Worksheet Solutions: Movements of Ocean Water | Geography Class 11 - Humanities/Arts PDF Download

Fill in the Blanks

Q1: The continuous flow of water in a definite direction is known as _______________.
Ans: ocean currents
Ocean currents are the continuous flow of water in a definite direction within the ocean.

Q2: Waves are primarily generated by the energy from the _______________.
Ans: wind
Waves are primarily generated by the energy from the wind, which transfers its energy to the water surface, causing the water to move in a wave-like motion.

Q3: The rise and fall of ocean water, mainly due to the attraction of the sun and moon, is called _______________.
Ans: tide
Tides are the periodic rise and fall of ocean water levels, primarily caused by the gravitational pull of the sun and moon.

Q4: The force that counteracts gravity in the formation of tidal bulges is known as _______________.
Ans: centrifugal force
Centrifugal force counteracts the gravitational pull of the Earth's rotation and plays a role in the formation of tidal bulges.

Q5: The highest tides in the world occur in the _______________.
Ans: Bay of Fundy
The Bay of Fundy in Nova Scotia, Canada, is known for having the highest tides in the world.

Q6: Tides that occur twice a month when the sun, moon, and Earth are in a straight line are called _______________.
Ans: spring tides
Spring tides occur during the full moon and new moon phases when the sun, moon, and Earth align, causing higher tide levels.

Q7: The force responsible for moving ocean water to the right in the northern hemisphere is the _______________.
Ans: Coriolis force
The Coriolis force causes objects in the northern hemisphere to be deflected to the right, including ocean currents.

Q8: Ocean currents influenced by heating by solar energy are caused by the expansion of _______________.
Ans: water
Heating by solar energy causes water to expand, creating variations in water density and influencing ocean currents.

Q9: Surface currents constitute about _______________ of all the water in the ocean.
Ans: 10 percent
Surface currents are the upper 400 meters of ocean water, making up about 10 percent of the total ocean water volume.

Q10: The mixing of warm and cold currents in the ocean helps to favor the growth of _______________.
Ans: planktons
Plankton, a crucial component of the marine food chain, thrives in areas where warm and cold currents mix, providing nutrients.

Assertion and Reason Based

Q1: Assertion: Tides are caused by the gravitational forces between the Earth, Moon, and Sun.
Reason: Tides occur due to the combined effects of the gravitational pull of these celestial bodies and the rotation of the Earth.
(a) Both Assertion and Reason are true, and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of the Assertion.
(c) Assertion is true, but Reason is false.
(d) Both Assertion and Reason are false.
Ans: (a)
Tides are indeed caused by gravitational forces, and the rotation of the Earth plays a crucial role in their occurrence.

Q2: Assertion: Waves are caused by the horizontal motion of ocean water.
Reason: The energy that drives waves is provided by the wind.
(a) Both Assertion and Reason are true, and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of the Assertion.
(c) Assertion is true, but Reason is false.
(d) Both Assertion and Reason are false.
Ans: (a)
Waves result from wind transferring energy to the ocean's surface, creating the motion observed in waves.

Q3: Assertion: Tidal bulges are higher on wide continental shelves.
Reason: The shape of bays and estuaries can greatly change tidal magnitudes.
(a) Both Assertion and Reason are true, and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of the Assertion.
(c) Assertion is true, but Reason is false.
(d) Both Assertion and Reason are false.
Ans: (a)
Tidal bulges are indeed influenced by the shape of the coastline, with wide continental shelves leading to higher tidal bulges.

Q4: Assertion: Warm currents bring warm water into cold water areas.
Reason: Warm currents are usually found on the east coast of continents in the high latitudes in the Northern Hemisphere.
(a) Both Assertion and Reason are true, and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of the Assertion.
(c) Assertion is true, but Reason is false.
(d) Both Assertion and Reason are false.
Ans: (b)
While warm currents do bring warm water into cold water areas, the assertion about their location is not always accurate.

Q5: Assertion: The Coriolis force causes ocean currents to move to the right in the northern hemisphere.
Reason: The Coriolis force is a primary force that initiates the movement of ocean currents.
(a) Both Assertion and Reason are true, and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of the Assertion.
(c) Assertion is true, but Reason is false.
(d) Both Assertion and Reason are false.
Ans: (a)
The Coriolis force does cause ocean currents to deflect to the right in the northern hemisphere, and it is indeed a primary force influencing currents.

Very Short Answer Type Questions

Q1: Define ocean currents.
Ans: Ocean currents are the continuous, directional movement of seawater in the ocean.

Q2: What causes the slowing down of waves as they approach a beach?
Ans: Waves slow down near the shore due to friction between the dynamic water and the seafloor.

Q3: What are tidal currents?
Ans: Tidal currents are the horizontal movement of water associated with the rise and fall of tides.

Q4: Explain the term "spring tides."
Ans: Spring tides occur during a full moon or new moon when the sun, moon, and Earth are aligned, resulting in higher tidal ranges.

Q5: How does the moon's position affect tide height?
Ans: The moon's position, especially during full and new moons, influences the gravitational pull on Earth's oceans, causing variations in tide height.

Q6: What are cold currents, and where are they usually found?
Ans: Cold currents are oceanic currents with cold water that flow along the west coast of continents in low and middle latitudes.

Q7: How do warm currents influence the climate of coastal regions?
Ans: Warm currents raise coastal temperatures and may bring rain, creating a milder and more humid climate.

Q8: Name the primary forces that influence ocean currents.
Ans: Primary forces affecting ocean currents include heating by solar energy, wind, gravity, and the Coriolis force.

Q9: What is drift when referring to ocean currents?
Ans: Drift is a term used to refer to the speed or rate of ocean currents, measured in knots.

Q10: What percentage of the ocean is made up of surface currents?
Ans: Surface currents constitute about 10% of all ocean water, located in the upper 400 meters of the ocean.

Short Answer Type Questions

Q1: Explain the relationship between the sun and the moon and the occurrence of tides.
Ans: Tides are primarily caused by the gravitational forces of the moon and the sun. The moon exerts the stronger gravitational pull, creating two tidal bulges on opposite sides of the Earth. When the sun, moon, and Earth align during a full moon or new moon, spring tides with higher tidal ranges occur. When they are at right angles during the first and third quarters of the moon, neap tides with lower tidal ranges are observed.

Q2: Describe the characteristics of ocean waves, including wave height, amplitude, and wavelength.
Ans: Ocean waves are energy disturbances in the water that travel horizontally. Wave height is the vertical distance from the bottom of a trough to the top of a crest. Amplitude is one-half of the wave height. Wavelength is the horizontal distance between two successive wave crests. Waves are not the actual movement of water but the transfer of energy across the ocean's surface.

Q3: Differentiate between semi-diurnal tide, diurnal tide, and mixed tide.
Ans: Semi-diurnal tides have two high tides and two low tides each day, with approximately equal heights. Diurnal tides consist of one high tide and one low tide each day, typically with similar heights. Mixed tides show variations in height, often occurring along the west coast of North America and certain Pacific islands.

Q4: Discuss the effects of ocean currents on the climate of west coasts of continents in tropical and subtropical latitudes.
Ans: The west coasts of continents in these latitudes are influenced by cold ocean currents, resulting in relatively low average temperatures with narrow temperature ranges. These areas tend to be arid and experience fog. In contrast, the east coasts, influenced by warm ocean currents, have milder winters and cooler summers with narrow temperature ranges. Warm currents lead to warmer and rainy climates.

Long Answer Type Questions

Q1: Discuss the factors that contribute to the formation and characteristics of ocean waves. Include the role of wind, wave speed, and wave size.
Ans: Ocean waves are generated by the transfer of energy from the wind to the water's surface. Factors influencing wave characteristics include wind speed, wind duration, and the area over which the wind blows. As wind imparts energy, waves grow in size and speed. The highest waves are typically found in the open ocean, and they continue to grow by absorbing energy from the wind. When wave depth is less than half the wavelength, waves break as they approach the shore, slowing down due to friction with the seafloor.

Q2: Explain in detail the causes of tides, including the roles of the moon, the sun, and the Earth's rotation. Discuss the different types of tides.
Ans: Tides result from the gravitational pull of the moon and the sun on Earth's oceans. The moon has a stronger influence due to its proximity. Tidal bulges, caused by the moon's gravitational pull, lead to high and low tides. Spring tides occur when the sun, moon, and Earth align, creating higher tidal ranges. Neap tides occur when they are at right angles. Earth's rotation contributes to the daily occurrence of two high tides and two low tides. Tides can be classified into semidiurnal, diurnal, and mixed types based on frequency.

Q3: Describe the significance of ocean currents in terms of their impact on climate, marine life, and navigation. Use specific examples to illustrate your points.
Ans: Ocean currents play a crucial role in regulating climate by redistributing heat across the globe. Warm currents raise coastal temperatures and lead to milder climates, while cold currents have the opposite effect. Ocean currents affect marine life by influencing nutrient distribution, which impacts fish populations. For example, mixing zones where warm and cold currents converge often have the most productive fishing grounds. In navigation, understanding ocean currents is essential for safe and efficient travel. For instance, the Gulf Stream in the Atlantic Ocean greatly affects ship routes.

Q4: Analyze the role of the Coriolis force in shaping ocean currents and its influence on the movement of warm and cold currents in the world's oceans.
Ans: The Coriolis force results from the Earth's rotation and deflects moving objects to the right in the northern hemisphere and to the left in the southern hemisphere. In ocean currents, this force has a significant impact on their direction. Warm currents tend to move to the right in the northern hemisphere and to the left in the southern hemisphere, while cold currents exhibit opposite movements. This influence of the Coriolis force helps shape the large accumulations of water known as Gyres. The interaction of the Coriolis force with other primary forces like wind, heating, and gravity drives the complex patterns of ocean currents worldwide.