UPSC MainsZOOLOGY-PAPER-I202510 Marks150 Words
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Q19.

Write short notes on the following in about 150 words each : (e) Biome

How to Approach

To answer this question effectively, define a biome and explain its key characteristics, emphasizing the role of climate. Then, briefly categorize the major types of biomes (terrestrial and aquatic) with a few examples. Conclude by highlighting their ecological significance and perhaps mention threats. Structure your answer with a clear introduction, a body detailing characteristics and types, and a concise conclusion.

Model Answer

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Introduction

A biome is a large-scale ecological region characterized by distinct climate patterns, vegetation types, and associated animal life, forming a major community of living organisms. These vast geographical areas are primarily defined by abiotic factors like temperature, precipitation, and soil conditions, which in turn dictate the types of flora and fauna that can thrive there. The concept of a biome helps in understanding the global distribution of ecosystems and the adaptations of species to their specific environments. Introduced by Frederic Edward Clements in 1916, biomes represent an international, non-regional classification of ecological communities.

Characteristics of a Biome

Biomes exhibit several defining characteristics that distinguish them from other ecological units like ecosystems:

  • Climate as a Primary Determinant: Temperature and precipitation are the most crucial abiotic factors shaping a biome. These determine the availability of water and the energy budget, influencing plant growth forms and animal adaptations.
  • Dominant Vegetation: The prevailing climate leads to a characteristic type of vegetation (e.g., forests, grasslands, deserts), which is often used to name the biome. This vegetation provides habitat and food for animal species.
  • Adapted Animal Life: Animals within a biome possess specific adaptations—physiological, behavioral, or structural—to survive the prevailing climatic and environmental conditions.
  • Large Geographical Scale: Biomes span vast geographical areas, often across continents, where similar environmental conditions prevail, leading to convergent evolution of life forms.
  • Multiple Ecosystems: A single biome can encompass numerous smaller ecosystems, all sharing the overarching climatic and biological characteristics of the biome.

Major Types of Biomes

Biomes are broadly classified into two main categories:

1. Terrestrial Biomes (Land Biomes)

These are biomes found on land, largely determined by temperature and precipitation. Key types include:

  • Forest Biomes: Characterized by dense tree cover. Examples include:
    • Tropical Rainforest: High temperatures, abundant rainfall, immense biodiversity (e.g., Amazon, Congo Basin).
    • Temperate Deciduous Forest: Moderate temperatures, distinct seasons, trees shed leaves annually (e.g., Eastern North America, Europe).
    • Boreal Forest (Taiga): Cold temperatures, coniferous trees (e.g., Canada, Russia).
  • Grassland Biomes: Dominated by grasses, often with seasonal rainfall.
    • Tropical Grasslands (Savanna): Scattered trees, distinct wet and dry seasons (e.g., East Africa).
    • Temperate Grasslands: Cold winters, warm summers, rich in grasses (e.g., Prairies of North America, Steppes of Eurasia).
  • Desert Biomes: Very low precipitation, extreme temperature variations, sparse vegetation adapted to drought. (e.g., Sahara, Atacama).
  • Tundra Biomes: Coldest biome, permafrost, short growing season, low-lying vegetation (e.g., Arctic regions).

2. Aquatic Biomes (Water Biomes)

These cover water bodies and are crucial for global climate regulation and oxygen production.

  • Freshwater Biomes: Low salt content. Examples include lakes, rivers, ponds, and wetlands.
  • Marine Biomes: High salt content, largest biome on Earth. Includes oceans, seas, coral reefs, and estuaries.

The interaction between these biotic and abiotic components defines the unique biodiversity and ecological processes within each biome.

Conclusion

In essence, biomes represent fundamental ecological divisions of the Earth, shaped by climate and characterized by specific plant and animal communities. Their classification helps us comprehend the planet's vast biodiversity and the intricate web of life sustained across diverse environmental conditions. However, biomes are increasingly under threat from anthropogenic activities, particularly climate change, which is altering temperature and precipitation patterns, leading to shifts in biome boundaries, species distribution, and increased frequency of extreme weather events, underscoring the critical need for conservation.

Answer Length

This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.

Additional Resources

Key Definitions

Biome
A biome is a distinct geographical region with specific climate, vegetation, animal life, and an ecosystem. It consists of a biological community that has formed in response to its physical environment and regional climate.
Ecosystem
An ecosystem is a smaller, self-contained unit within a biome, focusing on the interactions between living organisms (biotic components) and their non-living physical environment (abiotic components) within a particular unit of space.

Key Statistics

Climate change has altered marine, terrestrial, and freshwater ecosystems around the world, causing loss of local species, increased diseases, and driving mass mortality of plants and animals, resulting in the first climate-driven extinctions. The IPCC Sixth Assessment Report found that half of 4000 analyzed species shifted their distribution to higher latitudes or elevations in response to climate change.

Source: IPCC Sixth Assessment Report, United Nations

It is estimated that up to one million species are threatened with extinction, many within decades, due to factors including climate change and human land use. Irreplaceable ecosystems like parts of the Amazon rainforest are turning from carbon sinks into carbon sources due to deforestation.

Source: United Nations Environment Programme (UNEP)

Examples

Amazon Rainforest: A Tropical Rainforest Biome

The Amazon Rainforest is the largest tropical rainforest in the world, covering vast areas of South America. It is characterized by high biodiversity, consistent warm temperatures, and abundant rainfall, supporting millions of species of plants and animals. Its extensive tree cover plays a crucial role in global oxygen production and carbon sequestration.

Sahara Desert: A Desert Biome

The Sahara Desert in North Africa is one of the world's largest hot deserts, exemplifying a desert biome. It receives very little precipitation and experiences extreme diurnal temperature variations. The flora and fauna found here, such as cacti and camels, exhibit remarkable adaptations to conserve water and tolerate harsh conditions.

Frequently Asked Questions

What is the difference between a biome and an ecosystem?

A biome is a large-scale ecological region defined by similar climate, vegetation, and animal life across vast geographical areas (e.g., tropical rainforest). An ecosystem is a smaller, more localized community of living organisms interacting with their physical environment (e.g., a pond within a forest biome). Biomes contain multiple ecosystems.

Topics Covered

EcologyGeographyEcosystemsBiogeographyEnvironment