What is Cellulose?

Ok, so I cheated a bit with the title here, as none of my children have directly asked me what cellulose is. However, a little while ago I wrote a post called Why are Apples Crunchy? and I wasn't entirely satisfied with the answer I gave Garden Girl. A friend of mine, having read this post, came to my assistance and I was able to tell Garden Girl that apples are crunchy because they contain cellulose.

All plants and animals are made up of a bunch of cells. People are made up of millions of cells. When these cells are all bundled together they make a person, or a plant. They are a little bit like lego pieces, in that when they are fixed together they can make lots of different things. Cells are very clever because they can do lots of things, such as taking in all the good stuff we eat and turning it into energy. so we can run about. Plant cells do things like absorbing sunlight so a plant can grow and they give leaves their shape.

Cellulose, is the thing that makes cells rigid (hard). Plant cells have a wall around them and this wall has cellulose in it. The cellulose on the wall makes it hard and crunchy. The crunchier the vegetable or fruit, the more cellulose there is in the cell wall. So apples are crunchier than bananas because they contain more cellulose.

If you want to learn more about cellulose my friend found a really useful link on the dummies.com website, here.

And, to find out more about cells, have a look here.

Why are Ladybirds Called Ladybirds?

Garden Boy frequently asks me why things are called what they are and most of the time, a name is just a name for no particular reason. However, Ladybirds were reportedly named after the Virgin Mary. Our native Ladybird is red, with seven spots, the link being that the Virgin Mary is often depicted wearing a red cloak. The seven spots of a ladybird represent the seven sorrows and seven joys of Mary. The Virgin Mary is often referred to as 'Our Lady', hence 'Ladybird'. The 'bird' part of the name, I can only assume comes from the fact that ladybirds have wings and can fly.

When I passed this on to Garden Boy I simply told him that Jesus' mother, Mary is shown, in lots of pictures and statues, wearing a red cloak, just like a Ladybird. People frequently call, Jesus' mother 'Our Lady' and so the name Lady was given to the bug because it reminded people of Jesus' mother and her red cloak. And the bird bit is there because a ladybird has wings and can fly like a bird.

I refrained from mentioning the seven sorrows and joys as I didn't want further questions about the sorrows, but had he gone on to ask about the spots I think I would have told him that seven sad things and seven really fantastic things happened to Mary and the seven spots remind people of these. 

There are lots more interesting facts about Ladybirds on the UK Ladybird Survey website here.

Why Are Apples Crunchy?

I'm not sure I have really managed to answer this question, although I have satisfied Garden Girl with an answer of sorts. The actual question Garden Girl asked was 'Why are apples crunchy and bananas soft?' and I couldn't really find out why the two fruits have different textures. This is what I told Garden Girl...

Apples and bananas are fruits. A fruit is part of a plant or tree and is there for two reasons.

1. Whilst the seeds of a plant, or tree, are developing, a fruit protects them from animals, birds and the weather.

2.When the seed is ready to grow into a plant of its own, the fruit helps the seed disperse. That is, the fruit helps the seed find somewhere suitable to grow.

While they are growing, seeds are in danger of being eaten by animals and birds, or of being damaged by the weather. However animals (and humans) do not want to eat fruit until they are ripe. Thus a fruit does not become fully ripe, until the seed is ready. The fleshy part of the fruit, the bit we eat, grows around the seeds to stop birds and animals getting at them and to stop the seeds getting damaged. If an apple gets hit, the skin and flesh is bruised but the seeds stay safe. The soft part of a banana, similarly protects the seeds inside.

There are lots of different kinds of fruit. Some, like apples and bananas, have juicy flesh to protect the seeds. Some, like peas, have pods to protect the seeds inside. Some, like nuts have hard, dry shells to protect the seeds inside. Conkers and sweet chestnuts have a prickly fruit to protect them. 


When the seed is ready to grow into a new plant or tree, the fruit ripens. The fruit no longer needs to protect the seed. It must now find a way to spread the seed. Instead of trying to protect the seed from animals, the fruits now want to be eaten. Apples and bananas change colour to attract birds and animals.Now that they are ripe, the fruits have the flavour and texture which will make people and animals enjoy eating them.

Birds and animals cannot digest the seeds, so when they have eaten the fruit, the seeds pass through the body and come out with the poo. Animals poo in the soil where the seed can grow into a new plant. And even better than that, the animal poo acts as a fertilizer to help the seed grow, in the same way that we use manure and compost in the garden to help our vegetables grow. So apples are crunchy and bananas are soft because this is the way animals and people like to eat them.

Other seeds are scattered by the wind. Dandelions have little parachutes so they can float away and sycamore seeds have wings so they can fly away from the parent tree to a suitable growing place. When pea pods split open the seeds burst onto the ground ready to grow into a new plant. Spiky fruits will stick to the fur of animals as they pass by, dropping off sometime later, hopefully somewhere where the seed has room to grow.

So, back to the original question and I guess the answer is that apples have a crunchy, juicy flesh because this is the best protection for seeds, against the particular animals and weather to which an apple tree will be exposed. A crunchy texture is also the most appealing to people and animals who want to eat the fruit and thus help spread the seeds.  

Bananas are soft for the same reason. Banana bushes grow in different weather conditions to apple trees and are exposed to different animals, thus a soft fruit offers the best protection for seeds against these animals and conditions. When the fruit is ripe, a soft banana offers a more appealing texture to the animals and people that want to eat them.

Garden Girl seemed happy with this explantion but I am a little bit curious about what it is that makes an apple crunchy. Is it the amount of water that apples contains? Is a banana softer because it contains more starch? I really don't know and I failed to find anything useful in library books or on the internet, so if anyone knows the physical reason for why an apple is crunchy and a banana is soft, please let us know.

If you want to learn more about fruit we found these books really useful:

Flowers, Fruits and Seeds (Plants) by Angela Royston

Flowers and Seeds (World of Plants) by Carrie Branigan and Richard Dunne

However, there seemed to be quite a few books about fruit and seeds in our local library so if you can't get hold of these ones there is bound to be something useful.

 

Why Do We Have a Chin?

Whilst I wouldn't recommend a practical demonstration of why we have a chin, Garden Girl inadvertently did just that a couple of weekends ago. She was pushing one of those big round swings at a playground and didn't move out of the way in time. The swing came at her at head height and knocked her to the floor. It was her chin that took the brunt of the clash. On the way home, after she had been reassured that no-one could see the red marks on her chin, she asked me why we have a chin. I suggested to her that she had just found that out first hand. The chin could be there to protect the more delicate parts of the face from knocks and bumps. I pointed out that if she had not had a chin it would likely have been her mouth that got hit by the swing. The mouth is very important as it lets us eat and speak so we really want to keep it intact.

When we got back I had a little look on the internet to see if this was correct and I found that there are a few suggestions for our chins...

1) To protect the face from knocks
2) To help us speak properly
3) Because it looks good

When I explained the options to Garden Girl she was inclined to go with the protection theory, probably with thoughts of her own sore chin in mind. I am inclined to believe that all of the suggestions are true. Our bodies are complicated and certainly capable of assigning more than one function to a body part.

I had never thought too much about my chin before, but was amused when I came across this article in the Irish Times, that Ernie from Sesame Street had questioned why we have one...

http://www.irishtimes.com/newspaper/health/2011/0614/1224298853716.html

And if you want to watch the song 'One Fine Face' by Ernie and Elmo, you will find it here on You Tube:

http://www.youtube.com/watch?v=6j-7oVHPeA4

What is a Sonic Boom?

If you live in the South of England you likely will have heard a big loud bang yesterday afternoon which sounded much like thunder. We were dashing from the car in the pouring rain when we heard the loud crash and I made a comment to the children about there being a thunder storm. However, there was no lightening and no further thunder. It seemed a little odd, but in the dash to get dry I thought nothing more about it until Garden Dad came home and asked if we had heard the sonic boom. I explained to our Little Garden Helpers that the thunder we thought we had heard earlier was not actually thunder but a sonic boom. Inevitably, Garden Girl asked 'What is a sonic boom?' and the best I could offer by way of explanation was 'a very loud noise'.

I promised to find out for her and this evening I found a good explanation on the BBC website which talks about things like pressure and the speed of sound. It is worth a watch to get the full explanation, especially if you have older children looking for a more accurate and detailed insight, but I have put together a simpler explantion which I think will be more accessible for young children and which I hope remains more or less scientifically correct.

In very simple terms, the sonic boom yesterday was caused by an aircraft flying so fast that the air it was moving through could not move out of the way fast enough. As the aircraft hit the air it created a loud bang. Apparantly the sound of thunder is created in the same way, as lightening strikes the air at such high speeds that it essentially bangs into the air before it can move out of the way.

To find a fuller explantion take a look at the BBC website here.

Why Is It Dark In Other Countries When It Is Light Here?

What Garden Girl really asked me was, 'Why does Uncle M only get out of bed when we are already having lunch?' He currently lives in Peru and consequently there is a 5 hour time difference. In order to explain why this is, the best thing to do is get a ball and a torch, but I also used this diagram:

The earth is shaped like a ball and hangs in space. But it doesn't stay still. Although we can't feel it moving, the earth is spinning all the time. It never stops. It takes a full day (24 hours) for the earth to spin around once. I put a sticker on a ball to represent Garden Girl and showed her that as the earth spins, so does she. When the sticker is on the same side as the torch, light from the torch can reach the sticker. It is day time for the sticker when the torch light shines on it. When the ball has turned half way around, the torch light cannot reach the sticker so it is dark and night time for the sticker.

It is the same for our house. When our house is facing the sun, the sun light can reach us and it is daytime. When the earth has moved halfway around and our house is on the side facing away from the sun, the sunlight cannot reach our house. It is dark and it is night time.

Because people live all around the earth in different countries, as the earth spins around, the sun hits different countries at different times, so Uncle M wakes up 5 hours after us because that is when his house has just started to turn towards the sun.

I put a few stickers on the ball, in different locations, to show Garden Girl how one sticker might still be in the torch light, while another one is just entering the torch light, and yet another might still be in the dark. I asked her to tell me which sticker would be the next to wake up and to spot a sticker that will soon be going to bed. It was a fun activitiy that illustrated, not just that one side of the earth is light while the other side is awake, but that also showed how light arrives at different times for different countries.

Why Are Freezers Cold?

Garden Boy asked me this when he was rummaging in the freezer for some peas. He really wanted them for dinner and was not at all convinced I would remember if he left me to it. His faith in my memory is pretty spot on, but my basic food hygiene lessons have obviously been filed away in a reasonably accessible folder of my brain as I was able to recall the following.

Lots of teeny tiny living creatures, called bacteria, make their home on food. We can't see them and they do not harm us, unless they have been on the food for too long. If bacteria are allowed to live on the food for too long they grow bigger and the food starts to turn bad. If this happens it can make us sick.

Bacteria, however, don't like the cold. In fact they dislike the cold so much that when they get cold they become really lazy and go to sleep. While they are asleep they do not grow any more and they cannot make the food turn bad.

We make freezer's really cold so that we can stop the bacteria on food growing while we store it until we want to eat it.

And, yes, I remembered the peas.

Why do Birds have Beaks?

Garden Girl told me that last week, during her maths learning, she was bored. So instead of listening to her teachers tell her all about 'full and empty' she began to ponder birds. Why she picked this topic I have no idea, but one of the questions she asked me, as she skipped home from school that day, was, 'Why do birds have beaks?' and somewhere, from the bottom of my memory pit, a little light switched on and I was actually able to answer her question this time.

Birds need a tool for carrying out lots and lots of different types of activities, such as searching in the soil for worms, picking up and carrying twigs for their nests, ripping apart food, or scooping up fish. The beak is that tool. Beaks are very strong and each type of bird has a different shaped beak, depending what it needs to do with it.

When we arrived home we had a look at some bird pictures in books and on the internet. I chose birds with very distinctive beaks to show her:

Woodpecker, with its short, pointed and sharp beak for hammering holes is wood
Puffin, with a large, bowl-like beak in which they can store fish while they hunt for more
Eagles, with sharp, hooked beaks for tearing apart animals

We compared these to the beaks of birds we see in our garden, such as the robin, blue tit and magpie, which all have quite short beaks for fruit foraging, worm digging or insect catching.

Birds also have beaks, rather than mouths, because human and animal jaws, (the bones in the mouth area) are very heavy. Birds need to be very light so they can fly. I asked Garden Girl to feel her jaw bones, as she moved her mouth and to rest her chin on her hand, to get an idea how heavy the bones are. Beaks, although they are very strong, are also very light; perfect for flying.

There is a short and useful film on the BBC Nature website which explains some of the ways birds are adapted to be lightweight, which you will find here.

Other websites with information about bird beaks include:

BBC Nature
The RSPB
http://www.earthlife.net/birds/bills.html

Why do Parrots have Colourful Wings?

When Garden Girl asked me why parrots have colourful feathers I thought I knew the answer. However, I wanted to be sure I was giving her the right information, so I decided to double check on the internet. I thought this would be a quick bit of research but there is surprisingly very little about this on the internet. We also looked in a couple of books we have about birds but again, this specific question wasn't really covered. In the end we decided to ask an expert and we e-mailed ZSL to see if they could help. They were fantastic and replied about ten minutes later!

And the answer is that we don't really know!

There are two theories or ideas:

1. The colourful feathers are used to attract a mate. That is, a boy parrot trying to make a girl parrot like him enough to be his very, very best friend so they can have baby parrots together. Or, a girl parrot trying to make a boy parrot like her enough to be her very, very best friend so they can have baby parrots together.

2. The colourful feathers help parrots camouflage themselves. That is, hide themselves amongst colourful flowers and foliage so that any predators (other animals that might want to eat them) will think they are a flower.

Because animals cannot speak and tell us all about themselves we can't always learn everything we want to about them. Experts on parrots will have thought of these ideas by observing parrots in the wild, as well as by looking at what other birds and animals do. But these ideas have not yet been proven to be true. Which idea do you prefer? Could it be both?

While we were reading about parrots in one of Garden Girl's books (Feathers, Flippers and Feet, by Deborah Lock) we did discover a very interesting bit of information about how the colour in parrot feathers is created.

There is a chemical (a substance or special thing) in parrot feathers which reflects light to make the wings colourful. Light is reflected by bouncing back from the wings to be seen as colours.

If you want to learn more about parrots, have a look at these websites:

http://animals.nationalgeographic.com/animals/birds/parrot/
http://www.parrots.org/index.php/allaboutparrots/