Based on your understanding, choose the correct option.
Q1.
Ans: (a) 97 per cent
About 97% of the Earth's water is salt water, primarily found in oceans and seas. This leaves only a small fraction as freshwater.
Q2.
Ans: (a) transpiration
Transpiration is the process where water moves through plants from the roots to the leaves, where it evaporates into the atmosphere, contributing significantly to the water cycle.
Q3.
Ans: (a) difference in temperature
Ocean currents are primarily driven by temperature differences, where warmer water tends to move from equatorial regions toward the poles, while cooler water moves toward the equator.
Q4.
Ans: (b) wind, tides and waves
The mixing of surface water with deeper layers is facilitated by wind, tides, and waves, which help circulate nutrients and regulate temperature.
Q5.
Ans: (b) trough
The trough is the lowest part of a wave, situated between two crests.
Q6.
Ans: (a) warm ocean currents
Warm ocean currents typically flow from equatorial regions towards the poles, transporting warm water and influencing climate along their paths.
Q7.
Ans: (b) 11 March 2011
The devastating Great East Japan Earthquake occurred on March 11, 2011, leading to significant loss and triggering a massive tsunami.
Q8.
Ans: (a) drifts
Drifts refer to broad, slow-moving masses of water, such as the North Atlantic Drift, which significantly affect local climates.
Q9.
Ans: (a) Brazil Current
The Brazil Current is a warm ocean current that flows southward along the Brazilian coast in the Atlantic Ocean.
Q10.
Ans: (b) plankton
Plankton are microscopic organisms that form the base of aquatic food chains and are a crucial food source for many marine species.
Answer the following in one sentence.
Q1.
Ans: The hydrological cycle, also known as the water cycle, is the continuous movement of water on, above, and below the surface of the Earth, involving processes such as evaporation, condensation, precipitation, and runoff.
Q2.
Ans: Sources of freshwater include rivers, lakes, groundwater, glaciers, and ice caps.
Q3.
Ans: Salinity is the measure of all the salts dissolved in water, commonly expressed as parts per thousand (ppt) or grams per liter (g/L).
Q4.
Ans: Tides are the regular rise and fall of sea levels caused by the gravitational forces exerted by the moon and the sun, primarily consisting of spring tides and neap tides.
Q5.
Ans: The main factors responsible for ocean currents include wind patterns, the Earth's rotation, the moon's gravitational pull, and temperature and salinity gradients in the water.
Answer the following questions in brief.
Q1.
Ans: The temperature of ocean water varies depending on depth, latitude, and season, generally ranging from colder temperatures in deeper and polar regions to warmer temperatures in surface waters and near the equator.
Q2.
Ans: Waves are disturbances that transfer energy from one place to another without the transfer of matter, characterized by features such as crest (highest point), trough (lowest point), wavelength (distance between successive crests or troughs), amplitude (height from the still water line to the crest), and frequency (number of waves passing a point in a given time).
Q3.
Ans: The hydrosphere, comprising all the Earth's water, plays a crucial role in sustaining life by regulating climate, providing habitat for numerous organisms, and supporting agriculture, industry, and human consumption.
Answer the following questions in detail.
Q1.
Ans: The Great East Japan Earthquake, which struck on March 11, 2011, was a magnitude 9.0-9.1 undersea megathrust earthquake off the coast of Japan that triggered powerful tsunami waves reaching heights of up to 40.5 meters. The disaster caused widespread devastation across northeastern Japan, leading to over 15,000 deaths, destruction of homes, infrastructure, and severe damage to the Fukushima Daiichi Nuclear Power Plant, resulting in a nuclear meltdown and long-term environmental impacts.
Q2.
Ans: Spring tides occur during the full moon and new moon when the sun, moon, and Earth are aligned, which enhances the gravitational pull on the oceans and results in higher high tides and lower low tides. Neap tides occur during the first and third quarter moon phases when the sun and moon are at right angles to each other, which reduces the gravitational pull and results in less extreme high and low tides.
Q3.
Ans: Tides are useful in various ways including navigation, as they influence the depth of water bodies allowing for safer ship movements; tidal energy, which can be harnessed as a renewable energy source; fishing, as tides affect fish behavior and accessibility; and maintaining ecological balance, as tidal movements help circulate nutrients and cleanse estuaries and wetlands.
Q4.
Ans: Ocean currents affect climate regulation by distributing heat from equatorial regions to poles; influence weather patterns and storm pathways; impact marine biodiversity by distributing nutrients and organisms; and affect human activities through their influence on maritime navigation and coastal climates.
Q5.
Ans: Water pollution occurs through the introduction of pollutants such as chemicals, waste materials, and toxic substances into water bodies from industrial, agricultural, and residential sources. Water conservation is essential to sustain available water supplies for future generations, maintain wildlife and natural ecosystems, and reduce the energy and costs associated with treating and distributing water.
