NEET Practice Questions (MCQs) with Answers & Solutions

(b)Vertical distribution of different species occupying different levels in a biotic community is known as stratification. It refers to the vertical layering of a habitat; the arrangement of vegetation in layers. It classifies the layers of vegetation largely according to the different heights to which their plants grow. The individual layers are inhabited by different animal and plant communities.

Secondary succession is the series of community changes which take place on a previously colonized, but disturbed or damaged habitat. It is the process of regrowth of an ecosystem which undergoes a destructive event. 

The rate of production of organic matter (chemical energy) as biomass that primary producers (via photosynthesis) created in a given duration of time is called Gross Primary Productivity (GPP).

Net primary production is the rate at which all plants (producers) in an ecosystem produce net useful chemical energy, it is equal to difference between the rate at which plants in an ecosystem produce useful chemical energy (GPP) and the rate at which they use some of that energy during respiration.

NPP = GPP - respiration (by plants)

Secondary productivity is the generation of biomass or organic matter by heterotrophic (consumers) in a system.

Net productivity is the amount of energy trapped in organic matter during a specific interval at a given trophic level less than that lost by the respiration of the organisms at that level.

(c) Secondary productivity is the rate of formation of new organic matter by consumers. Primary productivity depends on the producers inhabiting a particular area. 

Phosphorus cycle is a sedimentary bigeochemical cycle. It describes the movement of phosphorus through the lithosphere, hydrosphere and biosphere and the main reservoir pool is lithosphere. Atmosphere does not play any significant role in the movement of phosphorus because phosphorus and phosphorus based compounds are usual solids at the typical ranges of temperature and pressure found on Earth. The production of phosphine gas occurs only in specialized, local conditions.

Green Plant   ->   Insect   ->   Frog   ->   Cobra     ->    Eagle
(producer)                  (Primary          (Secondary       (Tertiary              (Top
                                  consumer         consumer         consumer           consumer
                                      or                or Primary        or secondary       or Tertiary
                                 Herbivore)         carnivore)         carnivore)          carnivore)

Secondary succession or subsere is ecological succession that takes place in a recently denuded area which still contains a lot of organic debris, remains and propagules of previously living organisms. It is more common and caused by baring of an area due to forest fires, deforestation, excessive overgrazing, Landslides, earthquakes, repeated floods, etc. Only 50 to 100 years are required for establishment of a grassland over a recently denuded area. Formation of forest requires 100 to 200 years.

Pyramid of energy is graphic representation of energy per unit area sequence-wise in various rising trophic levels with producers at the base and top carnivores at the apex. Pyramid of energy is upright in all the cases. It is also more accurate than other types of ecological pyramids.

There are an estimated 2,00,000 varieties of rice in India alone. The diversity of rice in India is one of the richest in the world. Basmati rice has 27 documented varieties growth in India.

The amount of having matter present in an ecosystem in its different trophic levels is called standing crop. It is expressed in the form of number or biomass per unit area. Biomass is measured as either fresh weight or dry weight.

Dry weight is preferred over fresh weight as it is not liable to change with moisture content. Standing crop indicates the productivity and luxurience of growth.