Short and Long Questions: The Hydrosphere | Footprints Class 7: Book Solutions, Notes & Worksheets PDF Download

Short Answer Questions

Q1: What is the hydrosphere and why is it essential for life on Earth?
Ans: The hydrosphere refers to all the water on Earth, including oceans, lakes, rivers, and even groundwater. It is essential for life because all living organisms need water to survive and carry out their daily functions.

Q2: Describe the components of the water cycle.
Ans: The water cycle consists of evaporation, condensation, precipitation, and collection. Water evaporates from the Earth's surface, condenses in the atmosphere to form clouds, falls back to the Earth as precipitation, and collects in bodies of water or soaks into the ground.

Q3: Define fresh water and saline water.
Ans: Fresh water refers to water that has a low concentration of dissolved salts, such as water in rivers and lakes. Saline water, on the other hand, contains a high concentration of dissolved salts, like seawater in the oceans.

Q4: Explain the concept of salinity in ocean water.
Ans: Salinity refers to the amount of salt dissolved in ocean water. It is measured in parts per thousand (ppt). The higher the salinity, the more salt there is in the water. This salinity affects the density of ocean water and influences ocean currents.

Q5: How does temperature vary in ocean water?
Ans: Temperature in ocean water varies with location and depth. Near the surface, temperature changes with the seasons and can be influenced by sunlight. In deeper waters, temperature is more stable and colder.

Q6: What are the major movements in oceans, and what causes them?
Ans: The major movements in oceans are waves, tides, and ocean currents. Waves are caused by wind blowing across the surface of the water, tides are influenced by the gravitational pull of the moon and sun, and ocean currents are driven by a combination of factors including temperature, wind, and the Earth's rotation.

Q7: What is a tsunami, and what natural events can trigger it?
Ans: A tsunami is a series of large ocean waves caused by underwater earthquakes, volcanic eruptions, or landslides. These natural events can displace a large amount of water, leading to the formation of a tsunami.

Q8: How are tides formed, and what influences their height?
Ans: Tides are formed by the gravitational pull of the moon and sun on Earth's oceans. The position of the moon and sun relative to Earth determines the height of tides. When the moon and sun align, we experience high tides, and when they are at right angles to each other, we have low tides.

Q9: What are the importance and benefits of tides?
Ans: Tides are important for various reasons. They help to distribute nutrients and oxygen in coastal ecosystems, provide habitat for marine organisms, aid in navigation, and generate renewable energy through tidal power.

Q10: What are ocean currents, and how are they classified based on temperature?
Ans: Ocean currents are large-scale movements of water in the ocean. They can be classified as warm or cold currents based on their temperature. Warm currents originate from tropical regions and carry warm water towards the poles, while cold currents come from polar regions and bring cold water towards the equator.

Long Answer Questions

Q1: Explain the significance of the hydrosphere in sustaining life on Earth.
Ans: The hydrosphere plays a crucial role in sustaining life on Earth. It provides water for drinking, irrigation, and sanitation. It regulates the climate by absorbing and releasing heat energy. It also supports various ecosystems, providing habitats for countless species. Additionally, the hydrosphere is involved in the water cycle, which ensures a continuous supply of fresh water.

Q2: Describe the process of the water cycle and its importance.
Ans: The water cycle is the continuous movement of water on, above, and below the Earth's surface. It starts with evaporation, where water changes from a liquid to a gas and rises into the atmosphere. Condensation occurs when the water vapor cools and forms clouds. Precipitation happens when the condensed water falls back to the Earth as rain, snow, sleet, or hail. This water collects in rivers, lakes, and oceans, and the cycle begins again. The water cycle is important as it helps distribute water resources, replenishes freshwater sources, and plays a vital role in weather patterns.

Q3: Discuss the impact of human activities on the water cycle.
Ans: Human activities can have both positive and negative impacts on the water cycle. Deforestation and urbanization can disrupt the natural water cycle by reducing evaporation and increasing runoff, leading to floods and droughts. Pollution from industries and agriculture can contaminate water sources, affecting the quality and availability of freshwater. On the positive side, water management practices like building reservoirs and irrigation systems can help regulate water supply for agriculture and human consumption.

Q4: How do temperature and salinity affect ocean currents?
Ans: Temperature and salinity affect ocean currents by influencing the density of seawater. Cold water is denser than warm water, so temperature differences can create variations in density, leading to the formation of currents. Salinity also affects density, with saltier water being denser than less salty water. These density differences drive the movement of ocean currents.

Q5: Explain the formation and consequences of tsunamis with a real-life example.
Ans: Tsunamis are usually caused by underwater earthquakes, where the seafloor abruptly uplifts or subsides, displacing a large volume of water. This displacement creates a series of powerful ocean waves that can travel great distances. One real-life example is the 2004 Indian Ocean tsunami, triggered by a magnitude 9.1 earthquake off the coast of Sumatra, Indonesia. This tsunami resulted in the loss of hundreds of thousands of lives, extensive damage to coastal areas, and long-term economic and environmental impacts.

Q6: Elaborate on the factors influencing the height of tides and their practical applications.
Ans: The height of tides is influenced by several factors, including the gravitational pull of the moon and sun, the alignment of the moon and sun relative to Earth, and the shape of the coastline. Tides are highest during full and new moons when the gravitational forces align. The practical applications of tides include tidal energy generation, navigation in coastal areas, and fishing as tides can concentrate fish in certain areas.

Q7: How do ocean currents affect climate and marine life?
Ans: Ocean currents have a significant impact on climate. Warm ocean currents can bring heat from the tropics to higher latitudes, influencing regional temperatures. They can also affect weather patterns, bringing moisture or dry conditions to coastal areas. Ocean currents also play a crucial role in the distribution of nutrients and the migration patterns of marine organisms, influencing the productivity and biodiversity of marine ecosystems.

Q8: Discuss the role of ocean currents in global transportation and fishing industries.
Ans: Ocean currents have been utilized by the global transportation industry for centuries. They can help ships travel faster and more efficiently by taking advantage of favorable currents. Fishing industries also rely on ocean currents as they can concentrate nutrients and plankton, attracting fish and other marine species. Fishermen often target areas where warm and cold currents meet, known as upwelling zones, as they are rich in marine life.

Q9: Illustrate the importance of water conservation in the context of the hydrosphere.
Ans: Water conservation is crucial for the sustainable management of water resources and the health of the hydrosphere. By conserving water through practices like reducing waste, fixing leaks, and using water-efficient appliances, we can ensure a continuous supply of clean and fresh water for future generations. Water conservation also helps protect aquatic ecosystems and maintain the balance of the water cycle.

Q10: Examine the relationship between oceanic movements and weather patterns.
Ans: Oceanic movements, such as ocean currents and surface temperatures, play a significant role in shaping weather patterns. Warm ocean currents can transfer heat to the atmosphere, affecting air temperature and moisture levels. These changes can influence the formation and intensity of weather systems like hurricanes and monsoons. Additionally, ocean currents can transport moisture from one region to another, impacting precipitation patterns and contributing to the overall climate variability.