Geography · Environmental Studies

Oceanography and Hydrology

1,743 Questions

Find relevant questions on oceanography and hydrology that address aquatic ecosystems and physical geography. The topics include coastal landforms, coral reefs, ocean salinity, and tidal patterns. These concepts frequently appear in civil services and state level administrative examinations.

Coral reef structuresCoastal landformsOcean salinity patternsGlacial retreat impactsMangrove ecosystems

Oceanography and Hydrology Questions

Multiple choice

Which among the following statements does not characterise red tides?

  1. The occurrence of red tides may be natural or from human activities.

  2. Coastal water pollution can cause red tides.

  3. Iron-rich dust influx from large desert can cause red tides.

  4. Red tides are related to the movements of the tides.

  5. When the algae are present in high concentrations, the water appears to be discolored.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Red tides are unrelated to movements of the tides. They are not necessarily red and many have no discolouration at all.

Multiple choice

Percentage of salt in the sea water is

  1. 40 gr per kilo

  2. 50 gr per kilo

  3. 35 gr per kilo

  4. 25 gr per kilo
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Seawater contains approximately 3.5% salt by weight, which equals 35 grams per kilogram of seawater. This salinity level is consistent across most of Earth's oceans.

Multiple choice

Ocean surface currents follow clockwise circulatory paths in the northern parts of the Pacific and Atlantic oceans due to the

  1. convergence and divergence movements

  2. coriolis force

  3. density differences in sea water

  4. impact of prevailing winds
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ocean surface currents in the northern hemisphere form clockwise rotating systems called gyres, primarily driven by wind patterns and the Coriolis effect. However, the question specifically asks for the primary cause. The Coriolis force causes the deflection that creates the circular pattern, but it is the prevailing winds (trade winds and westerlies) that provide the initial energy and momentum to the surface currents. The impact of prevailing winds is the more direct and immediate cause of both the movement and the clockwise direction (combined with Coriolis). Options A, B, and C are incorrect because: convergence/divergence is a result not the cause, density differences drive deep ocean currents not surface ones, and while Coriolis causes the rotation, winds drive the movement itself.

Multiple choice

Which of the given statements is/are correct in reference to Law of the Sea Treaty?

Consider the following statements:

1. Sea baseline limit is based on territorial waters, archipelagic waters, contiguous zones, continental shelves and EEZs.

2. High seas include the water column beyond the exclusive economic zone (EEZ).

3. United States has extended U.S. territorial waters from three nautical miles to twelve nautical miles for national security purpose.

  1. Only 1

  2. Only 2

  3. Only 3

  4. All of the above

  5. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This statement is correct. High seas is the term used for water column beyond the Exclusive Economic Zone (EEZ) or beyond the territorial sea where no EEZ has been declared.

Multiple choice

Which of the following ocean layers is known as the euphotic zone?

  1. The top sunlit zone

  2. The bottom of the sea bed

  3. The zone where water temperature is near freezing

  4. The zone where photosynthesis does not occur

  5. The zone below the thermocline and above the seabed
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The top bright ocean layer is called the sunlit zone or the euphotic zone. In this zone, there is enough light for photosynthesis to take place. So, many plants and other photosynthetic organisms live in this zone as food is abundant.

Multiple choice

Tides are caused due to

Directions: Read the following passage and answer the question that follows.

Waves move water and energy from one area to another. Waves located on the ocean’s surface are commonly caused by wind transferring its energy to the water, and big waves, or swells, can travel over long distances. A wave’s size depends on wind speed, wind duration, and the area over which the wind is blowing. This variability leads to waves of all shapes and sizes. The smallest categories of waves are ripples, growing less than one foot high. The largest waves occur where there are big expanses of open water that wind can affect.
Tides are actually waves, the biggest waves on the planet, and they cause the sea to rise and fall along the shore around the world. Tides exist due the gravitational pull of the moon and the sun, but vary depending on where the moon and sun are in relation to the ocean as the earth rotates on its axis.

  1. earthquakes

  2. volcanoes

  3. waves

  4. gravitational pull of sun and moon
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It is given in the 2nd line of the 2nd paragraph of the passage. Thus, it is the correct answer.

Multiple choice

What is the relation between existence of life in oceans and all other life forms?

Directions: Read the passage and answer the question that follows.
     
Scientists believe that life on Earth began in the ocean, approximately 4 billion years ago. And in fact, it was only about 500 million years ago that life emerged from the ocean onto the land. That means that ocean life has existed for 8 times longer period. So, no matter how unimaginably long it was since the first creatures crawled out on land, to the age of the dinosaurs and to our time, all of that is but a small slice of a pie compared to the vast span of time in which the oceans have nurtured life. And even today, although living things now exist on nearly every part of the Earth's surface, in so many different forms, the ocean continues to be critically important to life on Earth.
To begin with, the ocean covers 70% of the Earth's surface and is still the home of the majority of Earth's living creatures. Secondly, the oceans are a vital part of the water cycle that brings rain to our crops and forests -- and drinking water to our cities. And the ocean also produces much of the oxygen upon which all human beings and animals depend. Many of our recent medical and scientific breakthroughs have been made possible in one way or another through ocean based research. Finally, the oceans provide fish and shellfish and other vital resources upon which humans depend, including jobs for millions of people.

  1. They existed at the same time.

  2. The ocean life has existed for 8 times longer period than the life on land.

  3. The life on land has existed for 8 times longer period than the ocean life.

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

'The ocean life has existed for 8 times longer period than life on land'. Thus, option (2) is the correct answer.

Multiple choice

Which of the following is/are the merit(s) of oceans?

Directions: Read the passage and answer the question that follows.
     
Scientists believe that life on Earth began in the ocean, approximately 4 billion years ago. And in fact, it was only about 500 million years ago that life emerged from the ocean onto the land. That means that ocean life has existed for 8 times longer period. So, no matter how unimaginably long it was since the first creatures crawled out on land, to the age of the dinosaurs and to our time, all of that is but a small slice of a pie compared to the vast span of time in which the oceans have nurtured life. And even today, although living things now exist on nearly every part of the Earth's surface, in so many different forms, the ocean continues to be critically important to life on Earth.
To begin with, the ocean covers 70% of the Earth's surface and is still the home of the majority of Earth's living creatures. Secondly, the oceans are a vital part of the water cycle that brings rain to our crops and forests -- and drinking water to our cities. And the ocean also produces much of the oxygen upon which all human beings and animals depend. Many of our recent medical and scientific breakthroughs have been made possible in one way or another through ocean based research. Finally, the oceans provide fish and shellfish and other vital resources upon which humans depend, including jobs for millions of people.

  1. Oceans provides life to variety of marine creatures.

  2. Due to oceans, our crops and forests get water.

  3. Oceans are helpful in medicine and science.

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

All of the given options are merits of oceans.

Multiple choice

What is the belief of scientists about the life in oceans?

Directions: Read the passage and answer the question that follows.
     
Scientists believe that life on Earth began in the ocean, approximately 4 billion years ago. And in fact, it was only about 500 million years ago that life emerged from the ocean onto the land. That means that ocean life has existed for 8 times longer period. So, no matter how unimaginably long it was since the first creatures crawled out on land, to the age of the dinosaurs and to our time, all of that is but a small slice of a pie compared to the vast span of time in which the oceans have nurtured life. And even today, although living things now exist on nearly every part of the Earth's surface, in so many different forms, the ocean continues to be critically important to life on Earth.
To begin with, the ocean covers 70% of the Earth's surface and is still the home of the majority of Earth's living creatures. Secondly, the oceans are a vital part of the water cycle that brings rain to our crops and forests -- and drinking water to our cities. And the ocean also produces much of the oxygen upon which all human beings and animals depend. Many of our recent medical and scientific breakthroughs have been made possible in one way or another through ocean based research. Finally, the oceans provide fish and shellfish and other vital resources upon which humans depend, including jobs for millions of people.

  1. Life on land began approximately 4 billion years ago.

  2. There was no life about 500 million years ago.

  3. Life came from ocean to land about 500 million years ago.

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to the passage, option (3) is the correct answer.

Multiple choice

________ is/are the main source that brings water to crops.

Directions: Read the passage and answer the question that follows.
     
Scientists believe that life on Earth began in the ocean, approximately 4 billion years ago. And in fact, it was only about 500 million years ago that life emerged from the ocean onto the land. That means that ocean life has existed for 8 times longer period. So, no matter how unimaginably long it was since the first creatures crawled out on land, to the age of the dinosaurs and to our time, all of that is but a small slice of a pie compared to the vast span of time in which the oceans have nurtured life. And even today, although living things now exist on nearly every part of the Earth's surface, in so many different forms, the ocean continues to be critically important to life on Earth.
To begin with, the ocean covers 70% of the Earth's surface and is still the home of the majority of Earth's living creatures. Secondly, the oceans are a vital part of the water cycle that brings rain to our crops and forests -- and drinking water to our cities. And the ocean also produces much of the oxygen upon which all human beings and animals depend. Many of our recent medical and scientific breakthroughs have been made possible in one way or another through ocean based research. Finally, the oceans provide fish and shellfish and other vital resources upon which humans depend, including jobs for millions of people.

  1. Rains

  2. Forests

  3. Water cycle

  4. Oceans
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

“Oceans” are the main source due which water cycle is formed, which brings rains to crops.

Multiple choice

A piece of land surrounded by water on three sides

  1. Eskers

  2. Peninsula

  3. Estuary

  4. Hamadas

  5. Aquifer
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A peninsula is a landform surrounded by water on three sides and connected to mainland on the fourth. Examples include the Indian Peninsula, Florida, and the Iberian Peninsula. This distinguishes it from islands (completely surrounded) and other coastal features.

Multiple choice

The narrow sinuous ridges composed of marines

  1. Eskers

  2. Peninsula

  3. Estuary

  4. Hamadas

  5. Aquifer
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Eskers are long, narrow, sinuous ridges composed of sand and gravel deposited by meltwater streams flowing within glaciers. They form distinctive winding hills that mark the paths of subglacial rivers during ice sheet retreat.

Multiple choice

The permeable rock layer, which retains water.

  1. Eskers

  2. Peninsula

  3. Estuary

  4. Hamadas

  5. Aquifer
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

An aquifer is an underground permeable rock layer that stores and transmits groundwater. The porosity allows water retention while permeability permits flow, making aquifers crucial sources of freshwater for wells and springs.

Multiple choice

The widened river mouth found at the point where a river enters the sea.

  1. Eskers

  2. Peninsula

  3. Estuary

  4. Hamadas

  5. Aquifer
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An estuary is a partially enclosed coastal body where freshwater from rivers meets and mixes with saltwater from the ocean. The widened mouth occurs due to the deposition of sediments as the river's current slows upon entering the sea. Eskers are glacial ridges, peninsulas are land extensions, hamadas are desert plateaus, and aquifers are groundwater reservoirs.