2) G- protein linked receptors- the ligand causes a change in receptor shape which attracts the inactive G-protein. Through the action of
GTPase, GTP displaces GDP through hydrolysis, activating the G-protein. The active G-protein can then activate other specific molecules. 3) Tyrosine
Kinase receptors- when the ligand binds, the receptor forms a dimer (two part structure). The tyrosine aa of the dimer is phosphorylated by the
hydrolysis of ATP and this activates the relay proteins. 4) Ligand gated ion channels- when the ligand binds, a change in shape occurs and specific ions
can move down the concentration gradient. An example would be neurotransmitters at the synapse of a neuron.
Second messengers are another important part of endocrine signaling. 1) cAMP (cyclic AMP)- adenylyl cyclase converts ATP to cAMP.
After a G-protein is activated, it activates the adenylyl cyclase. With the use of ATP, cAMP is formed. The cAMP then activates a protein kinase and an
eventual cellular response. 2) IP3- second messenger that are releases Ca2+ from the endoplasmic reticulum. This happens every time a muscle
contracts and during cell division. After a G-protein is activated and activates a relay protein, PIP3 (which is attached to the cellular membrane) is
broken off into two parts. DAG stays in the membrane, and IP3 acts as a second messenger that travels to the ER to release the gated calcium channels.
When PIP3 attaches to the channels, a shape change occurs and the calcium ions are released. The Ca2+ ions can also act as second messengers to
activate various proteins and result in a cellular response. Signal amplification occurs when a single ligand activates millions of molecules during a cell
response. The reason for all of the steps in the pathway is to cause an amplified response. Different responses to the same cell occur because of different
relay proteins, and different receptor types. Scaffolding proteins can make this response even quicker by binding several different molecules together. It
also brings proteins together so they can interact.
Multiple Choice Question:
A glucocorticoid is released from the adrenal cortex and
must be received by the target cells. Which of the
following receptors is most likely to receive the signal?
a.
G-protein linked receptor
b.
Intracellular receptor
c.
Tyrosine kinase receptor
d.
Ligand-gated ion channel
Free Response Question: cAMP is a second messenger
that is synthesized via a transduction pathway. Describe
the process that leads to the production of cAMP and
how cAMP causes a final cellular response. Explain the
function of second messengers and describe one
additional example of a second messenger in
transduction pathways. Include with your answer a
labeled diagram of the cAMP transduction pathway.
Answer Key
Multiple Choice Question:
A glucocorticoid is released from the adrenal cortex and must be received by the target cells. Which of the following receptors
is most likely to receive the signal?
a. G-protein linked receptor
b. Intracellular receptor
c. Tyrosine kinase receptor
d. Ligand-gated ion channel
Explanation: The endocrine glands of the body release steroids, a specific type of hormone. The adrenal cortex is an endocrine gland and
glucocorticoids are steroids that are responsible for regulating metabolism, inflammation, and for calming the body. Because steroids are
small, polar substances, they can diffuse easily through the cell membrane. They then bind to an intracellular receptor that makes a direct
transcriptional change.
Free Response Question:
cAMP is a second messenger that is synthesized via a transduction pathway. Describe the process that leads to the production of cAMP and
how cAMP causes a final cellular response. Explain the function of second messengers and describe one additional example of a second
messenger in transduction pathways. Include with your answer a labeled diagram of the cAMP transduction pathway.
Explanation: A ligand, or signal molecule, binds to the g-protein linked receptor on the cell
membrane. A G-protein is then activated with GTP. The G-protein then activates adenylyl cyclase.
Adenylyl cyclase uses ATP to make cAMP. cAMP then acts as a second messenger in the pathway.
cAMP is phosphorylated by protein kinases and a cellular response is initiated. Second messengers
function as a way to amplify a cellular response. This can be seen when a G-protein pathway
activates a relay protein that cleaves IP3 off of the PIP2 molecule. IP3 acts as a second messenger
and travels to the endoplasmic reticulum which holds Ca2+ ions. When it binds to the membrane
of the ER, the shape change causes the Ca2+ ions to be released and initiate cellular responses.
LO 2.20: The student is able to justify that positive feedback mechanisms amplify responses in
organisms.
SP 6.1: The student can justify claims with evidence.
Explanation: Positive feedback involves a change in some variables that trigger mechanisms
that amplify rather than reverse the change. For instance, in childbirth, the pressure of the
baby’s head against receptors near the opening of the uterus stimulates uterine contractions,
which cause greater pressure against the uterine opening, heightening the contractions,
which causes still greater pressure. Another good example of a positive feedback mechanism
is blood clotting. Once a vessel is damaged, platelets start to cling to the injured site and
release chemicals that attract more platelets. The platelets continue to pile up and release
chemicals until a clot is formed.
M.C. Question: Ethylene, a plant hormone, plays what part in fruit development?
A) It stimulates the ripening of unripe fruit.
B) It allows for the fruit to begin its reproduction process.
C) It causes the fruit to emit a pleasant fragrance that attracts
animals to consume it.
D) It allows the plant to uptake water through the root hairs
which provides fruit with an energy source.
Learning Log/FRQ-style Question:
Explain how lactation in mammals is the result of a positive feedback response.
ANSWER KEY- LO 2.20
Ethylene, a plant hormone, plays what part in fruit development?
A) It stimulates the ripening of unripe fruit.
B) It allows for the fruit to begin its reproduction process.
C) It causes the fruit to emit a pleasant fragrance that attracts animals to consume it.
D) It allows the plant to uptake water through the root hairs which provides fruit with an energy
source.
Explain how lactation in mammals is the result of a positive feedback
response.
A baby begins to suckle it’s mother’s nipple or teat and a few drops of milk are released. This
acts as the stimulus. The milk releases encourages the baby and releases a hormone known as
oxytocin in the mother, which further stimulates the release of milk. This is the response to the
stimulus. As the baby continues to suckle, more milk is stimulated to be released by the mother.
More stimulus results in more and greater of a response.
LO 2.36 The student is able to justify scientific claims with evidence to show how
timing and coordination of physiological events involve regulation.
SP 6.1 The student can justify claims with evidence.
The student should connect specific physiological responses that plants, animals, and
fungi/protists/bacteria have to internal and external (environmental) stimuli.
- In plants, phototropism is the process where a plant will grow (response) towards sunlight
(stimulus).
- In animals, hibernation (response) is regulated by seasonal changes in temperature
(stimulus).
- In bacteria, quorum-sensing coordinates transcription (response) within colonies of
bacteria when the density of the colony has reached a threshold (stimulus).
MC Question: A deer
running from the sight of a
wolf is an example of:
A)
B)
C)
D)
E)
An olfactory response
Taxis
Classical conditioning
Kinesis
Imprinting
FRQ: Of the following, choose two and
describe how they involve the relationship
between stimulus and response. Be sure to
include an example for each.
- Cell differentiation
- Behavioral conditioning
- Action potentials in neurons
Phototropism
Answers LO 2.36
Creating an Action Potential
MC Question: A deer running from the sight of a
wolf is an example of:
A) An olfactory response
B) Taxis – movement toward or away from
stimulus
C) Classical conditioning
D) Kinesis
E) Imprinting
Stem cells become differentiated, or made specific, during induction within an embryo; signal molecules are released from
an embryonic cell, beginning with a 4-cell embryo, and those molecules turn on a regulatory gene in a different cell which
begins the transcription of proteins to make the cell differentiated. One example is the vulva formation of nematodes where
an anchor cell releases signals onto the epidermis; the cells that receive the most molecules turn into the vulva.
Behavioral conditioning includes both classical and operant conditioning. Classical conditioning is involuntary behavioral
change that occurs when a stimulus is paired with a different desirable or undesirable stimulus to cause them to be
associated together; Pavlov’s dogs were trained to salivate at the sound of a bell because they became used to hearing the
bell before receiving food. Operant conditioning involves voluntary behavior where the subject, such as a bird, must
perform a behavior to get a reward or avoid punishment, like pecking at a button to receive feed.
An action potential is created when the amount of excitatory signals (EPSPs) overpowers the amount of inhibitory signals
(IPSPs) received by a neuron; the neuron must leave its resting potential of -70mV and must pass the threshold of -55mV to
fire. For example, if a neuron in the brain receives a rapid amount of epinephrine, the body will begin the fight-or-flight
response as more and more neurons respond by releasing the same neurotransmitter.
LO 3.22 The Student is able to explain how signal pathways mediate gene expression, including how this process can effect
protein production.
SP 6.2 The student can construct explanations of phenomena based on evidence
produced through scientific practices.
Explanation: Cell signaling starts with signal reception, signal transduction, and cellular response. Signal molecules (ligands)
bind to specific sites on receptor proteins (G-protein-linked receptor, receptor tyrosine kinases, or ion channel
receptor) embedded in the plasma membrane, which activates it. Receptors transmit information when a specific
ligand binds to it. Transduction is a multistep pathway where the receptor triggers a relay protein, which begins the
phosphorylation cascade (where different molecules in a pathway are phosphorylated in turn, each molecule adding a
phosphate group to the next one in line). Once phosphorylated the last kinase in the sequence enters the nucleus and
there activates a gene-regulating protein, a transcription factor. This protein stimulates a specific gene so than an
mRNA is synthesized (transcription). The mRNA is used by ribosomes in the cytoplasm to synthesize proteins
(translation). In other words, different activator proteins are present in different cells and activate different genes to
synthesize different proteins that cause differences in cell type, structure and/or behavior, and therefore gene
expression.
M.C. Question: Which of the following is not an example of signal molecules mediating gene expression?
A) Epinephrine regulating cell metabolism
B) Cytokines regulating cell replication and division
C) Ethylene regulating fruit ripeness
D) Chaperonins regulating sugar synthesis
E) Testosterone regulating male sex characteristics
Learning Log/FRQ-style Question
Prolactin is a hormone that initiates breasts to produce milk. Briefly explain each step involved
in cell signaling in terms of the diagram and the example given to show how signal pathways
mediate gene expression. (Cues: signal molecule, receptor, transduction, phosphorylation
cascade, response, mRNA, transcription, translation)
ANSWER KEY-LO 3.22
Which of the following is not an example of signal molecules mediating gene expression?
A) Epinephrine regulating cell metabolism
B) Cytokines regulating cell replication and division
C) Ethylene regulating fruit ripeness
D) Chaperonins regulating sugar synthesis
E) Testosterone regulating male sex characteristics
Prolactin is a hormone that initiates breasts to produce milk. Briefly explain each step involved in cell signaling in
terms of the diagram and the example given to show how signal pathways mediate gene expression. (Cues:
signal molecule, receptor, transduction, phosphorylation cascade, response, mRNA, transcription, translation)
Reception
Transduction
Response
In this pathway the prolactin is the signal molecule and it binds to a
receptor protein. When the signal protein binds, the receptor protein
initiates transduction by triggering a relay molecule and leads to the
phosphorylation cascade. Once phosphorylated the last kinase in the
sequence enters the nucleus where the response to the signal takes
place and causes a change in gene expression. The activated generegulating protein(transcription factor) causes a gene to be activated,
in this case the gene that stimulates breast milk synthesis. The
stimulation of a specific gene causes mRNA to be synthesized from
the DNA through transcription. The mRNA is used by ribosomes in the
cytoplasm to synthesize milk proteins through translation. The
presence of prolactin lead to the milk production gene being
expressed by producing milk proteins that led to milk production.
LO 3.9 The student is able to construct an explanation, using visual representations or narratives, as to how DNA in chromosomes is
transmitted to the next generation via mitosis, or meiosis followed by fertilization.
SP 6.2 The student can construct explanations of phenomena based on evidence produced through scientific practices.
Explanation: Meiosis is preceded by the replication of chromosomes in a similar fashion as what takes place during mitosis, but this one
replication is followed by two cell divisions called meiosis I and meiosis II. During meiosis I crossing over takes place so that DNA molecules
in nonsister chromatids break at corresponding places so that they can rejoin the other DNA in order to create DNA variation. The results
of these two divisions is the creation of four daughter cells rather than the two daughter cells from mitosis. These four daughter cells are
unique because they have half as many chromosomes (haploid) as the parent cell. It is very important to recognize that the cells only have
half the amount of chromosomes because this allows for the cell to become fertilized so that chromosomes from the female and
chromosomes from the male so that the cell can become diploid. After the gamete becomes fertilized the new diploid cell can begin the
process of mitosis. By beginning the process of mitosis the fertilized cell is able to continue replicating its DNA so that an embryo can begin
to form because the process of mitosis makes exact clones of the cell being replicated.
Multiple Choice Question:
Arrange the following five events in the order that explains how genetic variation takes place during meiosis.
1. Nonsister chromatids break at corresponding locations due to crossing over
2. Homologous chromosomes pair loosely
3. Chromosomes replicate to make to genetically identical
sister chromatids
4. Tetrads are formed and line up along the Metaphase
plate
5. Microtubules attach to each homologue
a) 1,3,4,2,5
b) 2,3,1,4,5
c) 3,2,1,5,4
d) 5,4,1,3,2
e) 3,2,4,1,5
Free Response Question:
Why is it necessary for fertilization that a cell undergo meiosis
in order to create four haploid gamete cells? Describe how
meiosis makes four haploid gamete cells and explain why
after fertilization a cell switches from using meiosis to mitosis.
Model of Mitosis (left) and Meiosis (right)
Multiple Choice Question:
Arrange the following five events in the order that explains how genetic variation takes place during meiosis.
1. Nonsister chromatids break at corresponding locations due to crossing over
2. Homologous chromosomes pair loosely
3. Chromosomes replicate to make to genetically identical
sister chromatids
4. Tetrads are formed and line up along the Metaphase
plate
5. Microtubules attach to each homologue
a) 1,3,4,2,5
b) 2,3,1,4,5
c) 3,2,1,5,4
d) 5,4,1,3,2
e) 3,2,4,1,5
Free Response Question:
Why is it necessary for fertilization that a cell undergo meiosis in order to create four haploid gamete cells? Describe how
meiosis makes four haploid gamete cells and explain why after fertilization a cell switches from using meiosis to mitosis.
It is necessary for a cell to undergo meiosis in order to successfully go through fertilization. Meiosis creates four haploid
game cells that have half of the total chromosomes as the parent cell. The Chromosomes are replicated during interphase
which creates two genetically identical sister chromatids. The during prophase I the homologous chromosomes are loosely
paired so that crossing over may take place. Crossing over is when the DNS molecules in nonsister chromatids break at the
same location and then rejoin to the opposite chromatid. This process creates DNA variation from the parent cell. After
crossing over is completed tetrads (a group of four chromatids) are formed and they line up along the Metaphase plate.
During metaphase I both chromatids are attached to microtubules from one pole or the other. During anaphase I the
chromosomes move towards the poles where they will remain attached at the centromere. At the very beginning of
telophase I each half of the cell has a complete set of haploid chromosomes until cytokinesis takes place. Cytokinesis is the
division of the cytoplasm so that two haploid cells are created. This completes meiosis I so that meiosis II may begin. All of
the steps from meiosis I are repeated during meiosis II except for crossing over. Once cytokinesis takes place for the second
time the final result will be four haploid, genetically unique cells. It is important that meiosis creates four haploid cells so
that when the cells are fertilized by the haploid gametes of the opposite gender the two gametes’ chromosomes can
combine to create a diploid cell. Once the original haploid gamete becomes fertilized then mitosis takes place. During
mitosis the cell is duplicated to create two genetically identical daughter cells to the parent cell. This is important because
the process of mitosis helps to create enough genetically identical cells so that an embryo may begin to form.
LO 1.28: The student is able to evaluate scientific questions based on hypotheses about the origin of life on
Earth.
SP 3.3: The student can evaluate scientific questions.
Explanation: Oparin and Haldane hypothesized that Earth’s early atmosphere had been a reducing
environment. This would have allowed for simple molecules to become organic compounds with the
energy from lightening or UV radiation. Experiments simulating early earth produced all the
monomers, amino acids, and purines and pyrimidines. Researchers also believe that some organic
compounds could have come from outer space in meteorites. Researchers have been able to make
polymers by dripping amino acids onto hot sand, clay, or rock. Nucleotides are believed to have been
created with the help of protobiont which can form from abiotically produced organic compounds.
There are still questions about the composition of early Earth’s atmosphere and if it actually was
reducing.
Multiple Choice Question:
What aspect of early Earth’s atmosphere aided the most
in the formation of organic compounds?
a)The existence of amino acids
b)The environment was electron adding
c)The lack of water
d)The large amount of red light
Free Response Question:
a) Explain one hypothesis about how the Earth was formed
b) Describe in detail an experiment that could be used to support
the hypothesis.
c) Give one possible source of error in the experiment described
above.
L.O. 1.28 Answer Key
What aspect of early Earth’s atmosphere aided the most in the formation of organic
compounds?
a)The existence of amino acids
b) The electron adding environment
c) The lack of water
d)The large amount of red light
Free Response Question:
a) Explain one hypothesis about how life on Earth was formed
b) Describe in detail an experiment that could be used to support the hypothesis.
c) Give one possible source of error in the experiment described above.
One hypothesis of how life formed on early earth is that the reducing environment
allowed for simple molecules to form organic compounds with the energy from
lightening. Miller and Urey tested this hypothesis in an apparatus they built to simulate
conditions on early earth. The reducing atmosphere was created with hydrogen,
methane, ammonia, and water vapor. The sea was simulated by a flask of warmed water.
Lightening was simulated by sparks from an electrode. The atmosphere was cooled by a
condenser and water and any compounds fell into the “sea”. The experiment produced
many organic molecules, including amino acids, sugars, lipids, purines, pyrimidines,
ATP, and all monomers. One possible error is that researchers do not know the exact
conditions of the early atmosphere. There may not have been enough methane and
ammonia to be reducing.
Learning Objective 2.13 – The student is able to explain how internal membranes and organelles contribute to cell functions.
Science Practice 6.2 – The student can construct explanations of phenomena based on evidence produced through scientific practices.
Explanation – The internal membranes and organelles contribute to the function of the cells in many different, but very specific and
individual, ways. For example, the Golgi Apparatus’ main role is to manufacture, store, sort, and ship everything that comes through
the cell. The Vesicles carry materials to the Golgi for sorting, and they also carry other materials to the plasma membrane. Another
organelle, known as the Lysosome, is responsible for the carrying out the process of hydrolysis to break down old cell parts. The two
most important organelles of a cell are the Mitochondria and Chloroplasts cell. The Mitochondria is the site of aerobic respiration,
during which three stages occur: 1. Glycolysis, 2. Krebs Cycle, and 3. Oxidative Phosphorylation. Aerobic respiration is a form of
cellular respiration that requires oxygen in order to generate energy. The Chloroplasts are responsible for the process of photosynthesis
in plants and other Prokaryotes only. Of these two important organelles are very important internal membranes, the mitochondrial
membrane and the thylakoid membrane, which also contribute to the cell’s function in a unique and important way. The thylakoid
membrane of a chloroplast is an elaborate system of interconnected membrane sacs that segregates the stroma from the thylakoid
space. Within the Thylakoid Membrane resides chlorophyll, which is needed to absorb sunlight. The Mitochondrial Membrane of the
mitochondria is responsible for the Electron Transport Chain (ETC) and Chemiosmosis. The purpose of the ETC process is harvesting
the energy of reduced coenzymes NADH and FADH2, which are formed in Glycolysis and the Krebs Cycle. The purpose of
Chemiosmosis is to create an influx of ATP. There is and will always be a strong relationship between an internal membrane and/or an
organelle and the cell’s function.
Multiple Choice Question: What is the difference between the Rough Endoplasmic Reticulum and the Smooth Endoplasmic Reticulum?
A) The Rough ER is used to transport materials, as the Smooth ER is
used to store them.
B) The Smooth ER stores Ca +2 while the Rough ER makes membrane
components.
C) The Smooth ER carry out hydrolysis, and the Rough ER carries out
dehydration synthesis.
D) The Rough ER ships glycoproteins, and the Smooth ER detoxifies
lipids.
Free Response Question: Organelles and internal membranes play
important roles in a cell, as they contribute to their function. Since
you know this information, answer the following questions related to
organelles and internal membranes. What are the building blocks of
the endomembrane system? What are THREE of their functions? What
does TWO of these building blocks create? Give ONE example of an
internal membrane of your choice and describe its function and
purpose. What happens if this particular process stops?
ANSWER KEY – Learning Objective 2.13
What is the difference between the Rough Endoplasmic Reticulum and the Smooth Endoplasmic Reticulum?
A)The Rough ER is used to transport materials, as the Smooth ER is used to store them.
B) The Smooth ER stores Ca +2 while the Rough ER makes membrane components.
C) The Smooth ER carry out hydrolysis, and the Rough ER carries out dehydration synthesis.
D)The Rough ER ships glycoproteins, and the Smooth ER detoxifies lipids.
Organelles and internal membranes play important roles in a cell, as they contribute to their function. Since
you know this information, answer the following questions related to organelles and internal membranes.
What are the building blocks of the endomembrane system? What are THREE of their functions? What does
TWO of these building blocks create? Give ONE example of an internal membrane of your choice and
describe its function and purpose. What happens if this particular process stops?
The building blocks of the endomembrane system are the nuclear envelope, rough endoplasmic reticulum,
golgi apparatus, smooth endoplasmic reticulum, lysosomes, vacuoles, and the plasma membrane. The
nuclear envelope surrounds the nucleus and has a membrane lined with pores, which regulate the movement
of RNA and proteins into the nucleus. Lysosomes contain enzymes that carry out hydrolysis to break down
old cell parts. Vacuoles store food and carry them to lysosomes for digestion. Important building blocks
such as the Rough ER and the Smooth ER make two separate things. The Rough ER makes secreted
proteins, membrane components, and glycoproteins. The Smooth ER makes lipids, metabolizes carbs, and
stores Ca+2 ions. One example of an internal membrane is the Mitochondrial Membrane, and its purpose is to
conduct the process of Oxidative Phosphorylation, which includes the Electron Transport Chain and
Chemiosmosis. This process creates between 30 to 32 ATP for the body’s use. This process could be
inhibited, leading to a huge energy loss for the organism. If respiration stops working, then the oxygen being
taken in by an organism would not reach its way to the blood stream, causing the organism to die.
LO 2.26 The student is able to analyze data to identify phylogenetic patterns or relationships, showing that homeostatic mechanisms
reflect both continuity due to common ancestry and change due to evolution in different environments.
SP 5.1 The student can analyze data to identify patterns or relationships
Although different species of animals are adapted to different environmental temperatures, each species has an optimal temperature range. Thermoregulation helps keep body
temperature within that optimal range, enabling cells to function most effectively, even as external temperature fluctuates. Ectotherms gain most of their heat from the surrounding
environment, with a metabolic rate so low, that the amount of heat it generates is too small to have much of an effect on body temperature. In contrast, endotherms can use
metabolic heat to regulate their body temperatures. Endotherms are capable of performing vigorous activity for much longer than is possible for most ectotherms. Endothermy
solves thermal problems of living on land, enabling terrestrial creatures to maintain stable body temperature fluctuations. For example, no ectotherm can be active in the belowfreezing weather that prevails during winter over much of Earth’s surface, but many endotherms function very well in these conditions. Most of the time, endothermic vertebrates
are warmer than their surroundings, but these animals also have mechanisms for cooling the body in a hot environment, which enables them to withstand heat loads that are
intolerable for many ectotherms. All animals are capable of maintaining a stable internal environment; however, the differences in means of reaching homeostasis emerge when
considering the environmental variability that exists amongst all organisms. All animals, regardless of phylogeny, habitat, or type of water produced, must attain a balance in water
uptake and loss. Osmoconformer’s internal osmolarity is the same as that of its environment, therefore they often live in water that has a very stable composition. Organisms that
are osmoregulators must control its internal osmolarity because its body fluids are not isoosmotic with its environment. Animals first evolved in the sea, and more animal phyla are
found there than in any other environment, explaining why most marine animals are osmoconformers. Freshwater animals gain water by osmosis and lose salts by diffusion as the
osmolarity of their internal fluids is much higher than that of their surroundings. Animals that live in temporary waters have the adaptation of anhydrobiosis which allows them to
lose almost all of their body water and survive in a dormant state when their habitats dry up. Land animals have the adaptation of body covers in order to prevent dehydration. In
most animals, one or more different types of transport epithelium acts as an essential component of osmotic regulation and metabolic waste disposal. These homeotic mechanisms
to attain an osmotic balance suggest a connection to a common ancestor as organisms evolved from the water; however, similarly to thermoregulation, differences emerge when
considering the organism’s habitat as marine or terrestrial.
M.C. Question
Which of the following statements concerning thermoregulation in ectotherms is true?
A) They can use metabolic heat to regulate their body temperature
B) Most organisms classified as ectotherms are mammals, birds, and insects along with a few fish and reptile species
C) They have the advantage of performing vigorous activity for long periods of time due to their ability to generate a large amount of heat metabolically
D)They are less equipped to survive extreme frigid weather as most of their heat is gained from the environment
FRQ Style Question
A)Based on the data presented on the graph on the left, describe thermoregulation as it occurs
in an endothermic mammal and ectothermic reptile.
B) Compare how environmental adaptations allow fish to survive in a saltwater
and freshwater environment.
Answer Key-LO 2.26
MC Question
Which of the following statements concerning thermoregulation in ectotherms is true?
A) They can use metabolic heat to regulate their body temperature
B) Most organisms classified as ectotherms are mammals, birds, and insects along with a few fish and reptile species
C) They have the advantage of performing vigorous activity for long periods of time due to their ability to generate a large amount of heat metabolically
D)They are less equipped to survive extreme frigid weather as most of their heat is gained from the environment
FRQ Question
A)Based on the data presented on the graph to the left, describe thermoregulation as it occurs in an endothermic mammal and ectothermic reptile. Explain
the advantages of each.
B) Compare how anatomical adaptations allow fish to regulate osmolarity in a saltwater and freshwater environment.
A) Using its high metabolic rate to generate heat, the bobcat maintains a stable body temperature across a wide range of environmental temperatures.
The snake, meanwhile, generates relatively little metabolic heat and conforms to the temperature of its immediate environment. The bobcat, being an
endotherm, has the advantage of performing vigorous activity for much longer than an ectotherm, allowing it to sustain long-distance running. As a
terrestrial animal, the bobcat will be able to maintain its stable body temperature in the face of environmental fluctuations. Ectotherms have the
advantage of tolerating fluctuations in internal temperature. Ectotherms can consume less food (based on body size) compared to endotherms. This
adaptation becomes extremely advantageous when supplies are limited.
B) Marine bony fishes, such as cod, are hypoosmotic to seawater and constantly lose water by osmosis and gain salt both by diffusion and from the food
they eat. The fishes balance the water loss by drinking large amounts of seawater. Their gills and skin dispose of sodium chloride; in the gills, specialized
chloride cells actively transport chloride ions out, and sodium ions follow passively. The kidneys of marine fishes dispose of excess calcium, magnesium,
and sulfate ions while excreting only small amounts of water. The osmoregulatory problems of freshwater animals are opposite those of marine
animals. The body fluids of most freshwater animals have lower solute concentrations compared to their marine relatives, an adaptation to their lowsalinity freshwater habitat. Water balance is maintained by excreting large amounts of very dilute urine. Salts lost by diffusion and in the urine are
replenished by foods and by uptake across the gills;chloride cells in the gills actively transport chloride and sodium follows.
LO 1.23: The student is able to justify the selection of data that address questions related to reproductive isolation and speciation.
SP 4.1: The student can justify the selection of the kind of data needed to answer a particular scientific question.
Explanation: Speciation can occur as a result of reproductive isolation. There are two types of mechanisms that cause
reproductive isolation, prezygotic and postzygotic mechanisms. It is a common misconception that reproductive isolation
always refers to physical barriers. Data can be used to defend or challenge concepts such as this. An example of the
importance of the justification of date is with reproductive isolation and speciation in primates, which underwent these
processes over millions of years. When studying these animals, it is important to select data that considers the amount of
time, rather than data that is limited to a short amount of time.
MC Question: Which of the following would provide data favorable for the study of reproductive isolation and speciation
of closely related species?
A) Multiple species under the same order that live in different biomes
B) A population of a species that was recently separated by the construction of a highway
C) Multiple species under the same genus that live in an isolated group of islands
D) A population of a species that has been observed to have lower birth rates for a number of years
FRQ Question: Explain why the data provided by the beaks of Darwin’s finches is significant and helpful
to the study of the reproductive isolation and speciation of these birds (see following figure). Identify
the possible reproductive barrier mechanism that caused the isolation. Discuss how genetic testing
could possibly provide more reliable data.
Answer Key LO 1.23
Which of the following would provide data favorable for the study of reproductive
isolation and speciation of closely related species?
A) Multiple species under the same order that live in different biomes
B) A population of a species that was recently separated by the construction of a
highway
C) Multiple species under the same genus that live in an isolated group of
islands
D) A population of a species that has been observed to have lower birth rates for a
number of years
Explain why the data provided by the beaks of Darwin’s finches is significant and helpful
to the study of the reproductive isolation and speciation of these birds (see following
figure). Identify a possible reproductive barrier mechanism related to the speciation.
Discuss how genetic testing could possibly provide more reliable data.
The data provided by the beaks of the finches provides insight to the diets of the birds.
This allows us to understand what could have caused reproductive isolation in this case.
The varied diets suggest that the birds were geographically isolated into different
habitats, causing different diets and mutations to arise. This can be seen in the beaks of
the birds. This is a form of prezygotic isolation, and it led to the speciation of the birds.
Genetic testing would provide more exact data pertaining to exactly where and when
species branched off from one another.
LO 2.37: The student is able to connect concepts that describe mechanisms that regulate the timing and
coordination of physiological events.
SP 7.2: The student can connect concepts in and across domain(s) to generalize or extrapolate in and/or across
enduring understandings and/or big ideas.
Explanation: Many biological process involved in growth and reproduction and homeostasis include temporal regulation and coordination.
Timing and regulation of physiological evens are regulated by multiple mechanisms. In animals, internal and external signals regulate a variety of
physiological responses that synchronize with environmental cycles and cues. An example of a physiological response is the Fight-or-Flight
response that is regulated by the adrenal gland. In plants, environmental stimuli and internal molecular signaling are involved with the regulation
of physiological events. An example of a physiological response in plants is phototropism. Phototropism is the plants movement in response to
light (A plants stem tilted toward the light source). Growth hormones cause the stem to tilt, so now the leaves are closer to the light source and
aligned to intercept the most light. Behaviors in both animals and plants are triggered by external stimuli and environmental cures and are vital
to reproduction, natural selection and survival.
M.C. Question: Suppose there is a phoenix roebelenii (miniature palm) in the
lobby of a hotel. This lobby is very well lighted and stays lit all night. An
employee alerts the hotel management that they need to remove the plant
from the lobby. He wants them to move the tree because
A) It will stimulate the stomata to release an excess carbon-dioxide and
oxygen
B) Phototropism will occur, causing the tree to bend towards the light source
C) will interfere with the photosynthetic rate causing the tree to grow to
rapidly and die
D) Alter the photoperiod of the plant resulting in a disruption of its natural
growth cycle
Learning Log/FRQ-style Question: Name two plant physiological responses.
Explain each.
Answer Key- LO 2.37
Suppose there is a phoenix roebelenii (miniature palm) in the lobby of a hotel. This lobby is very well lighted and stays lit
all night. An employee alerts the hotel management that they need to remove the plant from the lobby. He wants them
to move the tree because
A)
B)
C)
D)
It will stimulate the stomata to release an excess carbon-dioxide and oxygen
Phototropism will occur, causing the tree to bend towards the light source
will interfere with the photosynthetic rate causing the tree to grow to rapidly and die
Alter the photoperiod of the plant resulting in a disruption of its natural growth cycle
Name two plant physiological responses. Explain each.
- One plant response to light is de-etiolation or the browning or the “greening” of dark-grown potatoes. Here, sunlight is
the signal that is received by a phytochrome and it induces a signal transduction pathway as well as causing the influx of
Calcium (Ca2+) ions to initiate a 2nd signal transaction pathway. Both pathways lead to transcription of specific genes and
translation of the specific de-etiolation proteins. A plant’s physiological response to the length of day and night is
photoperiodism. One important response to its photoperiod in some plants is flowering. In these plants, flowering is
controlled by the overall length of day and night. Plants are split into two types, long night plants and short night plants.
Each one requires a specific amount of darkness to function properly. Because phytochromes are sensitive to either red or
far red light, a flash of either during the critical period could disrupt the system. The only flash of light that matters is
whatever color is used last.
LO 3.34 : The student is able to construct explanations of cell communication through cell-to-cell direct contact or through chemical
signaling.
SP 6.2: The student can construct explanations of phenomena based on evidence produced through scientific practices.
Explanation: Cells communicate through the use of chemicals, hormones or neurotransmitters for example, and with this communication
are able to produce a response that benefits the organism. With the binding of receptors, such as testosterone and insulin, receptors
inside the cell or in the membrane of the cell cause a transduction pathway that activates relay proteins to cause a cellular response.
Intracellular receptors reside within a cell and only respond to ligands that are able to pass through the membrane, for example
hormones. Intracellular receptors bind to transcription factors and induce transcription and translation to occur producing a
response. Ligands that are unable to enter the cell, rely on membrane-bound receptors to cause a response. Most common receptors
are G-Protein receptors, tyrosine kinases, and ion gated channels. These receptors phosphorylate proteins to cause a cellular
response. During transduction, second messengers may be used to induce a response, such as the use of IP3 to release calcium out of
the ER. Calcium can then act as a second messenger and activate relay proteins. In addition, scaffolding proteins may assist in cell
communication by activating various proteins at once. Cell communication also occurs through cell to cell direct contact, such as in
the case if neurons. Neurons release neurotransmitters into the synapse to be received by the next neuron. During cell
differentiation, early embryonic cells communicate as certain cells release chemicals to induce nearby cells to change their gene
expression.
M.C.Question: All of the following involve cell communication via membrane embedded proteins EXCEPT:
A) G-proteins
B) Testosterone
C) The formation of dimers
D) Sodium Ion Channels
FRQ-style Question: Describe, in detail, the communication of cells via a hydrophobic ligand and a potential response produced by the
ligand. Discuss the source cell, as well as the target cell.
Answer Key
All of the following involve cell communication via membrane embedded proteins EXCEPT:
A) G-Proteins
B) Testosterone
C) The formation of dimers
D) Sodium Ion Channels
Describe, in detail, the communication of cells via a hydrophobic ligand and a potential response produced by
the ligand. Discuss the source cell, as well as the target cell.
Communication between cells via a hydrophobic ligand could occur between testes cells and skin cells.
Testosterone, the hormone released by the testes, reaches the skin cell and acts as a ligand to an intracellular
receptor. Testosterone has the ability to enter the cell because of its similar properties with the lipids of the
membrane. The ligand binds to the active site of the intracellular receptor, causing the receptor to be
activated and enter the nucleus. In the nucleus, the receptor binds to a transcription factor, causing
transcription of DNA and translation of the mRNA strand. The synthesis of a protein may cause a response such
as hair growth to occur on the skin in response to the ligand testosterone.
LO 2.30: The student can create representations or models to describe nonspecific immune defenses in
plants and animals. (See SP 1.1,1.2)
SP 1.1: The student can create representations and models of natural or man-made phenomena and
systems in the domain.
SP 1.2: The student can describe representations and models of natural or man-made phenomena and
systems in the domain.
Explanation: Plants and animals have multiple, nonspecific immune responses. Nonspecific immune response is the first
and second line of defense when a foreign object tries to enter the body. The response will attack anything that it comes
in contact with. Parts of the nonspecific immune responses are: defense barriers, inflammatory response, and fevers. The
defense barriers in animals include skin, hair, and tears. Plants do not have specific defense systems like animals. Plant
possess nonspecific immune responses like macrophage, which are known as cell eaters. When a plant detects a part is
affected by infection, it triggers rapid localized programmed cell death, the microphage, to stop further infection.
M.C. Question: Leukocytes ingest pathogens and digest these pathogens
with the help of lysosomes. When studying lysosomes which type of
cell would probably provide the best opportunity?
A) Leaf cell of a plant
B) Phagocytic white blood cell
C) Bacterial cell
D) Nerve cell
Learning Log/FRQ-style Question: Animals come in contact with many pathogens, and rely on their nonspecific
Immune defenses to prevent the entry of pathogens in their bodies. A) List THREE common types of invaders that
require a systematic defense, and give examples of each. B) Explain how THREE types of nonspecific defenses
can prevent the entry of pathogens in animals.
ANSWER KEY- LO 2.30
Leukocytes ingest pathogens and digest these pathogens with the help of lysosomes. When studying
lysosomes which type of cell would probably provide the best opportunity?
A) Leaf cell of a plant
B)Phagocytic white blood cell
C) Bacterial cell
D)Nerve cell
Animals come in contact with many pathogens, and rely on their nonspecific immune defenses to prevent
the entry of pathogens in their bodies. A) List THREE common types of invaders that require a systematic
defense, and give examples of each. B) Explain how THREE types of nonspecific defenses can prevent the
entry of pathogens in animals.
A)Animals must defend themselves from invaders, five common types of attack that require a
systematic defense are virus, bacteria, fungi, protists, and cancers. A virus, bacteria, fungi, and protists
all attack from outside the body, and cancers attack from inside the body. An example of a virus includes
HIV, measles, and chicken pox. An example of a bacteria includes meningitis and tuberculosis. An
example of a fungus would be yeast. An example of a protists would be an amoeba.
B)The skin is one of the most important nonspecific defense against pathogens, because the skin is thick
and is covered by a layer of dead cells. The skin is dry, waterproof, and is resistant to bacteria. For
pathogens to enter the body it must make its way through the skin. Also a variety of secretions also keep
pathogens from entering. Antibacterial agents in the saliva, mucous in the sinuses, inner lining of the
body, and the acid in the stomach all work to fight away pathogens before they affect the body. Another
type of nonspecific defense is the macrophages, which ingest and digest pathogens from the
bloodstream.
Learning objective 4.3 The student is able to use models to predict and justify that changes in the subcomponents of a biological polymer
affect the functionality of the molecule.
Science Practice 3: The student can engage in scientific questioning to extend thinking or to guide investigations within the context of the AP
It is crucial to understand that the changes in the parts that make up thecourse.
polymers (large molecules) change the molecule as a whole by changing
that molecule’s properties. AP Biology students must be able to think critically about the interactions between the monomers of the polymer
and how a change in those specific monomers to other specific monomers will directly impact the shape, size and functionality of the
molecule. For example, by changing one amino acid in a large protein, the primary structure, the secondary, tertiary, and quaternary
structures will be affected because the properties of the R group in the single amino acid will change the intermolecular forces such as
hydrogen bonds, ionic bonds, disulfide bridges, and hydrophobic interactions of all levels of organization. Disruptions in these forces change
the shape of the protein, such as in Hemoglobin. When Glutamic acid is replaced with Valine, the function of Hemoglobin is rendered
incapable of function.
Multiple Choice Question:
Dimethyl sulfoxide reductase is a protein found embedded in the cellular membrane of bacteria.
It is able transport menaquinol from the inner membrane space to the outside of the cell where
it is reduced with dimethyl sulfite and water. A certain bacteria is found to have replaced the
intermembrane portion of the protein with different amino acids in its tertiary structure. How
might this affect the function of the molecule?
A) The protein will no longer be enabled to be embedded
C) The protein will be denatured
B) The protein will no longer be able to interact with menaquinol D) All of the above
Free Response Question:
Compare the structure and function of blood cells with Sickle Cell Disease with
normal red blood cell. Describe the differences between their primary, secondary,
tertiary and quaternary structures and how each level of organization impacts the next and
how the shape of the protein a changes its function.
Multiple Choice Answer:
Dimethyl sulfoxide reductase is a protein found embedded in the cellular membrane of bacteria. It is able transport menaquinol from the inner membrane space
to the outside of the cell where it is reduced with dimethyl sulfite and water. A certain bacteria is found to have replaced the intermembrane portion of
the protein with different amino acids in its tertiary structure. How might this affect the function of the molecule?
A) The protein will no longer be enabled to be embedded C) The protein will be denatured
B) The protein will no longer be able to interact with menaquinol D) All of the above
Free Response answer:
Compare the structure and function of blood cells with Sickle Cell Disease with normal red blood cell hemoglobin. Describe the differences between their primary, secondary,
tertiary and quaternary structures and how each level of organization impacts the next and how the shape of the protein a changes its function.
The function of the Hemoglobin molecule is to carry O2 on the surface of the Red Blood Cell. It has a Quaternary structure with four subunits, two alpha and two
beta. The difference in their primary structure is one single amino acid. The replacement of of Glutamic acid with Valium causes the secondary and
tertiary structures to fold differently because of the intermolecular interactions. In the case of sickle cell, this leaves a hydrophobic region of the protein
exposed to the environment, changing its shape drastically. This impacts the function of the hemoglobin molecule by causing them to interact with one
another to crystallize to form a fiber as well as having a huge reduction in the ability to carry oxygen. In normal hemoglobin, the molecules do not
associate with one another, keeping oxygen capacity high.
LO 1.26 The student is able to evaluate given data sets that illustrate evolution as an ongoing process.
SP 5.3 The student can evaluate the evidence provided by data sets in relation to a particular scientific question.
Explanation: There are several examples that prove evolution and natural selection is still happening today. Homologous
structures are one example of this concept, which are similar structures with different functions. A human arm and a cats leg are
examples of this as they share similar skeletal makeup but have different functions. Biogeography or the geographic distribution
of species is another example of evolution today. Similar species seem to be found in the same area as discovered by Charles
Darwin. The most tactile evidence of evolution are fossils. With fossils we can physically compare the skeletons of animals from
millions of years ago. In some cases we can get a DNA sample that provides comparison on a molecular level. When scientists
look at gene sequences they can compare them with other animals. Scientists can use a database called BLAST where they can
compare the sequence differences with past animals too. Once they hypothesize evolutionary relationships, systematists use
phylogenetic trees or cladograms too map these predictions. These maps depict how closely reflated species are and their
common ancestors.
M.C. Question: Which of the following is NOT an example of evolution still happening today
a. Biogeography
b. Natural selection
c. Analogous structures
d. Homologous structures
Learning Log/FRQ-Style Question:
Using the diagram below, determine how
the animals should be arranged on a cladogram.
What was your reasoning behind your arrangement?
Answer Key-LO 1.26
Which of the following is NOT an example of evolution still happening today:
a. Biogeography
b. Natural selection
c. Analogous structures
d. Homologous structures
Using the diagram below, determine how the animals should be arranged on
a cladogram. What was your reasoning behind your arrangement?
The Lancelet is most different from the
Leopard so they will be on extreme
opposites of the cladogram. We know
this because they do not have a
character trait present based off the
table. The leopard on the other hand
has every trait present. From there the
table works like stairs. The lamprey has
the second most absent traits and so
on and so forth.
LO 1.25: The student is able to describe a model that represents evolution within a population.
SP 1.2: The student can describe representations and models of natural or man-made
phenomena and systems in the domain.
Explanation: Scientific evidence supports the claim that evolution has occurred in all species, and continues to occur. This
continuous evolution occurs as the result of many various environmental factors and occurs in many different ways. For
example, chemical resistance in viruses models continuous evolution in the population. As a response to antibiotics, the
genome of the virus experiences changes through mutations to resist the antibiotics. The constant transformation of viruses
in response to antibiotics results in emergent diseases. Evolution within populations is further evident by observation of
phenotypic change in a population. For example, Darwin’s study of Galapagos Finches displays directional phenotypic
change within a population. The population of finches experienced varying mutations and in response to the demands on
the surrounding environment of individual birds, some mutations allowed the birds to become more “fit” to their
environment. The “fittest” finches were able to survive in their environments and produce viable offspring. The
environment constantly shapes organisms. Limbs and various structures of the eukaryotic organisms evolve in the same way
that organisms evolve. Hox genes adapt and genetic variation remains within the population.
M.C Question: Which of the following
represents an example of evolution within a
population?
A) There are more dark grey moths in a
population that was originally dominated by
brown moths in the years following a forest
fire.
B) A baby blue bird is born with one shortened
wing and survives to produce offspring.
C) The grass in your neighbor’s lawn appears to
grow greener following a rain shower.
D) The number of a certain species of bears
decreases following the extinction of the
trout that they prey on.
Learning Log/FRQ Style Question: Describe in detail why there might
be a new vaccine for the flu every season.
Answer Key
M.C Question: Which of the
following represents an
example of evolution within a
population?
A) There are more dark grey moths in
a population that was originally
dominated by brown moths in the
years following a forest fire.
B) A baby blue bird is born with one
shortened wing and survives to
produce offspring.
C) The grass in your neighbor’s lawn
appears to grow greener following a
rain shower.
D) The number of a certain species of
bears decreases following the
extinction of the trout that they prey
on.
Describe in detail why
there might be a new
vaccine for the flu
every season.
The flu appears every year and is sometimes deadly.
In an effort to prevent the acquirement of the flu,
many people get the “flu shot” every year. There
must be a new vaccine every year to account for the
new strains of the influenza that arise yearly. The
influenza virus experiences mutations, as any
population does, but the mutations of the influenza
virus sometimes creates a resistance to the
antibodies created by the body after being exposed
to the deadened version of influenza that is in a
vaccine. The mutated viruses are then “fit” for their
environment and survive to reproduce, usually
rapidly, thousands of viable offspring. As this happens
many different times in a single flu season, medical
technology is currently unable to keep up with the
many new strains of influenza that arise. That is why
there is a new flu vaccine yearly.
LO 3.10: The student able to represent the connection between meiosis and increased genetic diversity
necessary for evolution.
SP 7.1: The student can connect phenomena and models across spatial and temporal scales.
Explanation: Meiosis is important for evolution to occur. Unlike mitosis, in which a cell creates a copy of itself,
meiosis creates 4 daughter cells with the half the chromosomes of the parent cells. The genetic material of
the daughter cells differ slightly from the parent cell. The daughter cells are used in sexual reproduction. The
genetic diversity in meiosis is caused by crossing over, independent assortment of chromosomes, and
random fertilization. The genetic variation created by meiosis is necessary for evolution as it allows for
organisms to have new traits and mutations. This new mutations can help the organism to better survive its
environment. Without genetic variation in meiosis, mutations could not occur and evolution would also
never occur.
M.C. Question: Which in is not a way that meiosis creates genetic variation?
A) Independent assortment of chromosomes
B) Crossing over
C) Alteration of generations
D) Random fertilization
Learning Log/FRQ: Explain how meiosis is carried out. Also,
list and describe two ways meiosis creates genetic variation.
Answer Key LO 3.10
Which in is not a way that meiosis creates genetic variation?
A)
B)
C)
D)
Independent assortment of chromosomes
Crossing over
Alteration of generations
Random fertilization
Explain how meiosis is carried out. Also, list and describe two ways meiosis creates genetic variation.
Meiosis begins in interphase where the chromosomes are replicated. Then in prophase I, the homologous
chromosomes pair with one another and form a tetrad. In metaphase I, the homologous chromosomes line up
in the center of cell and the chromosomes are attached to a microtubule. In anaphase I, the pairs of
homologous chromosomes are split apart by the microtubules which pull the chromosomes to the poles of the
cells. Then in telophase I and cytokinesis, a cleavage furrow forms and the cell becomes two cells. That
completes the first round of cell division. In prophase II, in each cell, the chromosomes move toward the
metaphase II plates. Then, in metaphase II, the chromosomes are lined up in the center of the cell and are
sister chromatids are split apart in anaphase II. Finally, in telophase II, the two cells split apart again, creating a
total of 4 daughter cells. Genetic variation in meiosis is cause by crossing over and independent assortment.
Crossing over begins in prophase I when the homologous chromosomes get together. The DNA molecules of
the two nonsister chromatids switch between the chromosomes causing the chromosomes to be different. In
independent assortment, at metaphase I, the homologous chromosomes line up randomly. There is not a
particular order that the pairs have to line up in so there are a variety of different ways that the pairs of
chromosomes could line up in. This cause genetic diversity as the chromosomes can be split up into different
parts and that means the resulting cells could be very different results.
LO 3.16: The student is able to explain how the inheritance patterns of many traits
cannot be accounted for by Mendelian genetics.
SP 6.3: The student can articulate the reasons that scientific explanations and theories are
refined or replaced
Explanation: There are several traits which are passed using rules others than Mendel’s laws of inheritance. For instance
codominance and intermediate expression go against his law of dominance as neither display strictly dominant or recessive
traits but also a third mixed trait. Also epigenetic, sex-linked, and mitochondrial traits are passed down in ways that are
outside of the rules of “regular genetics.” Caused by different processes each type undergoes, for example epigenetics is
methylation or deactivation of genes on certain parts of a chromosome, such things are hard to predict and can be passed
down to offspring. Sex chromosomes have a unique inheritance pattern in that males can only ever be hemizygous for X and
contain the two options for chromosomes which decide sex and many diseases that can be passed down depending on
which parent it is from. While mitochondrial DNA is passed down only maternally. It can be seen that a gene is transmitted
irregularly by determining if the actual offspring ration and the expected outcomes are different
M.C. worried about genetic illness a man goes to genetic counseling,
in which they tell him his father and only uncle and aunt had the
same disease, also his grandmother had the same disease, yet his
DNA in entirely normal. Based on this information which type of
genetic disease is most likely in the mans pedigree?
A: Autosomal recessive C: Mitochondrial
B: Sex-Linked
D: Viral infection
FRQ: In Snapdragon plants homozygous dominant flowers (AA)
are red, while homozygous recessive flowers (aa) are white, but when
crossed produce pink heterozygous flowers. Explain why this is and
how it deviates from Mendelian genetics. Then describe two more
inheritance mechanisms that don’t follow Mendelian norms.
Answer key
•
M.C. worried about genetic illness a man goes to genetic counseling,
in which they tell him his father and only uncle and aunt had the same disease,
also his grandmother had the same disease, yet his DNA in entirely
normal. Based on this information which type of genetic disease is
most likely in the mans pedigree?
A: Autosomal recessive
C: Mitochondrial
B: Sex-Linked
D: Viral infection
•
FRQ: In Snapdragon plants homozygous dominant flowers (AA)
are red, while homozygous recessive flowers (aa) are white, but when
crossed produce pink heterozygous flowers. Explain why this is and
how it deviates from Mendelian genetics. Then describe two more
inheritance mechanisms that don’t follow Mendelian norms.
•
The Snap dragons are displaying incomplete dominance, as both phenotypes are being
expressed to the point that they form a color that is a mix of the two. Mendel’s first law
dictates that there is a dominant allele and a recessive one, and the dominant one will
display over the recessive one, yet in this case the dominant allele has not entirely
overpowered the recessive allele. Where as two other possible deviant inheritance patterns
include how mitochondrial DNA can only be inherited from the maternal gamete making any
diseases associated with it easier to trace. Also its possible to inherit the way some pieces of
DNA are suppressed, or methylated, known as epigenetics, these heritable changes are not
caused by alteration to the DNA sequence but by the expression of the same sequence.