Month: October 2020

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Life is a relay race

This story continues the adventures of the ferns in Nowhere Wood. The first part of the story is Climbing the walls.

The genome of the fern contains essential information that the fern needs to grow and  make new cells. At different times the fern produces spores, sperm and eggs and the two forms of the plant. The genome contains information on the growth of each of these stages.

The information in the genome is the same in every cell of the fern because an identical copy of the genome is found inside the nuclei of all the cells of this fern at every stage of its life.

The genome is found in the nucleus of each cell.

The genome is divided between a number of chromosomes. The diagram shows the genome of the Adder’s tongue fern. It has about 1440 chromosomes. This is the largest number of chromosomes of any organism in the world!

Fern genomes are larger than the genomes of other organisms, because they contain the information the fern needs to grow spores, sperms and eggs as well as the two forms of plant.

The genome contains the secrets of how to be a fern and how to move forward in the adventure. This information has been copied and passed on to each generation of ferns, ever since the first ferns evolved about 390 million years ago.

 

 

Life is like a relay race: genetic information is passed on from one generation to the next in the genomes of sperms, eggs and other gametes.

These ferns are having risky and uncertain adventures in time as well as space. If the secret information is not passed on correctly, then the species may become extinct. History shows us that most species that have ever lived on Earth are now extinct.

    1. Why do you think it is essential that the genetic information from parents to offspring is copied accurately?
    2. Why do you think the fern genome is so large, compared with other types of plant?

All change!

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Climbing the walls

A hundred years ago, Nowhere Wood was a sandstone quarry, and there is still a cliff face at the end of the wood.
How can this hart’s tongue fern grow on a vertical cliff face about two metres from the ground.

That is quite an adventure in time and space. This story explains how this fern can climb walls.


Ferns are an ancient group of plants, first appearing on Earth about 390 million years ago. That’s about 260 million years before the emergence of flowering plants.

Like fungi, another ancient group, ferns produce spores. They are the brown dots on the underside of this fern leaf. Spores are light and float in the air like particles of dust.

One spore floats up to a small crack in the rock face. Rainwater and the decaying remains of a leaf have formed a sticky, jam-like, humus inside the crack.  The spore sticks to the humus and germinates, developing into a tiny little plant, about 10 mm long.

This is a fern, but it is not the mature adult form. It has tiny roots that grow into the humus, drawing nutrients from it.
This small plant is called a gametophyte because it makes gametes for sexual reproduction. Gametes are sperm and egg cells. 


These gametes will come together to make the adult fern on the surface of the tiny gametophyte.

The gametophyte makes many small sperm that swim in the water on the surface of the plant. They swim towards eggs, which are much larger. This photograph shows a fern sperm fertilising a fern egg.

The sperm and the egg join together. A single cell is produced that will grow into the adult fern. Eventually this fern will make spores of its own.

This may sound like a long-winded and complicated adventure, but it seems to work well, because there are so many ferns in Nowhere Wood.

The fern exists in several different forms during its adventure: spores, eggs, sperm, gametophyte and adult plants. What do they have in common?

Each of these forms is made of one or many cells. Each cell contains a nucleus, and inside each nucleus is a genome. Genomes contain information. The information in the genome is the same in all of the different forms of the fern.

The genome contains the secrets of how to be a fern and how to move forward in the next step of the adventure.

  1. The fern exist in several different forms during its adventure: spores, eggs, sperm, gametophyte and adult plants. Think why is important that the genome in every form is the same? 

Life is a relay race

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Moving things on

The weather is warm and wet in Nowhere Wood.

These are perfect conditions for growing the fungi that spread  everywhere throughout the soil of Nowhere Wood. Fungi are Nature’s recyclers, feeding on the fallen leaves, fruits and wood.

Fungi feed on the wood of the dead oak trees, turning it into nutrients that provide energy and chemicals needed  to grow new fungal cells.  (These cells form long threads called hyphae). Some fungi can spread out over really large areas, several kilometres wide.

At this time of the year, the fungi are busy ‘ being’.

Then one night, silently and without warning, the fungi do something else.

They produce structures that we call “mushrooms” **.

Mushrooms are  fruiting bodies. They produce thousands of tiny spores.

Spores are small and light. They are carried on air currents to new places in Nowhere Wood, where they will germinate and grow into new hyphae.

Spores have often been found in the filters of jet aircraft flying at the edge of the atmosphere, so some spores can travel right round the world. When fungi produce spores they are ‘becoming’ something new: small, light and mobile versions of themselves.

Then, almost as soon as they arrive, it is all over. The fruiting bodies die and become food for other fungi and bacteria in Nowhere Wood.

This is how it is. The precious molecules are used, recycled and become part of the growth of new organisms. Nothing is ever wasted.



 

  1. Nearly all of the atoms present on Earth when life began to evolve about 3.7 billion years ago are still found on Earth today. Many of them are found locked inside living organisms. Sooner or later, all of these organisms will die. Imagine what life would be like without Nature’s recyclers.
  2. You are a collection of recycled atoms. Think about how carbon atoms enter and leave your body. [Hint, carbon atoms are found in carbohydrates and in carbon dioxide.]

You can read more about ‘being and becoming’ here.

 

**Some mushrooms are good to eat, others are really poisonous and can kill us. It is hard to tell them apart unless you are an expert, so it is sensible not to touch or eat any mushrooms you find in a wood.

Climbing the walls

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Squirrel wars

One hundred and fifty years ago, the oak woods near Nowhere would have been home to red squirrels. Now they have all disappeared.

The red squirrels have been replaced by grey squirrels that were introduced into the UK from the United States in the 1870s.

Grey squirrels spread to nearly all parts of the UK, replacing the red squirrels wherever they went. Now red squirrels are only found in a few places, where they are protected.

Grey squirrels are 60% better at digesting oak acorns than red squirrels, which seem to prefer hazel nuts. Oak acorns are much more common in Nowhere Wood than hazel nuts, and this favours the grey squirrel.

The success of grey squirrels at surviving and breeding in Nowhere Wood is due to the production of acorns, which varies from year to year.

Survival is a risky journey for any squirrel: the arrival of new competitors or interruptions to the food supply can pose real challenges.

 

Their lives are  adventures.

The word ‘adventure’ has two parts:

Ad means moving towards something.

Venture means attempting something dangerous or difficult, that is risky, with no guarantee of success.

Put the two together and you get the idea that the lives of all living organisms are risky journeys into the future, with no guarantee of success or survival.

If you like, you can think of life as:

organisms having adventures in time and space

  1. Think about the squirrels and the oak trees. In what ways are their lives adventures?  [Hint: think about what the word adventure means.]

 

Being and becoming in Nowhere Wood

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Organise and stay alive

Living organisms have very organised structures.

Everything depends upon the way that the different parts of their bodies work together.

The parts of this watch work together, so that the hands of the watch move round in a rhythm that we use to tell the time. The hands do this because of the precise organisation of all of the parts of the watch.

The ability to tell the time emerges from the watch, only when all of the parts move together smoothly. If anything goes wrong, the watch “stops” and the ability to tell the time disappears.

Living organisms are alive because they are organised. Everything depends upon the way that the different parts of their bodies work together.

For an organism, life emerges and exists for only as long as its parts work together smoothly.

If anything goes wrong, the organism becomes ill. If it is very serious, then the organism dies and its life disappears. This is difficult to think about, but it is a fact of life.

  1. One of the important features of human society is that we have learned how to care for the sick and the elderly. Hows does this help the survival of humanity?

Moving things on

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Being and becoming in Nowhere Wood

 

All living organisms are doing two things at the same time. They are:

Being (they are keeping themselves alive) and

Becoming (they are moving towards the next stage of their lives).

The butterfly is being and becoming at each stage of its life.

All of the animals and plants in Nowhere Wood are also “being” and “becoming”.

  1. How are the oak trees in nowhere Wood being and becoming?
  2. How are you being and becoming? 

 

Counting the ways to stay alive

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Counting the ways to stay alive

No one knows how many different kinds of animals and plants are alive today, and, sadly, we never will.

A survey in 2011 suggested that there are nearly 8 million species of animals and nearly 300, 000 species of plants.  Astonishingly, nearly 90% of these species have yet to be discovered, described or named. Many are found in hard-to-reach places, such as tropical rain forests or the deep oceans. Given the rate of man-made habitat destruction, it is possible that many of these species will become extinct before they can be named by scientists.  

These 8.1 million species are, for now, the success stories of evolution. Each is a unique way of solving the problems of surviving and reproducing in an unforgiving and changing environment.

All species, like this humpback whale, have special characteristics that allow them to survive in their chosen habitats.

But if the habitats change too much, such as when when the oceans become acidified, rainforests are cut down or burned, then species may no longer be able to survive and they become extinct. Forever. 

  1. Why does it matter that species of organisms become extinct before scientists can discover them?

Organise and stay alive