31 Years NEET Previous Year Questions: Organisms & Populations - 3 - NEET MCQ

Flora of thorn forests include Prosopis cineraria. Acacia senagal, Capparis decidua, Salvadora oleoides, Asparagus racemosus, Ephedra foliata.

Human population in world is estimated to have crossed 6 billion in the year 1999.

Natality refers to the rate at which new individuals are born. Adaptability refers to the capacity of the organisms to adapt themselves to their environment. 

The keystone species in an ecosystem are those who are the main contributors to the ecosystem.

Population is an aggregation or grouping of individuals of the same species at the same time in a particular area. Species is a grouping of individuals of one or more populations resembling each other in important morphological, anatomical and biochemical characters and can potentially interbreed. Biotic community is an assemblage of interdependent, and ecosystem is a self sufficient and self  regulating segment of nature comprising of a biotic community and its physical environment, both interacting and exchanging materials. The basic level of ecological organisation starts with the individual, the next more complex levels are populations, species, community and then ecosystem.

In ecological succession, climax community is a stable, self  perpetuating biotic community developing towards the end of biotic succession in an area and is in harmony with the climate of the region.

Human population growth in India can be regulated by following the national programme of  family planning.

In India, there is short life span of individuals and high birth rate as compared to other countries. That is why, the human population is heavily weighed towards the younger age groups.

Thomas R. Malthus put forward a theory of human population growth in 1778. He told that population grows in geometrical progression, whereas the means which support it, grow only in arithmetical progression.

The correctly matched pair is streamlined body for aquatic adaptation.
Parasitism-inter specific relationship in which one species (parasite) benefits for growth and reproduction and ollic species (host) harmed. Parasite live on or inside the body of host.

Sunken stomata is the characteristic feature of xerophytes which help in reducing loss of water from leaf surface. These type of stomata are found in Oleander or Pine.

Kerala & Assam. Tropical forests-are highly productive terrestrial ecosystem. Their environment conditions are not climate and wel moisture which causes for their higher productivity.

Producers. Number of individuals decreases at successive trophic levels.

Stenohaline : Steno meaning narrow and haline meaning salt. A fish cannot handle a wide fluctuation in salt content in water. Many fresh water fish tend to be stenohaline and die in environments of high salinity such as the ocean. Fish living in coastal estuaries and tide pools are often euryhaline (tolerant to changes in salinity) as are many species which have life cycle requiring tolerance to both fresh water and sea water environments such as Salmon.

Xeric environment is characterised by low atmospheric humidity.
Xeric environment is the environment of moisture deficiency. It is found in the desert. It is characterized by the less annual precipitation, low rate of vaporization, low atmospheric humidity and low temperature at night and high during the daytime.
 

Mutualism type of interactions are shown in plant roots in mycorrhizal region.

Loam soil is best suited for plant growth because it possesses good aeration, nutritive salts and good water retaining capacity.

A species is a group of individuals of same kind of phenotypic characters and can interbreed easily.

Soil particles size defines its texture. The mineral particles present in soil, vary enosmously in size the  fire fiagments. (consisting of sand, silt and clay particles) and coarse fiagments (gravel, copples and stones). The relative proportion's of sand, silt and clay in a soil is referred as soil texture. Fine textured soil have more of clay particles.
Water holding capacity-Larger soil particles like sand, gravel have large pores. This have high less holding capacity and higher percolotion rate field capacity is the of soil moisture or water content held in soil after excess water has drained away.

High organic matter darkens the colour of soil. This is soil.

When the interaction is useful for both the populations.

Deep black soil has high content of clay and humus, which makes it more fertile and so productive. Humus is amorphous and colloidal mixture of complex organic substances. It provides fertility to the soil.

Homeostasis is the property of an open system, especially living organisms, to regulate its internal environment to maintain a stable, constant condition, by means of multiple dynamic equilibrium adjustments, controlled by interrelated regulation mechanisms. 

Competition is most severe between the members of a population belonging to same niches.

Symbiosis or mutualism is a mutually beneficial association necessary for the survival of both the partners.