Hey, Penny, it's been a while since our last post, and I bet you're dying to know the rest of the living processes.
Yeah..., obviously... I was kind of worried you might have forgotten...
OK, try to conceal your excitement a little bit and let's go with the three remaining living processes.
Alright, I remember we already had nutrition, respiration, response and movement, which was actually a way of response.
Exactly, well done! The next life process is excretion, which is a fancy word for taking out of the body the waste material.
You mean the poop?
Well, yes, but not only. You see, all living things need to get rid of waste material. First of all, respiration, as we said the other day, implies producing carbon dioxide as a waste material, so releasing this carbon dioxide to the atmosphere is also a way of excretion. Just as the oxygen that the plants throw to the atmosphere during the photosynthesis is also a way excretion.
Then, of course, we have the poop, which just to sound a little bit more scientific we could call droppings. We produce these droppings as a byproduct of nutrition, and it's proper of animals, because we eat other living things, so we get some extra chemicals we cannot store, and the best way Nature has come across to allow us to take them out is poop. And pee, of course, we also have the pee (and even sweat, but that's mainly useful for humans). Plants, for their part, produce only the food chemicals they truly need, so they don't have so many things to get rid of.
Then, of course, we have the poop, which just to sound a little bit more scientific we could call droppings. We produce these droppings as a byproduct of nutrition, and it's proper of animals, because we eat other living things, so we get some extra chemicals we cannot store, and the best way Nature has come across to allow us to take them out is poop. And pee, of course, we also have the pee (and even sweat, but that's mainly useful for humans). Plants, for their part, produce only the food chemicals they truly need, so they don't have so many things to get rid of.
Yeah, I was kind of having some difficulties to picture a plant doing number two...
However, you will have no problem picturing plants doing our next life process: growth. In fact, plants keep growing most of their lives, whereas most animals usually have a growth period, after which our size doesn't increase. But, in any case, all living creatures grow. Growth entails mostly the overall increase in size, but in truth, it doesn't just mean becoming bigger, but also more complex and able to do a greater variety of things.
Growth requires nutrition and respiration, as for growing we need food chemicals gotten from nutrition and energy from respiration, in order to build new living material.
Growth requires nutrition and respiration, as for growing we need food chemicals gotten from nutrition and energy from respiration, in order to build new living material.
Great, so this leads us to the very last life process: reproduction!
Exactly, we are nearly done here. Reproduction is the process to perpetuate life and is the way by which a living creature creates a new living creature similar to itself. Many plants and some other life forms are capable of reproducing by themselves, by what is called asexual reproduction. However, many other living beings resort to sexual reproduction, which involves two different special sex cells joining together, these cells coming usually from different parents (so two different living creatures are needed). The process of these sexual cells joining is called fertilisation.
These sex cells carry DNA from their corresponding parent, and that is why children usually resemble in some way their parents. However, the combination of the DNA of both parents ensures that offspring (i.e., the children) are never exactly like their parents, which helps to perpetuate a species and don't become extinct.
So the problem with dinosaurs was that they used asexual reproduction and that's why they disappeared?
No, not at all. Not even remotely. But don't worry yourself about dinosaurs right now, Penny. We will get there. For the time being, just verify if dinosaurs were living creatures by checking these life processes.
These sex cells carry DNA from their corresponding parent, and that is why children usually resemble in some way their parents. However, the combination of the DNA of both parents ensures that offspring (i.e., the children) are never exactly like their parents, which helps to perpetuate a species and don't become extinct.
So the problem with dinosaurs was that they used asexual reproduction and that's why they disappeared?
No, not at all. Not even remotely. But don't worry yourself about dinosaurs right now, Penny. We will get there. For the time being, just verify if dinosaurs were living creatures by checking these life processes.
References:
Wenham, M. and Ovens, P., Understanding Primary Science, London: SAGE Publications
