Which one of the following types of organisms occupy more than one trophic level in a pond ecosystem?
Phytoplankton
Fish
Zooplankton
Frog
Which one of the following system constitutes the primary producers
Only a small amount of the energy stored in food is available to the next organism in a food chain because
Which of the food chains directly depends on solar radiations
Trees $\rightarrow$ Birds $\rightarrow$ Lice $\rightarrow$ Bacteria. Thus food chain is
$10\%$ law of flow of energy in ecosystem was proposed by