Thread: What does amoeba need for survival?

Can some one help me with this? How do I respond to questions like these from some one who believes in creationism or intelligent design.
Can simple life forms survive without depending on more complex life forms?
Is it possible to grow plants in soil with no organic matter?

It's not a matter of complexity.

A tulip is equally complex as a mouse, they're just complex in different ways.

Now autotrophs that utilize photosynthesis for their energy are necessary for heterotrophs (those that eat them) to survive. This isn't however proof against evolution, since autotrophs evolved first.

edit: Likewise, plants evolve long after bacteria so nitrogen fixers were already happily toiling away in soil making it possible for them to grow.

Some bacteria meet your criteria. They need no other living organisms. Some bacteria live in and near geothermal vents and use the chemical substances from geothermal vents as raw materials for their metabolism.
http://www.wisegeek.com/what-is-chemosynthesis.htm

Like I said autotrophs can live on their own, but heterotrophs need autotrophs to feed off of.

Whether they be lithoautotrophs, chemoautotrophs, or photoautotrophs.

Originally Posted by cpmartin2

Is it possible to grow plants in soil with no organic matter?

First a pedantic point. Soil, by definition, must contain organic matter and much of this organic matter will be alive (or recently so).

The main point is that early life likely arose in an environment rich in organic molecules. These are common in interstellar space and in the gas clouds from which the solar system is thought to have formed. The earths oceans would have contained a rich mixture of these and their more complex derivatives.

Originally Posted by John Galt

Originally Posted by cpmartin2

Is it possible to grow plants in soil with no organic matter?

First a pedantic point. Soil, by definition, must contain organic matter and much of this organic matter will be alive (or recently so).

The main point is that early life likely arose in an environment rich in organic molecules. These are common in interstellar space and in the gas clouds from which the solar system is thought to have formed. The earths oceans would have contained a rich mixture of these and their more complex derivatives.

Besides the point that plants are most certainly not the first form of life haha.

Plants in soil with no organic matter??

Absolutely yes. It is called hydroponics. Often sterile crushed pumice is used in place of soil. No organic matter included. All the minerals the plant needs are pre-dissolved in the water that is trickled over the pumice. Plants grow extremely well in that set up.

Originally Posted by skeptic

Plants in soil with no organic matter??

Absolutely yes. It is called hydroponics. Often sterile crushed pumice is used in place of soil. No organic matter included. All the minerals the plant needs are pre-dissolved in the water that is trickled over the pumice. Plants grow extremely well in that set up.

Actually I think it would be more correct to say plants growing without soil, as soil must contain organic matter to be soil (I think). As you say yourself pumice is often used instead of soil.
One of the reasons for hydroponics effectivness, is that you can isolate the plant from weeds that would otherwise steal nutrients. And that the delivery of nutrients to the plant is more efficient.

Technically speaking plants don't need any organic nutrients - that's why they are called primary producers in ecosystems. They take sunlight, carbon dioxide and inorganic nutrients (generally from soil, if you are talking about land plants) to build complex macromolecules.

So, plants do not require organics per se. Soil is best viewed (in the context of the original question) as a medium that provides structural support for root systems and easy access to dissolved inorganic nutrients (phosphorus, nitrogen, potassium etc).

Many plants don't even grow in soil and get their inorganic nutrients by other means.