Environment-2 Flashcards
define a food chain
Food chain is defined as an arrangment of the oneway flow of energy from the source fo solar energy to the top consumer through a series of organism by the processes of eating and being eaten.
Grass-mice-snake-hawk
give three characteristics of food chain
i) a food chain is straight,nidriectional and prceeds in a progressive straight line.
ii)Members in the first link are always producers and last levels are the decomposers.
ii)Members ate progressive higher levels are lesser in number
iii) it helps understand the food relationshi[ and interactions between the organisms in the ecosystem
iv) it also helped understand the movement of toxic substances through an ecosystem and find the problem of bio-maginifciation.
what are food pyramids
pictorial representation of food chain
whata re diff trophic levels
Trophic Levels are the various steps or levels in the food chain where transfer of food or energy takes place.
The autotrophs or the producers are at the first trophic level.
They fix up the solar energy and make it available for
heterotrophs or the consumers. The herbivores or the primary
consumers come at the second, small carnivores or the
secondary consumers at the third and larger carnivores or
the tertiary consumers form the fourth trophic level
how is the flow of energy
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.
state 10 percen law
Ten per cent law is an enunciation given by Lindeman (1942) which states that only 10% of energy contained in a lower trophic level is trapped by next higher tropic level, the remaining 90% being lost in transfer and respiration of the latter.
: It states that only 10 per cent of food energy is transferred from one trophic level to the next level. The
remaining 90 per cent energy is used in life processes (digestion, growth, reproduction, etc.) by the present trophic
level.
explain 10 percent rule
*The green plants in a terrestrial ecosystem capture about
1% of the energy of sunlight that falls on their leaves and
convert it into food energy.
*When green plants are eaten by primary consumers, a great
deal of energy is lost as heat to the environment, some amount
goes into digestion and in doing work and the rest goes
towards growth and reproduction. An average of 10% of the
food eaten is turned into its own body and made available for
the next level of consumers.
*Therefore, 10% can be taken as the average value for the
amount of organic matter that is present at each step and
reaches the next level of consumers.
why are there only few trophic levels
Since so little energy is available for the
next level of consumers, food chains
generally consist of only three or four
steps. The loss of energy at each step is
so great that very little usable energy
remains after four trophic levels.
There are generally a greater number
of individuals at the lower trophic levels
of an ecosystem, the greatest number
is of the producers.
what is a food web
Food Web is the network of various food chains which are interconnected at various trophic levels. Since an
organism can occupy position in more than one food chain, in a food web it occupies more than one trophic level.
It represents the feeding relationship within the community.
explain biological magnification
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 and animals. This is one of the ways in which they
enter the food chain. As these chemicals are not degradable, these get
accumulated progressively at each trophic level. As human beings occupy
the top level in any food chain, the maximum concentration of these
chemicals get accumulated in our bodies. This phenomenon is known
as biological magnification.
define biological magnification
Biomagnification refers to the accumulation of a toxin in the body of an organisms as we progress from one trophic level to another,. The concentration of a toxin in the primary consumer level will be very less than that of the concentration in the tertiaryconsumer level.
what do interactions between animals involve
We know that the food we eat acts as a fuel to provide us
energy to do work. Thus the interactions among various
components of the environment involves flow of energy from
one component of the system to another.
