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Environment and Biodiversity MCQs – 02 ( Ecological succession and Forests )

Ecological succession and Forests MCQs with answers and explanations for all examinations.

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1. The orderly sequence of change in the vegetation of an area over time is described as which among the following ?

(a) Biomes
(b) Ecological succession
(c) Trophic level
(d) Climax

Answer with detailed explanation

Correct Answer – (b) Succession

The orderly sequence of change in the vegetation of an area over time is described as succession or ecological succession.
It is a process by which an ecological community undergoes orderly and predictable changes following a disturbance or the initial colonization of a new habitat.
The process involves a progressive series of changes with one community replacing another until a stable, mature community develops.

2. Consider the following statements:

1. First plant to colonize an area is called the pioneer community.
2. The final stage of succession is called the climax community.

Which of the above is/are correct?

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

Answer with detailed explanation

Correct Answer – (c) Both 1 and 2

First plant to colonize an area is called the pioneer community.
The final stage of succession is called the climax community.
A climax community is stable, mature and long-lasting.

3. Consider the following statements:

1. Primary succession takes place over where no community has existed previously.
2. The pioneer species disappear as the habitat conditions change.

Which of the above is/are correct?

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

Answer with detailed explanation

Correct Answer – (c) Both 1 and 2

Primary succession takes place over where no community has existed previously.
In primary succession, the new site is first colonized by pioneer species that are often microbes, lichens and mosses.
The pioneer species disappear as the habitat conditions change and it leads to development of more complex and stable species.

4. Consider the following statements Secondary succession:

1. It is the sequential development of biotic communities after the complete or partial destruction of the existing community.
2. Unlike in the primary succession, the secondary succession starts on a well-developed soil.

Which of the above is/are correct?

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

Answer with detailed explanation

Correct Answer – (c) Both 1 and 2

Secondary succession is the sequential development of biotic communities after the complete or partial destruction of the existing community.
It occurs when a mature community is destroyed by natural events such as floods, droughts, fires, or storms or by human interventions such as deforestation, agriculture, overgrazing, etc.
Unlike in the primary succession, the secondary succession starts on a well-developed soil.

5. Consider the following statements:

1. Allogenic succession occurs when biotic factors or organisms themselves drive the succession.
2. Autogenic succession occurs when abiotic factors,or external forces drive the succession.

Which of the above is/are correct?

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

Answer with detailed explanation

Correct Answer – (d) Neither 1 nor 2

Autogenic succession occurs when biotic factors or organisms themselves drive the succession.
Example → Death and decay of existing species, Immigration of new species.
Allogenic succession occurs when abiotic factors,or external forces drive the succession.
Example → Volcanic eruptions, flooding, drought, earthquakes etc.

6. Teak wood is found in which among the following forests ?

(a) Tropical deciduous forests
(b) Tropical evergreen forests
(c) Montane forests
(d) Temperate evergreen forests

Answer with detailed explanation

Correct Answer – (a) Tropical deciduous forests

Tropical deciduous forests are characterized by trees that shed their leaves during a particular time of the year, usually in response to a dry season.
Teak trees are the most dominant species of trees found in these forests.
Bamboos, sal, shisham, sandalwood, khair, arjun, mulberry are some of the other commercially important species found here.

7. Rhododendrons are naturally found in which among the following areas ?

(a) Himalayas
(b) Central India
(c) South India
(d) None of the above

Answer with detailed explanation

Correct Answer – (a) Himalayas

Rhododendrons are evergreen or deciduous shrubs or small trees, with woody stems and broad, leathery leaves.
In India, they are naturally found on the foothills of the Himalayas.
It is the state flower of J&K, Himachal Pradesh, Nagaland.
It is the state tree of Sikkim and Uttarakhand.
Most species of Rhododendron have brightly coloured flowers which bloom from late winter through to early summer.

8. Hardwood trees like rosewood, ebony, mahogany are generally found in ?

(a) Tropical evergreen forests
(b) Tropical deciduous forests
(c) Temperate Evergreen Forests
(d) Mediterranean Vegetation

Answer with detailed explanation

Correct Answer – (a) Tropical evergreen forests

The trees like Mahogany and Rosewood are found in the tropical evergreen forest.
They are also known as the tropical rainforest.
In India, tropical evergreen forests can be found in the Western Ghats, the Jaintia and Khasi mountain ranges, and states like Kerala and Karnataka.

9. Mediterranean trees have thick barks and wax coated leaves. These features help them to perform which among the following ?

(a) Reduce transpiration
(b) Increase rate of water flow from roots to shoots
(c) Cut down the need for photosynthesis
(d) Increase the area of the leaves to step up glucose intake

Answer with detailed explanation

Correct Answer – (a) Reduce transpiration

Transpiration is the loss of water from the leaves through the stomata.
If transpiration is high due to large pores of the leaves, the water demand for the plant is likely to be high, which would make the survival of the plant difficult in the summers of the Mediterranean region.
Waxy leaves and thick barks reduce transpiration and thus reduce the water requirements and increase the chance of survival.

10. The process by which an organism maintains a constant internal environment to survive and function despite changes in the external environment is called as ?

(a) Metamorphism
(b) Homeostasis
(c) Autophagy
(d) Mitosis

Answer with detailed explanation

Correct Answer – (b) Homeostasis

The process by which an organism maintains a constant internal environment to survive and function despite changes in the external environment is called Homeostasis.
Autophagy is a process in which a cell breaks down and recycles old, damaged, cell parts.
Mitosis is a process in which a cell’s nucleus splits into two which leads to formation of two identical daughter cells.

11. Consider the following statements about the Temperate Deciduous Forests:

1. They are found in mid and higher latitudes.
2. Oak, ash and beech trees are generally found here.

Which of the above is/are correct?

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

Answer with detailed explanation

Correct Answer – (c) Both 1 and 2

A temperate deciduous forest is a biome characterized by broadleaf trees that shed their leaves in the dry season and regrow them in the spring.
They are found in mid-latitude areas, between the tropics and the polar regions.
Common trees found here are oak, ash, beech etc.

12. Deforestation affects which among the following soil properties ?

(1) Top soil content
(2) Microbial activity
(3) Nutrient content
(4) Water holding capacity

Select the correct answer using the codes below.

(a) 1, 2 and 3 only
(b) 1, 2 and 4 only
(c) 2 and 3 only
(d) All of the above

Answer with detailed explanation

Correct Answer – (d) All of the above

After deforestation, soil becomes exposed and rainwater can easily leach away nutrients in run-off water.
This causes the fertility of soil to decline.
Removal of the top layer of the soil during deforestation exposes the lower, hard layer which is less fertile.
Microbial activity in soil decreases due to the loss of forest.
Due to leaching, Nutrient content in the soil decreases.
Due to loss of tree roots, Water holding capacity of the soil also decreases.

13. Forest fires are major environmental concern as they can lead to:

1. Loss of valuable timber resources
2. Loss of wildlife habitat
3. Global warming

Select the correct answer using the codes below.

(a) 1 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) All of the above

Answer with detailed explanation

Correct Answer – (d) All of the above

Forest fires are major environmental concern as they can lead to following consequences:
- Loss of valuable timber resources
- Loss of large carbon sinks which can lead to an increase in CO2 in the atmosphere
- Degradation of soil
- Loss of biodiversity and can lead to extinction of plants and animals
- Loss of wildlife habitat
- Global warming
- Loss of livelihood for the tribals
- Health problems

14. Consider the following statements about the ‘Sundarbans’:

1. They host a large population of mangroves.
2. They are under threat due to freshwater flows from Brahmaputra and Meghna rivers.

Which of the above is/are correct?

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

Answer with detailed explanation

Correct Answer – (a) 1 only

The Sundarbans hosts the largest mangrove forests in the world.
It is located on the delta of the Ganges, Brahmaputra and Meghna rivers on the Bay of Bengal.
It is a UNESCO World Heritage site and also ‘Wetland of International Importance’ under the Ramsar Convention.
It is also famous for its Royal Bengal Tigers.
Sundarbans are under threat due Scarcity of freshwater flows from Brahmaputra and Meghna rivers.
Pollution from various sources is also impacting the delicate ecosystem of the Sundarbans.

15. If a tropical rainforest is removed, it does not regenerate quickly as compared to a tropical deciduous forest. This is because of the following reasons ?

(a) The soil of rainforest is deficient in nutrients
(b) The trees in a rainforest have poor viability
(c) The rain forest species are naturally slow-growing
(d) Invasive species invade the fertile soil of rainforest

Answer with detailed explanation

Correct Answer – (a) The soil of rainforest is deficient in nutrients

The soil of the rainforest is deficient in nutrients .
This is because of the heavy rains that occur almost every day.
Rainwater washes away the nutrients(Called leaching of nutrients) which reduces the fertility of soil.
Hence, Regeneration of new vegetation is very slow(takes decades).

A complete ecosystem for UPSC Civils and State PSC Preparation

Environment and Biodiversity MCQs – 02 ( Ecological succession and Forests )

Chapterwise MCQs

Short Notes

Also Read in Environment and Ecology MCQs :

Environment and Biodiversity MCQs – 01 ( Basics of Ecology )

Environment and Biodiversity MCQs – 03 ( Ecosystems and Biomes )

Environment and Biodiversity MCQs – 04 ( Nutrient cycles )

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