Skip to 0 minutes and 1 secondKAREN HORNBY: So hello to Beverly and Alex. And we've got some really interesting questions, which caused quite a conversation in the office today, actually, trying to work out some of the answers. But because plants carryout photosynthesis and respiration, if you had a plant and a mouse, for example, in a closed system in a box with the door shut and the windows closed, would the mouse be alive in the morning? So I'm assuming this is just referring to the plant would also be taking the oxygen. And if not, how would we explain that to students?

Skip to 0 minutes and 45 secondsALEX JENKIN: Someone asked me on the weekend about having plants in your bedroom, and whether that was bad for you because they use up oxygen and light. But I think, I suppose the key questions about this system is, how big? How big is your plant, and how big is your mouse? How big is your animal? So for example, a case of a few house plants in your bedroom is probably going to be fine. So, yeah, the attempt of approaching it with students, I think the answer is if your plant is big enough, could it use that much?

Skip to 1 minute and 21 secondsBEVERLEY GOODGER: And think it does depend on the size of the plant. But I mean, if an animal shares a closed space with another animal, usually by morning, both of them are alive. And they're both consuming oxygen. And therefore, I can't see-- I can't imagine a plant consuming more oxygen than an animal of the same size as the one that's asleep in the room. So in my mind, it would be unlikely that the plant would be the cause of suffocation in the animals in the room.

Skip to 1 minute and 59 secondsALEX JENKIN: Yeah. I mean, obviously, the bigger your plant, the bigger the space you need. Therefore, you've got more gas in the room to start off with. So yeah, I'm thinking about metabolic rate as well, how much do the organisms need to survive.

Skip to 2 minutes and 16 secondsBEVERLEY GOODGER: It would be interesting, wouldn't it, to work out oxygen consumption per gramme of animal, and oxygen consumption per gramme of plant during respiration at night. And work out whether or not, what volume of gas you'd have to have to support them both. Without doing the calculations, I agree with Alex. I think if it was a small plant, I think it would probably be-- well, there would be no problem at all.

Skip to 2 minutes and 45 secondsALEX JENKIN: Yeah, we're just talking overnight. Whereas if you put them in an environment where it was dark for longer than a period of, say, 12 hours-- that's quite a long night, anyway. So with that, actually-- because of the length of time comes into play as well. So as soon as it gets light in the morning, your plant's photosynthesizing again, as well as respiring.

Skip to 3 minutes and 12 secondsBEVERLEY GOODGER: I think if you wanted to make it as accurate as you could do, you could find some information on oxygen consumption per mass per unit time for the two organisms involved, the respiring plant and the respiring animal, and then make a direct comparison. So you could actually make it quite a mathematical investigation and get some maths in your science lesson.

Skip to 3 minutes and 40 secondsKAREN HORNBY: And I would have thought as well, you could link it to an biomes and ecospheres, where they've made those exact calculations. So we've got one here. And the bought ones are not cheap, I must say. But what you've got in here is seawater and living shrimp, although they're a bit tiny to see, microorganisms which provide CO2 and green algae as well. And so it is photosynthesizing. And that will last up to three years, although they have been known to go for 10 years. That's definitely an interesting thing to discuss with students, because I think they're looking into this sort of thing with planning trips to Mars, et cetera.

Skip to 4 minutes and 35 secondsALEX JENKIN: Oh, yeah, very interesting. I like that.

Skip to 4 minutes and 39 secondsKAREN HORNBY: I think NASA's doing quite a bit of research into how you can have ecospheres or closed systems with plants, animals, humans, bacteria, and so on.

Skip to 4 minutes and 52 secondsBEVERLEY GOODGER: Yes, but back to the overnight, I think if you're going to open the doors and windows in the morning, I think on the whole, the animals in the room would survive.

Skip to 5 minutes and 7 secondsKAREN HORNBY: Can a fluorescent bulb alone in a closed room without windows-- is that OK for photosynthesis? So this is a question about the wavelengths of light, I presume. And does it have to be natural light?

Skip to 5 minutes and 24 secondsBEVERLEY GOODGER: Alex might support that. Because you've done quite a lot with SAPS on that, haven't you?

Skip to 5 minutes and 28 secondsALEX JENKIN: Yes. Yeah, so a standard fluorescent lighting in a room is fine for keeping a plant alive. It depends on your plant. Some plants do do better in high light environments. But fluorescent tubing is exactly what they use in plant growth chambers. So here at the Sainsbury Laboratory, they have plant growth rooms. And they're filled with very-- albeit, very bright fluorescent tubes. And that's what they use to grow those plants. So the wavelengths that you get are fine. With a fluorescent bulb, it tends to get a curve of wavelengths, whereas with things like LEDs, you tend to get peaks of individual wavelengths. But actually, you don't need natural light for photosynthesis to happen. The fluorescent tubes are fine.

Skip to 6 minutes and 25 secondsIf you're doing a photosynthesis experiment, on the other hand, or a photosynthesis practical, it's really important that your bulbs are as bright as possible. Otherwise, you'll struggle to get a result in the amount of time. So for example, with the algae balls that we talk about, you can take a tube of algae balls and put them in a room with no windows and under fluorescent light. And the indicator will eventually change colour because the algae will photosynthesize. But that won't happen within the space of a lesson that you're teaching unless you're using a very bright bulb. So we recommend for photosynthesis practicals, we recommend bulbs that 1,200 lumens or brighter.

Skip to 7 minutes and 13 secondsAnd it's best to use lumens because of all the different types of bulb that are available, incandescent or filament bulbs, or compact fluorescent, or there's ones called energy-saving, LED, the fluorescent and halogen light bulbs, they've all got different wattage ratings. So the best thing to do is go for lumens, which actually tells you how bright something is. And that's for photosynthesis practicals. For growing up the algae, if you're going to do that practical, you need an even brighter lamp. And there's advice on our website about that. So I suppose that in short, yes, it's enough for a plant to photosynthesize. But it's not bright enough, for, for instance, in practical.

Skip to 8 minutes and 2 secondsKAREN HORNBY: Thank you. And we're going to talk now about the question that was posed at the beginning of week three. And then we went on to see how we could answer it during the week. But we wondered if you could explain or expand on how you might explain this to students in lesson. So if a whole plant can be grown from a piece of leaf, why can't we grow a complete human from a piece of finger?

Skip to 8 minutes and 36 secondsBEVERLEY GOODGER: Well, because we are thinking about stem cells, obviously, hopefully, your students would ask a question like that. Because it's something that they thought about for a long time. Why can you grow a plant from just a small section of tissues, but you can't grow a whole human? So I think the areas, really, that-- you know, it's a fantastic question. And I think most of us would be stunned by it and think, whoa, how do you answer this question? Where do we go? But really, it's about growth.

Skip to 9 minutes and 15 secondsSo if you say to your class, first of all, well, what must be different about the way that plant cells are growing, or can differentiate, compared to the way that the animal cells in the finger are growing you can differentiate? And although nobody can be expected to know why they can differentiate in different ways, actually making them realise that they do is probably a good starting point. So that's where I would start. The cells in the plant somewhere must have the ability to become all other kinds of cells. Whereas the cells in the finger can't. So that would be my starting point.

Skip to 10 minutes and 4 secondsAnd then from there, hopefully, by looking at stem cells in plants and then stem cells in animals, you'll be able to come back to it later on and think, OK, well, why maybe is it important that plants and plant cells can differentiate into any kind of cell throughout their life? Whereas on the whole, most animal cells can't? What do you think, Alex?

Skip to 10 minutes and 30 secondsALEX JENKIN: Yeah, I think you mentioned this. Obviously, you say most animal cells. And there obviously are interesting examples, such as various lizards and things, that drop their tails and grow new ones, or insects that can lose legs and that sort of thing. But standard-- I don't want to use the word higher animals, but they generally can't regrow parts of their body.

Skip to 11 minutes and 0 secondsI think, yeah, reflecting on why plants need to be able to do that. But I suppose also, why don't animals need to do that? And why lose that ability? That's not a question I have an answer to. But I suppose that's-- I think a couple of people mentioned this, is that, well, OK. I can see why it's an advantage for plants to be able to do this. Surely, it would be an advantage for animals to be able to do this as well.

Skip to 11 minutes and 33 secondsAnd I suppose-- and particularly, thinking about mammals, well, this doesn't really happen at all. I'm sure someone could point out an example where it does, having made that sweeping statement.

Skip to 11 minutes and 47 secondsBEVERLEY GOODGER: But I think also, it's just one of those questions which, as a teacher, you go, wow. And then you turn it on its head and say, well, what do you think? And you know, although it may be an area of the course that your students haven't quite yet started studying, they will have all sorts of brilliant ideas which can probably form a fantastic basis for your first lesson on this. Because some of them will be completely off the wall. And others will be drawing on the knowledge. So I think the question is a fantastic opportunity to say, well, we don't know. But what can we think of? And that's a wonderful part, in my view.

Skip to 12 minutes and 35 secondsKAREN HORNBY: Thank you very much, to Beverley and Alex. It's been really good fun reading some of the comments throughout of the course, and reading the conversation. So thank you.

Skip to 12 minutes and 51 secondsBEVERLEY GOODGER: Well, thank you.

Skip to 12 minutes and 53 secondsALEX JENKIN: Thank you very much. And thank you everyone, who's done the course as well. It's always great. Like, as Karen said, it's always great to read the comments.

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Teaching Biology: Inspiring Students with Plant Science

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