Why do flowers bloom in spring?

Spring has sprung! It might not feel too warm but outdoors it’s starting to look a lot more spring-like. Flowers have bloomed and buds are appearing on the trees. But what is it about spring that makes the plant world come to life?

ImageLeaves breathe in air, take in sunlight and use water from the roots to make food for the plant. But this process also requires energy. In this instance, it is light energy provided by the sun. Therefore, the more sunlight there is, the more food the plant is able to produce. The more food it has, the more the plant grows. Because the days get longer in spring, the plant is exposed to more sunlight in these months. This means the plant grows more quickly than in winter when it is darker.

The springtime increase in temperature also causes an increase in growth. Like all biological activity, plant growth speeds up with heat, provided it does not become too hot. The rise in temperature at this time of year means that plants grow more quickly and seeds germinate. Now bring on some warmer weather!

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At the root of the matter

In the depths of winter, with all the colourful parts of the plants hidden away, here at Storm we’re getting to know roots much better.

Roots are the underground part of a plant. Though you can’t see them, they play one of the most important roles. While the leaves bring sunlight and carbon dioxide into the plant, roots draw water and nutrients from the soil in order to feed the plant.

Most larger plants, like trees, often start with a large root, which then spread out into smaller roots. By spreading out, they are able to gain as much goodness as possible from the earth. The root also allows the plant to anchor itself in the ground, useful for when bad weather and animals shake it. If you’ve ever seen a tree felled in a storm, you’ll know how impressive the root system can be.

ImageAbove: Tree roots visible after the Great Storm of 1987

Roots such as carrots, parsnips and turnips can often be used as food for humans and animals. These types of plant have a single, large root, which is called a tap root. Traditionally, in climates such as the UK, root vegetables are a staple diet for winter. This is because the root hoards much of the plant’s food and water here. By keeping its food source underground it is better protected against predators and cold weather. So when your tomatoes, lettuce and berries disappear with the mid-autumn snap, the hardier underground root vegetables are doing just fine.

This makes them the perfect winter veg. A firm favourite at Storm is Jamie’s winter stew, using onions, carrots, parsnips and any other root veg you can get your hands on.

To learn more about how roots fit into the rest of the plant, keep an eye out for our app Naming Parts of Plants and Animals – out later this month!

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Hitchhiking, back-scratching and other inter-species favours

It’s not always such a savage world out there. Different species don’t only interact on a predator-and-prey level. Two species can provide a mutually useful service for each other (also called symbiosis). There are many examples of this:

  • Sea anemones hitchhike on the backs of hermit crabs, enabling them to travel further and eat the crab’s leftover food. But the crab also gains something too. Having these tentacled creatures on their backs fend off octopuses and other predators who might otherwise eat the hermit crab. Watch this guy moving his anemone friend from an old shell to a new.
  • African oxpeckers eat ticks off the backs of zebras and elephants. This enables the birds to eat but also does the bigger animals the service of removing parasites off their backs.
  • The classic example of symbiosis is often easily forgotten: simple insect pollination. The bees uses the flower’s pollen to make honey, while spreading the pollen further, enabling the plant to reproduce.

If your pupils are interested in learning more about different species, our brand new app Sorting for Early Science can introduce them to the foundation science vocabulary to get them started!

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Predator, prey, frogs and food chains

Most animals in a habitat can be classified as predators, prey or both. A predator is an animal which kills another animal (the prey) for food. For example, a snake is a predator because it eats frogs (prey). However, the frog is also a predator (however unintimidating it seems!) because it eats grasshoppers. With so many animals having differing diets, even a small environment can produce a food web such as this one.

ImageBecause the grass eats no other species, only consuming nutrients from the soil, we call it a producer. The fox and snake are called top consumers because no other species eats them within this habitat. But in certain habitats, large birds of prey eat snakes.

Food webs can be affected by even the most subtle increase or decrease in the number of any species. If, for example, the population of frogs increased in the above food chain, then several changes might take place:

1)       The number of grasshoppers would decrease because there are more frogs to eat them.

2)       More snakes would come to the habitat and prosper because there are more frogs to eat.

3)       Because there are more snakes, the number of rabbits will deplete as they will be eaten by the higher population of snakes.

Consider what might happen if:

a)       The population of mice increased

b)       The population of rabbits decreased

c)       A drought led to a poor crop of grass

Whether their population increases or decreases, each species within a habitat will be affected by changes in population to some degree.

If your class is interested in getting to grips with food chains, our app Pairing for Early Science introduces them with the foundation science vocabulary to get them started!

Below: predator extraordinaire, office cat, aka Mr Worthington

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Comet Ison – will it, won’t it?

There’s been much excitement lately around the possible sighting of Comet Ison next month. But what is a comet and why is everyone so excited about Comet Ison?

Comets are essentially large dirty snowballs, made of water, ice, dust and carbon-based compounds. Like planets, they orbit around the sun. But unlike planets, which are much larger and stay at the same distance from the sun, a comet’s orbit is elliptical (oval-shaped). This means they are sometimes closer to the sun than at other times.

When comets are closer to the sun, and therefore hotter, the material in the comet starts to melt into what is called a coma. This gives the nucleus a fuzzy appearance. Coma being Latin for hair, maybe ancient scientists thought the comet looked like it had a messy hairdo! Solar winds cause the coma to blow into a tail. Despite common depictions, tails don’t trail behind the comets but always away from the sun, blown by its winds.Image

What’s so special about Ison is how close it went to the sun. There had been three main theories about what the fate of this “sungrazer” would be. One, the comet could have exploded under the solar pressure. Two, it could have simply fizzled out. But what many of us hoped was that its closer encounter with the sun would give it a very bright tail. The disappointing initial prognosis on Friday was that Ison had “died” and fizzled out but since then there have been indications it might be brightening. We’re no wiser than we were before its brush with the sun!

If we’re lucky, the once-in-a-lifetime sighting of Comet Ison will begin in early December. Do send us any great pictures you get!

Another well-known comet is Halley’s Comet, which appears every 76 years. The most famous instance was just before the Battle of Hastings (as depicted left, in the Bayeux Tapestry) where William the Conqueror defeated Harold. Harold ignored warnings that it was a bad omen, however the comet became a portent of fortune for the victorious William! We won’t see Halley’s Comet until 2061.Image

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Exploding beans and animal droppings: seed dispersal in four methods

In case you hadn’t noticed, it’s getting colder, leaves are dropping and everything’s looking pretty miserable. But far from going to bed for the year, nature’s at work more than ever. Seed dispersal is a key process in paving the way for new growth next year.

For most plants, autumn’s the time for producing seeds. Conkers, acorns, dead flower heads in the back garden – these seeds are all being shed now. But they also need to be scattered around so that they can start growing roots. There are four main methods of seed dispersal.

Animal dispersal who’d have thought animal droppings were helping to spread plant growth? When birds eat berries, they also eat the seed. Wherever they poo, they’re also dropping seeds for new plants. And it’s not just by eating that animals do their part. Think of those goosegrass seeds (below) which stick to your clothes. Their little spikes can piggy back on birds, squirrels, foxes, even people, and drop off far away.

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Wind dispersalthose chilly breezes aren’t just there to make you shiver. They’re able to blow lighter seeds, sometimes over great distances, allowing new plants to take root far away. Watch how easily these dandelion seeds are swept away. When you’re next outdoors, look out for poppy seeds (very small and light) and sycamore seeds (with their “propeller blades”). These designs make them ideal for travelling further.

Explosive dispersalif you’ve ever sat near gorse on a sunny day, you might have heard mini explosions. When the pods of some plants dry out, they tighten around the seeds until they explode. This shoots seeds around the area, allowing an effective dispersal. Check out these exploding seed pods. You don’t have to go far to find this phenomenon either. Runner beans, broad beans, really almost any beans, explode to shed their seeds.

Water dispersal – rivers and larger bodies of water can deposit seeds miles from their original plant. Similarly to wind dispersal, this is most effective when the seeds are light. That’s one reason why willow and silver birch trees (often found near water) have such small seeds.

For all of these methods, an important goal is to spread the seeds as far as possible. This prevents over-crowding which can seriously affect growth. Ever tried planting seeds too close together on the veg patch? It doesn’t work!

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Shadow play

Shadow puppetry is an ancient form of storytelling through the use of puppets and light. It began about 2000 years ago in China when an emperor’s wife died, and his court created a shadow version of her so that the emperor could see her again.

Shadow theatres are still used today. Check out these people building a car out of just a few props!

You too can do it at home with just a torch and some paper shapes. Ask an adult to point a torch at a wall a couple of metres away. Then hold paper shapes between the torch and the wall to cast shadows on the wall. Here’s a good guide for making shadow puppets.

From animals to trees and smiley, sad and scary faces, you can make all sorts. Even your hands can create different animals – though some are more complicated than others! Can you guess what each animal is?Image

Shadows are made when an opaque (non see-through) object blocks light. The size and shape of the shadow depends on the distance between the light source and the object casting the shadow as well as the distance between the object and the surface on which the shadow is cast. The closer you move an object to the light source the bigger it gets. Try it – if you hold your hand ten centimetres from the torch it blocks out much more light than if you hold it a metre from the torch.

 Good luck casting shadows – let us know if you get any good ones!

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