Kia ora koutou, ko Douglas Walker, toku anua. I'm here tonight with Emma Campbell of Wellington Girls College. Emma is an expert biology teacher and she's going to run us through level three plants and animals tonight.
If you've got any questions please do just enter them in chat and I'll either, if it's an opportune moment, I'll interrupt Emma and ask her that question otherwise I'll collect the questions and ask them of Emma. at the end. So please do type your questions in chat and we'll look forward to raising those questions with Emma.
All right, without further ado, over to you Emma. Cool. Kia ora.
Welcome to this tutorial on Bio 3.3, Air, Plants and Animals External Standard. As Doug mentioned, I am Emma Campbell. I'm one of the biology teachers at Wellington Girls College and I'm going to take you through... the standard and also some questions, past exam questions and have a bit of the chat about a potential framework to work within with the standard.
So I'll just share my screen for you. Apologies. Fantastic, sorry about that. So as I mentioned we're going through plants and animals and I'm a very visual learner so I like to have a kind of a mind map to visualize how this topic fits together. I think it feels like there's a lot of content but when you look at it like this you can kind of see that actually it's not as big and scary as people might think it is.
It just covers quite a bit of stuff about plants and animals of course. The key idea is around how animals and plants respond to their external environment and the adaptive advantage of those responses. So pretty much why do they do it? So we can split the external environment up into looking at biotics, so the living environment, both members of the same species.
but also members of a different species as well. And we can look at how they respond to their non-living environment. So we look at their orientation spatially, but also in time as well.
So when it comes to this topic, I'm sure you'll recognise this. I've always looked at these and thought, well, what's the difference between demonstrating, understanding, demonstrating in-depth understanding and a comprehensive understanding? understanding?
What does that actually look like? And the way I have broken it down and talked to my students about is describing something demonstrates understanding. So that is saying, what is the response? Identifying what are the key terms, giving your definition. So what is actually happening?
What's the plant doing? What's the animal doing? And merit is more about, well, what's happening inside the organism? So How is it responding? What's actually happening within the plant or within the animal that allows it to respond in this way?
And finally, excellence is about linking ideas together. So that might be about linking to the adaptive advantage. Why are we seeing this? How does it help survival and reproductive success of the organism? Or it might be linking to the context of the question.
So often in this exam you get told quite a bit of information about the particular species and you want to be able to use that information and tie your ideas to it. So the examiners don't expect you to know every single thing about every plant or every animal, but they will give you any kind of information that they think is relevant. about that plant or animal and they expect you to be able to, I guess, read between the lines and work out exactly what it is that you are, how you can apply your ideas to it.
So back to this, I thought we would start off looking at the abiotic side. I think the biotic side, the intra and interspecific relationship is something we can actually visualize quite a lot when we look at our pets interacting with other animals and things like that. So it's a lot more relevant but the abiotic tends to be, I guess, the side that people might struggle to get their head around a little bit more. the more abstract side of things. So I thought we'd start out by talking a little bit about plants and how they orientate themselves.
So again working within that framework of what, how, and the adaptive advantage, we've got anastic responses and atropisms. So you want to be familiar with what is the response, so a non-directional movement and response to stimuli. In nastic response we're talking about venous fly traps for example.
They are able to move, it's not a growth movement. So how do they actually do it? It's not like they've got muscles like animals have. But they have actually the ability to control the turgor pressure of the cell. So the ability to draw water in or expel water out of the cell.
which is going to change the, I guess, the swollenness of the cell and cause these rapid movements. The adaptive advantage is going to be very much dependent on the context of the question. So for venous fly traps, for example, it's going to be around the digestion of the fly, they're extracting the nutrients. A lot of people talk about it eating the fly. Just be careful about this because they actually still photosynthesize.
That's not how they get their glucose but they get other nutrients that might be missing from the soil. Another one of course is tropisms. So this is one that comes up a lot in exams. So it's either growing towards the stimuli or away from the stimuli.
So the difference between that and a gnastic response is about growth. and the directional response. And it's caused by auxin.
So you would have learned about the plant hormone auxin that elongates cells and shoots and inhibits cell elongation and roots. And that's a how that becomes really important. So take for example this question on manuka. So this is taken from the 2017 exam and it's asking students to talk about tropisms in a newly germinating seed below the soil and be really careful with how you read questions because lots of students read this and immediately started talking about tropisms in plants, photosynthesis, positive phototropism but actually it's about below the soil level.
level, so light isn't a stimulus. So what the question is asking is it's talking about a radical, so a root and a plumule, so they're just the official names for roots and shoots, and how Michoamanuka trees also release chemicals into the soil. So what we can do is have a look at the question and get a feel for how our framework fits within that how, that what, that how, and the advantage with it.
So identify and describe the two different responses shown by the manuka seedling when it germinates below the soil. So again it gives you that hint for below the soil. So we are going to be talking there about positive and negative geotropism.
So I will just change my screen that I'm sharing so we can actually write on it. One moment, here we go. Sorry about this one.
So we've got a positive geotropism. That is in the roots because it is growing in the direction of gravity. So gravity is a stimulus and a negative geotropism. is what we're seeing in the shoots in the plumule as it grows against gravity.
So that is our what. So identify and describe. So you need to identify the name of the tropism, but also then describe what's acting as the stimulus. So the roots grow with gravity, the plumule will grow against gravity.
Finally, explain the interaction between the mature manuka and other plants growing nearby due to the release of the lactose boron in the soil. So that is around this through people quite a bit because it's there's a number of different ways that you could talk about it. Some students talked about allopathy. So you may have learned about allopathy which is when plant will release a waste product into the soil and it inhibits the growth of other plants. Or you could talk about it simply as exploitation relationship, which is when one organism benefits and the other is harmed.
So the manuka will benefit because it is able to reduce into a specific competition. It's inhibiting other plants from growing nearby. and so that they are able to get all the nutrients they need from the soil and have access to enough sunlight without having to compete with neighbouring plants.
It obviously will harm the other plants because it's a herbicide so it inhibits growth, it stops them being able to survive. So you can talk about it as an exploitation relationship. And because it's a herbicide, it's not going to help. question, it's an explain. You want to say how are they benefited and how are they harmed?
How are the other species harmed? Cool. Then we've got explain responses that occur below the soil level as the manuka germinates.
So this is when we get into the talking about the oxen, talking about what is actually happening. in the plant. So hopefully you have seen some sort of version of this diagram.
And so what we see happening is auxin, which is produced in the plant, it's a hormone, it sinks with gravity. So what we end up with is when a seed is growing horizontally, we end up with a buildup of auxin in the cells on the lower side, so as it goes with gravity. And because auxin behaves differently in cells in the shoot of the plant to in the roots, it causes the shoot and the roots to behave quite differently.
So auxin causes the cells to elongate in a shoot which causes, means the plant will bend upwards. In the roots however, the buildup of the auxin on the lower side of the roots will inhibit elongation. So while there is an amount of natural elongation in cells, the auxin is going to stop that from happening. And so it will cause the plant roots to bend downwards. So that's the actual mechanism behind it, what's actually happening inside the plant.
And then finally we go to a question around discuss the adaptive advantage of these two responses below the soil and compare them with the response once the plumial is exposed to light. So pretty much why is the plant doing it? Why is all this effort and work going into the shoots growing up and the roots growing downwards?
And that's when you need to I guess think about well what do, what are the roots in a plant responsible for. They're responsible for extracting nutrients from the soil. They're responsible for gaining water, which is really important for photosynthesis. And we know that plants need photosynthesis to make glucose as an energy source.
And we know that roots are really important for stabilizing and anchoring a plant into the ground. So these are the ideas that you will discuss. in terms of the adaptive advantage. In terms of why is it then important that the shoot grows up?
Well a seed's only got a finite amount of energy stored within it, within the food store, the cotyledon of the plant. And so it doesn't want to waste time growing in the wrong direction. It wants to be able to orientate itself quickly so that it can break through the surface of the soil and start photosynthesizing. Once it breaks through the surface of the soil, then light becomes the major stimuli and positive phototropism will kick into action as it grows towards that light source. So it's just a measure to, I guess, get it to where it needs to go quickly.
Then moving on to talk about animals. So we've got our orientation in space with animals, so you would have learnt about taxis and kinesis. So I think of kinesis as quite similar to nastic responses in that it's non-directional.
The animal is simply responding to a stimuli, it's not moving towards it or away from it. Instead, it's changing its speed or it's changing its rate of turning. The way I remember the difference...
is ortho so orthokinesis is when it changes its speed ortho is um a another word i guess for straight so orthopedic surgeon is somebody who will straighten bones um and so that's how you remember that whereas clino is about turning uh taxis is a movement towards a stimuli or away from the stimuli so think about If you lift a log and it's got slaters underneath, they will try and move away from the light source that they're exposed to. The adaptive advantage of both of those is that they want to get themselves out of unfavourable conditions. So whether it be light or moisture levels or towards a food source, they want to maximise their time spent. favourable conditions.
And then we start to think about the longer term distances. So that's where our homing and migration come in. It's often asked, homing and migration, the difference between the two. So migration is about a two-way mass movement whereas homing is just finding your way home. over unfamiliar territory.
Again working within our framework here what, how and our adaptive advantage. The how, the things that you want to be thinking about in terms of how migration occurs is what does the animal do to prepare for migration. So it might be something along the lines of a change in diet to build up fat stores.
It might be if it's a bird changing its feathers so that it's got feathers that are going to allow them to make that really long distance and triggers. So what is actually happening to trigger the migration movement? So when does the animal know when to go? Because you don't want to be the only bird that migrates and arrives at the breeding ground.
and no one else is there. So they need to synchronise themselves. So often it's an element of an internal biological clock, but also environmental cues.
More often than not, the cues that we're going to be looking at would be around daily temperature, would be one that you think would be a good trigger, particularly because migration is often seasonal. But Temperature is notoriously unreliable. Like you get hot days in summer and you get cold days, hot days in winter, sorry, and you get cold days in summer. So daily is actually probably a much more reliable system.
And then finally, how are they able to find their way? So for an animal to migrate or to find their way home, they need to first know where they are, but also what direction they're headed in. So that's where navigation comes in.
Now, unless they tell you what... navigation methods or what triggers what preparation the animal does they will be pretty open to interpretation I had look at some exams and it said things like what might the animal use to navigate which means that you could as long as you can justify what they'll do so maybe solar and magnetic fields then then they will mark that as correct. If they tell you in the context of the question, then they do expect you to identify that.
So make sure you read those questions really carefully. Again, with the adaptive advantages, it will vary depending on the animal and the evidence that they give you. But if you can talk about how the animal is going to spend time in favourable environments despite the seasons changing, maximizing food and breeding opportunities.
Anything that you can relate to increased survival and increased reproduction is really important because when it comes to the plants and animals the aim is to survive, to breed and to pass your alleles on to the next generation. However it is a high risk, high reward system so it takes a lot of energy. It leaves individuals really vulnerable to getting lost, also vulnerable to predation. I think everybody's probably seen those videos of bears and rivers eating salmon as they make their way upstream.
If your predators know exactly where you're going to be in a mass number, then there's every chance that they'll be there waiting for you. So things like that. However, when it comes to talking about the adaptive advantage, although there's cost, it's really important to recognise that the advantages outweigh the costs, otherwise they wouldn't do it.
Cool. So take this city share water question that was from the 2000, I think also from the 2017 exam. So pretty much what happens is the city of Shearwater spends part of the year in New Zealand.
And then when it starts to cool down, it will fly up into the northern hemisphere. So as we head into winter, it leaves in about March, May, and flies up into the northern hemisphere, arriving about June, July. from there they will return back to New Zealand in November. So actually they're probably returning about now. So they don't migrate as a flock okay so they do it individually which is interesting for birds.
Lots of birds will migrate together and share I guess share the load and learn the direction from one another, from the more experienced birds, but these guys do it individually and can actually fly 500 kilometers a day, which is massive because they're not that big of a bird. But if we look to the question, we can see that actually it still follows that framework from the earlier question, that what, that how, and the why. So describe migration.
That's where you're going to talk about what is migration. what is actually happening. Explain how the city shear water might determine the time. So that's where you talk about the how.
So how does it know when to go, the triggers. So it migrates once it's ready to breed, so that internal biological rhythm reaching sexual maturity and then also environmental cues that tell it the time of year as well, so day length. and how they may navigate. So notice they use their word may meaning they don't expect you to get it right.
but to use some kind of justifiable reasons. So for example, you probably wouldn't talk about them navigating using ocean currents because they're in the air, okay? So you could talk about them perhaps using the sun to navigate or the stars.
Lots of animals will use multiple navigation methods, so they might use the sun, the stars, and then on a cloudy day or cloudy evening, they use magnetic fields. because when it's such a high risk undertaking, you want to have a backup. So if you're going out driving cross-country, you might have a GPS, but you might also have a map in case your GPS fails.
Because if they get it wrong, they risk ending up in the wrong place, and they definitely don't want to be doing that. So that's our how, our what's actually happening with the bird to allow for this to happen. And then finally, we move into the costs and the benefits.
So talking about, well, what's the advantage to the city shareholder? But what are the costs as well? Recognising that it comes with a high energy cost and they could potentially get lost along the way, particularly because they do it alone.
And so they have this innate genetic sense of... direction or need to migrate but it's not always fail proof. But it's important to recognize that actually your benefits will outweigh your costs otherwise they wouldn't leave they would just stay in New Zealand. This is a trait that is not something they can control it's innate it's genetic and so it's been selected for over time.
So that's really fast through how plants and animals orientate themselves in space. But we can then look at time, I think, photoperiodism in terms of plants, and also actigrams and biological rhythms in terms of animals as well. So photoperiodism is how plants orientate themselves, because it's really important that plants are able to, I guess, synchronise their behaviours, synchronise their responses.
So it's important that they flower when other plants are flowering, otherwise you're not going to get any cross pollination. It's also important that you flower when your pollinators are active. You don't want to be the flower that is flowering in winter but your pollinators are hibernating.
So they have this phytochrome system which can feel quite intimidating because there's lots of words that sound the same. But if I was to be given a photoperiodism question, the very first thing I would do would be to draw this diagram on the page, even if it's just up in the top corner, to help kind of refresh my memory and help me to keep track of it. So pretty much there's a pigment called phytochrome.
There's phytochrome that exists in two forms, phytochrome red and phytochrome far red. Now the really interesting thing is the pigment can change between the two. So phytochrome red can change into phytochrome far red and phytochrome far red can change back to phytochrome red.
So what's happening is during the day when it's sunlight. The sun is shining, we know that the sun is made up of white light, so all of the colours of the rainbow are roi gibbiv. Roi, of course, beginning with R, red light is part of that. So what is happening is the sun shines, the plant is absorbing that red light, or the, sorry, the phytochrome red absorbs red light and it converts really quickly, really rapidly into phytochrome far-red. Then at night when the sun goes down, phytochrome far-red absorbs far-red light, which is just outside of the visible spectrum.
And it will slowly, very slowly convert back to phytochrome far-red. So phytochrome red to phytochrome far-red is really fast. converting back from phytochrome far-red into phytochrome red is really slow. So what actually is happening is there are three types of plants. There are short day plants, long day plants, and then day neutral plants.
So what phytochrome far-red does is it promotes flowering in long day plants and it inhibits flowering in short day plants. Day neutral plants, it doesn't affect it. Phytochrome red, the other form, doesn't actually do anything. It's inactive. It's only phytochrome far red that is the active form.
So take now for example, the days are long, it's summer, we're heading into summertime, so our days are stretching out longer and longer and so A long day means that we get a lot of conversion from whareka and red really rapidly into whareka and whare red. Because the days are long, the nights are short. So what is happening is with a short night, we don't have enough time for that slow conversion back from whareka and whare red into whareka and red.
So by the time the sun rises again at about maybe five in the morning, we still have... phytochrome far-red left in the sows and that is going to cause our long day plants to flower and it's going to stop our short day plants from flowering. During the winter we've got really short days and really long nights and because the nights are so long by the time the sun rises again maybe at eight o'clock in the morning all of the phytochrome far-red has converted back. to phytochrome red.
And so what that means is the long day plants will not flower and the short day plants will flower. So they're the plants that flower during winter time. So that is our how. What is the fact that the plants orientate themselves using the system, okay, in terms of time? Our how is talking about this diagram here.
talking about phytochrome red, phytochrome far red, promoting light, inhibiting flowering, inhibiting flowering etc. And then the advantage of it is the fact that the plants can synchronise their responses so they can make sure they all flower at the same time or they can make sure they are flowering when their pollinators are active. So as I mentioned before, The first thing I would do in an exam about phytoperiodism is draw that diagram. The next thing I would do is have a look at any kind of added diagrams that they give you. So for example, this diagram here showing the short day long day plants flowering is really common and how scientists expose the plants to different different types of light, okay, and ask them to explain what is happening and why.
Now this can get really confusing and it's easy to kind of get yourself muddled up, so that's why I say draw the diagram so that you can kind of follow it around with your finger, okay. So take the first plant on the left, okay, here we've got a long day and a short night. So we can see that we've had all of the phytochrome red convert to phytochrome far red, but it hasn't all converted back. So a long day plant is flowering, a short day plant is not.
Whereas in the second one, we've got the opposite situation. So what we see happening in winter. Then they often ask you to talk about, well, the scientists have... expose the plant to red light for an hour during the middle of the night and talk about what is happening there.
And all you need to do is think back to this diagram and think okay so phytochrome red has converted to far red and then it has converted back but because they've exposed it to an hour of light the phytochrome red once again converts to far red. So what we've ended up with is two short nights instead of one long night. Okay, so it can be, it can feel quite confusing initially when looking at this stuff, but if you just draw this diagram and think, okay, well, what are the scientists actually doing, then it can help you to make sense of it. Okay, another question that often comes up. is around actigrams and how to read actigrams.
So this is about timing responses in animals. Again, we can use our framework of what is happening, what is the rhythm that we're looking at, how is it happening, what's controlling it, for example, and then what are the adaptive advantages behind it. Before we can look at actograms, we want to, before we can answer any questions about actograms, we want to be familiar with how to read them.
So I've put one in here just so that we can kind of talk through it. And then we'll have a look at what that may look like in an exam question. Okay. So here we've got an animal that was held in captivity for 16 days.
During those 16 days... we monitored their activity, when they were active and when they were not. So the first thing you need to look at is the axes, the x and y axes, just like with any graph. So we've got the, going up the side, we've got days 1 to 16, and along the bottom, hours 0 to 24. So we know that because we're talking about 24 hours, we're going to be talking about a daily rhythm.
The reason I use daily and not circadian is because we use circadian rhythms when we talk about an internal biological rhythm. We'll come back to this in a moment. But essentially, the black marks on that actigram show us when our organism was active.
So from days one to eight. they were kept in 12 hours of light and 12 hours of darkness. So we can see that once it became dark at hour 12, our organism became active.
So that is our daily rhythm and they are nocturnal. Okay so that's our what. Okay now we want to have a look at well what actually happens when we start to manipulate the conditions. that our animal is in. Does this rhythm change at all?
So what they did from day eight onwards is they kept the animal in constant darkness. So they took away that environmental hue and they measured does the animal still follow a similar pattern? Is this internal or is it driven completely by light and dark? And you can see that actually it's about the same. the animal still becomes active and goes to sleep approximately every 12 hours.
So we can conclude that in constant conditions, the animal still shows this rhythm, so it is endogenous, endo meaning within, so it's internally driven. So from now on, we can give it that circa prefix, that circadian rhythm. Okay, so some of the keywords I've put down the side are our endogenous rhythm and zeitgeber. So zeitgeber means environmental cue.
So in this case, from days one to eight, our environmental cue was light and dark. That's our zeitgeber. When we remove that, the... rhythm continued, although it shifted slightly.
From that we can say that it is endogenous. We can also say that it is now free running, which means that it's running completely on its internal biological clock and not using environmental cues. Most animals rely on an internal clock, but also the environmental cues, the zygobers, to help. them keep their rhythm entrained.
We'll talk about why that is in a moment. So this is what we would expect. from an animal is that the rhythm still happens but it shifts slightly.
Okay so you may notice for example in the summer holidays perhaps you sleep a little bit later each day and because you slept a little bit later you go to bed a little bit later and eventually you get out of sync with your usual rhythm. When you go back to school you start setting an alarm clock which will help you to wake up. and to go to sleep.
So that is when you become entrained. A phase shift is what we see happening when the rhythm gets shifted. Okay so if you were to travel overseas for example you might feel a bit groggy for a couple of days because you're jet lagged but eventually your body adjusts to the same to the change and you go back to your being awake going to sleep being awake going to sleep cycle. That has been a phase shift. So these are words that the examiner will expect you to be able to use and to apply into the context.
So what I have here is a question from the 2016 exam. And it is a question that I guess threw a number of people because it's got two actigrams and they're showing slightly different things. So essentially they took a tree wetter and they placed it in an environment where it was in constant darkness for a number of days, looks about 45 days or so okay. They kept everything constant temperature, darkness etc. all the same to observe its biological timing.
So we see that in graph one. What they then did was they took a second wettif and they placed it in a environment where it was kept in 12 hours of dark, 12 hours of light for 18 days. At which point they exposed it to an extra eight hours of light when it should have been dark.
So they cause a phase shift, okay? And then they put it in complete darkness and observe what happens. So once again, if we look at the framework of our question, it follows that what, how, and adaptive advantage. So what is the activity that we're looking at? Well, we're looking at a circadian rhythm, okay?
And it's nocturnal. At the top of the question in the first paragraph it talks about the wetter being active once the sun sets where it will come out and forage for foliage and plant material and then during the daytime it stays hidden in holes in the tree or under the bark. So that's our what. Our how. okay, is what we can talk about with what's happening in the graphs.
Okay, so it's really important that you use these actograms. They wouldn't have given you them if they didn't want you to specifically talk about them. So explain how the rhythm is controlled. Well, we can see from graph one that it's going to have an internal rhythm, an internal biological clock.
It's a endogenous rhythm because it continues once it's in complete darkness. In normal circumstances it will be entrained to daylight. We can see that in graph 2 from days 1 to 18 where the wetter becomes active at the same time every day once it's in 12 hours of daylight, 12 hours of darkness. Then explain the effect of the additional eight hours on day 18 of the wetter and then what happens after it well what they've done is they've they've caused the phase shift so they've caused the wetter to be like oh i thought it would be dark but it's actually light i'll stay i'll stay hidden and remain inactive and then they cause that shift in the um biological rhythm okay so just like you would experience if you traveled overseas, okay, the wetter experience its own form of jet lag, I guess, okay, but call it a phase shift, not jet lag. And so then once it was kept in constant darkness, it goes into that free running period where it's approximately every 24 hours, but not exactly.
And then the final point that, well, why does it do this? The adaptive advantage, why does it have this control mechanism? Pretty much the wetter is the reason it was being active during the day. is to avoid predators okay birds okay um it's not about um food gathering okay it eats plants that are around day or night okay might be reducing competition but probably most likely reduces um predation and so it means that they can predict when night is going to be it means they don't have to keep poking their head out of the from under the bark. Is it dark yet?
No. Okay, go back in. So they can predict when the sun will set because they've got this internal mechanism, this internal clock, and it's going to maximize their feeding time.
It also means that they can adjust their changes, their behavior for summer versus winter. So for example, in summer, the sun sets much lighter, so they can adjust for that as well. Okay, so now we'll move into the biotic side of things. So the intraspecific relationships and the interspecific relationships. Again, we can apply that same framework, the what, the how, and the adaptive advantage.
So I know this is a lot of reading, you can pause the video and have a read through, but describe the response as well what is the intra-specific relationship. So we'll start with talking about intra-specific relationships. How does it occur and what's the advantage or the cost of this response? So a lot of the behaviors that we talk about with intra-specific relationships in terms of territories and hierarchies is about reducing competition because when it comes to competition nobody wins okay even the individual that gets access to the resource has had to spend energy that they wouldn't have had to spend otherwise okay so individuals of the same species might compete for mates they might compete for food nesting sites And we sometimes see this competition occurring through aggressive displays.
So think about primates like baring their teeth at one another, calling to one another, beating their chest. It's not to do, very rarely do they end up actually fighting or hurting one another. Because there's not really a whole lot of advantage in that.
If you can scare your competitor away simply by showing off, then that's better for you. Some other ways to reduce intra-specific competition is through territories. So having your own specific area of land that you have access to the resources in. And you are going to defend this. area you're going to stop anyone else from accessing it and you're going to do that by marking your scent so you often see like tigers rubbing up and down trees okay or like your dog for example might pee on the side of the house or on the car tires that type of thing it's marking its scent it's communicating with other dogs that this is my space okay or it could be aggressive displays.
The advantage of it is they get access to whatever's in that territory whether it's food, nesting sites, a safe place to raise their young, mates, but it does come with a cost and that cost is the energy that is required in maintaining it, particularly at high densities. The more individuals in an area the more they're going to try and come onto your territory. So the more energy you need to put into actually defending it. Another system is a system that we see in groups, which reduces intra-specific competition, and that is a hierarchy.
So that is a ranking system, which determines how resources would be shared out. So, for example, there's often, there might be an alpha, which would be the highest ranked individual, and they have access to food first, they have access to breeding mates. and then beta and then ranking down to the omega.
Now different species will have different systems, some might be quite linear so each person has an individual or each organism has an individual rank, others might be more banded okay so there might be a number, a couple of different betas for example. Again the advantage, the why, do they do this? Well if you're the alpha it's great for you because you get first access to resources, it's going to reduce competition because everybody knows that you get first access. And it also is going to be good for the species because you might be the strongest so you will have the alleles most suited to that environment and you will get to breed and pass them on.
For the lower ranked individuals, the omega, you get the chance to be part of the group essentially. So even though you may not get access to food first, you might have to wait your turn, you still get food that you may not have gotten otherwise. Okay and then we've got the more cooperative behaviors.
So the Group formations, we often see this in animals that work together in a group. So think lions or wolves, that type of thing. So they're actively responding to one another's presence.
So they could be closed groups, which means that you can't just come and go. Or they could be open groups, which are individuals can kind of come in and leave as and when they please. So a school of fish, for example. There's a number of example advantages to being part of a group of animals.
It means that you can share responsibilities. So for example, share the cost of raising young. You work together to get access to resources.
So lionesses, for example, hunt together to take down prey much larger than themselves. Diversity in numbers. in terms of predators, think about meerkats, there's always one like Sanctuary which is on the lookout for predators and then that also comes with a cost so competition for example, high density living is leads to an increased spread of disease so although there is increased interest specific competition a lot of species will get around that by hierarchy system.
Courtship and peer bonding is another cooperative relationship. It's about communicating with a mate that you are interested in breeding and what that relationship will look like. So for example, a monogamous relationship is when individuals have one single partner.
These could be short term for a breeding season or long term over a number of years. The benefit of that type of relationship is that they often share the cost of raising the young. So both parents are involved in raising the young, which has an energy cost to it. Then you've got the polygyny relationship, which is when a male may breed with multiple females.
so increased reproductive success, the poly-gaiandry relationship which is the vice versa and then the polyandry relationship. So each of those comes with their own adaptive advantages. And finally once they have the offspring, how much time and energy do they put into it?
So for example animals only have a very finite amount of energy. So do they put their energy into having a small number? of an offspring but they they protect them they look after them and the offspring have a higher chance of living or do you put that into what we call the our strategy which is when you don't raise your young but you take that energy and you put it into having lots and lots and lots and lots of offspring and surely purely by chance some of them will survive you So that's the strategy that we see, for example, in like seahorses and octopus, where in turtles, they have a whole lot of offspring, but most of them are going to die.
But because they've had so many, then by chance, some of them will live. Whereas a K strategy might be like an elephant, where they actually have very few offspring, but they look after them, they raise them. So this is from last year's exam. So the bat-eared fox. So a little bit about these species is they are a monogamous peer breeding, peer bonding, which means single male, single female breeding partners.
And once the pups are born, the father spends a lot of time helping to raise them as well. So they live in groups. They're not territorial, so they're not aggressive to one another.
And they groom one another. So allogrooming means grooming between members of the group that you're not necessarily related to. but both parents play a role in the parental care. So once again, we can apply our framework, our what, our how, and our why, or adaptive advantage. So what is meant by the terms monogamy and parental care?
So monogamy, one partner at a time. parental care, the parents providing protection and support to the young. An explanation of an advantage or disadvantage of each of the monogamous relationship in parental care. So why do we see this behaviour?
So the monogamous relationship means that because there's only, there's two parents involved, okay, they both share. the cost of raising the young. Okay but that comes with a disadvantage as well, particularly over long-term peer bonding.
So animals that might mate for life for example, it reduces genetic diversity because you don't get the same kind of exchange of alleles between individuals within the group. Parental care, the advantage is obviously to the young. and that they're much more likely to survive as individuals but the disadvantage is that that comes at a cost for the parent that requires energy to do that and it might mean that they're putting their energy into their pup survival instead of into their own survival.
And then finally discuss how behaviors mentioned above can enable the group to be successful despite potential negatives. of the behavior so you're kind of linking the ideas together here you're talking about the fact that because they're monogamous it allows them to share that cost of raising the young so put more effort into the parental care okay because they are living together as a group they're able to groom one another they are able to bond with one another and we start to see that that peer bonding So whilst there are downsides of these two behaviours, it's important to recognise that the positives are always going to outweigh the negatives, otherwise we wouldn't see this behaviour being selected for over time. All right, we're getting through.
Just quickly through the inter specific relationships and then we will finish up. I don't want to keep you for too long. into specific relationships. you may be a bit more familiar with because we see them we see them all the time so we've got mutualism um we're both members of the group benefit that is a really good example would be the flower pollinator example we've got commensalism so when one benefits and the other is unaffected so here we've got the shark and the remora fish the shark um as it eats will drop food and so the remora fish will pick that up. They benefit because they get access to whatever the shark's dropped.
The shark's not affected because it was dropping it anyway. Another example might be like a bird sitting on a rhino horn. Exploitation is one, so predation, obviously the animal getting eaten is harmed but the predator is benefited. And then finally competition.
when it comes to competition nobody wins because even if you get the resource it's come at a cost. Finally the last idea that you want to be familiar with are I guess strategies that we see in the exploitation relationships. So what does the predator do to increase its chance of surviving, of getting food, of being able to eat? But what does the prey do? because it's not defenseless.
It has some strategies of its own that are going to increase its chances of avoiding being eaten for example. Mimicry is a really interesting one where palatable species, so species that can be eaten, look very similar to unpalatable species, so species that cannot be eaten. as a means of trying to, I guess, avoid predation. Cool.
Okay. So that takes us through that whole topic. That was a marathon effort.
But, yeah, thank you very much for listening. If anyone's got any questions or anything. Well done, Emma. Thank you very much for that.
I really like that step-by-step approach through the what, the how, and the why. as well as your summary tables. And I hope a lot of students will get benefit out of pausing and going through those in a careful approach.
I really liked that question about the wetter. I remember trying to get my head around that at the time. And those two actograms were quite confusing.
So thank you especially for throwing that one in there. We haven't got any questions in chat, but I thought I might ask, what advice would you give to students? as they're preparing for the plants and animals paper? I would say past exam questions are really important, a really good approach.
I think whilst it's important to have your head around all the ideas, that higher level thinking is often about how you use the evidence that is given to you. And so the best way to practice that is to just work through. those past exam questions and practice extracting okay so they've told me about the bat ear fox and its grooming behaviors why have they told me about that and think about what how can I apply this to my understanding the next piece of advice I would say would be to make sure you set aside five minutes for each question to actually really plan it out um you It's really easy to go off on a tangent and to waffle. And before you know it, you've written four pages and actually haven't answered the question.
So setting aside five minutes for every question to actually, okay, what am I going to talk about? Write a plan, jot it down on the page, and you can tick it off as you go. Fantastic advice. Thank you very much, Emma.
And just a mention from... Tony Cairns that he really appreciated that and it was brilliant revision so thank you very much Emma and we look forward to catching up with you tomorrow night at the same time for the next and level three biopapers awesome fantastic looking forward to it thank you see you