Video: Advantages and disadvantages of sexual and asexual reproduction

﻿Hello, welcome to this Biology lesson. It's Mrs. Gibbs here. If you haven't done so already yet, please pause the lesson to write down the title. It's "Advantages and Disadvantages of Sexual and Asexual Reproduction". Now would also be a good time to remove yourself from any distractions. Make sure you're sat in a room where you won't be disturbed. Put your mobile phone to one side, and close any tabs that you might have open. Then we'll be ready to start the lesson. The equipment you'll need for today's lesson is a pen and something to write on. So if you've not got that yet, please pause the lesson. Go and get a pen and some paper or a notepad, come back. Once you're settled again, resume the video. We'll start this lesson by recapping sexual and asexual reproduction, which we've looked at over the past couple of lessons. Then we'll look in more depth at the advantages of asexual reproduction. Then we'll look at the advantages of sexual reproduction, and we'll look at examples of organisms that do both types of reproduction. To begin with then, we'll recap asexual and sexual reproduction. Asexual reproduction is reproduction only involving one parent. Cells reproduce by mitosis only, and there is no mixing of genetic material. The offspring that are produced are genetically identical, so we call those offspring clones. In sexual reproduction, there are two parents. Cells divide by meiosis and mitosis. Gametes fuse. Remember, those gametes have been formed through meiosis, and their genetic material is mixed. That is because when the gametes fuse, half the genetic material comes from the mother, and half comes from the father. The cell then divides by mitosis. That's why meiosis and mitosis are involved. And there is variation in offspring. Quick knowledge check then, which answer here is wrong about asexual reproduction? Five more seconds. I want you to point to the wrong answer about asexual reproduction. Three, two, one, well done. We should have said, "involves meiosis and mitosis". That's because meiosis is only to form gametes, and asexual reproduction does not involve gametes. Next one I want you to tell me what is wrong, but this time for sexual reproduction. Point to the wrong answer. Five seconds. Three, two, one, excellent. "There's no mixing of genetic material", that's wrong for sexual reproduction, because when the gametes fuse, genetic material is mixed. Now we're going to look at the advantages of asexual reproduction. Only one parent is needed. So it's more energy efficient, as there is no need to find a mate. Very often in sexual reproduction, having to find a mate can be very time consuming and require a lot of energy. So for example, stags, they would fight for a mate very often, but will do nesting in the hope of calling a mate, or bird song. In asexual reproduction, there is no need for that. It is faster than sexual reproduction. That's because there's no production of gametes in meiosis. Because it only includes mitosis, asexual reproduction is much faster. Many identical offspring can be produced, but that's when conditions are favourable. So this is an advantage, because conditions that are favourable might be, for plants, it might be good levels of sunlight. For bacteria, it might be good levels of oxygen. So if conditions are favourable, lots of offspring can be produced and they can be produced quickly. So if you've got, for example, a farmer who has got some crops, and all the conditions are favourable, they're producing a high yield, which means lots of crops, he can get them to reproduce asexually by mitosis, and that means there will be lots of identical crops from the way that the farmer wants them. So they are the advantages of asexual reproduction. I'm just going to get rid of my webcam, and I would like you to pause the video to complete your task, and then resume the video once you're done. So please pause the lesson now. I'd now like you to pause the lesson again to mark your answers. Resume once you're finished. Now we're going to look at the advantages of sexual reproduction. Sexual reproduction produces variation in the offspring. Remember, that's because gametes are formed, which are not genetically identical to the normal cells, and genetic information is mixed when gametes fuse, creating variation. If the environment changes, variation gives a survival advantage. What I mean by that is if conditions such as a frost, if we're looking at... Let's go back to our farmer example, with his crops, or her crops. If there's a frost, if all the crops are genetically identical, they could all die. However, if there's variation, it might be that some individuals within the crop would have a gene that would enable them to survive in a frost. That won't happen if they're genetically identical. However, if there's variation, some might survive and be able to reproduce. So that's what we mean by a survival advantage. We'll look more in that in future lessons, when we do natural selection. We're now going to check our learning, so please pause the video to complete your task. Once you're done, resume the video. Please now pause the video again to mark your answers, and resume the video once you've done that. We're now going to do a quiz to check our knowledge of sexual reproduction or asexual reproduction. So what you're going to do is you are going to point to the correct answer. If you think it's sexual reproduction, point to this box. If you think it's asexual reproduction, point to this box. So the first one then, it is more energy efficient. Is that sexual reproduction or asexual reproduction? Point to it, three, two, one. We should have said asexual reproduction. Really really well done. Next one then, it is faster. Point to the correct answer. Three, two, one. Brilliant, again, that is is asexual reproduction. What about the next one? There is variation in the offspring. Point to the correct answer. Three, two, one, fantastic. Sexual reproduction. Next one. Many identical offspring can be produced. Three, two, one. Asexual reproduction, well done. And another one. If conditions change, offspring are more likely to survive. Three, two, one. Sexual reproduction, well done. Remember, that's because there's variation in the offspring, so some might have genes that would enable them to survive a change in the environment. Some organisms are able to reproduce sexually and asexually. We're going to look at a couple of examples of those now. If we first look to the picture of the bottom left of a mosquito, you would have learned in an earlier topic that some species of mosquito carry the malarial parasite. The malarial parasite reproduces asexually in the human host, but sexually in the mosquito. So if you're bitten by a malaria carrier mosquito, that malarial parasite will reproduce asexually inside of the human. However, when the malarial parasite is in the mosquito, it reproduces sexually. Now if we look to the picture at the bottom right, that there represents fungi. Similarly, fungi can reproduce sexually, but will also reproduce asexually using something called spores. Some more examples of organisms that are able to reproduce sexually and asexually are strawberry plants and daffodils. Both of these plants can produce seeds sexually. So again, this is something that we would have looked at before when we talk about the pollen being a male gamete in plants, and the egg a female gamete. They will fertilise one another and produce seeds. That will create variation. Those seeds can then be dispersed, be it by clinging on to animal fur, or dispersed by the wind, water, or explosions. So that's sexual reproduction. They can also reproduce asexually through runners, for strawberries, or bulbs, such as daffodils. So if you look at the picture to the bottom left, that shows some strawberry plants along the line. That's strawberry runners. And on the right hand side, we've got bulbs there of daffodils, so they have been produced by asexual reproduction, so they will be genetically identical. On the next slide, I'm going to show you four species that reproduce both sexually and asexually. And I'm going to show you four pieces of information of how they do that, but they're jumbled up. So when I show you the next slide, I would like you to write them out in the correct order. So I'm going to move my webcam. I would like you to write out the four species and then match it with the correct description. So please pause the lesson now to do that, then resume once you're finished. How did you do? If you just check your answers there, and mark them. If you need to change anything, pause the lesson now, and resume once you are finished. We're now going to look at an example of an exam question. There's no need for you to write anything down, as I'm going to run through this example with you. If you pop your pen to one side, so you can give your screen full attention, I'll do this example, and then you'll be able to have a go at some of your own in a short while. Strawberries can reproduce sexually by seeds and asexually by runners. Explain why this is an advantage. So for this question, we need to talk about both sexual reproduction and asexual reproduction, and we need to say why both have advantages. Let's start with talking about the advantage of sexual reproduction by seeds. We would say that there is variation between offspring, 'cause we're explaining our answer. This means they are more likely to survive if there is a change in the environment. We don't need to give specific answers here, such as if the weather changes or light levels change. It's fine to say just that. Another advantage is that seeds can be dispersed, meaning the offspring can colonise new areas. Now let's talk about the advantages of asexual reproduction in strawberries. Many genetically identical offspring can be produced quickly, and that is ideal in favourable conditions. So there, we've got our advantages of both sexual and asexual reproduction in strawberries. What I'm going to do now is show you an exam question, and I'd like you to give it a go. I'm going to hide my webcam. And you can pause the slide and resume the lesson once you have completed the task. I'm going to read out the sentence, and you are going to say the words back to me that I'm missing. When the malarial parasite reproduces sexually, there is, variation, excellent, between the offspring. This means they are more likely to survive if there is a, change, fantastic, in the, environment, excellent. When the malarial parasite reproduces asexually, many genetically, identical, brilliant, organisms can be produced... How can they be produced? Quickly, fantastic, if conditions are, last one, favourable. You're now going to try this exam question on your own. So please pause the lesson and resume once you have answered the question. How did you do? When the answers come up, pause the lesson, and resume once you have marked your answers. In this lesson, we've recapped sexual and asexual reproduction. Then we've looked at the advantages of both asexual and sexual reproduction, and you've done a brilliant job at answering those exam questions. That's it for this lesson. Don't forget to click "next activity" to do the end of lesson quiz. And I'll see you in the next lesson.

Worksheet: Advantages and disadvantages of sexual and asexual reproduction

Exit Quiz: Advantages and disadvantages of sexual and asexual reproduction

Completed: Advantages and disadvantages of sexual and asexual reproduction

In this lesson we will look at the advantages and disadvantages of both types of reproduction. We will also learn about organisms who are able to reproduce both sexually and asexually, explaining why being able to do both is an advantage.

Biology

Advantages and disadvantages of sexual and asexual reproduction

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