A process defining organisms that grow and adapt to stimuli while maintaining a state of organization and energy production and being capable of reproduction.

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50
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11answers
13k views

Can humans survive without consuming life? [closed]

Some people say that it's awful that humans eat animals. They feel that it's barbaric, because you're killing life and then on top of that, you're eating it, and that you should eat vegetation ...
38
votes
8answers
6k views

Why does evolution not make our life longer?

Why does evolution not make life longer for humans or any other species? Wouldn't evolution favour a long life?
19
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4answers
5k views

Are mitochondria dead?

In the video "What is Life? Is Death Real?", the subject of mitochondria is raised at 2:58. At 3:12, the narrator says "[mitochondria] are not alive any more: they are dead." What currents of thought ...
11
votes
1answer
2k views

How can frogs tolerate freezing while humans cannot?

A wood frog can tolerate the freezing of their blood and other tissues. wiki, news2, but human beings can not. Some people plan to freeze their bodies/brains after death, and some of them have done ...
11
votes
3answers
3k views

Why did abiogenesis only happen once?

If the "primordial soup" theory of abiogenesis is to be believed, self-reproducing organisms spontaneously arose on Earth at least 3.5 billion years ago, surprisingly soon after the Earth cooled down ...
11
votes
1answer
168 views

Which biological kingdom comprises the greatest biomass on Earth?

Which of the five biological kingdoms - animalia, protista, plantera, monera, or fungi - has the largest biomass? To clarify, if the biomass of every species in each of these kingdoms was added up, ...
10
votes
2answers
297 views

Is there life on other planets and if so how frequent?

Some shed tears of joy as the news about the successful landing of the Mars Rover Curiosity came in. Then the most comprehensive 3D map of our observable universe was published. 2012 is literally an ...
9
votes
2answers
567 views

Do immortal organisms exist?

Do organisms exist that are able to live indefinitely if they are not killed by external factors? Under external factors I would consider things like predators and natural disaster but not illness by ...
8
votes
1answer
4k views

Can you consider a human as alive, or is it the cells on the body that are alive?

Sorry if this question seems strange, but in the recent time I have been interested in the question of what life is and how you can define life. My question: How long can individual cells live on a ...
7
votes
1answer
5k views

Why aren't organelles considered alive?

I'm taking a 3-week Bio I summer course, and my textbook says the cell is the smallest/basic unit of life. I asked my professor why organelles aren't a living unit, and her reply was that they aren't ...
6
votes
2answers
13k views

Why is dimethyltryptamine (DMT) being released during death?

I'm not very well informed about all the things related to biology and the current achievements of science in this field so if I'm wrong in anything I say, please let me know. Many times I've come ...
5
votes
1answer
66 views

Is there any evidence telling us what the oxidation state of early earth's atmosphere was?

I ask this question in relation to the origin of life. I realise it would probably be better suited to a geology stack exchange, but it does not yet exist. The Miller-Urey experiment gives a lab ...
4
votes
2answers
333 views

Are viruses self-propelled?

So obviously, viruses are nonliving. But when my teacher was teaching viruses in the video (we're doing "flip" learning this semester), the way he described it, it seemed like the viruses responded to ...
4
votes
1answer
242 views

Any examples of life forms on Earth that could have survived on Mars or Moon?

Do we know of any living forms on Earth that could continue to live on Mars?
4
votes
1answer
92 views

Current understanding of abiogenesis

I am trying to understand the current work on abiogenesis in biology, e.g. primordial soup, the Miller-Urey experiment, etc. How has our understanding of abiogenesis been revised since the Miller-...
4
votes
0answers
45 views

Did the Great Oxygenation Event also cause a mass extinction?

Its usually assumed that the Great Oxidation Event around 2.3 bya caused a great extinction of anaerobic life on earth. But as I was reading Nick Lane's book, ...
3
votes
2answers
343 views

Changing the definition of life?

Viruses at this period of time do not fit the current definition of life. Much of the reasoning behind this is that we currently believe that all life must be made up of cells. Also, many biologist/...
3
votes
6answers
4k views

are sperms considered living [closed]

recently i got into a debate with this question on hinduism.se , as the link given above shows, are sperms considered as living or non-living as far as my knowledge is concerned, sperms undergo ...
3
votes
1answer
222 views

Number of genes required to sustain life

Are there estimates of the minimum number of genes required to sustain life? In what I mean by life here, I don't include viruses.
3
votes
2answers
169 views

Do people with gout live longer?

Antioxidants reduce damage to tissue (by scavenging the free radicals) and thus may reduce ageing.It is known that Uric acid is a very good antioxidant. People with gout have excess accumulation of ...
3
votes
1answer
63 views

Could a single cell be brought to life?

If a scientist is observing a single cell under a microscope, and then realizes that the cell has died, is it possible to bring that dead cell back to life? For my inquiry, let's assume that the ...
3
votes
2answers
62 views

Would a person live longer, if such a person lived in a planet with lower gravity? (say, Mars) [closed]

I was wondering: some companies plan to colonize Mars, many of us know. But if one were to live on Mars, would this person live longer? It seems to me that a lower gravity would mean less overall ...
3
votes
1answer
130 views

What would classify those findings of the University of Sheffield experiment as aliens?

It's in the news that some experiment was able to capture some alien specimens during a meteor shower: http://www.ibtimes.com/aliens-are-here-scientists-say-they-have-proof-alien-life-there-should-be-...
3
votes
1answer
78 views

In our solar system which other planet could have been in the “habitable zone” in the past?

With changes in our solar system, such as planets moving away from the sun and the reduction in solar radiation, which other planets in our solar system could have been, in the past, in a suitable ...
3
votes
0answers
238 views

How close to Earth's core can organisms live?

We don't to know much about organisms living deep below the Earth's crust. Recently a team led by S. Giovanni discovered some microbes 300 m below the ocean floor. The microbes were found to be a ...
3
votes
0answers
97 views

What makes living beings alive? [closed]

To clarify, I'm not asking about the common properties of living organisms, such as reproducing and having a metabolism, etc. What I'm curious about is, what is the difference between organic ...
2
votes
1answer
176 views

How are minerals formed by biological processes?

News to me is that about 4500 of the 4900 minerals on Earth have been created by life. What are some examples of such processes? Are some minerals formed inside the human body?
2
votes
1answer
108 views

H O N C alternatives for organic life?

Most organic structures built from hydrogen, oxygen, nitrogen and carbon. They are represent 1-,2-,3-,4- bond relations (chemical valence) which allow to build variety of chain structures. Are there ...
2
votes
1answer
181 views

What is the name of the smallest self-replicating thing?

Some time last year, I found an article on Wikipedia about the smallest something to be able to reproduce. I don't remember exactly what it was, but I am fairly certain that after the initial ...
2
votes
1answer
319 views

Is reproduction intrinsically part of life? [closed]

If all of the characteristics of life are required for something to be defined as living, how can we account people or other life that can not reproduce?
2
votes
1answer
61 views

First life forms to evolve controlled flight

What was the first living organism able to fly in the skies and control their direction , not just Aeroplankton like bacteria and viruses carried by the winds but something like an winged insect or ...
2
votes
1answer
101 views

Life on other planets [duplicate]

first of all I'm not sure if I should post this here or in the astronomy stack. I think biologist are more likely to answer my question. To make it short: Why when looking for any sort of life on ...
2
votes
1answer
72 views

Does the existence of one species imply the existence of many other?

Reading one of Sir Arthur Clarke's scifi stories, I came across a statement something to the effect of, existence of a single species automatically implies the existence of many other species. So ...
2
votes
1answer
97 views

Have there been any experiments that duplicate chromosome copies from 23*2 to 23*3 or 23*4?

Deinococcus radiodurans is an amazing bacterium with a fantastic survival rate. It can survive to high doses of radiation, in a complete vacuum and in hydrochloric acid. How does this bacterium ...
2
votes
0answers
19 views

Have there been any studies on 'surf balls'? (not related to surfing)

I know the title sounds like something else, but I'm actually wondering about these things, which are also apparently called 'whale burps': This one was found on a beach on Lake Michigan. Does ...
1
vote
1answer
54 views

Is there any definition of life which makes viruses undeterminable?

There are many different definitions of life (RNA, something that comes through evolution) but not one I have seen which could not determine wheter viruses are living things (even though there are ...
1
vote
2answers
240 views

Plants without bacteria? is it theoretically possible?

I know from school, that all live on the Earth need bacteria as low-level "machines" that break down/extract/convert/produce chemical elements and combinations, other high-level organisms needed. But ...
1
vote
1answer
46 views

Does the new virus tree of life change their position between living and non-living things?

Viruses still do not fit the criteria of living or it's simplest form (the living cell), why would some say that the new virus tree of life makes it more closer to life? Aren't mitochondria in a point ...
1
vote
1answer
92 views

Which are the last cells of the human body to die?

When somebody dies, which are the last surviving cells of his/her body? Those of hair, nails, or some other obscure but resilient cells? Shedding light on why and how they are so vital might boost ...
1
vote
0answers
32 views

What a cell needs to survive? [closed]

I'm looking specifically at animal cells. I'm not sure if it needs only Glucose and Oxygen for Aerobic respiration.
1
vote
1answer
16 views

Atmospheric gas changes, and their effects life

I was curious how life on Earth, or an Earth-like planet, would be effected by changes in the gases which make up our atmosphere. Assuming there is a similar level of oxygen in an atmosphere, could ...
1
vote
0answers
20 views

What are the tests performed by NASA's Mars rovers to establish that life could survive on the planet?

I am particularly interested in the Mars Rovers, which are out there trying to find life. Do they believe that the tests they perform are sufficient to verify the existence of life (Also please ...
1
vote
0answers
23 views

What are the expected characteristics of the soil suitable for life and how are they quantified? [closed]

My question is related specifically to astrobiology. I am interested in the criteria astrobiologist look for when they attempt to determine if the elements necessary for life are present on an ...
1
vote
0answers
43 views

why water is a proof of a life? [duplicate]

I read that NASA looks for water on Mars or other planets as a sign of a life. I wonder why scientists look for water as proof of a life? isn't there any animal that drinks another liquid like ...
0
votes
1answer
148 views

Is the missing “life-ingredient” in today's Earth's existence the reason why we cannot recreate life?

As far as I know there was no report of "life" pop up in a lab or in the nature so far. Everything what we know is only some copy with less-or-more similarity to previous life-form. We certainly can ...
0
votes
1answer
40 views

What is the reasoning behind the Drake Equation?

I've read a bunch on how the Drake Equation is constructed, but I'm not able to understand some of the reasoning behind it. $$ N = R_* \cdot f_p \cdot n_e \cdot f_l \cdot f_i \cdot f_c \cdot L \cdot ...
0
votes
1answer
101 views

Biologically, does life and death matter? [closed]

(Sorry that I'm on mobile, so I can't make a good formated question (no links). I will add them later. Just can't resist the urge to ask) In the recent hot question about whether mitochondrial is ...
0
votes
1answer
101 views

Is there already discovered non-carbon form of life?

I have heard of some rumors going around about a living organism based on non-carbon. Is Has research been done with real form of life based on non-carbon? Or carbon-based life is only type of life ...
0
votes
1answer
60 views

What are the characteristics of a living organism? [closed]

It seemed fairly basic at first, and yet I have to ask because even a quick Google search reveals that it doesn't seem to be quite so straight-forward anymore. After more research, I found multiple ...
0
votes
1answer
69 views

What is the definition of the life biologically ? [duplicate]

I want to know what is the definition of the life biologically , on the other hand , what is the definition of the death biologically ?? However, I think it is a very difficult question to answer .