Q. Consider the following statements regarding energy flow:
1.Plants capture only 2-10 per cent of the photosynthetically active radiation and this small amount of energy sustains the entire living world.
2.The green plants in the ecosystem are called producers.
Which of the statements given above is/are correct?

[A] 1 only

[B] 2 only

[C] Both 1 and 2

[D] Neither 1 nor 2

Answer: C
Notes:

Explanation: 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).

  • We know that plants and photosynthetic bacteria (autotrophs), fix Sun’s radiant energy to make food from simple inorganic materials.
  • Plants capture only 2-10 per cent of the PAR and this small amount of energy sustains the entire living world. Further, ecosystems are not exempt from the Second Law of thermodynamics.
  • They need a constant supply of energy to synthesise the molecules they require, to counteract the universal tendency toward increasing disorderliness.
  • The green plants in the ecosystem are called producers. 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.

Source: Science NCERT