Mutualism is a type of symbiotic interaction in which both species benefit, such as bees pollinating flowers or fungi forming mycorrhiza with plants. It enhances survival, reproduction, and ecosystem balance. This Class 12 Biology concept is central to NEET under Organisms and Populations.
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Mutualism is a type of ecological interaction where two different species live closely together and both benefit from the relationship. Mutualism is one of the most elemental ideas in ecology that pertains to a kind of symbiosis. There are numerous examples from nature, one of them is the mutualism between flowers and bees where flowers offer nectar and pollen to the bees as their food and the bees help flowers in their pollination process by transferring pollen from one plant to another.
The organism within mutualistic interaction engages in an activity that will increase the chances of survival, growth and reproduction hence promoting a symbiotic relationship for both the species. Reciprocal associations play an outstanding role in the processes shaping the structure of ecosystems and affect the overall level of biodiversity. These aspects include aiding in the coexistence of other species, nutrient cycling, and making an ecosystem more resilient to change, which makes these organisms huge factors in the health of ecosystems across the globe.
The types of mutualism are listed below:
Obligate mutualism relates to a situation whereby both species are wholly dependent on each other and are unable to survive the reproductive process. The absence of one of them means that neither of the species can reproduce which will ultimately lead to its extinction. This is mostly a specific and close relationship where co-development is seen to be playing a major role in the sustenance of the dependency.
Examples: coral and zooxanthellae, termites and gut protozoa
Facultative mutualism refers to the modification of existing resources to produce a reciprocal interaction that is not obligatory. Although both partner species gain something from each other. Each is capable of living and reproducing on its own if pushed to it. The relationship can often be less formal and can fluctuate for a period depending on certain factors of the environment.
Examples: pollination by bees and seed dispersal by birds
Trophic mutualism is an association in which one species directly supplies another with a trophy or energy.
Defensive mutualism is one where one partner receives protection, defence or security from a predator or pathogen from the other partner.
Dispersive mutualism describes a situation where one of the parties helps enhance the dispersion of propagules of the other party’s offspring.
Various examples of mutualism can be observed in the natural environment.
Coral polyps depend on the zooxanthellae algae for essential nutrients which are derived from photosynthesis and in return the zooxanthellae algae rely on the coral polyps for shelter as well as nutrients.
Protozoa helps termites by breaking down cellulose from wood, in return the protozoa benefit from a stable environment and nutrients from the termite’s digestive system.
Flowers get pollinated by bees through the movement of pollen from one plant to another to get the nectar which is the food of bees. Bees and flowering plants rely on each other but are not obligated.
Many of the plants and fruits provide a food source to the birds which in turn provide natural reproductive means to plants as they release seeds in their droppings.
The mechanism of mutualism is described below-
Mycorrhizal Fungi And Plants
The mycorrhizal fungi are beneficial in forming symbiotic partnerships with the plants, especially trees in which they penetrate their root systems. The fungi increase the efficiency of water and nutrient uptake from the soil including phosphorus and nitrogen. In exchange, the fungi provide organic compounds, especially sugars and carbohydrates synthesized by the plant through photosynthesis.
Rhizobia Bacteria and Legumes
Rhizobia bacteria fixing nitrogen in soil connect with leguminous plants (including peas, beans and clovers) and form nodules on the roots of these plants. Inside these nodules, bacteria known as Rhizobia which fix the nitrogen from the air in the usable nitrogen, specifically, ammonium. The plants offer carbohydrates to the bacteria on which they feed and carry out their activities effectively.
Ants and Acacia Trees
Some types of ants exhibit protective mutualism with acacia trees. The ants reside in hollow thorns or other structures built by the acacia tree and the tree is protected by ants who attack any herbivore that attempts to feed on the tree. In turn, the Acacia tree offers the ants protection and food in the form of organs referred to as extrafloral nectary or Beltian bodies, which are nutrient-producing structures.
Cleaner Fish and their Hosts
Cleaner fish including cleaner wrasses and cleaner shrimp get involved in non-aggressive cleaning associations with other large fishes or other sea creatures. They feed on ectoparasites, skin and gill mucus, and consume dead tissue, and algae with the host’s skin or gill surface since cleaning has a positive impact on the host as well as reduces the chances of being infected.
Pollination Mechanisms
Pollination for the flowering plants and the pollinators (like bees, butterflies, birds). These are insects or animals that carry pollen from one flower to another to help in the process of pollination, which helps plants produce seeds. Consequently, pollinators are given nectar or pollen in exchange for them.
Seed Dispersal Methods
Some plants, for instance, depend on animals to disperse their seeds from one location to another; birds, mammals, insects, and others. Seeds are then eaten by animals and then defecated or relocated to other areas by the animals. This mutualism is beneficial in that it assists plants in finding and taking over new territories to propagate in.
Here are the key topics which are most important for the NEET exam:
Types of Mutualism
Rhizobium and Legumes
Examples of Mutualism
Q1. Which option is correct w.r.t mutualism ?
A mutualistic relationship is when two organisms of different species "work together," each benefiting from the relationship.
One example of a mutualistic relationship is that of the oxpecker (a kind of bird) and the rhinoceros or zebra.
Both (1) and (2)
None of the above
Correct answer: 3) Both (1) and (2)
Explanation:
A mutualistic relationship is when two organisms of different species "work together," each benefiting from the relationship. One example of a mutualistic relationship is that of the oxpecker (a kind of bird) and the rhinoceros or zebra.
Hence, the correct answer is option 3) Both (1) and (2).
Q2. Mycorrhizae are the example of :
Fungistasis
Amensalism
Antibiosis
Mutualism
Correct answer: 4) Mutualism
Explanation:
Mutualism -
This interaction confers benefits on both the interacting species. Lichens represent an intimate mutualistic relationship between the fungus and photosynthesising algae or cyanobacteria. Similarly, the mycorrhizae are associations between fungi and the roots of the higher plants. The fungi help the plants in the absorption of essential nutrients from the soil while the plant, in turn, provides the fungi with energy-yielding carbohydrates.
Hence, the correct answer is option 4) Mutualism.
Q3. The prickly pear cactus became unusually abundant after its introduction in Australia, because it
Had no coevolved herbivores
Formed new mycorrhizal association
Lost its thorns
All of these
Correct answer: 1) had no coevolved herbivores
Explanation:
Plant-animal interactions often involve co-evolution of the mutualists, that is, the evolutions of the flower and its pollinator species are tightly linked with one another.
- wherein
In many species of fig trees, there is a tight one-to-one relationship with the pollinator species of wasp.
Hence the correct answer is Option 1) had no coevolved herbivores.
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Frequently Asked Questions (FAQs)
It is very important in supporting the biodiversity, nutrient cycling, and stability and/or resilience of ecosystems. It also strengthens the efficiency of ecosystems by allowing such activities as pollination, nutrient absorption and degradation. In maintaining the ecosystems both reciprocally beneficial associations must be guarded for the sake of the natural habitats.
In this case, mutualism is a sort of symbiosis where both the parties in question have gain to derive from the association. While in commensalism one organism has an advantage and on the other hand, the parasite gets benefits on the cost of the host organism, mutualism can be defined as the relationship in which the participants have equal advantages and both organisms gain benefits which would improve their fitness and chances of survival.
Pollination: The bees and the flowering plants have mutualistic associations thus bees gain nectar which is food for them as they help transport pollen from one flower to another providing pollination services for the plants.
Mycorrhizal Fungi and Plants: The plants need the help of fungi in absorbing nutrients from the soil, in return, fungi obtain sugars that are produced by plants through processes such as photosynthesis.
Cleaner Fish and Their Hosts: Some fish eat parasites and decomposing tissue of other fish since the larger fish protect and feed the cleaner fish.
Symbiotic relationships are beneficial since they make the organisms of the two related species increase in fitness, increase in size and reproduce. Some of the benefits of these symbiotic relationships include enhanced nutrient uptake, protection from predators or diseases, enhanced means of reproduction, a means of pollination or seed shedding as well as enhanced health and stability of ecosystems.
They said habitat destruction, pollution, climate change, and the entrance of invasive species are human activities that may disturb mutualism. For instance, deforestation denies pollinators and plants places to live, while polluting affects helpful bacteria in the sphere of soil or water.