Organisms and Populations Test - 15

• In commensalism, one species is benefitted without the other being harmed. It is of two types periodic contact and continuous contact. 
• Some examples of periodic contact commensalism are jackal and hyenas accompanying big cats like tiger or lions, for eating small bits of leftover of prey's body; sucker fish attaches to the underside of shark and feed on small leftover when the shark is feeding. 
• So, the correct answer is option A.

• Abiotic components: These are non-living components of the environment and consist of two things, materials and energy (that may be light or chemical energy). Materials include land, air, water, minerals, salts, atmospheric gases, rainfall, temperature etc.
• Biotic components: These are living components of the environment and divided into autotrophic and heterotrophic components. An autotrophic component is the producers or green plants while heterotrophic component includes consumers (primary, secondary and tertiary consumers) and decomposers (microbes). Hence, all the given options are correct.

The term mortality is used to refer to the number of deaths in a given time or place or the proportion of deaths in relation to a population. Mortality rate is a measure of the number of deaths (in general, or due to a specific cause) in a population, scaled to the size of that population, per unit time

Forests are extensive self-sustained wooded tract of lands with a biotic community predominated by woody vegetation consisting of trees and shrubs with a close canopy. 

Predation is a type of interspecific competition. Predator feeds on another organism, called as prey.  A predator may become the prey of another organism. 

Nepenthes is commonly called as pitcher plant. It is a insectivorous plant. In this plant the leaf lamina is modified into a pitcher like structure. Insects are digested in pitcher.

Natality or birth rate is the rate of production of new individuals per unit of population per unit of time through birth, hatching, germination and vegetative propagation. If the natality rate increases the mortality rate the population rapidly increases.

The term mortality is used to refer to the number of deaths in a given time or place or the proportion of deaths in relation to a population. Mortality rate is a measure of the number of deaths (in general, or due to a specific cause) in a population, scaled to the size of that population, per unit time.

Natality is also known as birth rate. It is the rate of production of new individuals per unit of population per unit time through birth, hatching, germination or vegetative propagation.

Population Density is defined as the number of people living per square km. As per the provisional population totals of Census 2011, the population density of India has been 382 persons per square kilometer. Population density in the United States was last measured at 34.86 in 2014, according to the World Bank. Therefore population density of developing country like India is more than developed country like the USA. So, the correct answer is option D.