Category: General

Happy Half Term


PMG tips for half term:

  • Don’t do any schoolwork at all for one week
  • Do spend lots of time outdoors and with your friends
  • Find things to do that are fun.
  • Be nice to your family
  • Sleep lots……

Wise words

Just seen this photo on Twitter and thought it’s a good thing to remember at this time of year….

Air Pollution part 2: A* understanding for IGCSE Biology 4.11

It’s a cold February day in half term as I write this and I have already lit my log-burner in the living room downstairs.  When this was fitted a year or two ago, I was told it is now a legal requirement in the UK to also fit a detector for one atmospheric pollutant that can be produced as a waste product of combustion of biofuels.  This post is about that pollutant, carbon monoxide.

Carbon Monoxide

Carbon monoxide is a colourless, odourless gas.  It is produced whenever carbon-based fuels (coal, gas, wood, charcoal) burn in an atmosphere with a restricted oxygen supply.  The structure of a molecule of carbon monoxide is very simple:  it is a carbon atom covalently bonded to a single oxygen atom.


(My log burner has a control where you restrict air getting into the stove so that your massively expensive logs burn a little more slowly – hence the need for the CO detector)  Carbon Monoxide poisoning results in 200 hospital admissions per year in the UK and around 40 deaths.

Why is carbon monoxide such a deadly gas?

The symptoms of carbon monoxide poisoning are similar to flu.  Tiredness, vomiting, headache, stomach pain….  They are caused because when carbon monoxide is breathed in, it will diffuse into the blood in the alveoli of the lungs.  Carbon monoxide binds to haemoglobin, the protein found in red blood cells that transports oxygen.  It binds about 70 times as effectively to haemoglobin, forming a stable compound called carboxyhaemoglobin.  So it prevents haemoglobin molecules from transporting oxygen (and indeed carbon dioxide) around the body.


I hope that post is useful when you come to revise this section.  It also links in of course to the topic on blood and indeed the health consequences of cigarette smoking.  I’m sure I have posts on these topics as well to read if you are interested…..  I’m off now to get my chimney swept and to check the batteries in my Carbon Monoxide detector.

Digestion of Lipids: A* understanding for IGCSE Biology 2.29

A balanced diet will contain many different fats and oils.  The commonest type of molecule in these lipids is called a triglyceride.  They are made from a small molecule of glycerol attached to three fatty acids.


These triglycerides are too large to be absorbed in the small intestine (ileum) and so need to be broken down into their constituent parts.  In the digestive system there are enzymes called lipases that can catalyse the digestion of lipids into fatty acids and glycerol.


Most digestion of lipids happens in the duodenum.  The pancreas produces a lipase enzyme that mixes with the food in the duodenum.  Although bile does not contain any digestive enzymes, it does have bile salts that play an important role in the digestion of lipids.  Bile salts cause large fat droplets in the duodenum to change into many smaller lipid droplets – a process called emulsification. (Read my post on bile if you want more details here….)


Fatty acids and glycerol molecules are small enough to cross the epithelium in the villus in the ileum.  This absorption of fatty acids and glycerol is slightly different to the other products of digestion as they do not pass immediately into the blood.  They are assembled immediately into structures called chylomicrons and these move into the single, blind-ended tube in the villus called a lacteal.  The lacteals merge together into lymph vessels that eventually empty into the blood in the neck.  (Please read my post on absorption in the small intestine to read more about this)

National Schools Rackets 2015 – state of play

We have reached the end of four days of the National Schools Rackets championships sponsored by Brown Advisory.  Tomorrow we head to The Queen’s Club for the final four days, including the start of the main event, the Foster Cup.

Eton still has 10 boys involved overall which is not too bad a return after four tough days of competition.  In the Jim Dear (Under 15s) our three best players are still in the competition, although I think it is fair to say none has had to play a strong opponent as yet.  Jamie Hardy is playing as well as I have seen him, serving strongly on both sides and more importantly moving well in the rallies.  It is good to see that Louis Manson‘s injury from earlier in the half is not causing him any problems and he too has had two comfortable wins.  Luke Philipson has been playing aggressively, hitting the ball hard and dominating against smaller boys.  His test will come when he plays someone capable of returning his forehand serve from the right down the line – at the moment he stays too far up the court after his serve and this may be a problem in the next round.

The Incledon-Weber is for U16s and we have one boy still in the draw.  Harry Thistlethwayte had to play really well tonight to beat his doubles partner Bertie Duncan.   There were some really good rallies in this match, Bertie retrieving really well at times but Harry’s power and ability to hit winners helped him finish on top.

In the Renny Cup, there are two Etonians still competing: Luke Pitman and Salil Navapurkar have winnable matches on Thursday to look forward to.

The Foster Cup has not started yet but does tomorrow afternoon.  This event is for the 16 best players in the country and it is great that we have a quarter of the field, including both the top and the second seeds.  Rory Giddins is top seed and favourite and plays a good player from Malvern tomorrow.  George Nixon, his doubles partner is seeded 2 and has to play the potentially dangerous Cawston in round one.  Cawston is the son of a rackets professional and is a good mover and strikes a clean ball.  If George can dominate with his serve, he should be favourite to progress.  Tom Loup plays Rath from Harrow in a match featuring two hard-hitters.  Hector Hardman has a good match tomorrow against Jordache, also from Harrow, a competent opponent who won the Renny Cup last year so will not be lacking confidence.  Hector has been playing well this half and should be confident that he has the power and control to beat Jordache.  Hector’s serve will be crucial as cheap points at Queens can make all the difference.

There are rarely easy matches in the Foster Cup and all the Etonians will need to bring their best play to Queens tomorrow afternoon.   I wish them luck and hope we can keep many of the 10 still involved into Thursday and beyond…..

National Schools Rackets 5th-12th December 2015

The National Schools Rackets championships started today at Eton College.  The first four days of competition are being held here because of building works at the Queens Club in London but we move to London on Wednesday for the final four days of competition.

Full details of all matches and draws can be found on the attached pdf file.


E Michaelmas Biology trial 2015 – revision checklist

I suggest you go through this checklist and make sure you understand each point fully….. This list could be the basis for making some revision notes.

  • Understand the differences between atoms and molecules
  • What is a polymer?  Give some biological examples of polymers and describe their structure.
  • What are the chemical tests for glucose and starch?
  • How do enzymes work as catalysts?
  • Draw a graph to show how temperature effects the rate of an enzyme-catalysed reaction.  Annotate the graph to explain why this pattern is observed.
  • Now do the same but for the effect of pH on enzyme reactions…..
  • Write down the word and balanced chemical equations for photosynthesis.
  • Why is photosynthesis such an important process in the plant (and in the ecosystem)?
  • Draw an annotated diagram to show the structure of a leaf and how it is adapted for photosynthesis.
  • How do you test a leaf for starch?  How do you measure rates of photosynthesis using Cabomba? What variables could you alter in this set up?
  • Explain differences in function between xylem and phloem.
  • How is water absorbed in root hair cells?  Explain osmosis (good luck!)
  • What are the differences between diffusion and active transport?  Give two biological examples of each.
  • What is transpiration?  How can you measure it?
  • What factors affect rates of transpiration in a plant?
  • What is the difference between a pesticide and a fertiliser?
  • What are the advantages and disadvantages of chemical pesticides and biological control of pests?

Spectre: **** but not quite the perfect *****

A few breakfast thoughts about “Spectre”…. No spoilers I promise.


Sam Mendes continues to probe the Bond backstory in this excellent film.  The film contains enough references to some of the earlier works to keep even a true “Bond-nerd” like me happy.  There are small nods to Live and Let Die, OHMSS, From Russia with Love, ThunderBall and others all cleverly woven into a totally preposterous new story.  I felt that whereas Skyfall felt like something new for Bond, this film is very much meant as a return to the core values of the franchise:  exotic locations, cinematography, beautiful cars, a gorgeous female lead, black tie and ball gowns, Martinis.  There is even a villain with a white cat.

If Skyfall proves to be the high water mark of Bond (it is still my favourite Bond movie to date) then Spectre falls in only just behind.  Daniel Craig gives a superb performance of a cold, damaged man but still with an occasional warm glint in his eye.  He is ably supported by three great performances by the actors playing M, Q and Moneypenny.  All three hold the screen, Q in particular having the best one-liners and now even an action sequence in a mountain-top alpine health clinic.  The French actress Lea Seydoux playing the female lead is certainly a match for Bond on screen and the best scenes in the film are once she gets involved.  Her character like Bond’s has been damaged by life, her acting is great and she is certainly beautiful, very, very beautiful.

So why not 5 stars?  Well it comes down to just one thing.  Plot.  I know that having one that is terrible is also in the spirit of the earlier films but the plot here is so ludicrous, and the character of the villain so unexplained and unexplored that I could not give this the highest rating.  Blofeld is a cartoon baddy of course and the actor does his best with what he is offered, but the silliness of the story prevents this being a truly great film.  For me, Spectre also lacks the spine-tingling moments that made Skyfall so amazing.  I always shiver when the old DB6 appeared behind the garage doors and even its customary appearance here failed to make my hairs stand on end.  Indeed this is perhaps the main problem with this film – beautifully acted, great cinematography and locations but where are those special moments that make you smile inside?