Question

Which one of the following is an example of mutualism?
A) Lichens
B) Hypertrophy
C) Cuscuta
D) Nepenthes

Answer 1

Hint: Mutualism is a type of relationship between the host and a symbiont. Here both organisms benefit and no one is harmed. This relationship can be for the long term or for the shorter term. Ants live and feed on the nectar of acacia trees. Here ants are the mutualist and acacia trees is the host is an example of mutualism.

Complete answer:
There are five types of Mutualism.
i) Obligate Mutualism: In this type of mutualism, the relationship between two species are completely dependent on each other. This is found in most symbioses and non-symbiotic organisms.

ii) Facultative Mutualism: In facultative mutualism, the partners can coexist without depending on each other. But they form a diffuse relationship involving a varying mixture of species. This is found in honeybees and plants.

iii)Trophic Mutualism: Here the partners are specialized in complementary ways to obtain energy and nutrients from each other. For example, cows and bacteria.

iv) Defensive Mutualism: In defensive mutualism, one partner receives food and shelter and in exchange, they help the partner by fighting against the herbivores or predators or parasites. The aphids and the ants are an example of defensive mutualism.

v) Dispersive Mutualism: In dispersive mutualism, one partner receives food in exchange for another partner helps to transfer pollen. This is seen in honeybees and plants.

- Here lichens show mutualism. Lichens require carbon as a food source and it is provided by their symbiotic algae and/or cyanobacteria, which are photosynthetic. The lichen symbiosis is found to be a mutualism, both partners benefit.
- Hypertrophy is the increase in the size of skeletal muscle through the growth of its component cells.
- Cuscuta shows parasitism where one organism benefits at the expense of another.
- Nepenthes is an insectivorous plant.

Therefore the correct answer is option ‘A’.

Note: The relationship between humans and plants is a perfect example of mutualism. As humans require oxygen for life support and plants use carbon dioxide for carrying out photosynthesis. Here both species are mutually benefited.