AP Biology 2023 - FRQ Question 2 SOLVED!

Summary

Mr. 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

• 🌿 The video discusses question number two from the 2023 AP Biology exam, focusing on the effects of elevated CO2 levels on plant cells.
• 🌱 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.
• 📊 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.
• 🔬 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.
• 📈 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.
• 🌿 Part C asks to describe the relationship between CO2 levels and the number of mitochondria, with the video suggesting a direct relationship.
• 🌱 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.
• 🧬 The video explains the concept of phenotypic plasticity, where environmental factors like CO2 levels can influence the structure and number of organelles in plants.
• 📝 The video concludes by encouraging viewers to ask questions and subscribe for more AP Biology content, including answers to further exam questions.
• 👨‍🏫 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

00:00

🌿 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.

05:03

📊 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.

Keywords

💡AP Biology

AP Biology refers to the Advanced Placement Biology course and exam, which is a college-level curriculum offered to high school students. In the video, Mr. Chippen, an AP Biology teacher, is discussing a specific question from the 2023 AP Bio exam, indicating the educational context and the high level of academic rigor expected of students.

💡Photosynthesis

Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods with carbon dioxide and water. The video script mentions that elevated levels of CO2 increase the rate of photosynthesis, highlighting the fundamental biological process and its sensitivity to environmental conditions.

💡Chloroplasts

Chloroplasts are organelles found in plant cells and are the site of photosynthesis. The script discusses an increase in the number of chloroplasts per cell when plants are exposed to elevated levels of CO2, showing the direct impact of environmental factors on cellular structures.

💡Mitochondria

Mitochondria are known as the 'powerhouses' of the cell, generating ATP through cellular respiration. The video script investigates the effect of CO2 levels on the number of mitochondria per cell, emphasizing the interconnectedness of cellular processes and environmental factors.

💡Cellular Respiration

Cellular respiration is the process by which cells convert nutrients into energy. The script describes the role of the mitochondrial membrane in this process, particularly the electron transport chain and ATP production, underlining the importance of mitochondria in energy metabolism.

💡Electron Transport Chain

The electron transport chain is a series of protein complexes that transfer electrons in a stepwise manner, creating a proton gradient to produce ATP. The script explains its role in the inner mitochondrial membrane, illustrating a key component of cellular energy production.

💡ATP Synthase

ATP synthase is an enzyme that catalyzes the synthesis of ATP from ADP and inorganic phosphate. The script mentions its use of the proton gradient to create ATP, demonstrating the final step in the energy production process within mitochondria.

💡Graph

A graph is a visual representation of data, used to analyze and compare information. The script instructs on constructing a graph to represent the data in table one, showing the importance of data visualization in scientific analysis.

💡Phenotypic Plasticity

Phenotypic plasticity refers to the ability of an organism to change its phenotype in response to variations in the environment. The script discusses how environmental factors like CO2 levels can affect the structure and number of organelles, illustrating the concept of phenotypic plasticity.

💡Mitochondrial DNA

Mitochondrial DNA is the genetic material found within mitochondria, separate from the DNA in the cell nucleus. The script mentions a mutation in mitochondrial DNA affecting chloroplast development, highlighting the role of mtDNA in cellular function and inheritance.

💡Maternal Inheritance

Maternal inheritance refers to the transmission of genetic material from mother to offspring. The script predicts the phenotype of offspring based on the inheritance of mitochondrial DNA from the mother, demonstrating a fundamental principle of genetics.

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