Organisms and Populations Test - 13

The plant Yucca shows a mutualistic relationship with the moth Colpa aurea . Both can't complete their life cycle without each other. The moth lays its egg inside the ovarian cavity of the plant and in return, the plant gets pollinated as the moth visits another flower for laying eggs. Young seeds of Yucca are the source of food for the larvae of Moth. So, the correct answer is option 4.

Death is most important regulatory process on earth. It regulates population and avoids over-crowding on earth.

When a graph is plotted taking into consideration time on one hand and growth rate on the other hand, a 'S' shaped curve is obtained. It is called "grand period of growth". This curve mainly shows four phases of growth - 
1. Initial slow growth (lag phase) .

Immigration is the entry of individuals into a region for permanent or temporary settlement thereby increasing the population density of that particular region due to addition of individuals. Food shortage, disease and famine are the factors that would limit the growth of a population.

Amensalism is an interaction between two living individuals or populations of different species in which one organism or population does not allow, other organism or population to grow or live near it. Inhibition is achieved through the secretion of chemicals called allochemics. E.g., the roots and hulls of black walnut (Juglans nigra), produce a chemical called juglone. It is toxic to apple, tomato and alfalfa.

• Commensalism is the relationship between two species in which one is benefited while the other is neither benefited nor harmed. Sucker fish gets attached to the underside of a shark and gets food and protection whereas the shark does not get any benefit with this association neither it affected adversely.
• The association between algae and fungi in lichens is known as mutualism in which both the partners are benefited. In lichens, the fungus lives on the algae which manufacture the food through chlorophyll present in its cells, while algae enjoy the protection offered by the fungal envelope to live in very dry conditions.
• Orchids show a symbiotic relationship with trees in which they get their nutrition from them. This is a healthy relationship in which no harm is done to the trees and there is no benefit to trees from orchids. Such a type of symbiotic relationship is called commensalism.
  

Territoriality is the behaviour of animals or people that try to keep others away from an area that they use or control. Establishment of territories by animals is meant for ensuring availability of their needs. It occurs as a result of competition. Competition, in ecology, is the utilization of the same resources by organisms of the same or of different species living together in a community. It exists between individuals of the same or different species for food, light, space, shelter and mate.

Monarch butterfly escapes from predators because of its bitter taste. Viceroy butterfly (Basilarchia archippus) mimics monarch butterfly to escape from predators.

Pitcher plants eat small insects to supplement their nitrogen requirements. Hence, they are insectivorous plants. Nepenthes khasiana is an endemic plant to the Khasi hills of Meghalaya after which it is named. This species is critically endangered. Thus, the correct answer is option B.