The conditions for life on Earth

[Monster92]

Please can someone expand on the following conditions:

 

Availability of Water

Appropriate Temperature Range

Suitable Ambient Gases

Light

 

 

Is it possible to put the information simply with jargon explained

 

Thank you,

 

Monster92

[Ringer]

Expand in what way? There is a lot of ambiguity in your question, maybe explain what you want in more detail.

[Ophiolite]

Monster92,

would you expand on when this homework is due?

[Edtharan]

Water is a meduim that doesn't react with the molecules needed for life and thus allows them to exist and interact with each other easily.

 

If temperature is too high, it can cause damage or destroy the molecules necesary for life to form. If it is too low, then the reactions that need energy won't have it (and if water freezes then it stops being a good medium for the molecules to interact in as they would stop moving around). However, it appeas that a periodic variation in temperatures is necesary to assist with the initial stages of the formation of life.

 

Carbon is a very interesting element as it can combine with itself and with other elements in many different ways and produce many different types of molecules with a vast array of properties. So gasses with high carbon contents are probably necesary for life.

 

Light has energy, and as thermodynamics requiers a source of energy for a system to remain in low entropy (that is a highly ordered state). Light is one such source of energyas are hydrotheremal vents, black smokers, lightning, and so forth.

 

Have a look at this video for a good way that life might have formed: http://www.youtube.com/user/cdk007#p/c/0696457CAFD6D7C9/0/U6QYDdgP9eg

[steevey]

Please can someone expand on the following conditions:

 

Availability of Water

Appropriate Temperature Range

Suitable Ambient Gases

Light

 

 

Is it possible to put the information simply with jargon explained

 

Thank you,

 

Monster92

 

Ok, the specific atmosphere and Earth-magnetism we have on Earth shields us from the otherwise very powerful solar radiation and other cosmic rays.

Light itself thats not blocked by the atmosphere happens to be enough energy for the first lifeforms to use and also cause some important chemicals to form as well as drive a circulating whether system and currents. And since water is a very versatile chemical, many other chemicals which can store energy can by made from water by using the sunlight.

With the temperature, if it were too cold, reactions couldn't occur at a fast enough rate. If it were too hot, most organic bonds we see today wouldn't be stable and would break down under the heat.

Edited January 22, 2011 by steevey

[Monster92]

Thank you everyone . it's not homework it's just for study/revision. Can anyone expand on the suitable ambient gases? So far I have carbon dioxide for climate control and photosynthesis and nitrogen for protein synthesis. What other examples are there?

 

Thanks again

[Ophiolite]

If in the ambient gases range, lets not forget water vapour, which is valuable as a green house gas and as a prerequisite for rainfall, without which life would be largely confined to the oceans.

 

Also of potential use would be ozone, to minimise UV radiation. (Note here we are assuming 'life as we know it'. Other lifeforms may relish high UV concentrations, though the chemistry of carbon compounds would tend to suggest not. (And I'm not going down the non-carbon route in this thread.))

 

I think Edtahran's comments about water reactivity require clarification. The existence of hydrophilic and hydrophobic organic molecules is vitally important to Earth life. The bipolar character of water facilitates many reactions, promotes solution of key ions, etc. In short, water is damned reactive.

[steevey]

Thank you everyone . it's not homework it's just for study/revision. Can anyone expand on the suitable ambient gases? So far I have carbon dioxide for climate control and photosynthesis and nitrogen for protein synthesis. What other examples are there?

 

Thanks again

 

Ozone helps protect against powerful ultraviolet rays which a complete lack of would have killed any nascent life.

 

But otherwise just any surplus of air helps control the overall temperature around the surface of the planet. That's why on the moon which has no atmosphere, you could be buring hot on one side of your body and freezing on the other side.

Edited January 23, 2011 by steevey

[SMF]

Steevey, actually Monster92 is correct regarding CO₂. Because of the persistent greenhouse effect provided by the CO₂ in our atmosphere the earth, without it, would be in a perpetual ice age. SM

[Mr Skeptic]

Ozone helps protect against powerful ultraviolet rays which a complete lack of would have killed any nascent life.

 

Ozone protection is not necessary for life, just a few feet or water would work as well. Also ozone and even the oxygen necessary to have the ozone layer are very nasty for living things, and yes that goes even for the ones that need oxygen to live.

 

But otherwise just any surplus of air helps control the overall temperature around the surface of the planet. That's why on the moon which has no atmosphere, you could be buring hot on one side of your body and freezing on the other side.

 

Yes, and again water helps even more with this, both as a greenhouse gas and due to its high specific heat, and I'm sure that evaporating, condensing, freezing, etc also help transferring heat. Another cool thing about water is that it is less dense frozen than liquid, unlike almost anything else, so that it provides and insulating layer on top rather than freezing all the way to the bottom.

[Monster92]

Thank you everyone so much it's incredible helpful.

 

Just one more thing to consider

 

My text book says "tilted axis produces seasonal variations" then it doesn't say how .

 

Oh and I understand that there are exceptions to the main conditions. Although I think I need to know in the general sense.

[Mr Skeptic]

The tilted axes affect what parts of the world get how much sunlight. The key here is that the axis always points in the same direction as the earth goes around the sun. It's easiest to see if you imagine the tilt being 90 degrees, so that the northern and southern hemispheres would be entirely in the light all day long during their respective summers and entirely dark all their winter. In fact, that is what it is like at the poles even for our small tilt. But for most of us our tilt just means longer days during the summer and shorter during the winter, but we have a day/night cycle every day.

[SMF]

Precession adds a little variability to the tilt over long time periods.

[steevey]

Ozone protection is not necessary for life, just a few feet or water would work as well. Also ozone and even the oxygen necessary to have the ozone layer are very nasty for living things, and yes that goes even for the ones that need oxygen to live.

 

 

Well for life on land anyway, ozone is usually required. There's no way we'd survive a total lack of ozone if we were outside in the summer. Plants would burn up, and without plants, even the bugs that could maybe possibly survive that would die due to ecosystem collapse.

 

There's also fossil evidence for this since there was no life on land until the ozone was around 15% its current level. This is why bugs have a high resistance to UV light. They were around to adapt to when the ozone was much less than it is now. Its true life could exist in the sea without ozone, but not on land.

However, the ozone molecule is usually mildly poisonous, but not the actual 02, just the 03 itself. I'm sure if it was more prevalent that some life could adapted to it anyway.

Edited January 26, 2011 by steevey