Ecosystem-Structure & Function, Productivity & Decomposition

1 Mark Questions

1. How is 'stratification' represented in a forest ecosystem? [Delhi 2014]

Ans. The stratification, i.e. the vertical distribution of species at different levels, in a forest ecosystem can be represented as:

1. Tall emergent trees
2. Canopy trees Top most layers

1. Understorey trees
2. Shrubs

1. Herbs Bottom layers
2. Grasses

1. What does 'R' represent in the given equation for productivity in an ecosystem? GPP - R = NPP [All India 2014C]

Ans. In the given equation for productivity in an ecosystem GPP-R= NPP. 'R' represents the energy utilised by plants or producers in respiration. It is also referred to as respiration losses.

1. Mention any two reasons why the primary productivity varies in different types of ecosystems? [All India 2014c].

Ans. The primary productivity varies in different types of ecosystems as:

1. It depends upon plant species (producers) of a given ecosystem and their photosynthetic capacity.
2. It is dependent on various environmental factors like availability of nutrients.
3. Why are green algae not likely to be found in the deepest strata of the ocean? [All India 2013]

Ans. Green algae survive by utilisation of food synthesised by themselves through photosynthesis. At deepest layer in ocean, light is absent. So, photosynthesis does not take place and hence, green algae are not found in deep strata.

1. Write a difference between net primary productivity and gross primary productivity. [All India 2011]

Ans

Difference between GPP and NPP is:

Gross Primary Net Primary Productivity (GPP) Productivity (NPP) It is the rate of It refers to the production of biomass/organic biomass/organic matter available for matter by producers the consumption to during heterotrophs, left photosynthesis. after some respiration

losses.

1. What is secondary productivity? [Delhi 2009]

Ans. Secondary productivity is defined as the rate of formation of new organic matter by the consumers.

1. All the primary productivity is not available to a herbivore, give one reason. [Delhi 2009C]

Ans. All the primary productivity is not available to a herbivore because a considerable amount is utilised by the plants in respiration, while some is lost as heat into the environment.

1. What is net primary productivity of an ecosystem? [Delhi 2008C]

Ans. The amount of remaining energy or biomass in a producer after meeting the cost of its respiration is called net primary productivity of an ecosystem.

2 Marks Question

1. Differentiate between a detritivore and a decomposer giving an example of each. [Delhi 2008]

Ans Difference between detritivore and decomposer is:

Detritivore Decomposer Detritivore is an Decomposer is an organism that organism, which does breaks down the enzymatic detritus into smaller. degradation of particles, detritus into simpler i.e. fragments. inorganic substances. e.g. earthworm. e.g. some bacteria and some fungi.