Test: Organisms & Populations - 2 - NEET MCQ

The phrase “sharing of food” or “sharing of the table” describes commensalism. It is a long-term relationship between two species in which one species derives the benefit while other is neither harmed nor benefited.

The stationary phase is absent in exponential growth. Exponential growth is observed when resources in the population are unlimited. The population grows in geometric fashion and results in a J-shaped curve.

Hypersaline lagoons have very high concentration of salt (>100). Some organisms can survive in wide range of salinity. These organisms are called euryhaline species.

Xerophytes are plants that grows in deserts having very less water. Sunken stomata, leaves reduced into spines and CAM photosysnthesis are the characteristicfeatures of these plants. Cuticle is present on leaves to prevent loss of water.

Mycorrhiza is a mutualistic interaction between fungi and plants. About 80-90 percent of plants rely on mycorrhiza for the uptake of minerals (nitrogen, phosphorous, etc.) from the soil. While plants supply essential nutrients such as sugars to fungi for their proper growth.

Verhulst-Pearl logistic model of growth is more realistic growth model in comparison to exponential model of growth. Population growing in a habitat having limited resources shows sigmoid curve like growth before reaching to carrying capacity.

Mediterranean orchid Ophrys ensures pollination by co-evolution, sexual deceit and pseudo-copulation. One petal of flower bears an uncanny resemblance to female of bee in size, colour and markings.

E In competition, superior competitor eliminates the inferior one. This statement is called Gause’s competitive exclusion principle. Two closely related competing for same resources cannot co-exist indefinitely and inferior will be eliminated.

Biological control method adopted in agricultural pest control are based on the ability of predator to regulate prey population.

Age pyramid of expanding population is broader at base and thin upwards. Number of individuals in pre-reproductive age is more than post reproductive age. Population size is technically called as population density.

Species facing completion might evolve mechanism that promotes co-existence rather than exclusion that mechanism is called resource partitioning. In which they avoid completion by choosing different times of feeding or different foraging patterns.

The given figure is of sigmoidal growth. It is a logistic/ S-shaped growth curve. It is obtained due to the finite and limited source of resources in a population.

It indicates a stationary phase. The population achieves zero growth in the stationary phase. It is the last phase of logistic growth. It is due to many reasons such as exhaustion of resources, aging, etc.