gain and loss

A few days of heavy rain and 83° turned the noon walk through the woods into something of a steam bath making them feel like a tropical swamp.  The soft ground and heavy winds during a thunderstorm last night felled a large white oak leaving a huge hole in the ground and a lot of broken roots.  About 30 inches at the base and 90 feet tall it contains a lot of wood.

 

Where did all of that biomass come from?

 

Most people will tell you a tree comes from the earth and water (I've asked more than a few).  I'm guessing seeing the big hole left by the oak would convince them of it.  Some may add photosynthesis, but not have a clear idea. The real answer took a few hundred years to work out.

 

Johann Baptista van Helmholt was one of the first to try and understand the process.  In the 1600s he planted a willow tree and kept track of the weight of the water and soil he had to add.  After 5 years it had had gained 164 pounds, but the weight of the soil had only decreased by about 3 ounces.  He concluded that most of the tree came from water - soil wasn't a major contributor.  Although his water conclusion was wrong, at least he had shown the tree wasn't taking on soil.

 

The answer comes from photosynthesis ..  solar energy is used to convert water and carbon dioxide into a sugar and oxygen.  The energy of the sunlight is stored in the sugar which can be burned with oxygen yielding water and carbon dioxide and heat energy.  The most important chemical reaction for life...  

 

6H₂O + 6CO₂  + light energy -> C₆H₁₂O₆ + 6O₂

 

If you do the bookkeeping involved it looks like most of the mass comes from the carbon dioxide.  Looking more deeply under the equation's hood (it turns out to be a multistep process) it can be shown most of the oxygen released comes from water and not the carbon dioxide.  About 95% of the biomass of the tree, or plants in general, comes from the air!¹  Since all of our food ultimately comes from plants, we're using quite a bit of air in a way most of us don't think about.

 

That leads to another question.  When you lose weight, where does it go?  A survey of doctors, dietitians and personal trainers had divided up as follows:

 

 

 

That turns out to be mostly wrong.

 

First consider where extra weight comes from.  Independent of what you eat, your body will try to store excess food energy in the from of triglycerides in your fat cells.  Weight loss happens when your body needs more energy that you're taking in.  Usually it taps the fat cells breaking the triglycerides into several chemicals that can be burned to provide the energy you need.²  

 

To get at where the fat goes we need to look at its oxidation - The opposite of photosynthesis and an equation something like:

 

a mixture of C, H and O + O₂ -> some CO₂ + some H₂O + energy

 

The average fatty acid (and I had to look this up:-) is has three components which approximates to:

 

C₅₅H₁₀₄O₆ + 78O₂ ->55CO₂ + 52H₂O + energy

 

Sorting out where the oxygen goes is tricky, but it can be shown that 10 kg of fat is converted to 8.4 kg of carbon dioxide and 1.6 kg of water.³ 

 

 You get rid of most of your weight, 84% of it,  by exhaling it:-)

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¹ This excludes the water normally running in the plant or tree - we're just looking at the biomass it creates.

² It can also break down muscle, but this is usually a last resort or indicative of something gone wrong.

³ BMJ journal reference

 

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A fruity pound cake - adapted from an Alton Brown recipe

 

Pound Cake

 

Ingredients

 

° 8 ounces of softened unsalted butter plus some for the pan

° 15 oz (2 cups) white cane sugar and some for the pan

° 15 oz (3 cups) AP flour

° 1 tsp baking powder

° 1/2 tsp salt

° 4 large eggs

° 1 tsp vanilla extract

° 2 cups fresh blueberries

 

Technique

 

° oven to 325° F, rack in the middle

° coat a pan with butter and sprinkle with 2 or 3 tbl of sugar - I use a traditional tube shaped bundt pan that is probably about 9" in diameter

° Whisk 10 ounces of the flour, the baking powder and salt together and set aside

° Use a mixer and cream the butter and sugar at medium speed for about five minutes.  Add the eggs one at a time, then add the vanilla extract at beat until fluffy 

° Add the dry mix to the butter/egg mixture at a low speed.  Don't over mix.

° Mix the blueberries with the remaining 5 oz of flour and shake in a bag.  Fold into the batter and pour into the bundt pan.

° Bake for about 1 hr 20 min until a thermometer is clean and shows 210°F,  

° Cool on a rack

 

 

 

Comments

[Jheri]

Wonderful!!

[Brynne]

I can't wait to tell my almost 5 year old about this!

[Steve]

it is aimed at the kind of questions kids have... often they're interesting