Important questions 2025 test

 Notes by Peter P. Sir, copyright

 

 

What is Ecology? Define Ecology

 

Ecology is the scientific study of the relationship and interactions between organisms and their environment. The term ecology is derived from the Greek word Oekologie where “Oikos” meaning “household” and “logos” means “the study of”. The word "ecology" ("Ökologie") was coined in 1866 by the German scientist Ernst Haeckel. 

           Ecology is a branch of biology concerning interactions among organisms and their biophysical environment, which includes both biotic and abiotic components. The ecosystem is the fundamental unit of ecological studies.

Ecology is not synonymous with environmentalism, natural history, or environmental science. It overlaps with the closely related sciences of evolutionary biology, genetics, and ethology. An important focus for ecologists is to improve the understanding of how biodiversity affects ecological function. Ecologists seek to explain:

(i)Life processes, interactions, and adaptations

(ii)The movement of materials and energy through living communities

(iIi)The successional development of ecosystems

(iv)The abundance and distribution of organisms and biodiversity in the context of the environment.

 

The Ten Principles of Ecology

1. Evolution organizes ecological systems into hierarchies.

Individual organisms combine into populations, populations combine into species, species combine into higher taxa like genera and phyla. Each can be characterized by its abundance and diversity (number of kinds) in a given ecosystem or study plot. How and why abundance and diversity vary in time and space is the basic question of ecology.

2. The sun is the ultimate source of energy for most ecosystems.

Life runs on the carbon-rich sugars produced by photosynthesis; every ecosystem’s sugar output depends on how much solar energy and precipitation it receives.

3. Organisms are chemical machines that run on energy.

The laws of chemistry and physics limit the ways each organism makes a living and provide a basic framework for ecology. The supply of chemical elements and the sugars needed to fuel their assembly into organisms limit the abundance and diversity of life.

4. Chemical nutrients cycle repeatedly while energy flows through an ecosystem.

The atoms of elements like C, N, P, and Na go back and forth from spending time in living to spend time in dead parts of an ecosystem. But the photons of solar energy can be used only once before they are lost to the universe.

5. dN/dt=B-X+I

The rate that a population’s abundance in a given area increases or decreases reflects the balance of its births, deaths, and net migration into the area. Individuals with features that improve their ability to survive (i.e., not die) and make copies of themselves will tend to increase in that population.

6. dS/dt=D-X+I

The rate that the diversity of species in an area changes reflects the balance of the number of new forms that arise, those that go extinct, and those that migrate into the area. Individuals and species that have features allowing them to survive and reproduce in a local environment will tend to persist there.

7. Organisms interact—do things to each other—in ways that influence their abundance.

Individual organisms can eat one another, compete for shared resources, and help each other survive. Each pair of species in an ecosystem can be characterized by the kind and strength of these interactions, measured as their contribution to dN/dt.

8. Ecosystems are organized into webs of interactions.

The abundance of the population is influenced by the chains of interactions that connect it to the other species in its ecosystem. This often leads to complex behavior, and a key challenge in ecology is to determine what patterns of abundance and diversity can be predicted.

9. Human populations have an outsized role in competing with, preying upon, and helping other organisms.

Humans are one of the millions of species embedded in Earth’s ecosystems. The ability of humans to change the planet, abetted by our large population size and technological prowess increases our ability to shape the biosphere’s future. Humans, through principles 1-8, are currently changing the climate, re-arranging its chemistry, decreasing populations of food, moving around its species, and decreasing its diversity.

10. Ecosystems provide essential services to human populations.

These include products like timber, fiber, and food, regulating water and air quality, and cultural benefits like recreation. A key goal of ecology is to use principles 1-9 to preserve ecosystem services.

 

What is a Bio-Geo-chemical cycle?

Biological Chemical + Geological Process= Biogeochemical

       (“Bio” - living, “Geo” – earth - rock, “Chemical” - element).

 The cycling of the nutrients in the biosphere are called the biogeochemical or nutrient cycle.  It involves the movement of nutrient elements through the various components of an ecosystem.  There are more than 40 elements required for the various life processes by plants and animals; that it’s proper growth and development.  The most important elements are C, H, O, P, K, N, S, Ca, Fe, Mg, B, Zn, Cl, Mo, Co, I & Fe.  These elements are continuously cycling in the ecosystem through the biogeochemical cycles and the planet earth has no input of these nutrients.  The nutrients (matter) from the dead remains of organisms are recovered and made available to the producers by decomposers. The ways in which an element or compound moves between its several biotic and abiotic forms and locations in the biosphere is called a biogeochemical cycle. It is a movement of nutrients and other elements between living and non-living beings. Circulation of nutrients within the ecosystem or biosphere is known as biogeochemical cycles and is also called as ‘cycling of materials’.

 There are 3 basic types of Bio-Geo-chemical cycles

1. Hydrologic or Water cycle,  

2. Gaseous cycle (It includes atmospheric Oxygen, Carbon, and Nitrogen cycles)

and

3. Sedimentary cycle – It includes the cycles of Phosphorus, Sulphur, and Calcium - Which are present as sediments of earth.

The cycle starts by absorbing the chemical elements by the organism and is returned to the air, water, and soil through decomposition.

The description on water Cycles or Hydrological Cycles

The water cycle describes how water is exchanged (cycled) through Earth's land, ocean, and atmosphere. Water always exists in all three places, and in many forms—as lakes and rivers, glaciers and ice sheets, oceans and seas, underground aquifers, and vapor in the air and clouds.

          Water is not evenly distributed throughout the surface of the earth.  A major percentage of the total water on the earth is chemically bound to rocks and does not cycle.  Out of the remaining, nearly 97.3% are in the oceans and 2.1% exist as polar ice cubes.  Thus only 0.6% is present as fresh water in, the form of atmospheric water vapors, ground, and soil water.  The ice cubes and the water deep in the oceans form the reservoir.  Solar radiation and the earth’s gravitational pull are the main driving forces of the water cycle.  Evaporation, condensation, and precipitation are the main processes involved in the water cycle these processes alternate with each other.  Water from oceans, lakes, ponds, rivers, streams, and soil surface evaporates by the sun’s heat energy.  Plants also transpiration huge amounts of water through their leaves.  Water remains in the vapour state in the air and forms clouds, which float with the wind.  Clouds meet with the cold air in the mountainous regions above the forests and condense to form rain, which falls due to gravity.

States of Water

Through the water cycle, water continually circulates through three states: solid, liquid, and vapor.

Ice is solid water. Most of Earth's freshwater is ice, locked in massive glaciers, ice sheets, and ice caps.

As ice melts, it turns to liquid. The ocean, lakes, rivers, and underground aquifers all hold liquid water. 

Water vapor is an invisible gas. Water vapor is not evenly distributed across the atmosphere. Above the ocean, water vapor is much more abundant, making up as much as four percent of the air. Above isolated deserts, it can be less than one percent.

The water cycle consists of three major processes: evaporation, condensation, and precipitation.

(i)Evaporation

Evaporation is the process of a liquid's surface changing to a gas. In the water cycle, liquid water (in the ocean, lakes, or rivers) evaporates and becomes water vapor. Water vapor surrounds us, as an important part of the air we breathe. Water vapor is also an important greenhouse gas. Greenhouse gases such as water vapor and carbon dioxide insulate the Earth and keep the planet warm enough to maintain life as we know it. The water cycle's evaporation process is driven by the sun. As the sun interacts with liquid water on the surface of the ocean, the water becomes an invisible gas (water vapor). Evaporation is also influenced by wind, temperature, and the density of the body of water.

(ii) Condensation

Condensation is the process of a gas changing to a liquid. In the water cycle, water vapor in the atmosphere condenses and becomes liquid. Condensation can happen high in the atmosphere or at ground level. Clouds form as water vapor condenses, or becomes more concentrated (dense). Water vapor condenses around tiny particles called cloud condensation nuclei (CCN). CCN can be specks of dust, salt, or pollutants. Clouds at ground level are called fog or mist. Like evaporation, condensation is also influenced by the sun. As the water vapor cools, it reaches its saturation limit or dew point. Air pressure is also an important influence on the dew point of an area.

(iii) Precipitation

Unlike evaporation and condensation, precipitation is not a process. Precipitation describes any liquid or solid water that falls to Earth as a result of condensation in the atmosphere. Precipitation includes rain, snow, and hail. Fog is not precipitation. The water in fog does not condense sufficiently to precipitate, or liquefy and fall to Earth. Fog and mist are a part of the water cycle called suspensions: They are liquid water suspended in the atmosphere. Precipitation is one of many ways water is cycled from the atmosphere to the Earth or ocean.

(iv)  Other Processes

Evaporation, condensation, and precipitation are important parts of the water cycle. However, they are not the only ones.

(a)Runoff, for instance, describes a variety of ways liquid water moves across land. Snowmelt, for example, is an important type of runoff produced as snow or glaciers melt and form streams or pools.

(b)Transpiration is another important part of the water cycle. Transpiration is the process of water vapor being released from plants and soil. Plants release water vapor through microscopic pores called stomata. The opening of stomata is strongly influenced by light, and so is often associated with the sun and the process of evaporation. 

(c)Evapotranspiration is the combined components of evaporation and transpiration, and is sometimes used to evaluate the movement of water in the atmosphere.

 

Nitrogen cycles explanation:

Nitrogen Cycle is a biogeochemical process through which nitrogen is converted into many forms, consecutively passing from the atmosphere to the soil to organism and back into the atmosphere.It involves several processes such as nitrogen fixation, nitrification, denitrification, decay and putrefaction.

·       The nitrogen gas exists in both organic and inorganic forms. Organic nitrogen exists in living organisms, and they get passed through the food chain by the consumption of other living organisms.

·       Inorganic forms of nitrogen are found in abundance in the atmosphere. This nitrogen is made available to plants by symbiotic bacteria which can convert the inert nitrogen into a usable form – such as nitrites and nitrates

·       Nitrogen undergoes various types of transformation to maintain a balance in the ecosystem. Furthermore, this process extends to various biomes, with the marine nitrogen cycle being one of the most complicated biogeochemical cycles.

·       Human activities such as fossil fuel burning, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle

            The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. The majority of Earth's atmosphere (78%) is atmosphere nitrogen, making it the largest source of nitrogen. Botany –However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems.The process in the nitrogen cycle is to transform nitrogen from one form to another. Many of those processes are carried out by microbes, either in their effort to harvest energy or to accumulate nitrogen in a form needed for their growth. For example, the nitrogenous wastes in animal urine are broken down by nitrifying bacteria in the soil to be used by plants.

Stages of Nitrogen Cycle

Process of Nitrogen Cycle consists of the following steps – Nitrogen fixation, Nitrification, Assimilation, Ammonification, and Denitrification. These processes take place in several stages and are explained below:

(i)Nitrogen fixation

It is the initial step of the nitrogen cycle. Here, Atmospheric nitrogen (N2)which is primarily available in an inert form, is converted into the usable form -ammonia (NH3).

Types of Nitrogen Fixation

1. Atmospheric fixation: A natural phenomenon where the energy of lightning breaks the nitrogen into nitrogen oxides and is then used plants.
2. Industrial nitrogen fixation: Is a man-made alternative that aids in nitrogen fixation by the use of ammonia. Ammonia is produced by the direct combination of nitrogen and hydrogen, and later, it is converted into various fertilisers such as urea.
3. Biological nitrogen fixation: We already know that nitrogen is not usable directly from the air for plants and animals. Bacteria like Rhizobium and blue-green algae transform the unusable form of nitrogen into other compounds that are more readily usable. These nitrogen compounds get fixed in the soil by these microbes.

(ii) Nitrification

In this process, the ammonia is converted into nitrate by the presence of bacteria in the soil. Nitrites are formed by the oxidation of Ammonia with the help of Nitrosomonas bacterium species. Later, the produced nitrites are converted into nitrates by Nitrobacter. This conversion is very important as ammonia gas is toxic for plants.

 

(iii)Assimilation

Primary producers – plants take in the nitrogen compounds from the soil with the help of their roots, which are available in the form of ammonia, nitrite ions, nitrate ions or ammonium ions and are used in the formation of the plant and animal proteins. This way, it enters the food web when the primary consumers eat the plants.

(iv)Ammonification

When plants or animal die, the nitrogen present in the organic matter is released back into the soil. The decomposers, namely bacteria or fungi present in the soil, convert the organic matter back into ammonium. This process of decomposition produces ammonia which is further used for other biological processes.

(v) Denitrification

Denitrification is the process in which the nitrogen compounds makes its way back into the atmosphere by converting nitrate (NO₃-)  into gaseous nitrogen (N). This process of the nitrogen cycle is the final stage and occurs in the absence of oxygen. Denitrification is carried out by the denitrifying bacterial species- Clostridium and Pseudomonas, which will process nitrate to gain oxygen and gives out free nitrogen gas as a byproduct.

 

(vi)           Sedimentation: Nitrates of the soil are washed down to the sea or leached deep into the earth along with percolating water. Nitrates thus lost from the soil surface are locked up in the rocks, this is sedimentation of nitrogen. Nitrogen of rock is released only when the rocks are exposed and weathered.

 

 

Importance of Nitrogen Cycle

Importances of the nitrogen cycle are as follows:

1. Helps plants to synthesise chlorophyll from the nitrogen compounds.
2. Helps in converting inert nitrogen gas into a usable form for the plants through the biochemical process.
3. In the process of ammonification, the bacteria help in decomposing the animal and plant matter, which indirectly helps to clean up the environment.
4. Nitrates and nitrites are released into the soil, which helps in enriching the soil with necessary nutrients required for cultivation.
5. Nitrogen is an integral component of the cell, and it forms many crucial compounds and important biomolecules.

 

Carbon Cycle

 

Carbon cycle is the process where carbon compounds are interchanged among the biosphere, geosphere, pedosphere, hydrosphere, and atmosphere of the earth.

Carbon Cycle Steps

Following are the major steps involved in the process of the carbon cycle:

1. Carbon present in the atmosphere is absorbed by plants for photosynthesis.
2. These plants are then consumed by animals, and carbon gets bioaccumulated into their bodies.
3. These animals and plants eventually die, and upon decomposing, carbon is released back into the atmosphere.
4. Some of the carbon that is not released back into the atmosphere eventually become fossil fuels.
5. These fossil fuels are then used for man-made activities, which pumps more carbon back into the atmosphere.

The circulation of carbon between organisms and environment is known as the carbon cycle.  Carbon is an inevitable part of all biomolecules and is substantially impacted by the change in global climate.  Cycling of carbon between organisms and atmosphere is a consequence of two mutual processes of photosynthesis and respiration.  The releasing of carbon in the atmosphere increases due to burning of fossil fuels, deforestation, forest fire, volcanic eruption and decomposition of dead organic matters.  Atmospheric carbon dioxide is the source of all carbon in both living organisms as well as in the fossils (used as fossil fuel).  It is highly soluble in water. Oceans also contain large quantities of dissolved carbon dioxide and bicarbonates.  The carbon cycle (Fig) comprises the following processes: 

(a)Photosynthesis  Terrestrial and aquatic plants utilize CO2 for photosynthesis. Through this process the inorganic form of carbon is converted into organic matter in the presence of sunlight and chlorophyll.  The carbon dioxide is thus fixed and assimilated by plants. It is partly used by them for their own life processes and the rest is stored as their biomass which is available to the heterotrophs as food.    (b)Respiration is a metabolic process reverse of photosynthesis in which food is oxidized to liberate energy (to perform the various life processes) and carbon dioxide and water.  Thus the carbon dioxide of the atmosphere is recovered through this process.

©  Decomposition  After the death of the organisms the decomposers break down the remaining dead organic matter and release the left over carbon back into the atmosphere.

(d)  Combustion (burning)  Fossil fuel such as crude oil, coal, natural gas or heavy oils on burning releases carbon dioxide and carbon monoxide into the atmosphere.  Forests make a large amount of fossil fuel. Fossil fuel is product of complete or partial decomposition of plants and animals as a result of exposure to heat and pressure in the earth’s crust over millions of years.  Forests also act like carbon reservoirs as carbon fixed by them cycles very slowly due to their long life.  They release CO2 by forest fires.

 

 

Importance of Carbon Cycle

Even though carbon dioxide is found in small traces in the atmosphere, it plays a vital role in balancing the energy and traps the long-wave radiations from the sun. Therefore, it acts like a blanket over the planet. If the carbon cycle is disturbed it will result in serious consequences such as climatic changes and global warming.

        Carbon is an integral component of every life form on earth. From proteins and lipids to even our DNA. Furthermore, all known life on earth is based on carbon. Hence, the carbon cycle, along with the nitrogen cycle and oxygen cycle, plays a vital role in the existence of life on earth.

 

Sedimentary cycle explanation

Sedimentary cycles are the ones in which the reservoir is the Earth's crust. Sedimentary cycles include those of phosphorus, sulphur, iron, calcium, and other more-earthbound elements. Sedimentary cycle the sedimentary cycle is the small part of whole crustal cycle of dynamic earth ,in this cycle the sediments of the sedimentary rocks are recycle several time before destory. in sedimentary cycle the sedimentary cycle is consist of following various stages.

1. Weathering

2. Transportation

 3. Deposition

4. Erosion

 

 Mineral elements required by living organisms are obtained initially from inorganic sources.   Available forms occur as salts dissolved in soil water.   Mineral cycles essentially consist of two phases : (i) the salt solution phase, and (ii) rock phase.   Mineral salts come directly from earth crust by weathering.   Soluble salts then enter the water cycle.  By movement of water minerals move from the soil to streams, lakes and ultimately to sea where they remain permanently. 

 Other salts return to the earth's crust (outside) through sedimentation.   They become incorporated into sediments or rock beds and after weathering of rocks they again enter the cycle.   Plants and some animals take minerals in the form of mineral solution from their habitats.   After the death of living organisms the nutrients return to the soil and water through the action of decomposers (bacteria and fungi) and transformers.  Green plants at one end and decomposers at the other play very important role in circulation of nutrients. 

 

Phosphorous cycle

 

“Phosphorus cycle is a biogeochemical process that involves the movement of phosphorus through the lithosphere, hydrosphere and biosphere.”

What is Phosphorus Cycle?

Phosphorus is an important element for all living organisms. It forms a significant part of the structural framework of DNA and RNA. They are also an important component of ATP. Humans contain 80% of phosphorus in teeth and bones.

Phosphorus cycle is a very slow process. Various weather processes help to wash the phosphorus present in the rocks into the soil. Phosphorus is absorbed by the organic matter in the soil which is used for various biological processes.

Since phosphorus and phosphorus-containing compounds are present only on land, atmosphere plays no significant role in the phosphorus cycle.

Let us have a brief look at the phosphorus cycle, its steps and the human impact on phosphorus cycle.

Steps of Phosphorus Cycle

Following are the important steps of phosphorus cycle:

1. Weathering
2. Absorption by Plants
3. Absorption by Animals
4. Return to the Environment through Decomposition

Weathering

Phosphorus is found in the rocks in abundance. That is why the phosphorus cycle starts in the earth’s crust. The phosphate salts are broken down from the rocks. These salts are washed away into the ground where they mix in the soil.

Absorption by Plants

The phosphate salts dissolved in water are absorbed by the plants. However, the amount of phosphorus present in the soil is very less. That is why the farmers apply phosphate fertilizers on agricultural land.

The aquatic plants absorb inorganic phosphorus from lower layers of water bodies. Since phosphate salts do not dissolve in water properly, they affect plant growth in aquatic ecosystems.

Absorption by Animals

The animals absorb phosphorus from the plants or by consuming plant-eating animals. The rate of the phosphorus cycle is faster in plants and animals when compared to rocks.

Return of Phosphorus Back to the Ecosystem

When the plants and animals die they are decomposed by microorganisms During this process, the organic form of phosphorus is converted into the inorganic form, which is recycled to soil and water.

Soil and water will end up in sediments and rocks, which will again release phosphorus by weathering. Thus, the phosphorus cycle starts over.

 

Human Impact on Phosphorus Cycle

A number of human activities, use of fertilizers, artificial eutrophication, etc. has a great impact on the phosphorus cycle.

The phosphorus fertilizers increase the level of phosphorus in the soil. Overuse of these fertilizers reduces the fertility of the soil and is also harmful to the microorganisms present in the soil. When these are washed away into the nearby water bodies, they are hazardous to aquatic life.

During the shipping of food from farms to cities, the amount of phosphorus that is washed away in water causes eutrophication. This leads to the growth of algae. These form algal blooms or die, which is toxic to the aquatic ecosystem.

 

Sulphur Cycle

Sulphur is one of the most abundant elements on the earth. It is a yellow, brittle, tasteless, odourless non-metal. Sulphur is present in all kinds of proteins. Plants directly absorb sulphur-containing amino acids such as methionine, cystine, and cysteine.

Sulphur is released into the atmosphere by the burning of fossil fuels, volcanic activities, and decomposition of organic molecules.

On land, sulphur is stored in underground rocks and minerals. It is released by precipitation, weathering of rocks and geothermal vents.

The process of sulphur cycle is explained below:

• The sulphur is released by the weathering of rocks.
• Sulphur comes in contact with air and is converted into sulphates.
• Sulphates are taken up by plants and microbes and are converted into organic forms.
• The organic form of sulphur is then consumed by the animals through their food and thus sulphur moves in the food chain.
• When the animals die some of the sulphur is released by decomposition while some enter the tissues of microbes.
• There are several natural sources such as volcanic eruptions, evaporation of water, and breakdown of organic matter in swamps, that release sulphur directly into the atmosphere. This sulphur falls on earth with rainfall.

Steps of Sulphur Cycle

Following are the important steps of the sulphur cycle:

Decomposition of Organic Compounds

Protein degradation releases amino acids that contain sulphur. Sulphates are reduced to H₂S by the action of Desulfotomaculum bacteria.

Oxidation of Hydrogen Sulphide to Elemental Sulphur

Hydrogen sulphide oxidises to produce elemental sulphur. Certain photosynthetic bacteria from the families Chlorobiaceae and Chromatiaceae initiate the oxidation process.

Oxidation of Elemental Sulphur

Elemental sulphur present in the soil cannot be utilized directly by the plants. Therefore, it is converted into sulphates by chemolithotrophic bacteria.

Reduction of Sulphates

Sulphates are reduced to hydrogen sulphide by Desulfovibrio desulfuricans. This occurs in two steps:

• Firstly, the sulphates are converted to sulphites utilizing ATP.
• Secondly, the reduction of sulphite to hydrogen sulphide.

 

What is an Ecosystem?

An ecosystem is a system or a functional unit in the environment where biotic and abiotic components interact with each other. Abiotic components include water, soil, atmosphere, temperature etc. Living entities have an internal hierarchy within an ecosystem which are the producers, the consumers and the decomposers. They interact with each other giving rise to the food chain within an ecosystem.

Linking within these food webs forms the basis for complex webs and contribute to the existence of an ecosystem.All the essential material required for survival comes from the abiotic components of the ecosystem such as radiation, energy, water etc which are obtained as a result of various biological cycles.

Energy moves in a unidirectional path.

 

What is a Biome?

Biomes, on the other hand, is a zone on the earth, which is identified by a large scale climate and vegetation characteristics.They are climatically controlled association of entities. They are usually identified and named after the life form, for instance, grassland, coral reef, tropical rain forests etc.Species in different parts of a biome may appear similar in behaviour and appearance due to the similarity in the patterns of natural selection.

Examples of biomes – Tundra, temperate evergreens, taiga etc.

Difference Between Biome And Ecosystem:

Biome	Ecosystem
It is a large land area with a distinct climate and plants and animal species.	It refers to the interaction of biotic and abiotic components.
The geographical area is large.	The geographical area is small.
It depends upon the climatic factors such as rainfall, ice, snow, temperature, etc.	It does not depend upon the climatic factors.
It comprises multiple ecosystems.	It is a part of biome comprising biotic and abiotic factors.
It abounds in plant and animal species.	It is smaller in size and has fewer species of plants and animals.
All the organisms in a biome do not interact with each other.	All the organisms in an ecosystem interact with each other in trophic levels and food web.
It is affected by the latitude.	It is not influenced by the latitude.
Desert, grasslands, tundra, and tropical rainforests are some examples of biomes.	An ecosystem includes ponds, coral reefs, etc.

Key Points

• An ecosystem is smaller when compared to a biome as a biome can be distributed throughout the earth.

·        Unlike an ecosystem, a biome is strongly influenced by its physical factors such as climatic conditions such as snow, temperature, rainfall etc.

·        An ecosystem is not influenced by the latitude whereas a biome is influenced.

·        In an ecosystem, all animals interact in trophic interactions of food webs and chains whereas, in a biome, animals do not necessarily interact.

 

Question: Explain concepts of biome. Classify different types of biomes and illustrate them

Concept of  Biome

Biome may be defined as a large natural eco-system wherein we study the total assemblage of plant and animal communities. A biome is a place on earth that has the same climate, plant life and animal life over a vast area of land. Every place on earth is part of one biome or another.

A biome can be defined as a large biological community or an ecosystem where different types of living organisms including plants, animals, birds, insects, and humans are used to living in a certain type of climate. The word “Biome” was suggested by an ecologist Frederic Edward Clements in the year 1916 which referred to the word biotic community.

 

Factors Affecting Biomes

There are various factors which affects the size, location, and character of a biome. Important factors are as follow:

(i)              Length of day light and darkness. This is mainly responsible for duration of photosynthesis. (

(ii)            ii) Mean temperature as well as difference in temperature. Differences (both diurnal and annual) to find out extreme conditions.

(iii)           Length of growing season.

(iv)          Precipitation which includes total amount, variations over time and intensity.

(v)             Wind flow that includes speed, direction, duration and frequency. (vi) Soil types (vii) Slope (viii) Drainage (ix) Other plant and animal species

Types of Biomes

There are various types of biomes, the exact number of biomes in this world is still not known and keep on varying. The biomes include- desserts, different types of forest, polar regions,  national parks, bird sanctuaries, zoos, aquatic life and a lot more. Based on the certain similarities and to make the classification simpler, the biomes are main groups according to the predominant vegetation and characterized by adaptations of organisms. There are five major biomes in the world: aquatic, desert, forest, grasslands and tundra. These biomes are often broken down into numerous categories and sub-categories as well.

 

The two different types of biomes are:

(1)Terrestrial biomes or land Biomes

(II) Aquatic biomes

 

(i)Terrestrial biomes- explanation

 

The terrestrial or the land biomes are categorized and termed according to the climatic conditions and the climax vegetation of the region in which they are found. The climax vegetation also called the biological community of plants, animals, birds and other living species that is stable and dominant after the numerous years of evolutionary development.

However, according to this classification, there are four major types of biomes: (i) Forest biome (ii) Savanna biome Biomes The domain of Life on the Earth (iii) Grossland biome (iv) Desert biome

 

 

(ii)Aquatic biomes or water biomes

         Water is the most important and essential element among the biological community. The total earth’s surface is covered by water which is nearly 70 to 80 per cent. Therefore, aquatic biomes are the largest and widest biome in the world. There are numerous species of aquatic plants and animals, both large and small. This water biome mainly comprises aquatic plants and animals. The aquatic biome provides a vast array of habitats, which support a staggering diversity of species.

. There are two major types of aquatic biomes in the world:

• Marine biomes represents seas, oceans, estuary containg salts
• Freshwater biomes consists of rivers, streams, ponds, lakes and swamps

 

Explain forest biomes of the world

The forest biome occupies about one third of the Earth's surface and there are three different types of forests found around the world: tropical forests, temperate forests and boreal forests.

(i)Tropical Forests

Tropical forests are found near the equator, have super hot temperatures all year long and get up to 80 inches (2000 mm) of rain a year. Tropical rainforests are home to jaguars, toucans, gorillas and even tarantulas. Soem people even say that Kidzworld founder Allen Achilles lived in a biome in a previous life. Here you can also find an antelope called the royal antelope that is only as big as a rabbit.

(ii)Temperate Forests

Temperate forests are found in the Eastern United States, Canada, Europe, China and Japan. Temperate forests, which are also known as deciduous forests, have four distinct seasons, which means all the tree leaves fall off in the winter months. Tons of animals live in temperate forests like beavers, black and brown bears, deer, foxes, raccoons, skunks, rabbits and various bird species.

 

 

(iii) Boreal Forests (Taiga)

Boreal forests often get less rain than the other forests and are home to evergreen trees, which stay green all year long. This is because they have needles, which don't need as much water as regular tree leaves. Boreal forests are only in the Northern Hemisphere and can be found in every Canadian province.

 

 

Grasslands Biome

Grasslands are wide expanses of land filled with low growing plants such as grasses and wildflowers. The amount of rain is not enough to grow tall trees and produce a forest, but it is enough to not form a desert. The temperate grasslands have seasons including a hot summer and a cold winter. Grassland, area in which the vegetation is dominated by a nearly continuous cover of grasses. Grasslands occur in environments conducive to the growth of this plant cover but not to that of taller plants, particularly trees and shrubs. The factors preventing establishment of such taller, woody vegetation are varied.

 

Location of grassland : Grasslands are generally located between deserts and forests. The major temperate grasslands are located in central North America in the United States, in Southeast South America in Uruguay and Argentina, and in Asia along the southern portion of Russia and Mongolia.

 

The grasslands biome can be divided up into the temperate grasslands and tropical grasslands.

Types of Temperate Grasslands

Each major area of grasslands in the world has its own characteristics and is often called by other names:

• Prairie - Grasslands in North America are called the prairies. They cover around 1.4 million square miles of the central United States including some of Canada and Mexico.
• Steppes - The steppes are grasslands that cover southern Russia all the way to the Ukraine and Mongolia. The steppes stretch over 4,000 miles of Asia including much of the fabled Silk Road from China to Europe.
• Pampas - The grasslands in South America are often called the pampas. They cover around 300,000 square miles between the Andes Mountains and the Atlantic Ocean.

Types of Tropical grasslands

Tropical grassland biome, also called savanna biome, is a terrestrial biome that features vast open spaces consisting of scattered small shrubs and trees. Savanna biomes support some of the world’s most recognizable species such as lions, cheetahs, hyenas, zebras, gazelles, elephants, giraffes, wildebeests and warthogs.

Location

Savanna biomes cover up to half of Africa, huge areas of Australia, South America, as well as India. In Africa, savanna biomes are predominant in East Africa, typically acacia savannas. Many are found in popular game reserves of Kenya, Tanzania, South Africa, Botswana, Zimbabwe, and Namibia. The Serengeti savanna biome in Tanzania and Masai Mara savanna biome in Kenya are the most popular savanna biomes in Africa.

 

Desert Biomes

A desert biome is a collection of habitats that that develop in arid (dry) environments as a result of little rainfall (50cms per year) or no rainfall at all. Desert biomes are classified into four, with each having their own unique features, but have great similarity regarding living and nonliving composition. They include hot and dry deserts, semi-arid deserts, coastal deserts and cold deserts. In the midst of these 4 desserts exists numerous deserts in many areas across the globe.

Characteristics and features of desert Biomes

              They cover about 20% of the Earth and occur where rainfall is less than 50 cm/year. There are mainly four types of deserts in this biome – hot and dry, semiarid, coastal, and cold. These ecosystems are identified by the fact that they don’t get a lot of precipitation during the year. Only those plants and animals that are able to adapt to the climate and temperature of desert can survive there. About 1/5^th of the world is covered in deserts. The only continent that does not have a desert in Europe.

Hot and cold desert:

Deserts that receive rain as their main form of precipitation are called hot deserts while those which receive snow as their main form of precipitation are called cold deserts. Here are some quick and interesting facts about desert biomes.

                The largest hot and dry desert in the world is the Sahara Desert in Northern Africa. The Sahara is a sandy desert with giant sand dunes. It covers over 3 million square miles of Africa. Other major deserts include the Arabian Desert in the Middle East the Kalahari Desert in Africa. The cold desert includes the Gobi Desert in Northern China and Mongolia,