Page 216 - NCERT Science Class 10 English Medium

From the energy flow diagram (Fig. 13.4),
two things become clear. Firstly, the flow of
energy is unidirectional. The energy that is
captured by the autotrophs does not revert
back to the solar input and the energy which
passes to the herbivores does not come back
to autotrophs. As it moves progressively
through the various trophic levels it is no
longer available to the previous level.
Secondly, the energy available at each trophic
level gets diminished progressively due to loss
of energy at each level.
Another interesting aspect of food chain
is how unknowingly some harmful
chemicals enter our bodies through the food
chain. You have read in Class IX how water
gets polluted. One of the reasons is the use of
several pesticides and other chemicals to
protect our crops from diseases and pests.
These chemicals are either washed down into
the soil or into the water bodies. From the
soil, these are absorbed by the plants along
with water and minerals, and from the water
bodies these are taken up by aquatic plants

Figure 13.3
Figure 13.313.3
Figure 13.3
Figure
13.3
Figure
Food web, consisting of
many food chains

Figure 13.4
Figure 13.4
Figure 13.4 Diagram showing flow of energy in an ecosystem
Figure 13.4
Figure 13.4
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