CHRIS MONSOUR: Good morning, good afternoon, good evening,
AP Bio.
This is Mr. Monsour coming to you
from Tiffin Columbian High School
in beautiful Tiffin, Ohio.
And welcome to AP Daily Review.
I'm so glad to be back to see you
as we work our way through these next four videos,
getting you ready for your exam in May.
So we're just going to jump right ahead
into some multiple choice.
So the point of this section here
is to kind of get you ready for multiple choice.
So there's going be a set of questions.
Be sure to check out the PDF that's linked to the video
if you want to follow along.
I'm going to read these questions to you.
If you don't want to hear me, you can mute me
or you can follow along.
But this is-- I got your 15, so we're going to move.
So let's start with our first multiple choice.
Researchers investigating the regulation of neurotransmitter
release from presynaptic neurons proposed a model in figure 1,
there's the model, in which CDK5 a protein express
and axon terminals inhibits the movement of synaptic vesicles
to the presynaptic membrane.
To test their model, the researchers
used a modified version of green fluorescent protein,
GFP, which is that protein?
In slightly alkaline conditions, GFP
exhibits a bright green fluorescence.
So it just kind of lights up.
In acidic conditions, GFP exhibits no fluorescence.
Using standard techniques, the gene encoding GFP
is easily introduced in living cells.
By engineering the expression of GFP
in laboratory-cultured nerve cells,
the researchers found that a bright green fluorescence
was exhibited only when a presynaptic neuron was
given a certain stimulus.
That's a lot of reading, I know.
Just keep following along.
Here's our first question.
Which of the following observations
best supports the hypothesis that CDK5 negatively regulates
neurotransmitter release?
So when you're tackling, there's a lot of reading, I know.
So I'm going to go through, I kind of highlight it.
We're looking at expressed, which
means it's going to show up, inhibits, which means
it's going to decrease it.
So what I would tell you to do on your test,
I would mark up these pictures.
You paid for the test, right?
So mark them up.
So I circled that CDK5 there it's increasing.
When it's increasing, that blue arrow
shows that the synaptic vesicle is decreasing.
So mark up these models.
And so the question is negatively
regulates neurotransmitter release.
We're talking about a negative feedback.
I'm not going to do a whole lot of content here.
But again, you're looking for that relationship as one
increases, the other decreases.
So let's go to our question.
So again, there's your model already marked up for you.
Which of the following best observations best supports
the hypothesis that CDK5 negatively regulates
neurotransmitter release?
So again, we're looking at for that negative regulation.
I'm going to show you all the options first,
and then going to kind of read through them,
and we're going to kind of pick them apart.
So A, introduction of CDK5 protein into neurons
results in the movement of synaptic vesicles
to the plasma membrane in the absence of any stimulus.
Maybe think about that one.
B, uptake of a gene encoding CDK5
by neurons results in the movement of synaptic vesicles
in the plasma membrane in the absence of any stimulus, maybe.
C, suppression of CDK5 expression in neurons
inhibits the movement of synaptic vesicles
to the plasma membrane in response
to a specific stimulus, or D, inhibition
of CDK5 activity in neurons increases the movement
of synaptic vesicles to the plasma membrane in response
to a specific stimulus.
So pause the video, go through mark them up,
see which ones you think are correct.
But I'm going to kind of just keep
moving, so feel free to pause as you need to.
So we're looking for best supports hypothesis.
We're getting rid of A, introduction
into neurons results in movement.
It does not cause the movement.
If you go back to the arrows that you drew,
you can see that actually it's going to stop the movement.
So we're going get rid of that one.
B, uptake of gene encoding CDK5.
If you look at the model choice, there
was nothing about the gene encoding.
They're not going to give you information that they've not
provided necessarily.
So we're going to get rid of B.
C, suppression of CDK5 expression neurons
inhibits movement.
The suppression, no.
It's an opposite.
As the CDK5 increases, the suppression increases.
So it's a negative response.
This one is indicating that they are together,
so we're going to get rid of that one.
So if you picked D, give yourself
a round of applause, yay.
D is the best answer because it's telling you
that the inhibition of CDK5, if we flip those arrows
would increase the movement synaptic vesicles.
So again, it's not going to be straightforward.
You're going to have to think a little bit.
So that's why D is the best answer.
We're just going to keep moving.
Again, if I am speaking fast but I
want to try to give you as much information as I can.
Previous experiments indicate that CDK5 is active
only when attached to a protein called p35.
Which of the following best predicts
how p35 might play a role in regulating neuron function?
So again, you have your model.
And in this case, they're giving you
some more information in which the p35 will activate the CDK5.
And so they're working together.
So which one predicts how p35 might play a role
in regulating neuron function?
So again, we have our drawing over there.
I'm going to show you the option.
So we look at A, elevated intracellular levels
of p35 result in increased synaptic activity,
B, degradation of p35 results in increased synaptic activity,
C, reabsorption of p35 from the synaptic cleft
results in increased synaptic activity,
or D, attachment of p35 to synaptic vesicles
results in increased synaptic activity.
Again, you're looking at how they work together.
So CDK5 and p35 have to work together.
So again, there's our image.
There's a CDK5 increasing, the synaptic vessel would decrease.
So let's get rid of letter A because if we
have those elevated levels of p35
is not going to result in increase.
So we're going get rid of that one.
Let's go down to C, reabsorption of p35
from presynaptic and cause increases in synaptic activity.
Again, not correct.
Let's go to D. Again, it's not that the attachment of that p35
is not going to cause an increase in synaptic activity.
I say that four times fast.
The best answer is B, degradation or the breakdown
of that p35 results in increased synaptic activity
because that's what the model shows is.
So if you drew your arrows, you should be good on that one.
All right, we're going to move on to a different type
of question now.
And again, there is lots and lots of reading on these,
and I apologize.
So as you can see, there's our question.
I'll give you the question first.
Which of the following best explains
how biological communities near deep-sea hydrothermal vents
can exist in a habitat lacking sunlight?
Some of you may have been trained by your teachers
to read the question first.
That's fine, but I want to go up now and read the actual prompt.
The food web below represents feeding relationships
in a biological community near a deep-sea hydrothermal vent.
Hydrothermal vents are geysers on the seafloor that gush
superheated mineral-rich water.
The seawater surrounding hydrothermal vents
typically contain CO2, H2, hydrogen sulfide,
which is H2S, and methane, CH4.
Sunlight, this is important, however,
fails to reach the sea floor where
deep-sea hydrothermal vents are located.
As part of an investigation, researchers
collected living specimens from an area
near a deep-sea hydrothermal vent.
Mussels in the collection were found
to be dependent on molecular hydrogen in the seawater, which
is also important.
Also, the researchers discovered multiple species of bacteria
living in the gills of mussels.
Mussels use gills for filter-feeding and gas exchange
with the surrounding seawater.
On the basis of their experimental results,
looking at the experiment results,
the researchers hypothesized that some bacteria
living in the gills of mussels are capable of chemosynthesis.
If we look at our question, again, which of the following
best explains how these communities can exist?
So again, there's our focus.
We're focusing on the best explanation.
So let's go, again, pointing out to those in organics.
I just kind of underlined him again
for it just to kind of emphasize that point.
So let's go to the question number three.
Which of the following best explains
how biological communities near deep-sea hydrothermal vents
can exist in habitat lacking sunlight?
You may not necessarily really need to use this food web.
So let's look at A, B, C, and D. And so as we can see,
I'm going to read through this with you real quick.
A, environmental conditions on some distant planets
resemble those experienced by organisms
living near hydrothermal vents, heterotrophs metabolize
carbon containing compounds produced
by photosynthetic organisms that live on the sea floor, C,
some organisms rely on energy captured
from inorganic compounds to drive processes,
or D, some organisms that can tolerate
high temperatures are single-celled,
whereas other multicellular.
Again, pause the video because I'm
going to go through circular ants or check with your friends
if you're watching this class.
We're first going to get rid of B
because we're talking about these heterotrophs metabolizing
carbon containing compounds.
Photosynthesis in there, we're going to get rid of it.
Next, experience organisms living near hydrothermal vents.
But the first parts-- on distant planets, that's
not even part of the question.
Get rid of it.
Next, some organisms tolerate high temperatures.
Not part of the question.
You're going to get rid of it.
So again, when you're tackling these multiple choice,
you need to look for options that deal
with the question being asked.
So if we look at answer C, some organisms
rely on energy captured from inorganic compounds, that's
what those compounds were that I underlined
in the part of the question on the previous slide.
Again, give yourself a round of applause.
Yay, if you got that one correct.
We got one more question based on this model.
Researchers are investigating the evolutionary relationships,
that's key, among organisms found
near deep-sea hydrothermal vents and similar organisms
found closer to ocean surface.
Which of the following scientific questions, again,
a scientific question is most relevant?
So again, I underline that, highlight for you
because that's what they're asking you to do.
Here's all our options.
A, what large-scale geological events have occurred recently
in the Mid-Atlantic ocean?
I don't know.
You know, they really didn't talked about that.
B, do species found near deep-sea hydrothermal
vents all have the same haploid number of chromosomes?
Don't know if we know that either.
C, does water temperature at different ocean depths
affect relative levels of dissolved oxygen?
Maybe.
D, what are the nucleotide sequences of ribosome RNA,
genes that are found in the genomes?
This is the scientific questions about evolution, right?
So we're going to get rid of A because there's
nothing in there about Mid-Atlantic Ocean.
We're going to get rid of B because there's
nothing in there about haploid number of chromosomes.
We're going to get rid of C because there's nothing
there about water temperature.
We are looking for the evolutionary relationship.
The best one there is the ribosome RNA genes
because as we hopefully know, DNA, RNA evidence
is some of our strongest evidence for evolution.
So hopefully, you got that one.
Now, we're going to talk about wolves.
So again, if you want to read this to yourself, pause it.
I know my voice is like angels singing right now.
Wolves, a top predator, we're reintroduced
to Yellowstone National Park in 1995 after a 50-year absence.
In a multiyear study, the numbers of wolves and elk
were monitored.
The data are shown in figure one, which is on there for you
to look at.
In two different environments, scientists
monitor the percent of aspen trees browsed
by herbivores, that's two, as well as the growth of trees
that's three.
So they give you 1, 2, 3.
The upland environment consists mostly a flat forested areas.
The riparian environments are areas
along streams with steep, wooded banks.
So if you weren't sure what riparian meant,
they'll give you the definition.
So the first thing is set for 5 is,
based on the data, which the following is the best
explanation for changes in the elk population between 2000
2005?
The first thing I would do is I would put in two lines.
I draw a line at 2000, draw a line at 2005
because that's what they're asking you about.
I'm going to notice the wolves went up, elk went down.
I'm looking here at the percent aspen
browsed, that kind of in the riparian zone decreased,
and then I'm going to look at my aspen height that increase.
So you've got these models that you need to use.
So A, B, C, and D, let's look at our options here.
So the first one, the height of the aspen trees
increase during that time period.
If we can look at the graph, predation by wolves
is higher than before 1995.
Maybe.
C, the number of aspen trees increase
during that time period, or D, wolf populations
increased more rapidly in upland areas.
So again, if we please use your graphs,
we're going get rid of A, the height of aspen trees increased
in that time period.
There's really the height increase in that period.
They're looking at the aspen height in that riparian zone,
but that may not explain the changes in the elk.
B, sorry, next one is C, the number of aspen trees
increase during that time period.
We don't even have that data.
We just know that there's browse and their height.
So get rid of that one.
It's not part of the graph.
Let's get rid of D, wolf population decrease
more rapidly in upland areas.
We have no idea in what areas the wolves were.
So your best answer there is B, predation by wolves
was higher than before 1995.
If we look at our graph, if we go back even in 1995,
you can see that wolf population increasing.
So again, a round of applause.
Yay, give yourself a star if you got that one right.
Let's go on to number 6.
Based on the data, which of the following behaviors in elk
could account for the difference between the percent of aspens
browsed by herbivores and the height of aspen
trees and riparian and upland environment?
So I'm going to focus in.
We see that riparian upland.
I've circled that for you.
The percent browse is decreasing,
our elk population is decreasing.
So we should see a pattern here with the elk.
So let's look at our four options.
A, elk tend to avoid riparian areas
with a steep, wooded riverbank make
it difficult to escape predators,
B, elk tend to prefer riparian areas where
there is an easy access to water,
C, elk tend to avoid upland areas where trees
are too tall to be easily eaten, or D,
elk tend to prefer upland areas where
there are rich sources of mineral nutrients,
such as potassium and iodine.
Well, we don't prefer riparian areas because as you can see,
there's no relationship there, so we
get rid of B. We're going to get rid of C,
they tend to avoid upland areas, right,
because we're not sure of that based on the data.
D, prefer upland areas where there
are rich resources of minerals.
There's no reference to minerals.
Your best option there is A, they
tend to avoid riparian areas, which would make sense
because you can see the percent browsed is decreasing
and the aspen heights are increasing there.
All right, so far so good.
Let me get on to my next slide.
And all right, this is sticklebacks.
I'm going to read this quickly for you.
Again, pause it if my voice is going a little too fast.
The three-spined stickleback is a small fish
found in both marine and freshwater environments.
Marine stickleback populations consist mainly
of individual armor-like plates covering most
their body surface.
Approximately 10,000 years ago, some marine sticklebacks
colonize some freshwater environments.
And after many generations, the stickleback populations
lacked the armor plating typical of the marine.
Over a period between 1957 and 2005,
one freshwater population in Lake Washington,
a lake in a coastal region, changed
from having a majority of individuals
of low-plated to individuals of having high-plated
or completely plated.
So there's figure 1, it shows the distribution.
And if you notice, I'm going to point out some things here.
When you look at the question, which of the following
best explains the difference in the armor
of the Lake Washington stickleback populations
summarized in figure 1?
So we're looking for the differences.
And I might have put those arrows in to quickly,
but if you can see the low-plated decrease,
that's my blue arrow.
And then the completely plated increase, that's
my orange arrow.
So let's look at our four options here.
A, analysis of somatic cells using chromosomal staining
and light microscopy indicates stickleback fish have
a diploid number of 42, maybe.
B, stickleback males from natural freshwater populations
typically more aggressive when competing
for mates than stickleback males from laboratory-bred, possibly.
C, fish exhibiting low-plated phenotypes
were selected against in the Lake over the last 50
years, or D, migration of individuals
from other freshwater environments led to gene flow.
So again, read through those, ask your friends.
I can pretend my class is here.
Let's get rid of A. We have no idea about the diploid number.
That's not going to explain the difference.
Probably going to get rid of B as well because there's
nothing about the aggressive behavior.
And then also D, there's no information there
about the migration or typically the gene flow.
So your best answer there is C. This goes back
to the natural selection.
The fish that had the low phenotype were selected against
and that's why you see a change in the data.
Use the graphs, draw over those graphs.
That's what they're there for.
Let's go to number 8.
Again, I'm going to read this to you.
Again, pause it if you don't want to listen to me read it.
A completely-plated stickleback from marine population
was made it to low-plated.
The resulting F1, that's a key, hybrids
all displayed a completely-plated phenotype.
You got an F1 generation.
The F1 hybrids were allowed to interbreed, the resulting F2.
If you look at your results, you get approximately a 3
to 1 ratio.
That should be a giveaway, a 3 to 1 ratio.
Which the fine conclusions is best supported
by the results of the breeding experiment?
So again, we're looking for conclusions.
That 3 to 1 ratio should be a key to you.
So A, phenotypic variation F2 suggest the armor morphology
is controlled by many alleles.
Completely-plated phenotype is controlled
by dominantly of a single gene, C,
armor loss is an acquired characteristic
that's affected by one or more environmental factors,
or D, patterns of armor plating and stickleback populations
regulated by sex-specific signals.
We're going back to that F1 issue.
So we're going to get rid of A because that's
talking about many alleles by a single gene.
Get rid of C. If you see acquired characteristics that's
a little marked in, not going to happen.
Or D, patterns of armor plating are regulated
by sex-specific signals.
There's no information in there that's what happens.
So our best answer is B. There's your dominant allelle
of a single gene.
You got your F1s, F2s 3 to 1 ratio, right?
Sounds Mendelian to me.
So again, I just want to thank you
for spending the last 15 minutes of your time with me.
I know it was a lot to take in at once.
But again, if you use those techniques that I gave,
you draw on the models, use that information, hopefully,
that'll give you a little more reassurance or a little more
confidence when you answer those questions.
So again, this is Mr. Monsour signing off from Room 102
on Tiffin's beautiful Southside.
Have a great rest of the semester.
Good luck in May.
And keep it classy, AP Bio.