good afternoon ap bio this is mr monsoor coming to you live from room 102 and tiffany's beautiful south side welcome back to ap daily review um i'm gonna be guiding you through units one and two you may remember me from some previous ap dailies some of my greatest hits were photosynthesis and cell respiration so again i'm gonna you're gonna be seeing me four times over the next two weeks during review so i'm excited to be back and i'm excited that we'll be able to do this again so again um probably about 45 minutes and we're going to start with units 1 and units 2. so just want to do a quick overview of the examined dates i think it's always important that you know what to expect so when you're taking your ap bio exam you've got two sections and hopefully your teachers have already gone over this with you but just in case you know it's been a long year uh section one is 60 questions you get multiple choice questions you get one hour and 30 minutes and that's about half your score and then section two is six questions uh you've got two like what we call long frqs and then four short ones and that's about another hour and a half which is 50 of your score so again just glad to be here so let's just get rolling because like i said i got you for a brief period of time and got a lot of knowledge to to release here so let's just warm up so in this ap live review we're going to be looking at some following topics i'm going to look at units 1 and units 2. so in unit 1 properties of water we're going to look at structure and function biological molecules cell structure and function so exciting cell size tonicity and osmo regulation mechanism of transport and then what we're also what i'm also going to be doing i'm looking at some task verbs that are using free response questions and i'm really going to focus on those science practices so a lot going on but i promise you'll be on the edge of your seat so excited to be here so the first thing i want to kind of just introduce you are these task verbs using the frqs and so each one of my videos i'm going to cover three to four of these task verbs and i really think these task verbs are important for you to do well on the frqs so these are the following task verbs that are commonly used in a free response question so calculate so when you do a calculation you have to perform some mathematical steps so hopefully you've gotten some experience this year already calculating we're going to do a calculation in this video but when you're doing the calculations make sure you know you have like proper labeling of units significant figures those kind of things construct and draw these are if you see a constructor drawn in frq that's asking you to like create a diagram graph make a representation or a model and if you've watched my other videos i'm good about making models and then describe provide relevant characteristics of a specific topic so we may we may encounter three of these during this unit uh unit one and two review or we may not but each uh video i'm going to try to cover three to four of those task forms because those are really important for you to do well so calculate construct and draw and describe and we're going to incorporate some of these as we go so let's talk about properties of water so i've got a got some water here it's kind of like water so we're gonna in this first topic review over water we look at the structure of water what polarity means hydrogen bonds cohesion adhesion so as you see here if we look at this little model right i've got one oxygen i've got the two hydrogens so this would represent a water molecule so we're going to kind of focus on this for a couple minutes so a little check mark there so what they could ask you in a multiple choice question is describe the bonding that the point arrow is pointing to well there's that arrow so you need to ask yourself a describe so when you describe something you're giving a characteristic of it so describe the bonding area is pointing to well the arrow is pointing to that hydrogen bond between the hydrogen of one molecule and the oxygen of another right that's a description and so hydrogen bonding is very important water is very important that's usually why it's in the first unit because really for all these metabolic reactions to occur things like dehydration synthesis hydrolysis for occur they need water and so if you come to a question ask you to describe i like to think of like as a characteristic of it you know there's a difference between describe and explain which we'll get to so there's your hydrogen bond sometimes one of your skills i'm going to point out the skills here is a skill is a visual representation and so one of the skills that the college board and ap is going to is going to kind of test your or evaluate you on is your ability to look at a visual representation and make some kind of answer some kind of summary about it so in this case describe the concept represented the image above so we've got water we've got air we've got that blue line there but if you notice i've got all my little red and white models here representing water molecules and so if i just get it just right oh this one doesn't work there we go right magnets so anyways so say what what's the concept being represented in this image above so if you look you got air you got water if you remember your properties of water you're like well it could be adhesion there's cohesion surface tension and so hopefully you see that you know surface tension is one of those important properties of water but looking at that skill that you know looking at that skill of literal representation we could ask you describe the concept well the concept is surface tension right we're gonna describe it so it's when a hydrogen bond or hydrogen forms a bond with oxygen right and then you it creates these bonds along the water so things like water striders and stuff can walk along so that would be an example of how we could assess you on a skill but also incorporating surface tension was which is also an important concept in water so surface tension so there's my arrow pointing to the water all right so that's kind of the idea with water one other thing i want to point out with water which i don't have here is um that i don't have a slide so i'm going to kind of go back real quick is i've got some sodium chloride here and so sodium chloride my chloride is the green one my sodium's the blue one we could also ask you to describe what happens or what causes water right to what caused water have the ability to break these apart and so again that's based on water's polarity and so you may not be able to see this real well but what i've done here okay magic of uh the internet so here's my original sodium chloride you can see that if i place this sodium chloride in some water again this is a model all models are wrong i may end up with something like this and so as you can see i've got my blue one which is that sodium and if you notice the sodium has a positive charge all of those oxygens with the negatives are attached to it so that would be one of the concepts that we could ask you about is describe how you know water dissolves a substance so there's our chloride um excuse me sodium is blue chloride in green with a negative charge and as you can see on here my hydrogens being positive they attach so that would be a way to maybe like describe how water has the ability to dissolve a substance so all right topic 1.5 structure and function macromolecules so we're talking about macromolecules we really need to focus on types of macromolecules and the four elements of protein structure you may remember me you may remember me of course but for my other videos talking about protein structure with my friend the bendaroo so um as always though make sure you do refer to ap daily 1.5 for more detailed information on the structure and function so again we'll check our friend the check mark all right so let's look at an example so here are our four biomolecules we've got lipids nucleic acids carbohydrates and proteins these are all important this is the basis for the this is like foundational for the course because you're gonna you're gonna see lipids again in a unit when we talk about cell membrane you're gonna see nucleic acids in unit six we talk about dna and rna you're gonna see carbohydrates when you're in unit three talking about uh photosynthesis respiration you're gonna see proteins throughout also in unit 6. so we talk about lipids why lipids are important is because they're hydrophobic and that's how that cell membrane right the hydro the fact that lipids are hydrophilic helps with that cell membrane how it functions also the fact that lipids can be saturated unsaturated that bending right in an unsaturated lipid is very important for movement of materials nucleic acids like dna and rna or nucle which make nucleotide nucleic acids and nucleotides dna and rna again in unit 6 central dogma which we'll talk about later carbohydrates you know monosaccharides disaccharides glucose fructose galactose all those oases you got glycogen and starch which are going to be discussed later on in further units and of course proteins proteins you know talking about amino acids that peptide bond that bond that you know you got that central carbon amino group carboxyl group so all of these you why we spend so some time on is because they're foundational they're the basis so i'm going to talk about i'm going to show i'm going to focus on really the primary structure secondary tertiary of a protein so here's my bendaroo this would represent the primary structure right so again this is a model all models are wrong so just imagine there's a whole bunch of amino acids here and so in that primary structure it's that sequence of amino acids right that covalent bond that peptide bond that forms it once you start folding you get the secondary structure right so here's my helix right then i might get a little uh bend in it right my beta sheet and so again depending on how these molecules are interacting which i'm going to show you here in a second depends on the structure structure determines function as we know and then that tertiary structure which forms is when this can kind of ball up right and then we've got a quaternary structure which is assembled subunits i don't have assembled subunits but hopefully you get the idea that depending on the sequence of these amino acids the chemistry of those amino acids those r groups will determine how these things fold up and so i have another model here um and so i'll kind of show you here i've got these pins in here to represent the different types of amino acids and there are groups because this is going to kind of come into a question you're going to see in a little bit so this pin on the end here i'm going to say is hydrophilic all of these pins here hydrophobic so i could ask you an identify question identify uh if this uh r group is hydrophilic or hydrophobic that could be an identify i could ask you to describe the bonding well we could describe it as amino acids or bonded together by peptide bonds or i could ask you to explain this process but really what i want to show you is to kind of reinforce this hydrophilic towards the outside right water loving these ones here in the middle hydrophobic so they may start to like turn in on themselves away from the water and so again not not my uh not the most accurate but it is a model but you get the idea of how these molecules interact why understanding the chemistry behind those r groups but also being able to describe how they're formed so there's my bendaroo of whatever protein we're going to call it so far so good let's do a little practice practice is important hopefully you've been doing some practice in ap classroom which is very important so topic 1.5 skill here's a skill develop and justify a scientific argument using evidence so when you're developing and justifying an argument you have to have some evidence you're trying to come up with a conclusion right and you're gonna use evidence so i'm gonna read this to you a mutation results in the production of a version of a small protein that is only 105 amino acids long as shown in figure two five i said five five of the hydrophobic amino acids are missing from one end of the chain which of the following best depicts the tertiary structure of the two proteins well the first thing i always got to do is read the question right and so a couple things that i'm going to point out here in the question is you got five of the hydrophobic amino acids are missing so hydrophobic right those are water fearing they're missing from the one end of the chain and so the questions ask you which the following best depicts the tertiary structure so if you're asking about a depiction okay you're trying to take in the information and you need to come up with a conclusion so which of the following best depicts the tertiary structure of the two proteins well if you remember i kind of built you a tertiary structure i know you're gonna probably judge me a little bit so if we're looking at this tertiary structure right we got to look at the actual models that they give us be sure to look at the models so if we look at this one we have those hydrophobic amino acids hanging out there that i just highlighted but on this one they're missing so hydrophobic and if we know that the lighter gray ones are now hydrophilic he said hydrophobic and he said hydrophilic hydrophilic must be water loving right literally so can't be d because that's a perfect circle right it's an original protein it's a mutated protein you have a little thing hanging up on the end but that's really not showing you this folding original protein mutated protein again that that folding really doesn't represent that tertiary structure that complex structure so we're going to eliminate that one b again original protein you have that mutated protein you have all these sticking all these things sticking out on the original one i tried to model this after this question if you couldn't tell right okay this is not the original because the original these are hydro right so in the original one these are hydrophilic right so this does not work so if we look at that mutated protein the best answer has to be a and if you can see on a do you see that little bump sticking out right so the hydrophobic ones are gone so that little bump is that hydrophilic one sticking out so again you would you would select a because to develop to justify the claim is the fact is that little one is sticking out because you've changed something from being hydrophobic to hydrophilic hopefully that made sense maybe pause the video at this point you know try to answer it on your own but that's how we would take the information for you to create a uh argument so all right so topic so we're kind of done with unit one we're going to go into unit two again i could not cover two units in 45 minutes so we kind of i kind of picked the ones that i thought were most important so topic 2.2 cell structure and function right who doesn't love the cell so the highlights of 2.2 are subcellular components structural features of cells that allow organisms to capture store and use energy right those structures like the mitochondria the chloroplasts those kind of things there are some misconceptions though you really have to correctly identify an organelle so you can you can identify the you know the organelle but you don't always actually describe its function and i'll talk about that a little bit more and again as always refer to ap daily 2.2 for more detailed information so let's look at an example so we got an animal cell plant cell the organelles that you should know or really should know are which are which are in the content of course ribosomes rough er smoothie r golgi body or golgi apparatus mitochondria lysosomes vacuum chloroplasts so those are really organelles that you should know and you really should avoid um you should be able to characterize each of them but you really need to give the proper characteristics like ribosomes are made of rna and protein i would err on the caution of not saying that mitochondria is the powerhouse of the cell right that may not be giving the best description i like sight of oxidative phosphorylation myself but when you're looking at these organelles you really you need to know their their their their function what they do and again i'm going to kind of go back one slide so you see some ribosomes protein synthesis smooth er right working with ribosomes protein synthesis smooth er roughy our excuse me protein synthesis smooth er production of lipids golgi right we have a lot of processing there and then you've got your mitochondria which right production atp lysosomes breaking down materials vacuole for storage and your chloroplast side of photosynthesis i went through this kind of quick so maybe you might want to pause jot down your uh responses to see if you remember what your organelles are so we'll kind of go back to that so again try to avoid the like analogies to like factories and those kind of things so let's look at let's let's do a little practice here so here's a here's a skill making a claim and so when you make a claim again you're going to look at some evidence and make a statement so in an experiment researchers provided a radio-labeled amino acid to living plants a lot going on there we know it's an amino acid protein after one hour the researchers determined the amount of radio-labeled amino acid that was in each of several sub-cellular compartments well those sub-cellular compartments okay talking about a cell talking about a protein the results the experiment representing the table so if we look at that first table we can see that what the question is asking us to do is which of the following conclusions about the radio labeled amino acid best support the results of the experiment so we're looking for the results of the experiment so again you have to look at your data tables you have to look at any kind of table you have to read the captions underneath so looking at this table what jumps out at me is that i've got 2.7 uh amount of the radial labour amino acid in the mitochondrion i got 2.1 endoplasmic reticulum is 1.9 the cytosol has one so i definitely know that this is dealing with energy production and something with you know protein synthesis or something along those lines so it was incorporated nucleic acids that store biological information well we don't really see much there in reference to you know the nucleus is there but mitochondria nucleic acid that might be a tough one to kind of connect uh it was mostly incorporating the lipids that help separate cells from surrounding environment well with lipids you're thinking smooth er it was mostly incorporated into carbohydrates and form the protective structure outside the cell so carbohydrates not so much so the best answer would be b it was most incorporated proteins that regulate to manage metabolic reactions all right so proteins right the nucleus the dna in the nucleus right is responsible for transcription and translation which also makes protein the metabolic reaction mitochondria right so metabolic reactions those things requiring energy those things requiring atp that's why mitochondria is the best answer there so again making a claim my claim is that these uh radio radio labeled amino acids were incorporated into proteins that regulate and manage metabolic rates and again our reactions again pause the video right if you're trying to answer these ahead of time and to see how if my explanation matches your answer we're going to go on to cell size now so we talk about cell sizes topic 2.3 you've probably done a lab you've probably looked at cells underneath a microscope you may have done osmosis diffusion so when we talk about cell size we really need to think about the size of cells you need to be able to calculating service rate of volume ratio i'm going to show you the formula sheet here in a little bit but calculating right calculating you know you're going to have to do some math we all love math and then so that's the first thing but again some of the misconceptions that i find with my students we talk about cell size is that larger cells are more efficient just because it's bigger doesn't mean that it's going to material is going to move faster and as always refer to ap daily 2.3 for more detailed information so let's kind of talk about cell size a little bit more so you've you need to remember that the service area of the membrane has to be sufficiently large enough for materials to exchange right so i've got a large block here and a small block here right and so if i want something to get to the middle of these blocks these these models of cells which one's gonna be able to get there faster the smaller one because it has less distance to travel that's how i kind of look at it whereas this larger one it's going to take longer for materials to get in to get to where it needs to be so we talk about service area membrane it does have to be large for efficient material exchange to occur but also we have to look at the volume so a key point here a little ap hint as volume increases the surface area increases so i like to think of it as a balloon as you blow up a balloon that volume increases right and that the surface area for stuff to move across that balloon decreases and the other thing when you talk about cell size that cell membranes can fold to meet the demands for resource that occurs growth so if you think you may have talked about like in the digestive tract you have all these folds you're increasing the surface area because if or better yet in the mitochondria you have all of these folds by adding those folds here right let's pretend this is a these are some folds here right as i have these folds i'm increasing the surface area and so um that can meet the demand for whatever growth has to occur so let's do some practice so before we go into practice i do want to point out please look over your formula sheet when we this is just a sampling of it i'm not going to necessarily be doing any of these parts on the formula sheet but i just want to point out some things that i encourage you and uh to actually try to go through and work one type of question if you can from each of parts of the formula sheet so statistical analysis in this case i've got chi square on there these are things i'm not doing in this video but i really think it's important that uh just as a suggestion for myself as being an ap teacher for probably a long time to try to go through and work out something from each of these formula sheets again i'm not gonna have time to go over every single part of it but we're gonna look at a piece of it so find that formula sheet dig it out while we're doing this then we'll kind of talk about here a little bit so one of the skills that you'll have to perform again the mathematical calculations again is looking at that surface area to volume ratio so here's a question that was taken from ap classroom simple cuboidal epithelial cells line the ducts of certain human exocrine glands all right main point there cuboidal cells so they're in cubes that should be a giveaway various materials that are transported into or out of the cells by diffusion which of the cube shaped cells would be most efficient removing waste by diffusion and so as you can see they've given you different size cubes this would be a this would be d and i priorly kind of gave away the answer when i was talking about this earlier the first thing you need to do if you see a calculation right you're looking for the most efficient movements that's going to require calculation so i will show this on your formula sheet but you got a cube you go to your formula sheet so surface area of cube right six times the side squared and then you have your volume which is the surface um cubed so there's the mathematical problem there you work it out um on this one though i don't know since it's a mobile choice if i would use my time to do the calculation for each one of these as i've already explained the smaller the cell the more efficient at removing waste large cells it takes much longer for materials to move so you know if you look at a largest cell probably not efficient you could go through and calculate you could pause the video and calculate 40 30 20 and 10 if you'd like uh 30 20 but 10 this is the most efficient because if you think about yourself and your cells are very small if we had cells this large it would not be efficient however in an frq you may be asked to calculate and that might be the appropriate time in these multiple choice you may have to calculate but it does it is a time test so it does eat up some time so if you can think of things like okay small sales move stuff faster large stuff large cells move things slower all right so again i just want to show you the formula sheet i didn't want to give it away so when you're talking about calculating surface area volume ratio you have sphere solids cylinders cubes right you have the surface or you have the volume and they give you those definitions so again i would strongly encourage you to do some practice calculations over service air to volume ratio it is a very important concept in the ap program and so those were the two that i used for the previous question um again you will have that formula sheet when you take the exam so all right let's move on to topic 2.8 which is tonicity and osmo regulation so some of the highlights of tennis and asthma regulation is that there's different ways to describe relative tendency environments and osmoregulation how it contributes to health and survival organs is very important that's the highlight of 2.8 and as i always said refer back to 2.8 for more detailed information if you need to review so hopefully as you're going through these power points and these reviews you're jotting down ideas of like what you need to like maybe study because you know it's been a while so let's kind of look at an example so when we're looking at topic 2.8 tennis and aussie regulation i do want to hit some important concepts here and so we're talking about water it's important to understand that water will move by osmosis from areas of high concentration to areas of low concentration right and again that's passive transit we're going from high to low you can also say that water moves by osmosis from areas of high water potential to areas of low water potential again from high to low and you can also say that water moves by osmosis from areas of low osmolarity to areas of high osmolarity all of these are ways to describe the osmotic movement of water across a membrane i would just kind of familiar so familiarize yourself with these different terms high to low when we're talking about water high to low we're talking about water potential but low to high we're talking about osmolarity let's look at topic 2.8 tonicity and osmoregulation and so one of the things that they could ask you is can you explain water movements so we've got osmosis and animal cells we have three red blood cells or an animal cell in different solutions so can you explain the water movement so maybe pause the video here jot down some answers because when you do an explanation i think it's important that you include a because so i could identify these as cells in different solutions i could describe the movement of water when water is moving back and forth but an explanation requires more so if i say can you explain the water movement in isotonic solution well water is moving back and forth across that cell membrane because it's in an isotonic solution the amounts of solutes are equal on both sides and so it's in dynamic equilibrium the water's not necessarily there's no bulk movement in or out a hypotonic solution i can explain the water is moving in to the red blood cell or into the animal cell because there's more solute inside the cell than outside hypertonic solution for an explanation i could say that water is moving out of the cell because there's more solute in the environment so again identify describe the explain requires a bit more same thing with the plant cells osmosis and plant cells can you explain the movement of water and again at this point hopefully you know that isotonic right water's moving back and forth hypotonic right you're having more water move in than out and then in a hyper tonic you're having more more water move out than in and again the plant cell is unique because of that cell wall but again hopefully with the explain the water movement you understand that you know you need a little bit more like because of this so we kind of wrapping up this 2.8 um hypertonic solutions have a higher solute concentration high osmolarity relative to the solute concentration of cell this will cause water to move out of the cell these kind of help you with your explanations hypotonic solutions have a lower solute concentration low osmolarity relative to the solute concentration cell this will cause water to move into the cell right so we're moving out of the cell and hyper moving into and hypo isotonic solution there's equal concentration isosmatic and so they're going to move back and forth so your net movement will be zero so just kind of give you ideas if you pause the video for some explanations so here's your as we go into talk about tonicity we also need to talk about water potential here is a snapshot from the formula sheet and i'm going to talk about this because it is important to unders be able to calculate water potential so again i took this from your formula sheet if you got your formula sheet find it highlight it put a check mark on it knowing that you've at least talked about it so when we're talking about water potential water potential measures the tendency of water to move by osmosis and so this is the formula for water potential and again it's on that formula sheet so water potential that y looking thing is equal to solute potential plus pressure potential where the s is the solute potential and then that is your pressure potential there and so again that's the formula that you would use for water potential so again when we're talking about tennessee regulation water potential pure water this is important has a value of zero in an open container the key part there is an open container so if you've got pure water no solute zero plus zero water potential is going to be zero there you go there's the formula zero plus zero gives you zero there's your water potential pure water so in an open system right the pressure potential is zero so water potential is equal to solute potential so here's the formula for solute potential so your solute potential is equal to that negative icrt and again you have your formula sheet but i'm going to go through this with you so the ionization constant sucrose is 1 sodium chloride is 2. often if you look on the formula sheet they're going to ask you about sucrose for that ionization constant the molar concentration molarity in capital m is the moles of solute per volume of solution the pressure constant is 0.0831 bars per mole k and then your temperatures in kelvin temperatures in celsius plus 273 equals kelvin so they give you all the things on that formula sheet you just have to go figure out from the problem where those values go and so let's practice so calculate the water potential of a 0.5 molar sucrose solution at 21 degrees celsius in an open system we've it seems like we have a lot there and if you haven't done one of these before it can be overwhelming what i would encourage you to do pause the video try to work this out yourself if you haven't done it before but i'm going to work it with you so again i have my formula on the left of water potential is equal to pressure potential plus solid potential i have what my solute potential is negative icrt it's all there and so we're looking at our solute potential and so what we have we've been given is for your solute potential is equal to negative icrt so i've got .5 molar sucrose solution at 21 degrees celsius well there's the there's the example there for you so if you've already worked it out don't go too far so one again that negative so we've got one right that's our ionization constant that's the sucrose 0.5 molar that's where i got from the formula my pressure constant is always the same 0.0831 and then my temperature in kelvin which i gave you at 21 degrees celsius 21 degrees celsius plus 273 right and so we plug in those numbers and we get a negative 12.22 bars and so again don't get overwhelmed by doing these calculations there's the formula sheet it's going to be on the formula sheet for you you just got to take a deep breath and be like embrace the math embrace the math embrace the math i say it three times so that's an example but again if they give you if they're asking you about calculating water potential i would go after the solute potential first because that's usually probably the more difficult or what's going to require more work and again there's the formula i took it right from your formula sheet no surprises there's your water potential there's your solute potential solution there's all those values that i gave you so should not be a not be a surprise i actually like water potential calculations people think i'm weird but it's all right so we've already done that first part right we've calculated the um solute potential now we're gonna calculate the pressure potential here's the key it's an open system it excuse me it's open to the air so that pressure potential is gonna be zero there's nothing to calculate there it's gonna be zero it's an open system so maybe when you did a dialysis lab maybe use carrots or whatever it was an open system and so you just plug in your values remember that the solute potential was equal to a negative 12.22 bars we do some math again just tell yourself embrace the math embrace the math we get our water potential of a negative 12.22 bars so again i may have worked that kind of quick um if you don't remember how to do it maybe go back to the video work it out maybe ask your teacher from a teacher for some extra problems you know you can do this at dinner right sit down do water potential problems or maybe not all right another skill that's really important is constructing a graph and i'm going to include this skill in this first video because graphing is important especially on the frq so when you construct a graph plotter chart it could be x y log y bar histogram line dual y box and whisker pi these are right from the curriculum guide or the uh curriculum that ap teachers are to use and so when you're doing your graphs couple things remember you can get points for orientation we can ask you about labeling units scaling plotting type of graph so these are all things that can be asked of you to do so when you're doing graphs kind of keep these things in mind also trend line scale and so these are kind of those things that can be ask the view when you're constructing a graph so let's construct a graph so i've got a water potential problem here so water potential potato cells was determined in the following manner the initial masses of six groups of potato cores were measured the potato cores were placed in sucrose solutions of various molarities the masses of the cores were measured again after 24 hours percent change in mass were calculated the results are shown in the table so you you may have done a similar lab so they took potatoes they cored them out they took an initial mass they took they let them soak for 24 hours in different malaria solutions and they did the percent change in mass the question is asking is to graph these data on the axis provided and then from your graph find the apparent molar concentration osmolarity of the potato core cells so again you've got table one you've got molarity you've got your percent change in mass and so again graph these data and then you're going to also find the apparent molar concentration so when we're constructing a graph a couple things that i want you to look at as you can see i've graphed graphed it for you you could have paused the video graph it yourself across the top um you have your title you've got your units right and and then when you're trying to label your axes i always tell my students there's thing called dry mix dry dependent is the responding variable on the y-axis the mix stands for manipulated independent on the x but again making sure that you label those axes will sometimes get you a point as you can see i graph my data across the bottom there's my molarities there's my percent change in mass the question asked me to figure out what the osmolarity of the potato core was and so you wanna when we look at just showing you all my labels here we wanna see where that line crosses the zero because when it crosses zero that means that it's isotonic because it's not gaining water and it's not losing water so by that question of constructing that graph we were able to answer the question of what is the osmolarity of that potato core and even going further explain why there's a difference in percent mass change of the potato cores in different sucrose solutions again an explained question and explain looking for because well if we look at our graph right we can see that everything above the zero at one point was gaining mass right well it started out at zero but it's above that zero so there wasn't like it was there was more water at some point right not moving as quickly right it wasn't moving out of the cell and then if you look underneath that's where the water was moving out right so if you remember everything above the line was a one type of solution everything below the line was another type of solution so why was there a difference in percent change of mass potato cores different solutions well depending on the molarity of the solution right would lead to a different percent change in mass so some of those cells gained water water was moving in because of the solute concentration on the inside and some of those potato cores were losing water because of the solute concentration outside so that idea of an explain because and again there's our where it crosses the zero and then there's our data everything in red is above everything in blue is below so all right 2.9 we're going to kind of move on to 2.9 talk about mechanisms of transport so the highlights with this one is that uh we talk about mechanism of transport we gotta need to talk about passive and active transport and movement of large molecules and so we talk about passive and active transport that all goes back to energy right passive transport not requiring energy active transport requiring energy right because going against a gradient or requiring a a protein to have conformational change that materials can move in as always refer to ap daily 2.9 for more detailed information so let's look at look at an example so when we're talking about these examples we really when you you have to be able to describe forms of active transport so what can be moved into out of cell using this meth and how it happens so we talk about active transport like sodium potassium pump and essentially anything going against the gradient right we talk about passive transport those are things that can be moved in or out of the cell using this method do not require energy so things like osmosis diffusion um if you hear the mention of aquaporins that's going to be passive transport where active transport is going to require energy so i just want to kind of get you in that frame of mind especially if you're watching this in april and you haven't talked about active and passive transport since unit 2 maybe back in september so can you explain what's going on each picture so on the left side of my screen which hopefully i think is the left side of yours as well if you want to pause the video kind of write down what type of transport it is so right i'm going to look around in my room anybody anybody you guys know what kind of transport it is all right the ones where the molecules are moving across moving from high to low that's passive transport you don't see any kind of movement against a gradient you don't see any kind of requirement of energy so the explanation is is that that is passive transport because right it's an explain because there's no atp required because you're moving from high concentration to a low concentration the other one which is labeled active transport protein again that is an explanation for that one is that well that is active transport because because again it's an explanation you're requiring atp to cause a conformational change or you're moving materials against the gradient because as you see the movement of sodium you're going from a low concentration of sodium on the bottom to a higher concentration of sodium on top so again that explanation because it's very important all right let's practice a little bit so here is an image we've got cytoplasm you got solution surrounding a cell membrane we have a cell membrane we have some materials moving from high to low we've got some proteins embedded in that cell membrane so figure one high and low indicates a relative concentration of each ion and molecule the process by which several different ions and molecules move through a cell membrane is shown in figure one for each ion or molecule the relative concentration on each side of the membrane is indicated so again first rule read the question second rule read the caption third rule read the question again so it's asking you explain how the cell is maintaining a high concentration of sodium in the environment around the cell and explain hmm if this isn't explained i better include a all together class they all said because you couldn't hear them so you need to ex hopefully include a because or a little bit more than a description so go ahead jot down an answer all right definitely volunteers so i got that explained there's our low to high that should be the giveaway the explanation is that sodium ions are being actively transported from inside of the cell to the outside of the cell through a membrane protein so the explanation is that the the way that they're maintaining this is that they are moving they're being actively transported from inside the cell to the outside of the cell because they're trying to maintain that they're trying to maintain that transport all right so what should we take away a couple takeaways here one you need to review the suggested ap daily videos that i went through and suggested go back and review review your notes uh review the ap daily videos repeat review any progress checks like i said take the progress checks and don't cram have a plan you still have plenty of time and then also practice frqs and focus on task verbs and so speaking of frqs um i'm going to try to highlight one of each type of frq in each question so free response question one interpret interpret interpreting i'm sorry and evaluating experimental results is an eight to ten point question that presents you with authentic scenario you got data table or graph and it assesses your ability to the following four part a describe and explain which i talked about part b identify an experimental design procedure part c analyze or part d make and justify a prediction so again make sure you kind of look over these three response questions and kind of look over those task verbs so again next up will be margaret evans who is amazing and she'll be doing unit three cellular energenetics with you um and so margaret is awesome so you're gonna have a good time with that so again i just wanted to say thank you thank you all ap teachers i know you're working hard thank you to all you ap students you're working just as hard and again thanks for watching and i will see you in another video you