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HSC XII
Biology
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| Photosynthesis |
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Introduction
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| The different
life processes like nutrition, digestion,
respiration and reproduction take place in living
organisms. The exact nature or way in which these
functions takes place is the study of physiology.
PLANT PHYSIOLOGY deals with all life processes of
the plants. The chemical or physical changes
occuring inside the living cells or changes
taking place between plants and
the environment, are considered as physiological
processes. To understand the different
physiological processes, a working knowledge of
fundamental principles of physics and chemistry
is essential. |
| It is a well-known fact
that all living organisms depend on plants for
food. Therefore, green plants are the world’s
food as well as oxygen factories. Photosynthesis
is the process by which green plants manufacture
sugar. In this process the green plants put
together CO2 from air and
H2 from water in presence of light and
chlorophyll to produce sugar and oxygen. Sugar is
later converted to starch, lipids, malic acid,
proteins and other organic substances. A green
plant cell is just like a small food factory. It
synthesizes carbohydrates. In any factory, energy
is essential. This energy may be obtained by
burning coal or oil or by nuclear energy. Where
does the green plant get its energy? Obviously,
it gets it from sunlight. The chlorophyll has the
remarkable ability to absorb the sun rays with a
high degree of efficiency and to transfer the
energy to other molecules. Thus in this process
radiant energy of the sun is converted to
chemical energy which is utilized by living
organisms to perform their vital
activities. |
| Apart from the
considerable theoretical significance of plant
physiology in helping man to understand the world
in which he lives, plant physiology serves as a
foundation for numerous recent advances in
agriculture, forestry, pharmacology, plant
pathology and other fields of applied
botany. |
| Plant physiology also
promises to assume an increasingly important role
in agricultural research programmes in the near
future. As the world demand for food increases,
mankind faces complex problems. There will be a
sharp intensification of agricultural and food
research. These intensified efforts will lead to
demands on plant physiologists not only to supply
basic information about how plants grow and
develop but also to undertake research programmes
designed specifically to increase plant
yield. |
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