AP Biology 2023 - FRQ Question 2 SOLVED!
Summary
TLDRMr. Chippen, an AP Biology teacher, discusses Question 2 from the 2023 AP Bio exam, focusing on the impact of elevated CO2 levels on plant mitochondria. He guides viewers through the process of graphing data, analyzing species differences, and understanding the relationship between CO2 levels and mitochondrial count. He also addresses a hypothetical plant cross involving a mutation affecting chloroplasts and predicts offspring phenotype based on maternal mitochondrial inheritance. The video aims to help students understand the exam question and encourages subscription for more AP Bio content.
Takeaways
- πΏ The video discusses question number two from the 2023 AP Biology exam, focusing on the effects of elevated CO2 levels on plant cells.
- π± Scientists have observed that increased CO2 levels lead to more chloroplasts per cell in plants, and a study was conducted to see if a similar effect occurs with mitochondria.
- π The video provides a step-by-step guide on how to graph the data from the study, emphasizing the importance of labeling and error bars.
- π¬ Part A of the question asks to describe the role of the mitochondrial membrane in cellular respiration, particularly the electron transport chain and ATP production.
- π For Part B, the video explains how to construct a graph to represent the data, identifying the independent and dependent variables, and how to interpret the results.
- πΏ Part C asks to describe the relationship between CO2 levels and the number of mitochondria, with the video suggesting a direct relationship.
- π± Part D involves a genetics scenario where plants with white-striped leaves are crossed with green-leaf plants, and the video predicts the offspring's phenotype based on mitochondrial inheritance.
- 𧬠The video explains the concept of phenotypic plasticity, where environmental factors like CO2 levels can influence the structure and number of organelles in plants.
- π The video concludes by encouraging viewers to ask questions and subscribe for more AP Biology content, including answers to further exam questions.
- π¨βπ« Mr. Chippen, the AP Biology teacher, provides educational content to help students understand complex biological concepts and exam questions.
Q & A
What is the main topic of the video script?
-The main topic of the video script is the analysis of question number two from the 2023 AP Biology exam free response questions (FRQs), focusing on the effects of elevated CO2 levels on the number of chloroplasts and mitochondria in plant cells.
What is the role of the mitochondrial membrane in cellular respiration?
-The inner mitochondrial membrane is the site of the electron transport chain, which builds a proton gradient using electron carriers to power proton pumps. This gradient is then used by ATP synthase to create ATP.
What is the purpose of constructing a graph for the data in table one?
-The purpose of constructing a graph is to visually represent the data and determine which species show a difference in the number of mitochondria between normal and elevated levels of CO2.
What type of graph is suggested for representing the data in the video script?
-A bar graph is suggested for representing the data, with each species having two bars representing normal and elevated CO2 levels.
How should the y-axis of the graph be labeled according to the video script?
-The y-axis should be labeled with the number of mitochondria per 100 micrometer squared cell area, ensuring it is appropriately labeled for clarity.
What is the significance of error bars in the context of the graph?
-Error bars indicate the variability or uncertainty in the data. In the context of the graph, non-overlapping error bars suggest a significant difference between the number of mitochondria at normal and elevated CO2 levels for a given species.
According to the video script, what is the relationship between the level of CO2 and the average number of mitochondria per cell area?
-The relationship is directly proportional, meaning that an increase in CO2 levels leads to an increase in the number of mitochondria per cell area.
What is the significance of the white-striped leaves in the plant species mentioned in the script?
-The white-striped leaves result from a mutation in the mitochondrial DNA that interferes with the development of chloroplasts, affecting the plant's phenotype.
How does the inheritance of mitochondria affect the prediction of leaf phenotype in the offspring of the cross mentioned in the script?
-Since mitochondria are maternally inherited, and the ovules come from a plant with green leaves, all offspring are predicted to have green leaves due to the normal mitochondrial DNA inherited from the maternal plant.
What concept is used to explain why plants with the same genotype can differ in response to changes in atmospheric CO2 levels?
-Phenotypic plasticity is the concept used to explain how environmental factors, such as CO2 levels, can influence the phenotype of an organism with the same genotype.
What is the potential mechanism by which mitochondria respond to changes in CO2 levels according to the script?
-The script suggests that a cell signaling mechanism or the independent replication capacity of mitochondria could be responsible for their response to changes in CO2 levels.
Outlines
πΏ AP Bio Exam FRQ Analysis
Mr. Chippen, an AP Biology teacher, introduces the second question from the 2023 AP Bio exam, focusing on the impact of elevated CO2 levels on plant growth and photosynthesis. He discusses how increased CO2 leads to more chloroplasts per cell in various plant species. To explore the effect on mitochondria, six species were selected for a study comparing mitochondria count under normal and elevated CO2 conditions. A table with data is provided, and Mr. Chippen guides viewers on how to graph this data, emphasizing the importance of understanding the independent and dependent variables, and the creation of a bar graph to represent the data. He explains how to interpret the graph to determine if there's a significant difference in mitochondria count between normal and elevated CO2 conditions, noting that non-overlapping error bars indicate a difference.
π Graphing and Analyzing Mitochondria Data
Continuing the discussion on the AP Bio exam question, Mr. Chippen elaborates on how to graph the data from the table, suggesting a y-axis range from zero to three to accommodate the data points and error bars. He advises labeling the graph appropriately, including a legend to distinguish between normal and elevated CO2 conditions. He then analyzes the data, explaining that all six species show a significant difference in mitochondria count when exposed to elevated CO2 levels, as indicated by non-overlapping error bars. Mr. Chippen also covers parts C and D of the question, discussing the direct relationship between CO2 levels and mitochondria count, and predicting the phenotype of offspring from a cross between plants with green leaves and those with white-striped leaves, based on the maternal inheritance of mitochondria. He concludes by touching on phenotypic plasticity and how environmental factors like CO2 can influence the structure and number of organelles in plants.
Mindmap
Keywords
π‘AP Biology
π‘Photosynthesis
π‘Chloroplasts
π‘Mitochondria
π‘Cellular Respiration
π‘Electron Transport Chain
π‘ATP Synthase
π‘Graph
π‘Phenotypic Plasticity
π‘Mitochondrial DNA
π‘Maternal Inheritance
Highlights
Mr. Chippen introduces himself as an AP Biology teacher at Murray High School in Murray, Kentucky.
He discusses question number two from the 2023 AP Bio exam free response questions (FRQs).
Elevated levels of CO2 increase the rate of photosynthesis and growth in plants.
Scientists found an increase in the number of chloroplasts per cell when exposed to elevated CO2 levels.
A study was conducted to investigate the effect of elevated CO2 on the number of mitochondria in plant cells.
Six species were selected to quantify mitochondria numbers under normal and elevated CO2 levels.
A table with data on mitochondria numbers is presented for graphing in the exam.
Part A of the question asks to describe the role of the mitochondrial membrane in cellular respiration.
The inner mitochondrial membrane is the site of the electron transport chain, which builds a proton gradient for ATP production.
Part B requires constructing a labeled graph to represent the data in table one.
The graph should show the difference in the number of mitochondria between normal and elevated CO2 levels for each species.
A bar graph is suggested for representing species data with two bars for each representing normal and elevated CO2 levels.
Part C asks to describe the relationship between CO2 levels and the average number of mitochondria per cell area.
A direct relationship is observed where increased CO2 levels lead to an increase in mitochondria numbers.
Part D involves predicting the phenotype of offspring from a cross between plants with green leaves and white-striped leaves due to a mitochondrial DNA mutation.
The prediction is that all offspring will have green leaves as mitochondria are maternally inherited.
An explanation for phenotypic differences in organelle structure or number due to CO2 levels involves phenotypic plasticity and cell signaling mechanisms.
Mr. Chippen provides a walkthrough of the thought process for answering the exam question, aiming to help students understand the material.
He concludes by encouraging students to ask questions in the comments and to subscribe for more AP Bio material.
Transcripts
hello my name is Mr chippen I am the AP
biology teacher at Murray High School in
Murray Kentucky and this is question
number two of the 2023 AP Bio exam frqs
and I have here in front of us the
question number two I'll read the
question carefully or quickly and then
go through the different responses for
it elevated levels of CO2 increase the
rate of photosynthesis and growth in
Plants scientists studying the
mechanisms involved in these increases
examined a variety of species and found
that when plants are exposed to elevated
levels of CO2 there's an increase in the
number of chloroplasts per cell to
investigate whether elevated levels of
CO2 have a similar effect on the number
of mitochondrial and plant cells the
science then selected six of these
species to quantify
quantify the number of mitochondria per
cell when cells were exposed to normal
and elevated levels of CO2
and then here's your table
and this is the second question of the
frq and so you know we're going to be
expected to graph this
and so let's look at these together
first of all let's just get an idea of
the table this is I'm just kind of
walking you through the process that I
would take if I was taking this exam and
I see the numbers are anywhere from
looks like 0.3 being the lowest
and
2.2.4 being the highest maybe and notice
the error bars are pretty small
pretty small increments
um and so what I'm going to do is I'm
probably going to make this go from zero
to three
on my graph let's get there first
so part A describe the role of the
intermittent mitochondrial membrane
cellular respiration the inner membrane
is the site of the electron transport
chain you could probably also and so it
says describe the row so it's asking for
a little bit more than that and so it's
the site of electron transport chain and
the purpose of the electron transport
chain is to build a proton gradient
using electron carriers that are going
to power proton pumps to build that
gradient in the inner membrane space and
then the ATP synthase will use that
proton gradient in order to create ATP
don't need the prompt to do that so Part
B
using the template provided for your
response construct an appropriately
labeled graph represents the data in
table one determine the species which
species show a difference in the number
of mitochondria between normal and
elevated levels okay so
in the frq answers that are the actual
responses that they our response is the
questions that they give on the website
they don't provide a template for us and
so I don't have the same graph that they
provided for us and so I'll just walk
you through kind of my graphing process
first of all what is my independent
dependent variables so what's being
measured is the number of mitochondria
at two different levels right and so
that's going to be on my y-axis the
number of mitochondria and it's going to
be based on species and so this is going
to be my x-axis and this is going to be
a bar graph because
this is just species right there's no
there's no tracking there's no numbers
and so this is going to be a bar graph
and each species is going to have two
bars one that represents normal and
another that represents elevated and so
essentially
um six sets of bars or 12 different bars
in sets of two for each species so
you'll label species one two three four
five six along the bottom or around
along the x-axis and the y-axis are
going to be number uh mitochondria or
the number of mitochondria per 100
micrometer squared cell area and just
make sure you label that appropriately
and then you're going to also have to
provide some sort of Legend so that they
understand that you have a normal bar
and an elevated CO2 bar
and you know correctly level your air
bars and such but I would start the
graph at zero on the y-axis and then
move up to three and then appropriately
space out my spaces in there and then
probably leave some definitely leave
some space at the top so that you can
put your top error bars but even so if
you leave it at three so this is 2.4 and
it's going to be 0.2 so it's going to
get up to like point six two so
shouldn't be much of a problem and the
second part of this
determine which species show difference
and so I went ahead and looked at this
ahead of time and what you're looking
for in this question is if any of the
error bars overlap and so do any of the
species show a difference and if they
don't overlap then yes there is a
difference if they do overlap then
there's no statistical
significant difference between the two
and none of the species have overlapping
air bars and so the correct answer for
this is that all six species show a
significant difference
part C based on the data
in table one describe the relationship
between the level of CO2 and the average
number of mitochondria
per area of the cell
well the level of CO2 so when you have
elevated CO2 you have across the board
you have an increase in the number of
mitochondria and so you can says
describe the relationship you can say
that the two are directly related
because there's a direct relationship
because when the amount of CO2 goes up
the amount of mitochondria also go up
simple
uh Part D
the leaves of a particular plant species
are typically green but scientists
noticed in leaves a plant in which
leaves have a white stripes they
determine the stripes result from
mutation the mitochondrial DNA that's
important
that interferes with the development of
chloroplasts the scientists cross plants
using the pollen from a plant with white
striped plants
and ovules from a plant with green
leaves okay so this is important you
have to know these two terms pollen
ovules pollinates from the male plant
and obvious from the female plant it's
not something that I teach in my class
but hopefully just looking at the
prefixes ovule being a female
and the mitochondria has to do with
passing from the female organ
or the female cell so predict the
phenotype of the leaves of The Offspring
of the Cross and so since the ovules
come from
a plant with green leaves
and the mitochondrial DNA is what
affects this then I'm going to say that
I'm going to predict that all the plants
are going to have green leaves what is
my justification my justification is
that mitochondria are maternally
inherited and because the maternal
mitochondria have normal mitochondria
then all the offspring are going to
inherit those normal mitochondria and
have a normal phenotype
that's my justification
explain why plants with the same
genotype are able to are able to differ
in the structure and or number of
certain organelles in response to
changes in atmospheric levels of CO2
this would be simple right we we talked
about phenotypic plasticity in class and
we talked about the idea that
environmental factors can influence
phenotype and so you could say for your
explanation you could mention phenotypic
plasticity or you could just say that
environment can affect phenotype how
does that work part of your explanation
should be that it could be a cell
signaling mechanism that the cell once
it receives a certain amount of CO2 will
create more mitochondria or you could
even mention that the mitochondria
independently respond to the amount of
CO2 since mitochondria are able to
replicate independent of the rest of the
cell hopefully this was helpful this was
a big question uh typically the graph is
going to give you one two three four
points it'll be three for the construct
part one for the determined so four five
six seven eight nine points for this one
is what I am seeing
hopefully you got all nine points
um if you have questions please ask Down
Below in the comments would really
appreciate if you would subscribe to my
channel I will be making more AP Bio
material in the future and I will also
be releasing the answers to questions
three through six in the very near
future thank you for watching
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