Curiosity is the foundation of learning, which is why Zigya follows a unique model of non-pedagogical approach to learning. Zigya's approach is designed to ensure that students remain curious to know more and build on self-reliance having timely answers to their questions.

← Back

(a) Explain primary productivity and the factors that influence it.

(b) Describe how do oxygen and chemical composition of detritus control decomposition?

(a) The amount of biomass produced per unit area over a time period by plants during photosynthesis is defined as the primary productivity. It is expressed as weight or energy. Productivity can be mainly divided into gross primary productivity (GPP) and net primary productivity (NPP). GPP is the rate of production of organic matter during photosynthesis.

Primary productivity is directly proportional to the amount of carbon dioxide, sunlight and water. It is inversely proportional to respiratory losses. NPP = GPP - Respiratory losses (R)

(b) Decomposition is an oxygen consuming process thus it is directly proportional to the concentration of the oxygen in the environment. It is controlled by the chemical composition of detritus and climatic conditions. The decomposition rate decreases when the detritus is rich in lignin and chitin while it is quicker if the detritus contains nitrogen and water-soluble substances such as sugars.

Fill in the blanks with suitable words :
1. Plants are called as .......................because it fixes carbon dioxide.

2. In ecosystem, dominated by trees, the pyramid is.......................type.

3. In aquatic ecosystems, the limiting factor for the productivity is.......................

4. Common detritivores in our ecosystem are.......................

5. The major reservoir of carbon is.......................

Define ecological pyramids and describe with examples, pyramids of number and biomass.

Define decomposition and describe the processes and products of decomposition.

Give an account of energy flow in an ecosystem.

Write important features of a sedimentary cycle in an ecosystem.

Outline salient features of carbon cycling in an ecosystem.

Which one of the following has the largest population in a food chain ?

The second trophic level in a lake is :

Secondary producers are :

What is the percentage of photosynthetically active radiation (PAR), if incident solar radiation is considered 100% ?

Distinguish between the following :
(a) Grazing food chain and detritus food chain

(b) Production and decomposition

(c) Upright and inverted pyramid.

(d) Food chain and food web

(e) Litter and detritus

(f) Primary and secondary productivity.

Describe the components of an ecosystem.

What is primary productivity ? Give brief description of factors that affect primary productivity.

Describe the advantages for keeping the ecosystems healthy.

Explain the carbon cycle with the help of a simplified model.

Explain how does:

(a) a primary succession start on a bare rock and reach a climax community?
(b) the algal bloom eventually choke the water body in an industrial area?

It is often said that the pyramid of energy is always upright. On the other hand, the pyramid of biomass can be both upright and inverted. Explain with the help of examples and sketches.

(a) Explain the significance of ecological pyramids with the help of an example.
(b) Why are the pyramids referred to as upright or inverted?

(a) Taking an example of a small pond explain how the four components of an ecosystem function as a unit.
(b) Name the type of food chain that exists in a pond.

(a) Explain primary productivity and the factors that influence it. (b) Describe how do oxygen and chemical composition of detritus control decomposition?