Lesson video

Welcome to today's lesson from the unit Heredity and DNA.

The title of today's lesson is Heredity.

What we're going to be looking at today is how features can be passed down through generations from parents to offspring.

And at what point in the lifecycle these take place.

We're also gonna look at how we managed to get a variation between offspring of the same parents.

My name's Mrs. Barnard, and I'm going to be taking you through today's lesson.

And our outcome for today's lesson is that by the end of today's lesson, you should be able to describe what is meant by heredity and why offspring usually looks similar to their parents.

As with all science lessons, we've got some keywords to be looking out for.

So have a little look at that keyword list there.

We've got reproduction and offspring, we've got inherit, heredity and variation.

I'm just gonna put a slide up now of the definitions.

So if you want to pause it here and write these down so that you can refer back to them later in the lesson, then you can do.

Okay, our lesson today is in three parts.

So we've got making offspring, so that's the point in the lifecycle where offspring are produced.

And then we've got inherited features.

So how features are passed from one generation to the next.

And lastly, we've got variation between offspring.

So how siblings can look similar to each other and how they inherit their features from their parents.

Okay, let's get started.

So first of all, reproduction is one of the common processes of living organisms. So you remember those seven common processes of living organisms, movement, respiration and sensitivity, growth, reproduction, excretion and nutrition.

And all living organisms reproduce at some point in their lifecycle.

So here's a couple of examples.

So we've got butterflies there.

So we've got a butterfly that produces an egg, and then the egg hatches to form a caterpillar.

And then the caterpillar goes into a chrysalis, and then it comes out after it's reformed as a butterfly.

And then you can see reproduction is the stage between the butterfly and the egg being produced.

So let's look at that similarly for a frog.

So we've got a frog and we've got a frog spawn, and then we've got a tadpole, and then we've got a froglet.

And reproduction happens between the frog and the frog spawn being produced.

Okay? All of those other arrows indicate growth is taking place.

Right then.

So when organisms reproduce, they make offspring.

And you will notice this just from the world around you, that offspring often resemble their parents, but not always at every point in their lifecycle.

So let's see what I mean by that.

So first of all, let's go back to those frogs again.

So when frogs reproduce, they make frog spawn.

Now, frog spawn doesn't really look very much like frog.

And then when the frog spawn hatches, it turns into tadpoles.

And I hope you've all had the chance to see tadpoles at some point.

And they don't really look like their parents.

They don't really look like frogs.

But then you can see as the tadpoles grow and change and they start to get arms and legs, you can see these froglets in this picture here, they're looking a lot more like their parents.

So at this point in their life cycle, they're starting to resemble their parents.

So let's have a look at this next example here.

So we've got daffodils.

So daffodils, they produce bulbs and they're in the ground over the winter, and then they come up in the spring, don't they? All daffodils come out.

So at that point in their lifecycle, they don't really look much like the plant or the flower that's above the ground when they're bulb, but when they germinate and they grow, they start to then resemble their parents at that point in their lifecycle.

And then finally, we've got humans, which is the most obvious example that we see around us.

Now, babies look a lot more similar to their parents than tadpoles do to frogs when they're born.

But as they grow, they look more similar to their parents as their features become more similar.

And it's at that point in their lifecycle that they look similar to their parents.

So let's have a little check activity.

So we've got some parent organisms here, and we've got their offspring.

So what I would like you to do is match the correct parent to its offspring.

So we've got four letters and four numbers.

So we should have a letter and a number for each answer.

So if you pause, have a go, and then I'll check back with you afterwards to see how you got on.

Okay, let's see how you got on with this one then.

So let's maybe start with the easiest, which is the monkey.

And hopefully, you found that it's monkey offspring with the little baby here.

They're very cute.

So that's a3.

Now the frog's a little bit more tricky, but we have discussed it as in our previous examples.

So the offspring of the frog is the frog spawn.

This point in its lifecycle, they don't look that similar.

And then this next one is a tree.

So it's an oak tree.

Remember, trees and plants are living organisms as well.

And its offspring is this little sapling, this little oak sapling that's coming out of an acorn there.

And then finally, we've got a lady bird.

Now you might have seen these little guys in the garden.

These are the little babies of lady birds, nymphs, and they sort of look a bit similar in coloration, but they still look quite different.

So if you see those when you're out and about, now you'll know what they are.

So those are the babies of lady birds.

Okay, so if you've got those right then well done.

So it's a3, b1, c4, and d2.

Okay, time to have a bit of a practise with a longer answer question now.

So we have here Lucas and Sofia, and they are discussing what the puppy of two terriers would look like.

So that's a picture of two terriers there, those two white dogs there.

So Lucas says, "It could look like a Great Dane." So that's a picture of a Great Dane underneath because dogs can give birth to any breed of dogs.

Dogs are the same species.

So that might be true.

And Sofia says, "It will look like a terrier because terriers can only give birth to terriers." So what we would like you to do is explain why Sofia is the most correct, but also to discuss the correct and incorrect ideas from both Lucas and Sofia.

So I'm gonna give you a little bit of time to do some writing.

So when you're ready, unpause the video, and we'll go through your answers.

Okay, how did you do with that one then? Let's have a look.

So remember the task was to explain why Sofia is the most correct, but also to discuss the correct and incorrect ideas from both of their answers.

So we've got Sofia is the most correct because when organisms reproduce, they make offspring of the same kind.

And Lucas is incorrect as a Great Dane does not resemble a terrier closely.

So even though dogs do reproduce to give dogs, he was right in that, the two terriers would actually reproduce to produce puppies that have similar features to the parents, so to the terriers, okay? So if you've got those ideas of the similar features in the offspring, then you've got the right idea.

So, well done.

So we're gonna move on to the next cycle in our lesson, which is inherited features.

So, offspring looks similar to both of their parents as both of them have passed features on.

So here's a couple of examples.

We've got some parent geese here.

Now you can see that one of the parents has a slightly grayer wing than the other parents.

So the parents do look different from each other, but their offspring looks similar to both of the parents.

And then another example here with a lion and a lioness and their cub.

And you can see that that cub has similar features from both of its parents.

That is because the offspring have inherited these features.

So that's a key word.

So you inherit features from the parent to the offspring.

So they are passed down, and this process is called heredity.

So those are two of our key words for today's lesson.

So inherited and heredity.

So heredity is the process of organisms passing on features to their offspring.

So the offspring of the same parents are called siblings.

So like if you've got any brothers and sisters, you might have heard them referred to as your siblings.

Okay? So siblings can look similar, but not identical, to one another as they do inherit features from both their parents.

So you can see we've got some human siblings here, so they look similar to each other, even though one's a boy, one's a girl, but not necessarily exactly the same 'cause they both inherit features from both their parents.

And the same here in these cats, these kittens, you can see that they look similar to each other, but not exactly the same, but they look similar because they've inherited features from both of their parents.

Now, there is an exception, and the exception is identical twins.

So identical twins can look absolutely identical, okay? And they have both inherited features from their parents, but they have inherited the same combination of features from their parents.

So time for a quick check.

So true or false, all of the baby's features, this is a baby girl, have been inherited from her mother.

So for this baby girl, is it true or false that all the baby's features have been inherited from her mother? So I'll let you answer that first, then we'll look at the justification.

Okay, the answer is false.

So, well done if you got that right.

But now I want you to choose which of these answers below is the best reason, the best explanation for why that is false.

Is it the baby inherits its features from its mother under its grandmother, or is it the baby inherits features from both of its parents? Okay, so the answer is that the baby inherits features from both of its parents, okay? Sometimes people think that the features come down from the mother's side and that a baby girl would inherit all the features from her mother, but that's not the case.

The baby girl would inherit features from both of its parents.

Okay, so what different types of inherited features can there be? So inherited features are visible characteristics or invisible processes that are passed on from parents to offspring.

So let's have a look at this cat and we'll get some little examples of things that can be inherited.

So we have fur pattern, fur colour, tail length, eye colour, ear shape.

Now lots more features are inherited, but these are just a few examples of things that are really clear to us when we look at something that are inherited.

So a cocker spaniel and a poodle have a puppy, and the puppy's breed is called cockapoo.

Now you might have seen some of these puppies around or dogs around, or you might have one in your family.

Okay, so what I would like you to do is to explain the features that this puppy, this cockapoo puppy has got from its parents.

So look really closely at the features of both the parents and decide which ones have been passed on to its puppy.

Okay, so you're gonna need a few minutes to write a good, long explanation for this.

So if you pause the video and then we'll come back and see how you got on.

Okay, so you might have got some different features to the ones that I've included in my explanation.

So we're explaining which features that cockapoo puppy has received from both of its parents.

So number one, it's inherited short ears from the poodle.

So they're a bit shorter there than the cocker spaniel, but it's fur colour seems to be a mix of both of them, the white from the poodle and the darker brown fur from the cocker spaniel.

So it's sort of halfway between the two, and then we can see it's inherited the shape of its eyes.

They're sort of those sort of sad looking round eyes, okay? And it has inherited wavy fur.

Now it's interesting this 'cause the poodle's got quite curly fur, and then the cocker spaniel's got like long wavy fur.

So the cockapoo's sort of got a wavy fur that's somewhere in between those two.

Okay, so if you've got some of those and if you've got some others, that's absolutely great, okay? But we are looking for features that have been inherited from both parents.

Okay, it's time to move on to the third part of our lesson today.

And the third part of our lesson is variation between offspring.

So offspring inherit features from both of their parents and offspring from the same parents are called siblings.

So you can see this picture here is a group of siblings, and you can see how they look quite similar to each other.

So they've inherited some of the same features from both of their parents.

However, have you ever thought about why you may look different from one of your siblings even though you have the same parents? The reason is because you've inherited a different combination.

So there are lots more features available from your parents than you need.

So each new offspring will receive a different combination of those.

Now, sometimes you might find that siblings are quite similar to each other, and that's because they've received a more similar combination.

Or you might find that siblings are really different from each other, and that's because they've received a very, very different combination of features.

But they're all those features that are available from both of their parents.

And this gives us variation in offspring.

So there's variation between them, differences between them.

So we're gonna have a little go at modelling a longer answer now.

So we're gonna do it together and then you are gonna have a go at doing it by yourself.

So we're gonna start with these kittens.

So these kittens are siblings, so they are offspring of the same parents.

Now you can see they look quite similar to each other, but in some ways they look different.

So we are going to explain why these siblings look different from each other.

So the parents have different fur colours.

One parent might have black fur and the other might have tabby fur or white fur.

And the offspring inherit a different combination of fur colours from their parents.

So now it's time for you to have a go.

So we've got some cows here.

And these cows are siblings.

So I'd like you to use the answer, the model answer to write your own answer about these cows siblings.

So if you pause the video, then I'll come back after, and we'll go through your answer.

Okay, how did you get on? So did you get any of these points here? The parents had different fur colours.

One parent may have had some white fur, and the other parent some brown fur.

One parent may have a pink nose and one a brown nose.

And the offspring inherit a different combination of fur and nose colours from their parents.

Okay, so if you've got an answer similar to that or some of the same points, then well done.

So we're gonna move on now to a practise task.

So here is a family and it's made up of a mother, a father, and two biological children.

Harry looks similar, but he doesn't look identical to Louis, his brother.

So what I would like you to do is write me an explanation using your model answer from the last task to help you with this, and explain why Harry and Louis do not look identical.

Now, in your answer, I would like you to include the key words, inherited and offspring, okay? So pause the video and then we'll come back and have a look at how you've got on.

Okay, so there's our family again with Harry and Louis.

So we're gonna explain why Harry and Louis don't look identical to each other, and we're gonna use the words, inherited and offspring, in our answer.

So first of all, Harry and Louis are both offspring of the same parents.

That's important if we're going to compare them to each other.

And they have both inherited features from both of their parents, but they've inherited different features or different combinations of features.

Louis has inherited the brown hair of his dad and the brown eyes of his mum, whereas Harry has inherited the blonde hair of his mum and the blue eyes of his dad.

So, time for the summary of today's lesson.

So, reproduction is one of the common processes of living organisms. All living organisms reproduce at some point in their lifecycle and make offspring.

The offspring resemble the parents at some point in their lifecycle.

Offspring looks similar to both of their parents as they inherit features from both of them.

This process is called heredity.

Offspring of the same parents are called siblings.

They look similar but not identical unless they're identical twins to one another as they inherit features from both of their parents.

And each offspring inherits a different combination of features from their parents.

So that concludes our lesson on heredity.

Well done for your work today.