Bonding with Ecosystems – Maharashtra Board Class 9 Solutions for Science and Technology (English Medium)
- Living things in the environment are biotic factors.
- Biotic factors, abiotic factors and their interaction with one another form an ecosystem.
- Earth itself is one large biome.
- The number of biotic factors in an ecosystem is decided by abiotic factors.
- Green plants in the living world are autotrophs or producers.
- Organisms that depend directly on autotrophs are known as herbivores or primary consumers.
- Detritivores feed upon dead bodies of living things.
- Each level in a food chain is called a trophic level.
- Bear (Others are primary consumers).
- Deer (Others are apex carnivores).
- Frog (Others are detritivores).
- Heterotrophs in an ecosystem are consumers.
Autotrophs in an ecosystem are producers.
- Carnivores in an ecosystem form the third trophic level.
Herbivores in an ecosystem form the second trophic level.
- 100% energy is never passed on from each trophic level to the next one.
10% energy is passed on from each trophic level to the next one.
- The flow of energy in an ecosystem is unidirectional.
The flow of nutrients in an ecosystem is cyclic.
- The health of an ecosystem is judged by the flow of nutrients and energy.
- Niche: The ecological role played by an organism and the space filled by it in an ecosystem is known as its niche.
- Food chain: The linking of organisms within an ecosystem with respect to eating and being eaten is called a food chain.
- Decomposers: Organisms which decompose and break down organic matter obtained from dead and decaying bodies into inorganic nutrients and return them into the soil are called decomposers.
- Detritivores: Organisms feeding on dead bodies of autotrophs or heterotrophs are called detritivores.
- Plants prepare their own food by the process of photosynthesis. While doing so, they use water and nutrients from the soil, solar energy and chlorophyll.
- This food is taken up by herbivorous animals which in turn become food for carnivorous animals as both cannot prepare their food.
- So, the production of food by trapping solar energy is done only by plants in the ecosystem.
- Therefore, plants in an ecosystem are called producer
- The beginning of any food chain starts with the Sun as it is the ultimate source of energy.
- This solar energy is stored in the form of food molecules by plants.
- When energy is transferred from one trophic level to the next, it is always in one direction. Some energy is utilised for metabolic activities, while some is lost.
- No energy in any ecosystem goes back to the Sun.
- Therefore, the flow of energy in an ecosystem is unidirectional.
- Every living organism needs nutrients for its survival which are taken up from the surrounding ecosystem.
- Plants absorb different nutrients from air, water and soil, while animals take these either from plants or animals.
- Decomposers degrade the dead and decaying matter and release these nutrients back into the soil.
- These nutrients are again taken up by plants and then by animals.
- Thus, the flow of nutrients in an ecosystem is cyclic.
- Decomposers feed on dead and decaying organic matter.
- While feeding, they convert these organic substances into simple inorganic ions and return them to the ecosystem. These are then taken up by plants.
- If decomposers were not present in an ecosystem, the dead and decaying organic matter entering an ecosystem would remain trapped forever in the food chain.
- Lesser quantities of nutrients would then circulate in the ecosystem.
- As a result, waste matter would pile up without decomposition.
- Converting dead and decaying organic matter into useful nutrients is thus a very important function played by decomposers.
- Therefore, decomposers are crucial biotic factors in any ecosystem.
- Biome is a major ecosystem with similar biotic and abiotic factors.
- Several habitats intersect in a biome.
- The two types of major biomes are land biomes and aquatic biomes.
- Land biomes are of several types, such as grasslands, tropical rainforests, hot deserts and frozen tundra and taiga.
- Aquatic biomes can be either fresh water biomes such as rivers, lakes and ponds or marine biomes such as seas and oceans.
- Within a biome, there are smaller ecosystems; these are unique in their composition and function.
- A food web is the intricate and complex network of different food chains.
- In nature, food chains are never simple. One organism can feed on a variety of other organisms and in turn can be eaten up by another set of predators. This forms a web-like relationship between different organisms.
- For example, an insect may eat leaves, seeds or fruits, and this insect may be eaten by frog, lizard or mammals like rat. Then a bird may eat a rat too.
- Similarly, a frog eats insects, a snake eats a frog, which in turn can be picked and eaten by a bird.
- Thus, the feeding relations are not simple. This intricate complex network, i.e. food web operates in every ecosystem.
- Energy pyramid is a diagram which shows the energy levels of different trophic levels.
- When organisms feed upon each other, it is the energy which is transferred from one trophic level to the other.
- All the energy is not passed on to the next level as some energy is used for life processes and some is energy is lost in the surrounding as heat. So, some energy is given to the next trophic level.
- Owing to this, the energy level goes on decreasing from one level to the next level. If the quantity of this energy is diagrammatically represented, a pyramidal figure is formed.
- Producers trap the solar energy and they have the highest amount of energy. As you go up the pyramid, apex carnivores at the top receive the lowest amount of energy.
- Thus, the energy pyramid shows how energy travels up a food chain.
- Bio means living organisms, geo is soil or surrounding.
- The nutrients are always transferred in a path through air, water or soil into the bodies of living organisms and back to the air, water and soil. This cyclic path is called a biogeochemical cycle.
- Plants take up the nutrients from air, water and soil and use them to prepare their own food. These food molecules are further used by living organisms (consumers).
- On the death of plants and animals, these nutrients are released into the soil and air by decomposers. In this way, the nutrients keep flowing in an ecosystem in a cyclic manner.
- The elements such carbon, nitrogen and phosphorus are always circulated in any ecosystem through such biogeochemical cycles.
The following measures are to be taken to maintain a balance in nature:
- Plants should not be destroyed beyond a certain limit, as doing so causes a reduction in the number of producers.
- Animals should not be hunted or killed as it disturbs the food chain.
- Apex carnivores should not be killed as it may affect the population control of herbivores.
- Nature maintains its own balance through food chains and food webs. So, we should not meddle in this inter-relationship.
- Exploitation of natural resources, deforestation, over-construction and pollution should be stopped as these human activities affect the natural balance.