Serenade the Sun

It's amazing what a ball of mostly iron will do if you shine a light at it for four billion years.

'Dawn sun worship' by Philip Alexander

We've finished our course content in TAL biology so today we were looking back with the theme of light. This year is the UN International Year of Light and our Sun is the reason we are here: From what you ate today and how you traveled to where you are, to how life survived long enough for humans to evolve. We found eight biological processes that respond to light...

Plants:

• Phototropism - When shoots grow towards the light, and roots away.
• Photosynthesis - Nature's solar panel: converting light energy into sugar since the first oceans.
• Phytochromes - Pigments that control when a plant flowers or a seed germinates.
• Etiolation - More a response to the absence of light, when plants stretch under a rock.

Humans:

• Iris reflex - Controls the amount of light that enters the eye.
• Sight - The obvious one: Perceiving light rays as images.
• Tanning - Pigmentation of the skin.
• Vitamin D - Amazingly we can make a vitamin in our skin!

Add more in the comments!

The longest neurone in the human body is one of the peripheral neurones in the leg, travelling from the base of the spine to the foot - over 1 metre in some people!
Running this a close second is the neurone from the motor cortex to the lower part of the spine...

These are single cells, with highly specialised axons that span huge distances for their size. The question now is: how long could they get? If they grow proportional to a person's height, are they capable of indefinite growth if given sufficient nutrients?

Over a metre long and not visible to the naked eye...

(http://diamidinophenylindolee.tumblr.com/post/59584066686/single-neuron-under-the-electron-microscope)