Water and Life Study Guide

Life on earth cannot survive without water. It is a precious natural resource. Life with water supports all human, plant, animal life, and other purposes.


Water is the amplest compound on earth, and there is no life without water. Around 65% of a cell's volume is water and 70% by mass, and living organisms have developed mechanisms for conserving and appropriating water. Water accounts for 99.4% of metabolites in Escherichia coli through molar concentration.

Water is generally referred to as a liquid state, and it stays in liquid over a broad range of temperatures. Almost 75% of the earth's surface is covered by water, as it is the most common chemical substance available on earth.

Water is one of the essential elements to create life and maintain life. Water found in nature is not pure, and it includes various dissolved substances. It needs to pass multiple stages before it is available for consumption. All organisms, large or small, have products or substrates for biochemical reactions that transform water.

Why is Water Essential for Life?

Water is essential for life because all living organisms are dependent on it. It is the vital element through which life exists.

  • Water is a colorless, inorganic, transparent, tasteless, and inorganic chemical substance.
  • Water helps with regulating temperature in the environment.
  • Human tissues contain about 20-25% water in bone cells and 80-85% in brain cells.
  • Most of the reactions of cells occur in the presence of water.
  • Water helps in maintaining body temperature.

Properties of Water

properties of water Source

- Water is an excellent solvent

Water can dissolve many ionic and polar substances. Water is essential for life because it travels through the water cycle and takes many vital nutrients. This property makes water critical to life.

- Water is polar

Water molecules are polar, with a partial positive charge on the hydrogen and a partial negative charge on the oxygen. When there is a difference in electrical charge between different parts of the same molecule is known as polarity, this makes water a polar molecule because oxygen and hydrogen atoms in water have a different charge.

- Water is less dense in solid-state

When water freezes, the molecules create a crystalline structure that makes more space than the liquid state. This is the reason why ice floats.

- Water has a high heat magnitude

Water requires lots of energy to increase its temperature. This allows water temperature in a pond to stay constant all day, irrespective of changing atmospheric temperature.

Structure of a Water Molecule

water molecule properties Source

A water molecule consists of one oxygen atom and two hydrogen atoms. The oxygen atom in a water molecule attracts negatively charged electrons more strongly than hydrogen atoms because this oxygen atom in water is a bit negatively charged and the hydrogen atom Is a bit positively charged.


  • All living things require water
  • Without water, life as we know it would not exist
  • Water molecules consist of one oxygen atom and two hydrogen atoms
  • Water helps in transporting minerals and nutrients in the body
  • Most of the habitat exists because of the water on earth


1. What is the relationship between water and life?

Life can not be sustained without water, and water helps transport nutrients and essential molecules in all living things. Every living organism needs water to survive on earth.

2. How important is water to live?

Water is important for every living thing on this planet; there would be no life without water. Through water, the cycle of the earth is still stable. A human body consists of 75% water, which helps transfer nutrients in every part of the body. In plants, water helps in the process of photosynthesis.

3. What are the five benefits of water?

  1. Through water, all essential vitamins and minerals are transported in the bodies of all living organisms.
  2. It helps in maintaining body temperature in plants and animals. Plants lose water through transpiration, and animals lose water through sweating to decrease their body temperature.
  3. It is an essential part of photosynthesis; without water, no food can be produced
  4. It plays an essential role in the digestion of food; water creates saliva, which breaks down the food.
  5. Water is used in cooking activities, drinking and household needs, industry, agriculture and other uses.

4. How do we use water in our daily life?

-We use water for many activities such as drinking, washing, preparing, and growing food, making it the most important element for life. Water also produces electricity, creates the material, and helps in transportation.

5. What are three reasons why water is essential?

  • Water carries nutrients to all cells in our body and oxygen to our brain.
  • Water allows the body to absorb and assimilate minerals, vitamins, amino acids, glucose, and other substances.
  • Water flushes out toxins and waste.

6. Why do we say water is life?

Living organisms depend absolutely on water to exist. Water is utilized in all the cells, organs, and tissues, to help maintain body temperature and perform other important bodily functions such as nutrient transport to all the cells and oxygen supply to our brain.

7. What are the four life-supporting properties of water?

  1. Cohesive and adhesive behavior.
  2. Ability to moderate temperature.
  3. Expansion upon freezing.
  4. Versatility as a solvent.

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  1. Importance of water.https://byjus.com/chemistry/importance-of-water/. Accessed Nov 26, 2021.
  2. Water and Life.https://link.springer.com/article/10.1007/s00239-020-09978-6. Accessed Nov 26, 2021.
  3. Water and life.https://flexbooks.ck12.org/cbook/ck-12-biology-flexbook-2.0/section/1.19/primary/lesson/water-and-life-bio/. Accessed Nov 26, 2021.