Life cannot exists on earth without water -explain
Answers
Answer:
Without water, life — animal, plant, or human—cannot exist.
Explanation:
Nothing on our planet can survive without water. It covers 70% of the surface and about 60% of our body is composed of nothing but water.
Water is everywhere. It’s a good thing too. Because without it, life as we know it would not be possible.
There are organisms on Earth that do not need oxygen to live. They metabolize hydrogen or methane or a number of other compounds. Plants breathe CO2 and get much of their energy from the Sun through photosynthesis. There is life at the bottom of the oceans which have never seen the sun and get all of their energy from hydrothermal vents on the seafloor.
For one, water is a liquid across a wide range of temperatures on Earth. A liquid is a much better transport medium for nutrients and other life-necessary compounds than a solid. It just happens that most of the water on Earth can exist in its liquid form.
Water is also a great solvent. It has been called the universal solvent because so many different kinds of substances can be dissolved in water. All life needs to take in substances to generate energy and flush out waste products and toxins. Because of water’s knack for dissolving all kinds of substances, it makes an ideal medium for both tasks.
This is important to life because it means water is sticky. It tends to clump together. This allows it to be sucked up as continuous stream through the roots of plants or circulated through our blood vessels against the force of gravity.
Since life got its start in water, if frozen water was denser than its liquid state that would mean that ice would sink. Ponds, lakes, and the ocean would freeze from the bottom up — killing any life within it. As it is, water freezes from the top down, allowing life to survive in the relatively warmer liquid water underneath the ice.
Anybody who has ever taken a drink of ice water on a hot day can attest to water’s cooling abilities. But it does more than quench our thirst.
Water vapor in the atmosphere also acts as a greenhouse gas, keeping the planet warm enough to sustain life.
We don’t know of any kind of lifeform that can survive without water. That’s why NASA is so focused on finding water or the right conditions for liquid water exist on other planets. It’s the only indicator we have that life could be possible.
On Saturn’s moon Titan, the average temperature is a chilly -179 degrees celsius. That’s cold enough to freeze a bottle of rubbing alcohol solid. Yet Titan is the only object in the solar system known to sustain liquid on its surface. This isn’t water though. It’s methane. Water does exist on Titan but it’s frozen and as hard as stone.
If life existed on Titan, it would use methane in place of water. It would metabolize hydrogen and this should have an effect on the composition of the atmosphere — an effect large enough to be measured.
There are smaller amounts of hydrogen in the lower levels of Titan’s atmosphere than expected — just the kind of reading we would expect to get if something was metabolizing hydrogen on the surface.
But these results are only preliminary and they’re just as likely to be evidence of how much we don’t understand of the chemical processes going on in Titan’s atmosphere as they are evidence of a lifeform using a biochemistry we have never encountered before.
So for now, life as we know it will have to make do with good old fashioned water.
Explanation: