Page 12 - 11-Bio-1 Introduction

1. Introduction eLearn.Punjab

organ formation is far more complex and defined. Organs are part of organ systems where total
functions involved in one process or phenomenon are carried out.

The organ level of organization is much less definite in plants than it is in animals. At the most,
we might distinguish roots, stems, leaves and reproductive structures. Clear cut functions, the
distinguishing features, can be assigned to each of these structures. Roots are involved in anchoring
the plant, storage of food and procuring water and minerals. The shoot supports the entire plant
while the leaves are primary organs for food manufacture. Flowers or other reproductive structures
are involved in producing the next generation (reproduction).
The complexity of the organ systems of animals is associated with a far greater range of functions
and activities than is found in plants.

Individual (Whole Organism)

Various organs in plants and various organ systems in animals are assembled together to form an
individual - the whole organism. The whole organism has its individuality as far as its characteristics
are concerned. It is different from other members of the same species in certain respects. The
various functions, processes, activities of an organism are coordinated. In an animal all the systems
work in coordination with each other. For instance if a man is engaged in continuous and hard
exercise, not only his muscles are working but there is an increase in the rate of respiration and
heart beat to supply the muscles with increased oxygen and food which they need for continuous
exercise. In animals the coordination is achieved by means of nervous system and endocrine
system, whereas in plants only long term regulation of activities is brought about by hormones.

Organism works as a whole and it interacts and responds to the environmental changes as a whole.

Population

A population is a group of living organisms of the same species located in the same place at the
same time. Examples are the number of rats in a field of rice, the number of students in your
biology class, or human population in a city.

Population is a higher level of biological organization than organism (whole) because here a group
of organisms of the same species is involved. This level of organization has its own attributes which
come into being by living together of a group of organisms of the same species.

Some of these attributes are gene frequency, gene flow, age distribution, population density,
population pressure etc. All these are new parameters which have appeared due to population of
an organism. You will study them in detail in population ecology.

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