The basic unit of ecological hierarchy is individual because a community starts building from an individual which grows onto form an entire ecosystem. 

The biosphere is made up of the parts of Earth where life exists, but there is uneven distribution of living organisms in the biosphere. The biosphere extends from the deepest root systems of trees, to the dark environment of ocean trenches, to lush rain forests and high mountains.
Scientists describe the Earth in terms of spheres - Lithosphere, Atmosphere, Hydrosphere. Since life exists on the ground, in the air, and in the water, biosphere overlaps all these spheres. Biosphere has existed for about 3.5 billion years.

A.An organism is an individual living thing. It can be as simple as a single-celled Amoeba or it can be as complex as a human being.
B.A tissue is a collection of structurally similar cells acting together to perform a specific function.
C.An organelle is a small constituent of a cell that has a specific function. For example, mitochondria (called as powerhouse of the cell) aids in generating energy for cell functions.
D.An organ is a group of tissues that performs a specific function. For example, stomach and kidney are organs. 

The biosphere is a global ecosystem composed of living organisms (biotic) and the nonliving (abiotic) factors from which they derive energy and nutrients. It is a relatively thin life-supporting stratum of Earth's surface, extending from a few kilometres into the atmosphere to the deep-sea vents of the ocean. 

All the biotic and the abiotic components together form biosphere or ecosystem. A biosphere is composed of all living organisms and nonliving things. The population is the number of individuals in a given area. Biome includes all flora and fauna. A trophic level is defined as the position of an individual in the food chain. So, the correct answer is option C.

The biosphere is the biological component of earth systems, which also include the lithosphere, hydrosphere, atmosphere, etc. The biosphere includes all living organisms on earth, together with the dead organic matter produced by them. 

The term biocoenosis means ecological community. It was coined by Carl Mobius. It describes an association of populations of different species living together in a defined habitat with some degree of interdependence and community ecology is the description and analysis of patterns and processes within the community.

The different populations of the same organism present in particular geographical areas are called as local populations or demes. A local population adapted genetically to its particular environment is called as ecotype. There may be several ecotypes of the same organism, which show variations amongst them.

Biological or biotic community is an assemblage of populations of different species of bacteria, fungi, plants and animals, which live in a particular area and interact with one another through competition, predation, mutualism etc. Each biotic community has a specific composition and structure. 

Synecology is the ecological study of  interactions between species in communities.

Biological or biotic community is an assemblage of populations of different species of plants, animals, bacteria and fungi which live in a particular area and interact with one another through competition, predation, mutualism etc. Each biotic community has a specific composition and structure e.g., pond community.

Keystone species is a species, which has a significant and disproportionately large influence on the community structure and characteristics. It has often considerable low abundance and biomass as compared to dominant species. Removal or decrease in number of keystone species causes serious disruptions in structure and function of community.

Biosphere  is biologically inhabited part of Earth, along with its physical environment consisting of lower atmosphere, land and water bodies in other words-atmosphere, lithosphere and hydrosphere.

Biosphere  is biologically inhabited part of Earth along with its physical environment consisting of lower atmosphere, land and water bodies (in other words-atmosphere, lithosphere and hydrosphere).

In an aquatic ecosystem, fishes can consume phytoplanktons and other producers. In such a system, fishes will be primary carnivores or primary consumers or herbivores as compared to the grazing food chain. Some bigger fishes can consume smaller fishes. In this case, bigger fishes will act as secondary consumers or secondary carnivores feeding on primary carnivores. Thus, fishes can occupy more than one trophic levels. Phytoplanktons will always be producers and zooplanktons will always be primary consumers. The frog will always act as secondary consumer feeding on primary consumers i.e., insects. Thus, the correct answer is option B.

Biosphere is biologically inhabited part of earth along with its physical environment consisting of lower atmosphere, land and water bodies.
Biome is a large regional unit delimited by a specific climatic zone, having a particular major vegetation zone and its associated fauna eg tundra desert, ocean etc. 
Ecotone is the transition zone between two communities, e.g., forest and grassland.
Biota is a general term, which refers to living organisms.

Man made or artificial ecosystems have low stability. Because usually man is interested in only a few economically beneficial species only and only those species will be used by man to create an ecosystem e.g., agriculture field is a man made artificial ecosystem having only those plants which are economically beneficial. Thus, the correct answer is option A.

Biome is a large regional unit delimited by a specific climatic zone, having a particular major vegetation zone and its associated fauna. For example, tundra desert, temperate deciduous forests etc. 

Ecosystem is a segment of nature or biosphere consisting of a community of living beings and the abiotic or physical environment both interacting and exchanging materials between them.

The ecosystem is a segment of biosphere consisting of a community of living beings and the abiotic or physical environment, both interacting and exchanging materials between them. The word ecosystem was first coined by Tansley in 1935 and previously the term 'biocoenosis' was used.

The highest level of ecological hierarchy is biosphere because it consists of the surface and atmosphere of earth or another planet.  It cannot be ecosystem because that consists of only biological communites, similarly, it cannot be biomes because a biome consists of many ecosystems but is a part of the biosphere, it cannot be a landscape because it is a land that does not have a fixed natural boundary. 

A large naturally occurring community of flora and fauna occupying a major habitat is known as biome e.g. forest or tundra

• Man and the Biosphere Programme (MAB) is an intergovernmental scientific programme.
  
• It was initiated in 1971 by UNESCO. 
  
• It aims at establishing a scientific basis for the improvement of relationships between people and their surrounding environments.
  
• So, the correct option is 'Man and Biosphere programme'.

The living world consists of many ecosystems. There are 2 main factors present in an ecosystem, namely abiotic (nonliving) and biotic (living). All of these factors interact with each other. The living world is divided into a different sphere, namely:

• A biome is a community of plants and animals that have common characteristics for the environment they exist in. 
• They can be found over a range of continents. 
• Biomes are distinct biological communities that have formed in response to a shared physical climate. 
• For example, an aquatic biome can contain ecosystems such as coral reefs and kelp forests and The great barrier reed along the cast coast of Australia.
• Hence, The great barrier reed along the cast coast of Australia can be categorized as Biome. 
• So, the correct answer is 'Biome'.

There are 4 levels of hierarchy in an ecosystem, the organism level, population level, community level or ecosystem level and the biosphere level. Among them the biosphere level is the highest level and represents the totality of all things on Earth, including their interactions. The biosphere includes all ecosystems on Earth and how they interact together. So, the correct option is 'biome'.

'The Great Barrier Reef' is considered as a biome. Since biomes are climatically and geographically defined as contiguous areas with similar climatic conditions on the Earth, such as communities of plants, animals, and soil organisms, and are often referred to as ecosystems. 'The Great Barrier Reef' is the world's largest coral reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,300 kilometres over an area of approximately 344,400 square kilometres.

In ecology, a community or biocoenosis is an assemblage or associations of populations of two or more different species occupying the same geographical area and in a particular time. The term community has a variety of uses. In its simplest form it refers to groups of organisms in a specific place or time. 

The term ecosystem was first coined by Roy Clapham in 1930, but it was ecologist Arthur Tansley, who fully defined the ecosystem concept.

The biological spectrum is made up of all living organisms divided into three domains, coexisting across various levels of biological organization.

The biosphere is the part of the Earth and its atmosphere in which living organisms exist or that is capable of supporting life. The biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, geosphere, hydrosphere, and atmosphere.

The biosphere is composed of all living organisms. Plants, animals, and one-celled organisms are all part of the biosphere. The biosphere includes all the areas inhabited by living things, like the hydrosphere, which includes all the water; the atmosphere, which includes all the air; and the lithosphere, which includes all the land.

The term ecosystem was first coined by Roy Clapham in 1930, but it was ecologist Arthur Tansley who fully defined the ecosystem concept.

Human species more powerful than others in his ability to manipulate the environment. Man has created new artificial ecosystems - cities, where soil has been covered with concrete and steel. Man also changes weather year round to suit his needs. All this has finally changed the biosphere into a human-dominant environment, called as noosphere. This self-sufficient biosphere is being used by man as a means of resources for himself unmindful of the needs of other organisms.

The term ecosystem was first coined by Roy Clapham in 1930, but it was ecologist Arthur Tansley, who fully defined the ecosystem concept.

British botanist A.G. Tansley first introduced the term ecosystem to describe a group of living organisms and its effective environment. Tansley's definition in 1935 referred to the whole system, including not only the organism complex, but also the whole complex of physical factors forming the environment of the biome. 

The biosphere is the global ecological system, integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, geosphere, hydrosphere, and atmosphere.

• It is mostly the climate (temperature and precipitation) in an area, that determines its biome. This is because climate limits the species of plants, that can grow in an area. In turn, the species of plants determine the kinds of animals, that live there. 
• A biome's boundaries are determined by climate more than any other factor. E.g., tundra is colder and has a shorter growing season than other biomes, it has fewer kinds of vegetation. 
• Towards the equator, precipitation becomes increasingly important, producing temperate communities of desert, grassland, and forest in increasing order of precipitation. 
• In the tropical and subtropical biomes, which occur in the equatorial latitudes, there is a relatively smaller range of temperatures during the year, and their variation is also determined by the amount of precipitation. 
• Another important factor is the altitude. Changes in vegetation occur with increasing altitude. 
• Soil is an important factor as it will determine the type of vegetation and biodiversity of that area. 

The biosphere is composed of all living organisms. Plants, animals, and one-celled organisms are all part of the biosphere. The biosphere includes all the areas inhabited by living things, like the hydrosphere, which includes all the water; the atmosphere, which includes all the air; and the lithosphere, which includes all the land.

In ecology, a community or biocoenosis is an assemblage or association of independent and interacting populations of two or more different species occupying the same geographical area and in a particular time. 

The tropical rainforest is a biome located around the equator. It has the highest biodiversity of all the earth's ecosystems, both in flora and fauna as well as microbes. This high diversity is due to the optimal growing conditions at equatorial locations. Abundant rainfall and warm temperatures, as well as intense sunlight. 

The ecosystem is a segment of biosphere consisting of a community of living beings and the abiotic or physical environment, both interacting and exchanging materials between them. The word ecosystem was first coined by Tansley in 1935.

Under natural conditions, all living organisms in an ecosystem are interacting, co-habitating and interdependent. This enables the self-sustenance in an ecosystem. A change in any of these results in collapse of the ecosystem. Thus the correct answer is option D.

Some communities such as tropical oceanic islands appear to be particularly vulnerable to invasions. The vacant niche hypothesis suggests that island communities and some others are relatively impoverished in numbers of native species and thus cannot provide biological resistance to newcomers. Hence, they are most vulnerable.

Ecotone is the transition zone between two communities, e.g., forest and grassland. Ecotone has an admixture of species belonging to both the communities. Some specific species also occur exclusively in ecotone. As a result, ecotone possesses higher number of species than either of the two communities. The increased number and even density of species in a region of ecotone or community border is called Edge effect. The species which are found primarily, most abundantly or spend most of their time in ecotone or community boundary are known as Edge species.

An ecotype is a population (or subspecies or race) that is adapted to local environmental conditions. The implication is that those individuals which were best adapted to the prevailing conditions left the most offspring. Moreover, those more successful individuals carry genes that are partly responsible for their success in that environment. Thus, the adaptations of these ecotypes are based on the interactions of their own special sets of genes with their own environment.

Agroecosystem is also called as ecosystem on agricultural land. It is created by man. It includes biotic and nonbiotic components involved in that unit and their interactions.  It is unstable because of lack of variety and lack of biological control. It also lacks self-control.

An ecotype is known as the population of a species that survives as a distinct group through environmental selection and isolation and that is comparable with certain species.

An open system is defined as a system wherein there is free exchange of both matter and energy with the surroundings. The system has interaction with the external environment. A close system is defined as a system where there is no exchange of either matter or energy with the surroundings. All the ecosystems on Earth are called as open systems. Earth is an open system for energy. 

The living world is made up of different communities living in it. Some of these communities are the communities living in oceans, fresh water and forest communities, communities living in grasslands and deserts. These communities have different individuals belonging to them and have certain different characteristics. So, option D is the correct answer.

An incomplete ecosystem is cave. Its habitat is not suitable for primary productivity. It lacks sunlight and primary plant productivity. The animals and plants are present only at the entrance of cave as limited sunlight reaches at the entrance.

An ecosystem consists of biotic and abiotic components. Biotic components or living things include animals, plants, microorganisms. Abiotic components or nonliving things include air, soil, temperature. It is of two types, natural ecosystem and artificial or man made ecosystem. Examples of natural ecosystem include forest, aquatic ecosystem. Examples of man made ecosystem includes aquarium, zoo, botanical garden. In man made ecosystem, the plants and animals grow or survive outside their natural habitat in an artificial environment.

• A biome is a group of ecosystems with similar climates and organisms.
• There are five major biomes in the world. They are the forest, desert, grassland, aquatic and altitudinal biomes.
  
• Hence Combined ecosystem forms Biomes.
• So, the correct answer is 'Biomes'.

Gene flow is the passing over of genes from one population to another population. There are a various factors that affect the gene flow. The largest unit of population in which gene flow is readily possible is biological species. In species, successful interbreeding is possible which results in the successful reproduction and hence the gene flow. 

A biome  is a community of plants and animals that have common characteristics for the environment they exist in. They can be found over a range of continents. Biomes are distinct biological communities that have formed in response to a shared physical climate. "Biome" is a broader term than "habitat"; any biome can comprise a variety of habitats. hile a biome can cover large areas, a microbiome is a mix of organisms that coexist in a defined space on a much smaller scale. For example, the human microbiome is the collection of bacteria, viruses, and other microorganisms that are present on or in a human body. A 'biota' is the total collection of organisms of a geographic region or a time period, from local geographic scales and instantaneous temporal scales all the way up to whole-planet and whole-time scale spatiotemporal scales. The biotas of the Earth make up the biosphere.

An organism (or an individual ) is a living unit of nature and is the most basic unit of ecological hierarchy. 

Rainfall usually happens in tropical grasslands between late spring and early summer. Average rainfall a year in grasslands is 50 to 90 cm or 20-35 in. 

In competition both partners are adversely affected as they compete for the same resources, in predation one partner is harmed other is benefited, in parasitism one partner is harmed other is benefited, mutation is not a interaction. So the correct option is "competition"

In ecology, a community or biocoenosis is an assemblage or association of populations of two or more different species occupying the same geographical area and in a particular time.

The capability to bounce back and to use physical and economic resources effectively to aid recovery following exposure to hazards can be termed as community resilience.

The biosphere is defined as the part of Earth, which is habituated. There are different subdivisions of biosphere. These are known as -

Ecosystem is made up of living and nonliving components. It is of two types, natural ecosystem and artificial ecosystem. Natural ecosystem is also called as macroecosystem. Artificial ecosystem is called as microsystem. Microecosystems can exist in locations which are precisely defined by critical environmental factors within small or tiny spaces. A man-made microecosystem is crop field. It is independent of solar energy. 

Oceanic island communities are more vulnerable to invasion by outside animals and plants than those of main lands. These islands include high volcanic-based islands like Hawaii and low coral islands like Marshalls. These areas are susceptible to invader impacts. This is due to lack of natural competitors and predators which control populations in the ecosystems.  

Ritual contests with little risk to injury help individuals to display their stereotyped aggression which in turn prevent other organisms to attack it. Organization of individuals of a grouped according to their dominance refers to as dominance hierarchy. The agonistic behaviour such as ritual contest with little risk leads to maintenance of stable hierarchy. 

The social foresting species is:

A sacred grove is any grove of trees that are of special religious importance to a particular culture. These are also called sacred woods. They are examples of in-situ conservation of biodiversity. Such groves are found throughout the world. In our country, such groves are found in Meghalaya.

Oran is a major coastal city located in the north-west of Algeria. It is an important city of Algeria due to its commercial, industrial, and cultural importance. It is a sacred landscape. A legend says that in 900 AD, lions still lived in the area. The last two lions were hunted on a mountain near Oran and are elsewhere referred to as "mountain lions".