Question: 100% NCERT covered from Particular Keyword.Explanations are 100% from NCERT | [Difficult level: Easy] From NCERT NEET Derived Question.
What proportion of the PAR (photosynthetically active radiation) is captured by plants?
1. 1 - 10%
2. 2 - 10%
3. 5 - 15%
4. 5 - 25%
Answer:2. 2 - 10%
👉Except for the deep sea hydro-thermal ecosystem, sun is the only source
of energy for all ecosystems on Earth
👉Of the incident solar radiation less
than 50 per cent of it is photosynthetically active radiation (PAR).
👉Plants
capture only 2-10 per cent of the PAR
👉plants and photosynthetic bacteria (autotrophs)
👉In a terrestrial
ecosystem, major producers are herbaceous and woody plants.
👉Likewise,
producers in an aquatic ecosystem are various species like phytoplankton,
algae and higher plants.
👉Some common herbivores are insects, birds and mammals in terrestrial
ecosystem and molluscs in aquatic ecosystem.
👉A simple grazing food chain (GFC) is depicted
below:
Grass→ Goat→ Man:
(Producer) →(Primary Consumer)→ (Secondary consumer
👉The detritus food chain (DFC) begins with dead organic matter. organisms include mainly
fungi and bacteria.
These are also known as
saprotrophs (sapro: to decompose).
👉In an aquatic ecosystem, GFC is the major conduit for energy flow.
As against this, in a terrestrial ecosystem, a much larger fraction of energy
flows through the detritus food chain
👉Detritus
food chain may be connected with the grazing food chain at some levels
👉omnivores:
These natural interconnection of food chains make it a food web.
👉Each trophic level has a certain mass of living material at a particular
time called as the standing crop.
👉The standing crop is measured as the
mass of living organisms (biomass) or the number in a unit area
👉The
biomass of a species is expressed in terms of fresh or dry weight.
Measurement of biomass in terms of dry weight is more accurate.
👉The number of trophic levels in the grazing food chain is restricted as
the transfer of energy follows 10 per cent law
👉Do you think there is any such limitation in a detritus food chain?
Answer:
There is no limitation in detritus food chain for number of trophic level because 10% rule is not applicable and high magnitude of energy
