Question

Read the sources given and answer any four from the questions given below:

A pyramid of biomass represents the total biomass or 'standing crop' (dry weight) of organisms at each trophic level at a particular time. The pyramid of biomass is always upright as given below but in some aquatic ecosystems it could be inverted also. Inverted pyramid means that the biomass of producers is less than that of the next trophic level, i.e., herbivores. It occurs in some aquatic ecosystems in which the producers are algae and phytoplanktons, which have short life-spans but rapid increasing rate. Hence the biomass of producers, i.e., phytoplanktons is smaller than the biomass of zooplanktons it supports. Also the biomass of zooplanktons is less than the biomass (dry weight) of large and long-lived fishes they support.

1. In the above pyramid of biomass, which trophic level represents the more biomass than primary carnivores?
   1. producers and carnivores
   2. herbivores and secondary carnivores
   3. producers and herbivores
   4. both (a) and (c)
2. In an aquatic ecosystem the pyramid of biomass is
   1. upright
   2. triangular
   3. inverted
   4. squarish
3. The biomass of zooplanktons in an aquatic ecosystem is
   1. more than phytoplanktons
   2. less than phytoplanktons
   3. more than large fish in water
   4. both (b) and (c)
4. The pyramid of biomass of an aquatic system is inverted, where the producers are algae and phytoplanktons because
   1. short life span and rapid increasing rate of zooplanktons than phytoplanktons
   2. short life span and rapid increasing rate of phytoplanktons than zooplanktons
   3. biomass of algae and phytoplanktons is maximum
   4. biomass of zooplanktons is more than that of phytoplanktons
5. In the trophic levels the second trophic level is always occupied by
   1. carnivores
   2. herbivores
   3. producers
   4. decomposers

Answer 1

1. producers and herbivores
2. inverted
3. more than phytoplanktons
4. biomass of zooplanktons is more than that of phytoplanktons
5. herbivores