[Biology Class Notes] on Water Pdf for Exam

Water is a tasteless, odorless, colorless chemical substance mainly formed from oxygen and hydrogen as main compounds. Without water, no living creature can survive. Humans, animals, plants, microorganisms all require water. Water is found naturally on the surface and is an essential natural resource. Humans need water to drink and survive; animals require water for sustenance, plants too require water to grow and nourish themselves. Today we examine the sources and uses of water. We also cover an in-depth assessment of the different parts of the water cycle- from condensation and precipitation, to evaporation of water into the atmosphere. 

 

Sources of Water

Sources of water are the origins of where we get rain. Approximately 97% of the earth’s surface is covered with water. Approximately 3% of water is fresh water which can be used for drinking, and other household purposes and the remaining is the sea and ocean water which is salty. But with the process of desalination, the ocean water can be converted into drinkable freshwater.

  1. Rainwater: Water that we get through rains can be preserved in water bodies for consumption. Several water bodies are built by humans to conserve this precious natural resource. We get rainwater through the water cycle, which we will discuss later in this chapter.

  1. Ice Glacier: Snow falls when accumulated over time forms glaciers. Over time, glaciers advance and retreat. Retreating contributes towards blue color characteristics of glacial lakes by ground-up surface material called rock flour.

  1. Surface Water: Water bodies such as lakes, ponds, rivers, and streams get water through rainfall and ice melt. The surface water is the most convenient way to draw water for regular day-to-day uses. With adequate filtration, it is made fit for consumption.

  1. Underground Water: Sometimes, through the porous soil and fractures in rock surface seeps the groundwater into the earth. It is then accumulated into underground aquifers and reservoirs. Usually, underground water is contaminated and must be purified through various chemical processes.

 

Uses of Water

Water is used for multiple purposes like household use, industrial use, agricultural use, transportation, electricity, and other such uses. Let us elaborate on how water is used for these purposes.                                                              

  1. Household Use: In our everyday life we use most water for drinking, apart from that it is used for bathing, cleaning, cooking, washing, watering plants, etc.

  1. Industrial Use: Various industries use water to produce certain drinks and beverages. Also, water is used to clean or wash products or machines in industrial sectors at large.

  1. Agricultural Use: In the agricultural area, water is used to grow crops through the process of irrigation, farming, frost control, and gardening. For growing healthy plants providing water in the quantity they require is essential.

  1. Transportation: One of the most extensive transportation of goods is done through seas and oceans, which is known as water transportation. Delivering products from one place to another utilizing water transport has become convenient for large items like cars and bikes.

  1. Electricity: Electricity is another primary form of resource which is obtained through the water. Without electricity, it is not possible to run daily activities. Also, power is essential in the household as well as industries to run machinery.

 

Now that we have learned what the uses of water are, let us learn further about how we get water through the process of the water cycle.

 

Water Cycle

The water cycle is a continuous process. It is referred to as a cycle because water from the seas, ocean, river, or other water bodies goes to the sky and from sky, it comes back again on the earth’s surface in the form of rain; see below diagram:

 

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In this diagram, the whole process of the water cycle is explained which we will elaborate through specific points.

  1. Evaporation: From the surface of the ground like oceans, seas, rivers, ponds, lakes, wells, and other such water bodies rise to the sky in the form of gas. It means that when the temperature of the earth increases above its average temperature (heats) water is formed into a gaseous state and goes up in the atmosphere. 

  1. Condensation: Now, when the water reaches the atmosphere, it converts into vapor or droplets of water again due to decrease in the temperature, which means it turns back into the clouds in the form of water vapors, this process is known as condensation. 

  1. Precipitation: When water vapors become heavy, they again fall on the earth’s surface in the form of rain, snow, or sleet. It fills the water bodies on the earth’s surface with water, forming a gaseous state again into a liquid state and pouring down is known as precipitation. As this cycle repeats, again and again, it is known as the water cycle.

 

Importance of the Water Cycle 

The water cycle is a crucial process as it ensures the availability of water to all the living organisms living on the planet. Without the water cycle, the earth will run out of freshwater, leading to the extinction of human beings. Here are the reasons why the process of the water cycle is important: 

  • Evaporation that occurs during the water cycle helps in the purification of the water. During this process, all the impurities present in the water are left behind. 

  • The water cycle distributes water all around the world and feeds all the living organisms on this planet. 

  • Without the water cycle, it will be difficult for the plants to grow and the animals to survive. Some organisms are vulnerable to the changes in the water cycle, which can lead to a drastic drop in their population. So, the process of the water cycle sustains life and maintains the right balance in the ecosystem.     

  • The process of the water cycle impacts the earth’s ecosystem, which drives the biogeochemical cycle. In this cycle, substances such as calcium, nitrogen, hydrogen, carbon, etc., move through biotic and abiotic spheres of the Earth. 

How to learn the Water – Sources, Uses and Water Cycle? 

To start learning about the concept of Water – Sources, Uses and Water Cycle, you will need a reliable study resource. can provide you with helpful study materials to help you understand the Water – Sources, Uses and Water Cycle with ease. This topic is one of the most important parts of your academic syllabus. That is why you must have a clear understanding of what water is and why it is important for all living beings on this planet. The Water – Sources, Uses and Water Cycle will take you through the important concept of the water cycle. It is an essential process that makes water available to all human beings, animals, and plants. To revise the Water – Sources, Uses and Water Cycle, you can follow these tips: 

  • You can use ’s free learning platform to revise the concept of Water – Sources, Uses and Water cycles. We explain every topic related to water in simple language that allows you to understand the concept easily. 

  • Read and go through the explanations of Water – Sources, Uses and Water Cycle thoroughly to gain a better understanding of this crucial concept. 

  • You can note down the important points from the Water – Sources, Uses and Water Cycle and make a summary of the topic that will help you in quick revisions during your exam. 

  • Learn the concept of the water cycle through the diagram. You can practice making the diagram for your exam as pictorial presentations make the concept easy to understand for both student and teacher. 

  • Once you are done with the Water – Sources, Uses and Water Cycle, you should try to answer the exercise questions given at the back of the chapter to test your knowledge. Also, explore more questions related to the concept of Water – Sources, Uses and Water Cycle in reference books and guides. 

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