31 Years NEET Previous Year Questions: Organisms & Populations - 2 Free

Competition occurs for light, food and space among organisms in which all partners are adversely affected in an ecosystom.

Cuscuta, or Dodder plant, is a parasitic plant that wraps around other plants for nourishment. Cuscuta is found on outer side of the host and is total stem parasite. Cuscuta a parasite of Acacia.

If a population (e.g reindeer population) is allowed to grow in a predator free environment, the population grows beyond carrying capacity and there occurs population crash due to sudden shortage of food. Such growth curves also occur in insect populations during rainy season, and in algal blooms.

Geometric representation of age structure a characteristic of population.

Praying mantis is a good example of camouflage. Camouflage is the natural colouring of an animal which enables it to blend in with its surroundings.
A praying mantis, or praying mantid, is the common name for an insect of the order Mantodea. Often mistakenly spelled preying mantis (a tempting mistake, as they are notoriously predatory) they are in fact named for the typical “prayer-like” stance. The word mantis derives from the Greek word mantis for prophet or fortune teller. A praying mantis from India

The formula of exponential growth is dN / dt = rN where dN / dt is the rate of change in population size, r is the biotic potential and N is the population size.

In the sigmoid growth cur ve growth is slow in the lag phase. Growth rate remains stable during the stationary phase and it declines during the senescent phase. Growth increases logarithmically during the exponential phase.

Desert show maximum difference between day and night temperature.

The growth curve for bacteria is sigmoid. First phase is the phase of slow growth- Lag phase. Second phase is the period of accelerated growth - Log phase. Third phase is the phase when growth rate  becomes stable - Stationary phase. Finally growth rate declines.

The biotic potential is defined as the physiological capacity of organisms to produce their offspring under natural conditions. It is also called reproductive potential. In nature, the biotic potential of organisms is enormous but all the organisms do not survive due to the lack of food and space. There are also a number of diseases and predatory organisms, that feed upon other organisms. The carrying capacity is the maximum number of individuals which the environment can support or sustain.