hello bisque 132 this is the beginning of recorded lecture 3-1 uh still on plants but but not for long i know plants took up uh the majority of the previous exams material but there's just one last topic in this platform and physiology chapter that i think is really really important before we can be done with plants and that is uh the transport of water and solute it's how stuff moves around now if you if you read this section in the textbook there's a lot of math here but i'm going to try to give you the the non-math version of this because i i don't think understanding the equations and all that stuff is really important in an introductory class so a concept that we're going to run into as we go through this is the concept of water potential which if you try to break it down into the non-math version it is very simply the potential energy of water that's kind of a weird thing to think about that water just existing has potential energy the the take home message regarding water potential what we're going to bring up later is the idea that water moves from high water potential to lower water potential so keep this in the back your mind as we're talking about things moving around and water potential changing if something has high water potential that means there's going to be a tendency of water to move away from it to areas that have lower water potential so just keep this statement in mind it'll definitely come up later so there are actually two systems involved in the transport here uh there's one system that deals with transporting water and then there is a separate system that's involved in transporting solutes and dissolved sugars and stuff um let's talk about water first so this is going to be a ground up transportation system of course water being absorbed uh in the in the roots uh from the surrounding soil and then sent upward toward the leaves that need that water to do photosynthesis so this is always you know from down to up this is going to involve three separate stages here that work in three different ways uh so let's start this journey of water uh step one from the soil to the root cells so let's uh zoom in on this part of the figure here um okay so the way this works has to do with you know as this says uh water potential so by manipulating the concentration of solutes in these root cells by you know making sure that there are a lot of just dissolved sugars and stuff like that in these cells that creates low water potential remember what i said water moves from high water potential to lower water potential so if you create root cells that have a low water potential water is just going to move from the surrounding soil into those root cells as simple as that so increasing the concentration of solutes in the root cells creates low water potential therefore water moves to the root cells from the soil okay that was simple enough now we have to now we have to go up uh so this is uh from the roots uh to the stems uh this process if we zoom in here this process is going to involve as this says cohesion and adhesion uh you might remember this uh from bisque 130 cohesion and adhesion these are both defined in the key terms cohesion is the tendency of water to stick to itself adhesion is the tendency of water to stick to other things and these forces together are going to result in what's called capillary action where just because of the tendency of water to stick to the stuff around it if you have a tube in water this water is going to fight against the force of gravity and rise up the tube because it's wanting to stick to the walls of that tube this is you know artificial setup with a glass tube and a beaker uh but this is you know exactly what we see when we look at the tubes of xylem for example so yeah the water is going to crawl up the walls of this xylem because of cohesion and adhesion simple as that so even though these were defined in earlier chapters they should be on the key terms for this chapter as well so from the roots up through the stems cohesion and adhesion draw water up the xylem and finally we need to make it from the stems to the leaves because again those are the cells that actually need this water photosynthesis consumes h2o uh and so these are the cells that actually really need it zooming in on this this is the weirdest process or weird in my opinion this is going to involve something called transpiration so transpiration is where water evaporates out of these leaves it's lost it goes away it exits the plant body and what that does is that causes negative water potential in these leaves and again to go back to the slide remember what we said water moves from high water potential to lower water potential so if these leaves have low water potential because they've you know lost a bunch of water through these uh stoma stomata due to due to evaporation that is going to draw water from the stem from the xylem into these leaves and this kind of sounds stupid i mean the whole point is that these these cells need water you're getting water by losing water and that's exactly what this is i mean i guess there's a saying in the business world you got to spend money to make money and that kind of rings true here these these this tissue acquires water by losing water so a fun statistic is about 90 percent of all water that a plant absorbs initially about 90 of it is just lost due to transpiration uh not even not used for photosynthesis at all 90 of it just gone but as weird as this is it works uh there is a net gain of water water is used for photosynthesis it's just giving it away you know having it evaporate is what transports it to these cells so here's my summary of this from stems to leaves transpiration causes negative water potential in the leaves therefore water moves you know from uh high to low water potential from the xylem to the leaves so they can use this water so weird to wrap your brain around that they're wasting water to get water but it it works okay so this was you know half of things this was the xylem this was a transport over water uh now we have to talk about phloem and the transport of dissolved sugars now before we do that there are some terms that you should be familiar with photosynthesis in these leaves produces what is in broad terms called photosynthates so when we're talking about sugars like sucrose they just fall under this broad term of photosynthates so that's what we're talking about now the transport of photosynthates uh these cells producing these are called sources leaves for example are a source and they are transported to areas of the plant called sinks so these are just areas of the plant that need those photosynthates this can be roots they're obviously not doing photosynthesis and they're actively growing they need energy uh young shoots you know they they require an input of energy because they're actively growing really fast developing seeds or fruits uh they definitely need an input of energy and so this translocation process is what's going to transport a photo and then here's here's the sentence that pulls in all of these terms together photosynthates are transported from sources to sinks hopefully that made sense and the important thing is that this can be up or down so the transport of water was always up uh but you know if you're going you know from leaves to roots obviously that's down but if you're going from leaves to to developing seeds or to younger parts of the of the shoot that that can be up so this process of translocation is not always in a single direction that being said in this particular example i'm going to use it's showing the source up here and the sink down here but it could be either direction okay so just as with the transport of water we could break this into into three stages the first stage here is moving from the source cell into the phloem this process involves what's called active transport and hey maybe this sounds familiar to you we talked about active transport in bisque 130. uh this is a very different example from you know neuron cells but uh active transport uh spends energy you're expending atp to move stuff from one side of a membrane to another so uh we're spending energy to do this i say we plants are spending energy to do this but in the end it's going to be worth it so this process called translocation sugars are moved from the source to the phloem by active transport and this costs energy okay now you may have noticed that you know this figure about translocation it's supposed to be about movement of the phloem uh but this figure also has the xylem labeled over here uh well if you'll remember xylem and phloem are paired with one another in vascular bundles you know whether it's eu dicot or a monocot uh they're always right next to one another xylem and phloem and here's the reason why xylem has a relatively low number of dissolved sugars it's mostly water and phloem especially in these parts where you've been actively transporting a bunch of it over has a high concentration of dissolved stuff maybe this sounds familiar to you discussing the the concept of low concentration of solutes and high concentration of solutes well this is where osmosis comes into play again flashback to disc 130. uh so what is going to occur now in this sort of second step osmosis which you know i've put in the key terms again this is water moving from low to high solute concentration osmosis is going to cause water to move from the nearby xylem into the phloem and again this is because they are next to one another and this doesn't cost any energy at all but water is going to move from the xylem to the phloem now we bring in water potential again yes it's involved in this too so having a bunch of water come into the phloem is going to increase the water potential of the phloem keep that in the back of your head the phloem is now under you know has a high water potential we're about to be done here final step we got to get these solutes into the sink cells in this example it's a root but somewhere into the sink and this is going to involve water potential these sink cells simply have lower water potential than the phloem remember water always moves from high water potential to low water potential so it's as simple as this the phloem contents these uh photosynthates move to the sinks because they have lower water potential and this doesn't cost any energy at all so hopefully this made sense i think these these figures do a good job of showing this and you know i broke down each of these transportation steps into into three easy stages but yeah i think that this is important to understand uh as a capstone to talking about plants now there are a couple of plant chapters left if you're following diligently along in this textbook uh but we're skipping these uh you know chapter 31 about soil and plant nutrition and chapter 32 plant reproduction i'm sure if you take a plant biology class you'll you'll definitely touch on these topics but for an intro biology class just in the interest of time we have so many other things to get through i'm skipping these chapters completely in the interest of time so we are now done with plants and ready to move on to animals so just like we've done with the previous chapters before we talk about uh specific groups of animals we have to have just some generic background about animals in in general uh there's going to be a lot of background though in fact this chapter uh this short chapter introduction to animal diversity is all just sort of background and so it might seem kind of dry at first but but a lot of this is sort of laying the groundwork defining these concepts and these terms that we are going to see play out in the the next couple of chapters about animals so okay feature features of the animal kingdom what is an animal well animals are all heterotrophs this should sound familiar to you here's a heterotroph a heterotroph defined in the key terms an organism that consumes organic substances or other organisms for food for carbon there are of course several different types of heterotrophs that we see among animals we see carnivores eating meat we see herbivores eating herbs eating grass omnivores eating either you know a bear will will chow down on some tubers and berries as well and then parasites that's also a form of heterotrophy you know you're stealing energy over a long term but you're getting it from an organic source so heterotrophs can be carnivores herbivores omnivores or parasites um most uh animals have complex tissue structures uh we'll see this play out when we when we look at the tissue structures of animals in the next chapter uh importantly no cell walls extracellular matrix this might look familiar from disc 130 you know fungi had chitin cell walls and plants had cellulose cell walls animals don't have any cell walls at all we've got this extracellular matrix instead it's a looser connection of proteins and carbohydrates instead of a thick rigid wall animals have a diplotic life cycle so this is not a haplodiplogic life cycle it's a diplotic life cycle what this means is only the the only multicellular form is is the diploid form so uh here's familiar uh should be familiar human life cycle showing the diplomatic nature here we've got diploid cells we've got haploid cells but unlike plants the only form that is multicellular is the diploid form when we go haploid it's only for egg or sperm there are no multicellular haploid structures in an animal in a diplomatic life cycle most animals are motile meaning they can get from one place to another uh but some of them are cecil or sessile meaning they stick around and they filter feed or they they don't actively move from one place to another so reusing this bear again you know walking around grabbing fish and then yeah here are some uh some muscles an example of a cecil animal and again we'll use these terms again in the next couple of chapters another distinguishing feature of animals as compared to fungi and plants is animals have complex development and a fixed body plan so what i mean by this is the the genetic program for the development of a black bear for example going back to this again uh is very very specific from from the from the get-go from a single cell all the way up to to the adult form there are very complex instructions saying okay develop you know a face that's this size and two ears and four limbs and you know all of this stuff very specific so this this black bear is always going to end up having you know four paws and two eyes and two ears it's all very specific um compared to you know your typical plant your typical tree uh you know how tall does this tree grow uh it depends how many how many branches does the tree have uh how long are those branches in what direction and angle do those branches point well that sort of stuff depends on the environment the trees around it where the sunlight is coming in and and things like that so and fungi are similar the body plan that these organisms have is greatly dependent on the environment but animals again in contrast uh have a very complex way of always coming out the same way instead of uh it's got a random number of branches from individual to individual because they're in different environments so that's what i mean by complex development uh fixed body plan another thing that we see in animals is sexual reproduction um this is you know egg plus sperm equals zygote you know breaking it down to you know the simplest way possible uh but we also have asexual reproduction in some animals so yep there's our sexual life cycle and yeah here's an example of asexual reproduction again not all animals can do this but some can here's a sea star uh having a fragment torn off growing into a new individual so animals all have sexual reproduction some are also capable of asexual reproduction now i used this figure in a couple of slides ago but let's look at this more uh in more depth now animal embryonic development um just briefly looking at this trust me there's a lot of detail i'm skimming over but the first few stages here are i think important to understand so uh when animals develop they start with a zygote you know that's the result of egg plus sperm there are going to be a few cell divisions but importantly these are cell divisions without growing in size so this eight cell stage is about the same size as the zygote so it's you know dividing but it's not growing so this is called cleavage uh from there the cells are going to to grow in size and do more divisions going uh going further on to the 16 to 32 32 cell stage this is called a blastula the blastula can be hollow or filled with yolk depending on the animal you're talking about but eventually something is going to happen to this blastula called gastrulation this is where a pore called the blastopore it's basically an indentation forms in this blastula uh this is if you can imagine it because this is still microscopic this indentation is eventually going to lead to the formation of a digestive tract and it's going to result in cell layers we'll talk about both of those things further in the chapter but for now here's my my summary of this animal embryonic development the zygote divides like i said without growing in size several times this is called cleavage one cell two cell four cell eight cell it's simple enough um the blastula is this 16 to 32 cell stage it can be hollow or filled with yolk and then we have that indentation gastrulation occurs as an indentation in the blastula called the blastopore don't get these mixed up the blastula is that group of cells the blastopore is the indentation makes sense it's a kind of like a pore an indentation or whatever as that forms this creates a digestive tract and this results in cell layers so again we'll we'll bring this up again but i felt like i should introduce these terms now okay and another i'm saying because this is this is complicated another thing that i really want to bring up now when we're talking about animals in general is hawks genes so as i said animal development is super complicated and and very specific there are lots and lots of genes that are involved in you know telling us how to grow into a very specific body plan and it takes a lot of genes to you know say to build an arm for example it would be incredibly inefficient to have a huge set of genes that you know say okay make an arm and then another set of genes to say okay make a different arm that's a mirror image and then another set of genes genes that say oh build a leg it's and then another leg it's much easier to use the same sets of genes for all four limbs and just change them slightly this is and i think there are probably some computer science majors the you know in in the course or at least people with a passing familiarity with computer science this is not unlike a scripting language in programming calling on you know other um scripts for example to do these things it's an efficient way of organizing your genes so you don't have to have a separate set of genes for every little piece of the body you can broadly use these sets of genes called homeobox genes or hawx genes applied in different contexts to do different things and you know this is true in that human here this is true in a mouse and so hawks genes because uh animals especially vertebrates uh have so much in common with one another these homeobox genes end up being incredibly conserved you know our arm is very different from the arm of a mouse but the genes that we use to build a basic arm structure there's a lot that we have in common with a mouse so okay how do i summarize this so homeobox genes also known as hox genes are found in virtually all animals these are described as master control genes that can turn on or off many genes that are involved overall in you know the development of a body plan and here is an interesting way to look at the the similarity here when we look at comparative embryology so these are some embryos of six very different animals but at this stage they kind of all look the same it's because they're calling on the same homeobox genes to direct this development it's only as they go further along in their development the things begin to look a little bit different okay we're seeing a slightly different body plan in these two compared to these four let's proceed further with body development and okay now they're looking a lot more fish like over here and looking more like something that walks around on four limbs over here if you you want to know what these are going to eventually end up being fish salamander tortoise chicken rabbit human but again to go back to this at a certain point they all look very very similar to one another that's because of these conserved hox genes in all these different animals giving them the same instructions so again talking about these homeobox genes embryonic development in diverse groups of animals you know from from fish to humans is very similar because of these conserved genes now and another interesting thing about these is if you if you start to mess with these that can really mess with the overall body plan because again these are sets of genes that say okay build a limb like this and build it here and build another limb like this and build it over here if you start making mutations or alterations or duplications in these things that's going to profoundly affect the body plan what do i mean by that well a lot of experiments have been done in fruit flies trying to understand how these work and this looks like mad science but really was just trying to understand how hawks genes work um here is a a fruit fly uh with legs instead of antennae so uh again just by messing with hawks jeans and here's another fruit fly normal pair of wings here just a duplication two sets of wings just doubled up on this part of the body so again this is you know not just mad science even though it looks like it these experiments were done to understand the role of these in overall development so my point here is mutations in in these hox genes or in the expression of them can result in dramatic developmental alterations because that's what they do they're involved in directing development of the body plan messing with them is obviously going to mess with the body plan okay so now we're moving on to a section with a bunch of key terms features used to classify animals and again this is going to seem kind of dry but we're going to come back to these ideas as we go through uh the various and interesting types of invertebrates and vertebrate animals so let's talk about symmetry there are three basic types of symmetry that we see in animals they are bilateral symmetry so this is defined in the key terms as a type of symmetry in which there's only one plane of symmetry so the left and right halves of the animal are mirror images we've got a beetle here but you can look at your own body to see this uh humans have bilateral symmetry uh another type of symmetry is called radial symmetry defined in the key terms a type of synergy with a symmetry with multiple planes of symmetry with body parts or rays arranged around a central disk so there are many ways that you can draw sort of a plane through this animal and have mirror halves on either side and yep here's a coral polyp with that kind of symmetry and finally no symmetry at all so sponges are going to be the exception to a lot of the rules that were laying down there are you know exceptions to these rules for for example and we'll we'll see that when we talk about sponges but sponges don't have any symmetry at all they're more like a tree and how they grow they don't have this complex development that we've been talking about so three main types of symmetry and animals again these two are in the key terms bilateral and radial uh and asymmetrical or no symmetry is another possibility here now to go back to this again one of the things that i mentioned when we have this gastrulation is the formation of cell layers so here's a way to look at this this is an animal this is a cross section of a tube so this is really weird to think about but most animals you know with the exceptions being the simple ones like sponges and jellyfish uh or sponges i suppose um most animals have a tube shaped body humans have a tube shaped body we've got a mouth we've got an anus it you know goes all the way through we're basically just a tube so that creates layers of cells on the outside and on the inside so one way to have a tube shaped body is to be what's called diploblastic diploblastic dye means two diploblastic animals have two cell layers uh an ectoderm on the outside and an endoderm on the inside and this you know non-living layer in between the two of them so diploblastic animals have two cell layers endoderm is the interior layer ectoderm i'm gonna say exterior instead of outside just to try to not get these mixed up anterior endoderm exterior ectoderm they just kind of sound like they fit with one another so you know use that to not get them mixed up and it is possible to be more complicated than this though so diploblastic animals are sort of the simplest way to have these cell layers you can also have triploblastic animals where you have the ectoderm on the outside the endoderm and the inside but instead of a non-living layer of stuff in between you have a third layer of tissue in between called the mesoderm in the middle so these are triplo tri means three triploblastic animals have three cell layers endoderm mesoderm in the middle again miso middle it's easy one to one and then ectoderm on the outside again we're going to see these cell layers come into play in later chapters now among triploblasts there are three additional groups based on a body cavity so uh let's there's a good figure to illustrate this and again all of these are triploblasts ectoderm mesoderm endoderm the difference between these three worms and it's not just going to be worms but the three uh you know examples here are all different worms has to do with an additional cavity here so it is possible to have no additional cavity i mean you have the cavity in the middle that the digestive cavity this is a tube but if you just have the ectoderm mesoderm and endoderm this is called an acelamate body it's possible to have a body cavity here uh within the mesoderm so look at this this uh labeled celium it's spelled it's spelled coelom it is pronounced celem it's weird um it is fully within the mesoderm layer this is important here so animals that have this coelom cavity uh are in addition to the three cell layers of course are called celamates or euselamates and the third way to do this is to have a body cavity in between the mesoderm and the endoderm so look closely at this this this cavity here and sort of light brown is not within the mesoderm uh it's touching the endoderm on one side touching the mesoderm on the other this type of body cavity where you're in between these two cell layers is called a pseudo celium and animals with this are called pseudocelimates so all three of these are are defined in the key terms here and again these only apply to triploblasts acylamates eucelimates also known as celamates and pseudocelimates and and so obviously the key terms provide a you know a wordy definition of these but i i think a picture is worth a thousand words in this case and these are a good way to get these get these straight about what these three uh what these three things mean additionally there is a way to break down animals based on this gastrulation event and this is not going to sound like a very you know important distinction but it's going to end up being a major cladistic split splitting complex animals into two clades based on what this blastopore forms so so in a group called protostomes this initial indentation this blastopore during gastrulation the initial indentation becomes the mouth and eventually is going to extend and and form the anus so remember these are two tube shaped animals so protostomes mouth first then the anus deuterostomes are the exact opposite and there are some other differences in you know their eat cell stage but i'm going to focus on this deuterostomes this initial indentation in the blastopore becomes the anus and eventually extends to form the mouth so protostomes are mouth first deuterostomes are anus first again seems like such a small distinction but it's going to result in two clades because this way of doing things is going to be passed on to descendants and it's a key way to identify your two major clades two major groups within animals so here's my summary of that among animals with bilateral symmetry and a triploblastic body plan so this this distinction of protostome or deuterostome this only applies to bilaterally symmetrical animals and to animals with uh with three cell layers uh anything else is sort of n a if you're trying to say whether it's protozoa deuterostome there are two groups based on what develops from the blastopore protostoma deuterostomate and these are in the key terms but you know to put it simply uh mouth first then anus anus first and then mouth okay so there's supposed to be a section in here about animal phylogeny but that's what we're going to do in the the next couple of chapters talk about phylogenetic trees and all that stuff so i'm kind of sort of skipping this for now ah okay what we do have finally in this in in this sort of short intro chapter to animals is a history of the history of the world history of animals so i i brought this up briefly uh when we were talking about protists but i'm going to introduce this idea again that animals likely evolved from this group of colonial protists these coano flagellates uh and you know here's a a typical sponge cell like coanocyte and yeah it looks it looks just like the protist cell uh so you know again i brought this idea up again but i'm reintroducing it here animals likely evolved from colonial protists having developed a genetic program for multicellularity so these protists were not multicellular they just you know got together in a colony when there are enough of them around animals are all multicellular they just have a genetic program to make them have to form a multicellular structure instead of just a colony so there's genetic evidence for this you can sequence coanoflagellates you can sequence sponges and their their sequences look more similar to one another than to anything else and then of course the the physical traits that i just showed sponges share physical traits especially in these choanoflagellate cells uh or i'm sorry coanocyte cells looking like sponges share physical traits with these protists as well so this is the the origin of uh animals from from these colonial protists okay now we can move on to history of the world and this is way more complicated than it looks uh but even so we we don't actually have time to get into this in this particular recorded lecture uh this is where i typically run out of time in in-person lecture so we will talk about history of the world the evolutionary timeline focused on animals in the next recorded lecture this is the end of three one