Question

Ammensalism is an association between two species where
A. One species is harmed and other is benefitted
B. One species is harmed and other is unaffected
C. One species is benefitted and other is unaffected
D. Both the species are harmed

Answer 1

Symbiotic relations are mainly characterized by the benefits and physical. In mutualism association both the species are benefitted. Ammensalism is the type of association in which one species remains unaffected while other is harmed. Commensalism is the relationship in which one species is benefited while other is unaffected. In parasitism association one species is harmed while other is benefitted.

Complete answer:
Ammensalism is the ecological interaction between two species. In this type of interaction an individual species harms another without obtaining any benefit. There are mainly two basic modes: competition, in which a larger or stronger organism excludes a smaller or weaker one from the living space. This is also called competitive elution. If one species is unaffected but the other is damaged or killed by a chemical secretion, the process is called as antibiosis.
For example: Bread mold penicillin has great effect in combating bacterial infections. Another example is black walnut,a substance that can destroy many herbaceous plants within its root zone.
Parasitism is observed when parasite worms affect the mammals etc. in this type of symbiosis one species is harmed while the other is benefited. In commensalism, one species is benefitted while the other species is not affected. For example: Dead snails used as homes by Hermit crabs . From the above information we know that ammensalism is an association between two species where one species is harmed and the other remains unaffected.

So, the correct answer is option B.

Note: Allelopathy is observed in amensalism association. In this phenomenon the shading out of one plant by a taller and wider one is observed and the inhibition of one plant by the secretions of another. Excretion of toxic substances also results in allelopathy. Most of the microbes show parasitic relationships as they feed on human tissue. For example: cholera, leishmaniasis, and giardia. Mutualism association is found in bacteria present in the gut that aid digestion in both humans and animals.