|Can be limited by factors such as light, water, and nutrient availability
Upright vs Inverted Pyramid Table
|Represents a stable ecosystem with a broad base and a narrow top
|Represents an unstable ecosystem with a narrow base and a broad top
|Energy flows from the base of the pyramid (producers) to the top (apex predators)
|Energy flows from the top of the pyramid (decomposers) to the base (producers)
|Top predators have a lower biomass but a higher energy content
|Producers have a higher biomass but a lower energy content
|Indicates a healthy ecosystem with high biodiversity and energy transfer efficiency
|Indicates an ecosystem with low biodiversity and inefficient energy transfer
|Commonly observed in terrestrial ecosystems such as grasslands and forests
|Commonly observed in aquatic ecosystems such as oceans and lakes
|Exhibits a trophic structure that follows the 10% rule, with only 10% of energy transferred from one trophic level to the next
|May exhibit a trophic structure that does not follow the 10% rule, with energy loss at each trophic level
Food Chain vs Food Web Table
|Linear representation of energy flow from one organism to another
|Complex representation of energy flow from multiple organisms in an ecosystem
|Shows a single pathway of energy flow through the ecosystem
|Shows multiple interconnected pathways of energy flow in the ecosystem
|Consists of only one trophic level for each organism
|Consists of multiple trophic levels for each organism, with some organisms occupying more than one level
|Usually involves a predator-prey relationship
|Involves multiple feeding relationships, including predator-prey, herbivore-plant, and omnivore relationships
|Less complex and less diverse than a food web
|More complex and more diverse than a food chain
|Does not show the entire energy flow in the ecosystem
|Shows the entire energy flow in the ecosystem
|Shows the transfer of energy and nutrients in a simplified manner
|Shows the transfer of energy and nutrients in a more detailed manner
|Organic matter on the soil surface
|Dead organic matter in the soil
|Freshly fallen leaves, twigs, fruits, seeds, etc.
|Decomposed organic matter, such as humus, decomposed plant and animal matter
|Usually larger in size
|Smaller in size
|Slow decomposition rate
|Fast decomposition rate
|High nutrient content
|Lower nutrient content
|Provides a habitat for soil organisms and protects the soil from erosion
|Provides nutrients for plants and soil organisms
|Found on the soil surface
|Found within the soil
|Plays a crucial role in nutrient cycling and soil health
|Provides nutrients for plant growth and supports soil structure
|Fallen leaves, twigs, branches, acorns, cones, and fruits
|Humus, dead plant roots, animal remains, and feces
Describe the components of an ecosystem.
Solution: There are three components of the ecosystem:-
(a) Autotrophs or producers which have the capacity to manufacture their own food or which can fix the radiant energy of the sun into chemical energy, e.g., green plants and photosynthetic bacteria.
(b) Heterotrophs or consumers who are unable to manufacture their own food and depend upon other organisms for their food. These are of the following types:
- Primary consumers or herbivores depend upon producers or green plants for their food.
- Secondary consumers or carnivores live upon herbivores.
- Top consumers or top carnivores live upon secondary consumers.
(c) Decomposers or micro consumers decompose dead organic substances of producers and consumers into simple substances and thus continue mineral cycles, e.g., bacteria, fungi, actinomycetes, etc.
Define ecological pyramids and describe with examples, pyramids of number and biomass.
Solution: An ecological pyramid is a graphic representation of an ecological parameter, as a number of individuals present in various trophic levels of a food chain with producers forming the base and top carnivores at the tip. Ecological pyramids were developed by Charles Elton (1927) and are, therefore, also called Eltonian pyramids.
There are three types of ecological pyramids – (1) Pyramid of numbers (2) Pyramid of biomass (3)Pyramid of energy
Pyramid of numbers: It is a graphic representation of the number of individuals per unit area of various trophic levels stepwise with producers at the base and top carnivores at the tip. In a grassland, the producers, which are mainly grasses, are always the maximum in number. This number then shows a decrease towards the apex, as the primary consumers (herbivores) like rabbits, mice, etc. are lesser in number than the grasses; the secondary consumers, snakes, and lizards are lesser in number than the rabbits and mice. Finally, the top (tertiary) consumers hawks or other birds, are the least in number. Thus, the pyramid becomes upright.
Pyramid of biomass: The amount of living organic matter (fresh and dry weight) is called biomass. Here, the different trophic levels of the ecosystem are arranged according to the biomass of the organisms. In grassland and forest, there is generally a gradual decrease in the biomass of organisms at successive levels from the producers to the top carnivores. Thus these pyramids are upright. But in the pond ecosystem, it is inverted because the biomass gradually increases from the producers to carnivores.
What is primary productivity? Give a brief description of factors that affect primary productivity.
Solution: Primary productivity of an ecosystem is the amount of energy fixed or biomass synthesized by primary producers or green plants per unit area per unit time during photosynthesis. Factors affecting primary productivity are –
-Plant species inhabiting a particular area
lit deserts, sunlight is abundant but water is scarce or nutrients are lacking. Therefore, in such areas, water & nutrient supply become the limiting factors.
Define decomposition and describe the processes and products of decomposition.
Solution: Decomposition is the breakdown of dead or waste organic matter by microorganisms. Decomposition is both physical and chemical in nature. Processes involved in decomposition are – fragmentation, catabolism & leaching.
Fragmentation – The process primarily due to the action of detritus feeding invertebrates (detritivores) causes it to break into smaller particles. The detritus gets pulverized when passing through the digestive tracts of animals. Due to fragmentation, the surface area of detritus particles is greatly increased.
Catabolism – Enzyme degradation of detritus into simpler organic substances by bacteria and fungi.
Leaching – The process by which nutrients, chemicals, or contaminants are dissolved & carried away by water, or are moved into a lower layer of soil.
Various inorganic and organic substances are obtained by decomposition. Inorganic substances are obtained in the process of mineralization while organic substances are obtained in humification. A dark-coloured amorphous substance called humus is formed by decomposition. Humus is highly resistant to microbial action & undergoes extremely slow decomposition. It serves as a reservoir of nutrients.
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