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Environment and Biodiversity MCQs – 03 ( Ecosystems and Biomes )

Most important MCQs from the chapter – Ecosystems and Biomes MCQs for UPSC, State PSC and Other Examinations.

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1. The transitional zone between two distinct ecosystems is known as ?

(a) Ecotype
(b) Ecade
(c) Ecosphere
(d) Ecotone

Correct Answer –  (d) Ecotone

  • An ecotone is a transitional area between diverse ecosystems. 
  • It has some of the characteristics of each bordering ecosystem and also often contains species which are unique to ecotone and not found in the overlapping communities.
  • some examples of ecotones:
  • Mangrove forests → The transition zone between marine and terrestrial ecosystems.
  • Estuaries →  The transition zone between freshwater and marine ecosystems.
  • Grasslands →  The transition zone between desert and forest ecosystems.

2. The speed of decomposition of organic matter in soil is determined by which of these major factors ?

(1) Soil organisms
(2) Temperature conditions
(3) Moisture conditions
(4) Quality of the organic matter

Select the correct answer using the codes below:

(a) 1 and 2 only
(b) 2, 3 and 4 only
(c) 3 and 4 only
(d) 1, 2, 3 and 4

Correct Answer –  (d) 1, 2, 3 and 4

  • All the given factors play a role in determining the speed of decomposition of organic matter in soil.
  • High temperature and high moisture aid the process of decomposition.
  • Soil organisms, including microorganisms, use soil organic matter as food. As they break down the organic matter, the nutrients such as Nitrogen and Phosphorus are released into the soil in forms that plants can use.

3. Consider the following statements about the Mangrove forests:

1. They have high biodiversity.
2. They mainly grow in coastal intertidal zones.

Select the correct statement(s) using the codes given below:

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (c) Both 1 and 2

  • Mangrove forests are made up of trees and shrubs that can grow in low-oxygen, salty soil. 
  • They are generally found in coastal intertidal zones.
  • Mangrove forests stabilize the coastline, reducing erosion from waves, tides, and storm surges.
  • Mangrove forests enjoy high biodiversity. These are home to a variety of plants and animals, including some species that are unique to these forests.
  • In India, They are mainly found in the Andaman and Nicobar Islands and the deltas of Mahanadi, the Godavari and the Krishna.

4. Consider the following statements about the Estuaries:

1. They are among the least productive ecosystems in the world
2. Some estuaries form an ecotone of freshwater and salty seawater.

Select the correct statement(s) using the codes given below:

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (b) 2 only

  • Estuaries are the wetlands that are usually found where rivers meet the sea.
  • Estuaries are home to unique plant and animal communities that have adapted to brackish water – a mixture of fresh water draining from the land and salty seawater.
  • Estuaries are the examples of ecotone. An ecotone is a transition area between two biomes where two communities meet, integrate and thrive together.
  • Estuaries are among the most productive ecosystems in the world.

5. Which of the following is an example of a Biome ?

(a) Tundra region
(b) Lake Pangong
(c) Himalayan forests
(d) Ganges River

Correct Answer –  (a) Tundra region

  • Biome is a large geographical area with a distinct climate and a community of flora and fauna.
  • Biomes can include multiple ecosystems.
  • Some of the major biomes of the world are forests, grasslands, deserts and tundra biomes.

6. Kelp forests are underwater areas with a high density of which among the following ?

(a) Brown algae seaweed
(b) Coral reefs
(c) Mangroves
(d) Tropical Rainforests

Correct Answer – (a) Brown algae seaweed

  • Kelps are large brown algae seaweeds. 
  • They grow in shallow oceans. 
  • They are recognized as one of the most productive and dynamic ecosystems on Earth.

7. Mosses and lichens together are most likely to be found in which among the following climatic zones of the world ?

(a) Tropical
(b) Temperate
(c) Tundra
(d) Desert

Correct Answer –  (c) Tundra

  • Tundra is the global biome that consists of the treeless regions in the north (Arctic tundra) and high mountain (alpine tundra) areas of other continents.
  • It has a very short growing season due to extreme cold throughout the year.
  • The vegetation of the tundra mainly consists of grasses, dwarf shrubs, mosses, and lichens.

8. Consider the following statements about the Corals:

1. They protect coastlines from storms and erosion.
2. They provide nursery grounds for economically important fish species.

Which of the above is/are correct?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (c) Both 1 and 2

  • Coral reefs are formed by hard corals, which grow in warm, shallow, and clean water. 
  • Coral ecosystems has a huge economic significance as they are:
    • Source of food for millions
    • Protect coastlines from storms and erosion
    • Provide habitat and nursery grounds for economically important fish species
    • Provide income source to local economies from fishing
    • Used for recreation and tourism

9. The Great Barrier Reef is located in ?

(a) Pacific Ocean
(b) Atlantic Ocean
(c) Indian Ocean
(d) Mediterranean Sea

Correct Answer – (a) Pacific Ocean

  • The Great Barrier Reef is the world’s largest coral reef complex located in the Pacific Ocean off the coast of Australia.
  • It is also a natural World Heritage Site.
  • The distribution of coral reefs is determined by factors such as water’s temperature and salinity.

10. Consider the following statements about the wetlands:

1. They are among the most productive ecosystems in the world.
2. They protect shores from wave action and reduce the impacts of floods/Tsunamis.

Select the correct statement(s) using the codes given below:

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (c) Both 1 and 2

  • The wetlands are among the most productive ecosystems of the world comparable to rain forests and coral reefs.
  • They have an immense variety of species of microbes, plants, insects, amphibians, reptiles, birds, fish and mammals.
  • They protect shores from wave action and reduce the impacts of floods/Tsunamis.
  • They keep water pollution in check by absorbing pollutants and improving water quality.

11. Which one of the following is the most stable ecosystem ?

(a) Desert
(b) Mountain
(c) Ocean
(d) Forest

Correct Answer – (c) Ocean

  • The Ocean is considered as the most sustainable and stable ecosystem.
  • The ocean’s huge volume means that small changes do not affect the stability of the ecosystem.

12. The concept of ecological niche was first introduced by ?

(a) C.C. Park
(b) E.P. Odum
(c) J. Grinnell
(d) G.E. Hutchinson

Correct Answer – (c) J. Grinnell

  • Joseph Grinnell was the first person to introduce the concept of ecological niche.

13. Consider the following statements about the Niche of an organism :

1. A Niche is unique for an organism.
2. While habitat is a geographical place, a niche is the relationship of an organism with the components of an ecosystem

Select the correct statement(s) using the codes given below:

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (c) Both 1 and 2

  • An ecological niche refers to the interrelationship of an organism with the biotic and abiotic factor affecting it.
  • A Niche is unique for an organism in a given ecosystem/habitat.
  • Please note that  a habitat may consist of many niches as it supports different organisms at the same time.

14. What is the primary source of food for organisms in the marine ecosystem ?

(a) Phytoplankton
(b) Zooplankton
(c) Seaweed
(d) Grasses

Correct Answer – (a) Phytoplankton

  • Phytoplanktons are main producers in the marine ecosystem and thus these are the primary source of food for marine life.

15. Consider the following statements about the ecosystem of Savanna Grasslands:

1. Main vegetation is tall grass and short trees.
2. Trees usually have broad trunks.

Select the correct statement(s) using the codes given below:

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (c) Both 1 and 2

  • Savanna grassland is a type of grassland with scattered trees and a continuous layer of tall grasses.
  • It experiences long periods of drought, hence Trees found here usually have broad trunks and animals with long legs for migration.

Also Read in Environment and Ecology MCQs :

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