A Question of Autumn

Why do leaves change colour in the autumn? It’s a simple question with a simple answer, you might say – they start to die. But there is a bit more to it than that, if you’re interested in the science, and how it can produce some of nature’s most picturesque scenery.

Every autumn the leaves from deciduous trees change colour before falling to the ground. This is due to the fact the leaves contain many chemical pigments, the most important being chlorophyll. Chlorophyll makes leaves green and helps in the process of photosynthesis, which attracts sunlight to the tree, helping them grow. Leaves also contain the chemical carotene, which has a yellow colouring. Carotene lives in the leaves all year, but is masked by the green of the chlorophyll.

The process of leaves turning from green to yellow, red or brown, is dependent on the climate. When autumn approaches and the warmer temperatures of summer begin to dip, the chlorophyll within the leaves begins to break down. Other pigments that live beneath the chlorophyll, such as the carotene, come forward.

Chlorophyll is dependent on water as well as sunshine. As the climate cools and the tree draws colder water up through its roots, the tree prepares for winter. It does this by growing a thin layer of cells over the water tubes in its leaves, closing them up in preparation. Without a regular supply of water, the green chlorophyll starts to disappear and the other colours in the leaf, such as the yellow carotene, can be seen. In some trees, when the leaf cells build, the water blocking wall which seals the tubes in the leaf’s stem traps sugar inside the leaf. This turns the sap and therefore the leaf red, or even purple.

The final part of the process before a leaf falls is when the water within the tree dries up completely. This dehydration kills any remaining green chlorophyll, as well as the yellow and red pigments. Consequently, the leaves turn brown and start to die, becoming dry and crunchy before they fall from the tree.

All in all, it’s quite a complicated and intricate process that provides us with this often beautiful time of year. When it isn’t raining at least!

Today marks the birthday of a man who History has shown to be one of the great pioneers of modern medicine, whose work led to the advent of vaccination. Bearing in mind how much we rely on these to protect us against numerous conditions and diseases now, it is one worth remembering.

Born in Berkeley, Gloucestershire on 17 May 1749, Edward Jenner was the son of the local vicar. He was only 14 years old when he became an apprentice to a surgeon, and began training to be a doctor. Working in the countryside, Jenner noticed that, despite the rife nature of the smallpox disease across England, the milkmaids never suffered from it. They didn’t even show signs of the scarring that commonly affected smallpox sufferers. He did know, however, that the milkmaids often suffered from the far less serious condition of cowpox. Jenner therefore began to work on the theory that perhaps milkmaids did catch the smallpox disease, but had somehow become immune to it.

Taking his thought processes further, Jenner speculated that if you had the relatively harmless cowpox, then perhaps you wouldn’t get the far more lethal disease of smallpox at all. Wanting to prove his theory, in 1796 Jenner carried out his now famous experiment, which involved using a needle to insert pus from Sarah Neales, a milkmaid with cowpox, into the arm of an eight-year-old, James Phipps. A few days later, Jenner then exposed James to the smallpox. The boy failed to contract the disease, and Jenner concluded he was now immune to it. Calling this new method vaccination (after the Latin word vacca, meaning cow), Jenner submitted a paper to the Royal Society the following year about his discovery. It was met with some interest, but further proof was requested. Jenner proceeded to vaccinate and monitor several more children, including his own son.

Although the results of Jenner’s study were published in 1798, his work met with opposition, and even ridicule. It wasn’t until 1853, 30 years after Edward Jenner had died, that his smallpox vaccination was to be made a compulsory injection across both England and Wales. However, Jenner’s work would ultimately lead to a wave of medical innovation, and further, to the large number of life saving vaccinations available today. For this, he is surely worthy of remembrance.

Almost every health scare these days seems to concern viruses. From bird flu and Ebola and now to Zika, these pathogens appear to have medicine on the hop. But what exactly is a virus, and why are viruses such a problem?

A typical virus is a remarkably simple machine. It is just a short stretch of nucleic acid (DNA or RNA) surrounded by a protein coat. The nucleic acid contains coded information for making new virus particles, while the protein coat may help the virus gain access to its host. And that is that. Viruses have no membranes, no complicated machinery for carrying out reactions, and no metabolism like one of your own cells. Viruses do not feed, move, or respond to their surroundings like proper organisms. And they are so small that they were not even visible until 1939, following the development of the electron microscope.

However, introduce a virus into a host cell and the results are dramatic. It hijacks the cell’s processes and redirects them exclusively to the manufacture of more of itself. New virus particles are then budded-off from the surface, each surrounded by a piece of host cell membrane. Or, the cell splits open, releasing hundreds of new particles to infect other cells. Either way, viruses damage and kill our cells, which is what makes us ill when we have a viral infection.

Another trick of viruses provides a hint as to their origins. The genes in our own cells are remarkably like virus particles, also consisting of nucleic acid (DNA in this case) surrounded by protein. Sometimes a virus splices itself into this host DNA like an extra gene. The virus then lies low, being copied with the rest of the DNA when the cell divides, and passing to each of the daughter cells produced. Later, it may emerge without warning to form more viruses in the normal way, causing illness years after it first invaded. This is what happens when the chicken pox virus causes shingles in later life, or when people recovered from Ebola relapse, as recently happened to the Scottish nurse Pauline Cafferkey.

So, if viruses are constructed and can behave just like normal genes, perhaps that’s what they really are? Perhaps they are “escapee genes” that left their cells long ago to take up an independent existence? That would explain why they find it so easy to invade and take over our cells, and why we find it so difficult to defend against them.

Whatever the truth of their ancient origin, viruses present modern medicine with a formidable challenge. Antibiotics do not work against them, and the particles mutate rapidly to keep ahead of vaccines prepared to defeat them. One thing is certain: Ebola and Zika are not the last health scares that they will bring us.

Viruses and the diseases that they cause, including ‘flu and Ebola, are covered in depth by the new A Level Biology course recently launched by Oxford Open Learning. You can find out more about the course here: http://www.ool.co.uk/subject/a-level-biology/

 

By far the biggest killers in today’s Britain are cancer and circulatory disease. Of the 501, 424 people who died in 2014, 29% died of cancer and 27% from heart attacks plus strokes. There is no doubt as to why charities seeking a cure for these scourges attract so much public support.

By contrast, leaving aside ‘flu and pneumonia, which mainly kill the already weakened elderly and infirm, infectious diseases account for a mere 0.6% of deaths. Your chances of being cut down by one of these in your prime of life is comparable with that of the threat from road traffic accidents or suicide. The reason we are dieing largely from heart disease and cancer is not because they are becoming more virulent, then. It is simply because we are living longer. Whereas in 1900 the average life expectancy in this country was just 48, now it is 81.

Antibiotics, the drugs used to treat bacterial infections, are a recent invention. Alexander Fleming stumbled upon them by accident in a London laboratory in 1928, though the first, penicillin, only went into mass-production in 1944. When it did so, it reduced at a stroke the number of deaths from infections, making hospital operations safe, battlefield wounds less fatal, and many serious diseases treatable.

Bacterial resistance to antibiotics emerged as a problem in the 1950s, but it has now become critical. Resistant bacteria have the ability to transfer their resistance to other species as well as passing it on to their offspring. So, once established, resistance to a particular antibiotic spreads rapidly, and bacteria with multiple resistances emerge. By 2004, bacteria resistant to almost all known antibiotics had appeared, while in 2015, bacteria resistant even to the”antibiotic of last resort” appeared in southern China. It is expected to spread to the west shortly.

In April 2014, the World Health Organization (WHO) sounded the alarm on this topic in no uncertain fashion. It spoke of a “major global threat” from such antibiotic-resistant bacteria, and an imminent return to a pre-antibiotic era, where people regularly die from the simplest of infections. If and when this happens, you would be far more likely to die from sepsis following a cut, or from airborne or waterborne bacterium, and less likely to live to an age when cancer and heart disease are a concern.

There is, though, a glimmer of light on this dark horizon. Traditional antibiotics are developed from defensive chemicals produced by fungi and bacteria. However, our own cells also produce chemicals that attack bacteria. They are short proteins (peptides) produced on our own cellular protein-assembly machines, called ribosomes. From this comes their acronym, RAMP antimicrobials (ribosomally synthesized antimicrobial peptides). These antimicrobials carry a positive electrical charge on their molecules and are attracted to the negatively charged outsides of bacterial cells. Once attached to the bacteria, they punch holes in the bacterial wall or membrane, killing the cell.

These natural defence molecules have been around for millions of years, during which time bacteria have failed to develop effective resistance to them. So, if this is the case, and if effective artificial mimics of natural RAMPs can be made, we may yet avoid a potential return to the dark ages of pre-antibiotics.

Bacteria, the discovery and action of antibiotics, and the emergence and spread of resistance, are all covered in depth in the new A level Biology course recently launched by Oxford Open Learning. You can find out more about the course here: http://www.oxfordhomeschooling.co.uk/subject/biology-a-level/

 

HMSBeagle

HMS Beagle moored off the coast of Australia

Charles Darwin was born on February 12th, 1809, in Shrewsbury, Shropshire, England. Although he had no formal education as a botanist or naturalist, Darwin was fascinated by natural history, and dedicated his life to its study.

In July 1838, Charles Darwin presented his paper on his theory of evolution to the respected Linnean Society in London for the very first time.

Having worked on his theory for over twenty years, Darwin’s thoughts on how animals and mankind evolved through a process of natural selection had a major impact on the scientific world and the church. Until Darwin began to share his ideas, ideas about natural history had been dominated by the Church of England, who saw the origins of all living things as working to God’s plan.

Darwin’s theory stated that within a species, individual animals show a wide range of variation. These individual animals with characteristics most suited to their environment are more likely to survive and produce offspring. He also said that the offspring of stronger parents would be more likely to survive than others, as would their own children. By contract, those creatures that are poorly adapted to their environment are less likely to survive, and therefore less likely to successfully reproduce.
Darwin conclude that over a long enough period of history therefore, a species would gradually adapt to best suit its environment, and would evolve into a stronger group. Those species that were weak would die out. This theory became known as ‘Natural Selection’ and coined the phrase ‘The Survival of the Fittest.’

Darwin began writing down his ideas on evolution in 1836, after the end of his five year voyage of discovery on the HMS Beagle. By December 1838 he had developed the main principles of his theory. Over the next few years he went on to refine his ideas with the help of three close supporters, geologist Charles Lyell, botanist Joseph Dalton Hooker and naturalist Thomas Huxley.

The help of Huxley, Lyell, Hooker and others was essential, as Darwin was widely criticized, especially by the church, for his ideas. Ideas, of course, which science has since proved to be correct.

BrainstormingBrainstorming, a method of a group sharing their ideas for a forthcoming project, essay or assignment, was developed in 1953 by Alex Osborn.  This technique is an excellent way of recording existing ideas, and stimulating new ones.

Osborn had four basic rules when brainstorming-:

1. No criticism of other people’s ideas
2. The wilder the idea, the better
3. Aim for quantity of ideas, and quality will follow
4. Try combining ideas to develop new ones

When brainstorming, give yourself a time limit of ten to twenty minutes. Write the subject you are planning to discuss in the centre of a large piece of paper and each time an idea is spoken, draw a line away from the subject and write it down.
As each new idea is developed and written down, your brainstorming mind-map will begin to grow across the page like a spider’s web of potential story, essay, or project ideas.

It is still possible to use this brainstorming technique to create new ideas for your work when you are working on your own. It is an excellent way to make sure you have a note of all the elements you want to include in your next piece of work.
Solo brainstorming is known as clustering.

Once you have written your subject, story character name or project title down in the middle of a sheet of paper, give yourself two minutes to write down all your immediate thoughts. When you’ve done that, look at each of your notes in turn and ask yourself, ‘Why do I think I wrote that?’ Spend two minutes considering each note and add new ones until you have formed a new ‘cluster’ of ideas for each point and have enough information and theories to be able to complete your assignment to the best of your ability.

By creating so many ideas in this way, whether alone or in a group, you can form a far wider breadth of work than you would have done if you’d written a list; and because everyone’s brain has its own memories and experiences, every brainstorming or clustering experience will be unique. Therefore, so will your work. It is this unique quality which makes the brainstorm such a valuable and enduring method.

Inn_brainetworksLearning is inevitable. We all do it. Generally it means to learn knowledge or a new skill….but is that all?

We learn from birth, maybe even before. We learn to talk, walk and play as babies and young children. Our school syllabus as young people and various things teach and develop us as we get older. Jobs, hobbies, skills, languages, education courses, professional training. We’re actually very good at it and you can always get better at it too, which is nice.

Scientists have been fascinated by learning and how the brain does it for a long time. They say we’re better people for it ( you could look up Maslow’s triangle and Carl Rogers’ ‘fully functioning person’ ). You can obviously feel a sense of achievement and as you might expect, that will usually do yourself some good.

But how do we do it? And when? You can usually manage your learning yourself to some extent and it’s probably more effective if you do. When do you work best; in the morning or late at night? When the mood takes you? None of these are right or wrong. But some of them might work best for you, and that’s what counts. Are you better at reading, listening, doing, copying? All are recognised ‘Styles of Learning’ ( maybe have a look at Kolb?). There’s even a learning exercise called ‘sitting next to Nellie’ ¨because “Nellie” knows what she’s doing and if you watch her so will you.

The science of learning is interesting and very current. Cognitive neuroscience is a branch of science that really looks at the brain. Is it a good thing? Well, it’s taught at a very good university in UCL, which alone should point to its value.

So how do we feel about this new-found freedom in learning and the ‘fashion’ of brain science? Is it all a bit much? Is it a bit false, perhaps? More personally, do you wish you’d been better at school, even that your teachers had been a bit more strict or traditional? Or are you happy to manage yourself? Do you want freedom or direction? Oh, and while we’re at it, do we also think we learn attitudes and understanding? Why not tell us what you think?

There are many more aspects of learning, but if you are interested in the subject, it could be best to go and discover them for yourself. It’s all part of the process!

Photosynthesis, especially in tropical rainforests, is hugely beneficial to us.

Photosynthesis, especially in tropical rainforests, is hugely beneficial to us.

The term photosynthesis comes from the Greek words φῶς or phōs, which means “light”, and σύνθεσις, or synthesis, which means “putting together.”

Photosynthesis takes place within plants; particularly within the delicate mesophyll tissue, that makes up part of the leaves of green plants (Leaves are made up of mesophyll tissue, epidermal tissue, which covers the whole plant, and xylem and phloem which transport water, minerals and sucrose around the plant).

During the photosynthesis chemical reaction, carbon dioxide and water are converted into glucose (the plant’s food) and oxygen. The reaction requires light energy, which is absorbed by a green substance within leaf cells, called chlorophyll. These tiny leaf cells contain chloroplasts, which in turn, hold the chlorophyll.

Plants absorb water through their roots, and carbon dioxide through their leaves. Some glucose is used for respiration, while some is converted into insoluble starch for storage. The stored starch can later be turned back into glucose and used in respiration. Oxygen is released as a by-product of photosynthesis.

Three factors can limit the speed of photosynthesis – the sunlight’s strength, carbon dioxide concentration and temperature. Without enough light, even if there is plenty of water and carbon dioxide, a plant cannot photosynthesise fast enough. The higher the sunlight levels and intensity, the faster the speed of photosynthesis will be. Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide. If it gets too cold, the rate of photosynthesis will decrease. Conversely, plants cannot photosynthesise if it gets too hot.

In summary- photosynthesis happens within leaves of all green plants, and occurs to varying degrees of intensity according to four factors-:
1. Sunlight (beating down on the leaves, it provides the energy required for photosynthesis)
2. Chlorophyll (which is contained in the leave’s chloroplasts)
3. Water (which reaches the cells through the xylem)
4. Carbon Dioxide (which diffuses into the leaf)

Photosynthesis is the process which maintains atmospheric oxygen levels, and it supplies all of the organic compounds and most of the energy necessary for all life on Earth. This makes it one of nature’s most important chemical reactions.

Lights_out,_sort_of_(2384136179)At 20:30 this coming Saturday night (29th March), people all over the world will participate in Earth Hour by turning off all unnecessary electrical equipment in their homes and businesses. More strikingly, all unnecessary lights will also be switched off, including those of some of the most famous landmarks across the world.

Earth Hour, organised by the WWF (World Wide Fund for Nature), has become increasingly popular since it was first done in 2007.  Back then, it took place in just one city – Sydney, Australia. In 2009, this had increased to 96 participating countries, and, by 2012, participating countries came from each of the seven continents of the world.  Technology giants have also participated in Earth Hour’s history by setting the background of their logos and videos to black, thereby symbolising the lights being turned off. clearly, Earth Hour really is now a worldwide event.

The WWF stresses that Earth Hour is not designed to significantly reduce carbon emissions itself (although many participating cities and countries publish impressive data regarding their decreased electricity consumption during Earth Hour), but instead is intended to raise awareness of environmental issues across the world. In 2012, Earth Hour was extended to include a campaign called I Will If You Will. The idea of IWIYW is that individuals inspire each other by sharing energy saving challenges. Again, technology has played a huge part in promoting the campaign, with IWIYW challenges being posted on YouTube, for example. This extension of the Earth Hour campaign shows that the original goal of the project – that of increasing awareness of and engagement with environmental issues – has been successful.

Obviously, the sheer number of people who participate in Earth Hour across the world (over 1.8 billion in 2011) is inspirational in itself. For this author, though, the images of the famous landmarks without their lights on are the most striking. In previous years, this list of landmarks has included Buckingham Palace, the Eiffel Tower and the Sydney Opera House. There’s something about the symbolism of seeing landmarks so permanent a part of the world’s landscape in such a different way, which makes quite an impact, and really highlights the importance of the environmental issues being discussed.

So, will you be participating in Earth Hour this weekend? If nothing else, try and find some photos of the cities and countries that will be taking part this year. You might want to find out which celebrities are endorsing the campaign and why they’ve chosen to do so  (Last year the UK’s ambassadors were McFly!).  It would be be interesting to hear what you think of the whole thing; is switching the lights off for an hour a meaningful way to engage people in such important issues, or just a bit of a gimmick? Will you one of the millions of people across the globe turning off your lights this Saturday night?

320px-Richard_Huish_College_Exam_HallThe UK exam system is set to change quite a bit over the next three or four years. Both the A-level and GCSE systems are going through significant changes, starting with A-levels. What does this mean for current and prospective students?

As long as you take all your examinations by June 2016, you are unlikely to be affected by the changes. So, for instance, you might aim to do your exams in June 2015 and then defer to June 2016 without noticing any significant change – you will be following the same specification, doing the same style of exams, etc.

It is only if you are planning to study through to June 2017  ( or beyond ) that you need to find out the timescale for changes and work out how these will affect you. Indeed, if you want to take GCSEs only, those exams will still be the same in 2017 and it is only in the June 2018 exam series that the changes to specifications will bite.

The A-level situation is more complex because of the nature of the exams (currently in two parts, AS and A2) and because the specifications are not all changing at the same time.

The most important change is that although there will still be AS exams, these will NOT count towards the full A-level qualification. They will be separate stand-alone qualifications.  At the moment, you can carry foward your AS results as half your A-level. In future, students will have to do the whole A-level at the end of the two-year study period. The first of the new AS exams will be held in June 2016 but the old-style AS specifications / exams will also be held for the last time in most subjects at the same date.

A good summary of the timeline of changes is on the AQA website at http://filestore.aqa.org.uk/admin/library/AQA-W-REFORM-TIMELINE-ALEVEL.PDF.

Looking at that, you will see that those “old”-style AS results cannot be carried across to the A2s in 2017 (in Phase 1 subjects). To get the full A-level in 2017, you would effectively have to start again, with the specification that has not yet been released. So, unless you are clear that you want an AS qualification ONLY, we should strongly advise against aiming to defer AS studies to June 2016 (in Phase 1 subjects) – unless you’re doing A2 at the same time and/or you are clear that it is the last chance for the A2 as well.

The list of Phase I subjects includes most of the subjects taught by OOL and OHS. The only subjects (Phase 2) where we all have an extra year are Maths and languages (e.g. French and Spanish). There may be fewer centres hosting old-style AS exams in June 2016, of course.

Right now, our general advice to all prospective A-level students would be to make sure you finish your AS studies in June 2015. Then you will have a choice between stopping (having passed your AS exams) or carrying your marks forward to the full A-level in 2016. Then make sure you finish the  full programme in 2016 or you may find that the specification has changed radically.

The situation is not quite so complicated for GCSE candidates. The main change to the GCSE system will be that (for most purposes) you will only have ONE chance to sit your GCSE exams. You won’t be able to do GCSEs a module at a time. Instead you will have to sit the entire GCSE in one exam-sitting. It is likely that there will also be rather less coursework in a number of subjects, with more stress placed on exam-performance, but the final details of this have not yet been confirmed.  Teaching to the new GCSE specifications will begin (in schools) in June 2016 for first examination in June 2018, so the old specifications still have quite a bit of shelf-life.

Even if the new GCSE arrangements do not suit distance learners, there will still be ample opportunity to sit the IGCSE (or Certificate) alternatives to GCSE. The IGCSE / Certificate specifications are not planned to change at all and they will continue to have the same value as GCSEs and they will remain a more practical option for many distance learners in the years to come.

Good luck in making the right study choices!

 

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