Biology Today - February 2018

Class XII

Analysis of various PMTs from 2013-2017

2013

2014

2015

2016

2017

AIPMT/NEET

31364

AIIMS

12–13

AMU

115––

Kerala

–325–

K-CET

–3–4–

J & K

–211–

ORGANISMS AND POPULATIONS

• Ecology is the branch of biology concerned with the study of inter-relationship between
  living organisms and their environment.


• The term ecology was coined by Ernst Haeckel in 1889.

Subdivisions of Ecology

Autecology

• Study of individual plant or the population of individual
  plant species in relation to environment.

Synecology

• Study of plant communities and their
  relationship with environment.

VARIOUS LEVELS OF ECOLOGICAL ORGANISATION

• The hierarchy in the levels of organisation connected with ecological grouping of organisms
  is called ecological hierarchy or ecological levels of organisation.
  Individual
  Basic unit of ecological hierarchy as it continuously exchanges materials and information with its
  environment. It is distinct living entity which carries out all life processes in its body, separate from those in
  other individuals. New individuals develop from pre-existing ones.

Population

Group of similar individuals in a particular geographical area or space.

Biotic community

Assemblage of populations of different species of plants, animals, bacteria and fungi which live in a

particular area and interact with one another through competition, predation, mutualism, etc.

Ecosystem

Segment of nature consisting of a biological community and its physical environment, both interacting and

exchanging materials as well as energy, HJ, pond ecosystem.