Shankar IAS Test: Marine Organisms - Free MCQ with solutions for UPSC Environment

Concept:

Food chain: A food chain shows the feeding relationship between different organisms in a particular environment and/or habitat. A food chain shows how energy is passed from the sun to producers, from producers to consumers, and from consumers to decomposes such as fungi. They also show how animals depend on other organisms for food.

• Food chain is distributed between Autotrophs, Hetrotrops, and Decomposers i.e Producers, consumers and decomposers.
• Autotrophs produce their own food like plants, trees and some algae.
• Heterotrophs are consumers i.e. animals, man, insects etc.
• Decomposers are bacteria, fungi etc.

Thus, the correct sequence is Grass → Grasshopper → Frog → Snake → Hawk.

Quinine is a medication used to treat parasite causing malaria disease.

• It is extracted from the bark of the cinchona tree.
• Quinine was first isolated in 1820.
• Quinine is also used for the treatment of babesiosis.
• Quinine is the ingredient in tonic water that gives it its bitter taste.
• Quinine is on the world health organization's list of essential medicines.
• Malaria is caused by plasmodium parasite.

Drugs like vincristine and vinblastine extracted from vinca rosea are used for the treatment of blood cancer.

Reserpine extracted from the plant serpentine is used for the treatment of systolic hypertension.

The correct answer is Streams, River and Spring.

• The pond is not an example of a Lotic ecosystem.

Key Points

• The lotic water is a classification of the freshwater bodies on the basis of the flow of the water.
• The lotic water is composed of flowing water bodies.
• The water of these types of water bodies does not stay in one place but rather moves or flows from one place to another.
• In the first option, we are given streams, rivers, and springs.
  • Streams, rivers, and springs are all flowing bodies of water.
  • Hence, these are all examples of lotic water.
• ​A river is a flowing body of water.
  • Lakes and ponds are still bodies of water.
  • Hence, the river is an example of lotic water and the lake and ponds are examples of lentic water.
• ​Swamps and lakes are both still bodies of water.
  • Hence, these are both examples of lentic water.
• ​​Lakes and ponds are both still bodies of water.
  • Hence, these are both examples of lentic water.
  • From the above information, we can conclude that the streams, rivers, and springs are examples of lotic water.

The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere.
Since our planet and its atmosphere form a closed environment, the amount of carbon in this system does not change. Where the carbon is located in the atmosphere.
On Earth, most carbon is stored in rocks and sediments, while the rest is located in the ocean, atmosphere, and in living organisms. These are the reservoirs, or sinks, through which carbon cycles.
Carbon is released back into the atmosphere when organisms die, volcanoes erupt, fires blaze, fossil fuels are burned, and through a variety of other mechanisms.
Thus, coal, limestone, petroleum, and animal shells are all result of the Carbon Cycle. Hence, Option 4 is the correct answer.

The ecosystem is completely dependent on solar radiation.

• For eg. forests, oceans, grasslands, lakes, rivers, and deserts. 
• This type of ecosystem is known as the Natural ecosystem.
• Man-made ecosystems are those ecosystems that are dependent on solar energy.
• For eg. agricultural fields and aquaculture ponds.
• Such ecosystems are also dependent on fossil fuels.
• For eg. urban and industrial ecosystems.
• An ecosystem is a community of living organisms in conjunction with the non-living components of their environment, interacting as a system.
• These biotic and abiotic components are linked together through nutrient cycles and energy flows.
• A forest ecosystem is a functional unit or a system that comprises soil, trees, insects, animals, birds, and man as its interacting units.

• A lake ecosystem is an aquatic food chain. It consists of different trophic levels.
  • The first trophic level is phytoplankton.
  • They produce their own food.
• Zooplankton is the primary consumer in aquatic food chains.
  • They feed upon phytoplankton. They are present in the second trophic level.
  • Hence, the second most important trophic level in a lake is zooplankton.
  • Small fishes feed upon zooplankton.
  • They are present in the third trophic level. Similarly, big fishes and other bigger aquatic animals are present in the fourth trophic level which feed upon small fishes.
• Thus, the correct answer is 'Zooplankton. 

An ecosystem is an interaction of biological community organisms between each other and their physical environment.
The lithosphere is the outer part of the Earth it is made up of the crust and the top part of the upper mantle. 
A biome is a large community of vegetation and wildlife which are adapted to a specific climate.
The five major types of the biome are:

• aquatic 
• grassland 
• forest 
• desert
• tundra

CONCEPT:

• An ecosystem forms the basic building block of an environment.
• It consists of both biotic and abiotic components and their continuous interactions with each other.
• Ecosystems can broadly be classified into two types, namely:
  • Natural ecosystem – naturally occurring
  • Artificial ecosystem – man-made ecosystems

An aquatic ecosystem includes standing fresh water, running fresh water, as well as the ocean and seas around the world.

Lentic ecosystem

• Lentic ecosystems are those water bodies whose water is still.
• These ecosystems range in size from very small ponds or pools that may be temporary, to large lakes.
• Examples: ponds, marshes, pools, ditches, lakes, and swamps. 

Lotic ecosystem

• Lotic ecosystems are those water bodies whose water is flowing.
• These ecosystems can vary in size dramatically from small trickling streams to mile-wide rivers that travel for thousands of miles.
• Examples: rivers, streams, canals, and springs.

Thus, lakes, ponds, and pools are examples of a lentic ecosystem.

Ecosystem:

• Ecosystem is an open system with inputs, internal transfers and outputs of energy and nutrients.
• Sunlight is the initial energy source for nearly all ecosystems.
• The different types of ecosystems are-
  • Natural Ecosystem:
    1. Terrestrial ecosystem
    2. Aquatic ecosystem
    3. Lentic - lake, pond or swamp
    4. Lotic - river, stream or spring. Hence, statement 2 is incorrect.
  • Artificial Ecosystem:
    1. ​Dams
    2. Gardens
    3. Botanical parks
    4. Zoos
    5. Aquariums
• ​Aquatic ecosystem include standing fresh water (such as lakes), running fresh water (such as streams), as well as the ocean and seas around the world.
• Estuaries, intertidal zones, rocky and sandy shores, tropical reefs and regions of the open ocean are major marine ecosystems. Hence, statement 1 is correct.

• An ecosystem has two components the biotic components consisting of living things, and the abiotic portion, consisting of elements that are not alive. 
• The nonliving constituents are said to include the following category, habitat, gases, solar radiation, temperature, moisture, and inorganic and organic nutrients.
  • ​Hence, Statement 1 is incorrect.
• The living organisms may be sub-divided into producers, consumers, and decomposers. Abiotic Components include basic inorganic and organic components of the environment or habitat of the organism. 
  • Hence, Statement 2 is incorrect.
• The inorganic components of an ecosystem are carbon dioxide, water nitrogen, calcium phosphate all of which are involved in the matter cycle (biogeochemical cycles). 
• The organic components of an ecosystem are proteins, carbohydrates, lipids and amino acids, all of which are synthesized by the biota (flora and fauna) of an ecosystem and are reached to the ecosystem as their wastes, dead remains etc. the climate 'microclimate' temperature, light soil etc. are abiotic components of the ecosystems.

• Net primary productivity, or NPP, is gross primary productivity excluding the rate of energy loss to metabolism and maintenance.
• It is the rate at which energy is stored as biomass by plants or other primary producers and made available to the consumers.
  • Net primary productivity (NPP) = Gross primary production (GPP) - Respiration (R)
• Rainforest exists in broadband across the Earth's warm, moist equatorial regions.
  • It has an NPP of about 2000-4000 g/m² per year.
  • The oldest living ecosystem can be found in the Rainforest.
  • Due to extreme rainfall, a rainforest includes dense forests with tall and evergreen trees.
  • The plants are too large in height so that the sunlight is not able to enter the forest.
• Due to extreme heat and scarcity of rainfall, the Desert has one of the driest ecosystems and because of this reason very little diversity and plants are found in the desert.
• Various kinds of living animals, plants and microorganisms(biotic), as well as non-living (abiotic) chemical and physical factors, are found in lakes and streams due to the freshness of water.
• Grassland occurs naturally and is dominated by grasses.
  • The plants that are found in Grassland do not grow much and are non-woody.

• A biodiversity hotspot is a biogeographic region that is both a significant reservoir of biodiversity and is threatened with destruction.
  This statement is correct. According to the definition of a biodiversity hotspot, these are areas that are both rich in endemic species and under threat from human activities. The criterion for an area to be considered a hotspot is that it must contain at least 1,500 species of vascular plants as endemics, and it must have lost at least 70% of its original habitat.

• Globally, the total number of biodiversity hotspots has witnessed a decline over the years.
  This statement is not correct. The total number of biodiversity hotspots has not decreased over time. In fact, more regions are continuously being recognized as biodiversity hotspots due to increased awareness and the discovery of new regions that qualify as hotspots. Therefore, the number of hotspots has either remained the same or increased, rather than declined.

• The Himalayas and the Western Ghats are the only two biodiversity hotspots in India.
  This statement is not correct. While the Himalayas and the Western Ghats are two of the biodiversity hotspots in India, they are not the only two. India has four biodiversity hotspots: the Himalayas, Western Ghats, Sundaland (including Nicobar Islands), and the Indo-Burma region.

Therefore, Correct Answer -Option B

• Some animals eat both plants as well as other animals, those who heart both are called omnivores.
• The omnivores eat plant food as well as the meat of other animals.
• Some of the examples are Man, dogs, crows, and ants.
• Man is called an omnivore because he eats both, plant food as well as the meat of animals.
• There is another type of producer and consumer who are extremely small. 
• Planktons:
  • They are very minute or microscopic organisms freely floating on the surface of the water in a pond, lake, river, or ocean.
  • Planktons float near the surface of the water and provide food for many fish and other aquatic animals.
• There are two types of planktons:
  • Phytoplanktons:
    • The microscopic aquatic plants freely floating on the surface of the water in a pond, lake, river, or ocean.
    • The free-floating alga is an example of phytoplanktons.
    • Phytoplanktons are capable of producing food by the process of photosynthesis.
  • Zooplanktons: ​
    • The microscopic aquatic animals freely floating on water are called zooplanktons.
    • The free-floating protozoa are an example of zooplanktons.
    • A very, very small fish is also zooplankton.

The pyramid of energy in any ecosystem is always upright. This means that the amount of energy present at each trophic level decreases as you move up the food chain. This happens because energy is lost as it is transferred from one trophic level to the next, through processes such as respiration, heat loss, and incomplete digestion. As a result, there is less energy available to organisms at higher trophic levels, which limits the number of individuals that can be supported. Therefore, the pyramid of energy is always upright, with the base representing the primary producers, and the top representing the apex predators.

• Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as lowland equatorial evergreen rainforest.
• A mangrove is a shrub or small tree that grows in coastal saline or brackish water.
  • The term is also used for tropical coastal vegetation consisting of such species.
  • Mangroves occur worldwide in the tropics and subtropics, mainly between latitudes 25° N and 25° S.
• Tropical Rainforests has the maximum bio-diversity among the given options.