Lichens are very useful pioneers in succession on a bare rock, especially because:
1. they are sensitive to environmental pollution
2. they have various modes of nutrition
3. they help in the formation of soil
4. they would prevent colonization by parasites

The correct sequence of seral stages in primary hydrarch succession [pioneer to climax] would be:

The amount of nutrients present in the soil, at any given time, is referred to as:
1. Standing state
2. Standing crop
3. Primary productivity
4. Secondary productivity

The nutrients in an ecosystem are:

The reservoir is located in the Earth’s crust for:
I. Gaseous type of nutrient cycle
II. Sedimentary nutrient cycle
1. Only I
2. Only II
3. Both I and II
4. Neither I nor II

The function of a reservoir of nutrient cycle is to:
1. synthesize minerals
2. transfer minerals to other ecosystems
3. meet any deficit
4. destroy the unwanted minerals

The dry weight of living organisms is mainly made up of:

The maximum percent of total global carbon is found:
1. in fossil fuels
2. in atmosphere
3. dissolved in oceans
4. in biomass of microbes

The amount of carbon dioxide in the atmosphere is regulated mainly by:
1. the atmosphere itself
2. human activities
3. decomposition by microbes
4. the oceanic reservoir

Carbon dioxide is returned to the atmosphere by all the following except:
1. photosynthesis by the primary producers
2. respiratory activities of producers and consumers
3. decomposers
4. volcanic activity