i get a little overwhelmed when thinking of how life come to be as it is today, if not a little anxious sometimes, as it is after all a little mind blowing, perhaps this is my lack of understanding of biology at a higher/ degree level, makes it a little more daunting. I just look around and think, 'wow this wasn't here at some point'

Could you perhaps help by answering some BIG questions?

i don't understand how life can arise from essentially nothing, how can this be, how can RNA/DNA self replicate?

How can Random mutations produce a highly amazingly sophisticated functioning organs that require each other to work? Surely there is nothing random about an organ that pumps blood around the body? What came first blood or the heart? How did the stomach evolve, what came first the mouth or the stomach? Where did the waste go before we evolved a bowel?

How did two sexes evolve to work so perfectly to produce offspring? Surely this was a very gradual process, and how did one day they 'just fit together'

How did a womb evolve, where did a mammal carry its young before a womb and a vagina?

Why did it take so long the simplest life forms to evolve, when in the Cambrian explosion,  such sophisticated organisms evolved in such a short space of time, surely this would have needed longer?

Finally I know this is a physics question, but if you could help me out? How is iit possible for matter to create itself out of nothing and produce the Big Bang?

Reading back over this, I know it sounds as though I am some sort of 'creationists', I know logic tells me that is not true, I'm just genuinely a bit stumped how to work those questions out, do you have to e a little more educated past GCSE science level to grasp this? Is it unanswerable?

A great many questions! Too many to answer here.

Here are some links to start you off.

First, abiogenesis and the RNA world

Evolution of complexity
http://en.wikipedia.org/wiki/Evolution_ … complexity
http://www.scientificamerican.com/artic … omplexity/

Questions regarding the evolution of genitals and sex have been asked before on this site:
http://www.askabiologist.org.uk/answers … p?id=10179
http://www.askabiologist.org.uk/answers … hp?id=4664
http://www.askabiologist.org.uk/answers … php?id=900

on the cambrian explosion specifically:
http://www.askabiologist.org.uk/answers … php?id=111

Forget the word "random". Mutation is random, but evolution doesn't happen until you get selection, which is definitely not random. To put it another way, evolution has elements of chance in it (called stochastic) but is over all a highly ordered process.

What came first "blood or heart"; That one is easy, blood. When you are very small you don't need a heart to pump fluid, it just kind of sloshes around inside and does a good enough job (look up hemocoel, and osmosis). When body sizes increased, osmosis isn't fast enough so you need a pump and much more efficient system (circulatory system).

Your digestive tract is virtually the first recognisable structure in the embryo that will become you. We have had a two-ended mouth/anus system for a long, long time, well before there were humans. There are some animals without an anus, and they discard wastes back out through their mouths.

The question about the big bang is definitely not biology, so don't expect any expert answers here. However, your assumption that "something" came from "nothing" may not be correct. There may have been something before the universe, we just don't know what. Basically it's an open question:)

"Forget the word "random". Mutation is random, but evolution doesn't happen until you get selection, which is definitely not random. To put it another way, evolution has elements of chance in it (called stochastic) but is over all a highly ordered process."

My favourite soundbite explanation of natural selection may be helpful here. Mutation throws dice, but selection only keeps the sixes.

Well genetic drift is also random and can lead to fixation of essentially randomlyselected genes leading to a change in the population / species. So some elements of evolution can be random, but that is very different (as noted above) to saying that evolution as a whole is random, selection is random, or that various features / changes have come about rnadomly.

David's point is actually really important - evolution can be defined as "modification with descent" or taking a genetic view "change in allele frequencies with time". At the level of DNA sequence most geneticists think that a lot (most?) evolution is neutral. Mutations happen (to first approximation "randomly") and in many cases they then either persist or don't according to the whim of drift (i.e. selection, or lack thereof, may often be irrelevant).
I think a lot of confusion in the public stems from failing to realise that evolution is not synonymous with natural selection. However, we (scientists) often also fail to explain that natural selection is not the only mechanisms of evolution. Perhaps the reason for this is that many of us are interested in the evolution of traits/features/behaviours that do effect fitness (and so are under strong selection). In such cases we often say "evolution" as (convenient) shorthand for "evolution by natural selection" or what we sometimes term "adaptive evolution".