Zooplankton are primary consumers in aquatic food chains that feed upon phytoplankton.
Therefore, they are present at the second trophic level in a lake.
Write a difference between net primary productivity and gross productivity.
Answer
Gross productivity-Rate of production of organic matter during photosynthesis Net primary productivity -Available biomass for the consumption to heterotrophs/GPP-R = NPP.
State what does ‘standing crop’ of a trophic level represent?
Answer
There is unidirectional movement of energy the higher trophic level and its levels has a certain mass of living material at a particular time called as the standing crop. It represent values for dry blomass (standing crop).
How is ‘stratification’ represented in a forest ecosystem?
Answer
Trees occupy vertical stratra, shrubs the second layer and herbs/grasses occupy the bottom layers/vertical distribution of species, at different levels.
Write the equation that helps in deriving the net primary productivity of an ecosystem.
Answer
Net primary productivity (NPP) is an ecosystem can be derived using the following equation:
NPP = GPP-R.
= (Gross – Primary Productivity) - (Respiratory Losses).
What does ecological niche of an organism represent?
Answer
The ecological niche (of an organism) signifies the range of conditions it can tolerate, the resources it utilises, and its functional role in the ecological system.
How is stratification represented in forest ecosystem?
Answer
Stratification is the way in which different species in an ecosystem are placed or arranged vertically, occupying different levels. It is a way of minimising competition for limited resources vital for survival.
Answer the following questions:
Over the years, it has been observed that some of the lakes are disappearing due to urbanisation. In absence of human interference, depict by making a flow chart, how do the successional series progress from hydric to mesic condition.
How is net primary productivity different from gross primary productivity?
Answer
Net primary productivity refers to the biomass/ organic matter available at the producer level to the primary consumers, i.e. GPP-Respiratory losses. Gross primary productivity is the rate of production of biomass/ organic matter by producers during photosynthesis.
What is meant by productivity of an organism? How is it expressed in a terrestrial ecosystem?
Answer
The rate of synthesis of energy containing biomass by any trophic level per unit area in unit time is called its productivity.
$\text { It is expressed in terms of } \mathrm{g}^{-2} \mathrm{yr}^{-1} \text { or } \mathrm{kcal} \mathrm{~m}^{-2} \mathrm{yr}^{-1} \text {. }$
Man can be a primary as well as secondary consumer'. Justify this statement.
Answer
Man can be a primary as well as secondary consumer because man eats plants as well as meat of other animals. So, man is herbivores as well as carnivores.
Answer the following questions:
Colonisation of a rocky terrain is a natural process. Mention the group of organisms which invade this area first. Give an example.
Answer
Pioneer species invade the area first.
For example, lichen.
How is the net primary productivity of an ecosystem derived?
Answer
Gross primary productivity (GPP) – Respiratory loss (R) = Net primary productivity (NPP); it is the amount of energy/ biomass available in the producers for consumption by herbivores.
A Volcano erupted in Hawaii, and lava covered land that had been framed for centuries. Eventually, new lichens, and then plants, grew on the lava. Is this an example of primary or secondary successions? Give the reason also.
Answer
This is an example of primary succession: Because this begins from a state of little or no life.