Q.1. In relation to Gross primary productivity and Net primary productivity of an ecosystem. Which one of the following statements is correct? (2020)
(a) Gross primary productivity and Net primary productivity are one and same.
(b) There is no relationship between Gross primary productivity and Net primary productivity
(c) Gross primary productivity is always less than Net primary productivity.
(d) Gross primary productivity is always more than Net primary productivity.
The gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis. Some of this organic matter is lost because of the respiration of plants. The remaining primary productivity is the net primary productivity.
Q.2. Which ot the following ecological pyramids is generally inverted? (2019)
(a) Pyramid of biomass in a sea
(b) Pyramid of numbers in grassland
(c) Pyramid of energy
(d) Pyramid of biomass in a forest
Pyramid of biomass in an aquatic ecosystem (e.g., pond, sea) is usually inverted because the biomass of fishes exceeds the biomass of phytoplanktons.
Q.3. What type of ecological pyramid would be obtained with the following data? (2018)
Secondary consumer : 120 g
Primary consumer : 60 g
Primary producer : 10 g
(a) Inverted pyramid of biomass
(b) Pyramid of energy
(c) Upright pyramid of numbers
(d) Upright pyramid of biomass
The given data depicts the inverted pyramid of biomass, usually found in aquatic ecosystem. This can be understood by taking an example of a pond in which phytoplankton (10g) represents the producer. Small fishes (60g) feeding upon these phytoplankton represent primary consumers which are further eaten by the big fishes (120g) representing secondary consumers.
Q.4. Which ecosystem has the maximum biomass? (2017)
(a) Grassland ecosystem
(b) Pond ecosystem
(c) Lake ecosystem
(d) Forest ecosystem
Q.5. The primary producers of the deep-sea hydrothermal vent ecosystem are (2016)
(a) Green algae
(b) Chemosynthetic bacteria
(c) Blue-green algae
(d) Coral reefs
Hydrothermal vents are cracks in the ocean floor that emit jets of hot water loaded with minerals and chemosynthetic bacteria. These bacteria are autotrophs that oxidise hydrogen sulphide in vent water to obtain energy which is used to produce organic material. These chemosynthetic bacteria are the primary producers and form the base of vent food webs. All vent animals ultimately depend on bacteria for food.
Q.6. Which of the following would appear as the pioneer organisms on bare rocks? (2016)
(b) Green algae
The bare rocky habitat is extremely hostile to living beings. There is no water, as the substratum does not absorb rain water. There is no nutrient holding mechanism. Plants cannot grow on these rocks. The first inhabitants or pioneers of such a habitat are usually lichens as they are resistant to desiccation and extreme temperatures.
Q.7. Which one of the following is a characteristic feature of cropland ecosystem? (2016)
(a) Absence of weeds
(b) Ecological succession
(c) Absence of soil organisms
(d) Least genetic diversity
Cropland ecosystem is an artificial or man-made terrestrial ecosystem which is created and maintained by human beings for their maximum benefits. Therefore, they will have least genetic diversity.
Q.8. The term ecosystem was coined by (2016)
(a) E. Haeckel
(c) E.P. Odum
(d) A.G. Tansley
The term ecosystem was coined by A.G. Tansley in 1935.