Study tips that actually help

Ecosystems and Energy flow Class 12 Biology Chapter 14 Questions And Answers Maharashtra Board

Q. 1. Multiple choice questions 1. Which one of the following has the largest population in a food chain?a. Producersb. Primary consumersc. Secondary consumersd. Decomposers Answer. (a) Producers 2. The second trophic level in a lake is ……………………(a) Phytoplankton(b) Zooplankton(c) Benthos(d) Fishes Answer. (b) Zooplankton 3. Secondary consumers are …………………….(a) Herbivores(b) Producers(c) Carnivores(d) Autotrophs Answer. (c) Carnivores 4. What is the % of photosynthetically active radiation in the incident solar radiation?(a) 100%(b) 50%(c) 1-5%(d) 2-10% Answer. (b) 50% 5. Give the term used to express a community in its final stage of succession?a. End communityb. Final communityc. Climax communityd. Dark community Answer. (c) Climax community 6. After landslide which of the following type of succession occurs?(a) Primary(b) Secondary(c) Tertiary(d) Climax Answer. (a) Primary 7. Which of the following is most often a limiting factor of the primary productivity in any ecosystem?(a) Carbon(b) Nitrogen(c) Phosphorus(d) Sulphur Answer. (c) Phosphorus Q. 2. Very short answer question. 1. Give an example of ecosystem which shows inverted pyramid of numbers. Answer. Number of insects dependent on a single tree, is an example of ecosystem having inverted pyramid of numbers. 2. Give an example of ecosystem which shows inverted pyramid of biomass. Answer. Oceanic ecosystem has inverted pyramid of biomass. 3. Which mineral acts as limiting factor for productivity in an aquatic ecosystem. Answer. Phosphorus acts as limiting factor for productivity in an aquatic ecosystem. 4. Name the reservoir and sink of carbon in carbon cycle. Answer. Atmosphere is the reservoir of carbon cycle, while fossil fuels embedded in ocean and oceanic waters are the sink of carbon in carbon cycle. Q. 3. Short answer questions. 1. Distinguish between upright and inverted pyramid of biomass Answer. Upright pyramid Inverted pyramid 1. In upright pyramid, the number and biomass of the organisms which are at first trophic level of producers is high. 1. In inverted pyramid, the number and biomass of organisms at first trophic levels of producers is lowest. 2. The biomass goes on decreasing at each trophic level. 2. The biomass foes on increasing at each trophic level. 3. The base of the pyramid is always in large number of producers. 3. The base of pyramid is always in small numbers of producers. 4. Pyramid is always upright. 4. Pyramid is always inverted. 2. Distinguish between Food chain and Food web. Answer. Food chain Food web 1. Food chain is the linear sequence of organisms for feeding purpose. 1. Food web is interconnections between many small food chains. 2. In food chain the flow of energy is through a single straight pathway from the lower trophic level to the higher trophic level. 2. In food web, the energy flow is interconnected through numerous food chains in the ecosystem. 3. In a food chain, members present at higher trophic level feeds on only single type of organisms. 3. In a food web, one organism can feed on multiple types of organisms. 4. Energy flow can be easily calculated in food chain. 4. Energy flow is difficult to calculate in a food web. 5. In food chain there is increased instability due to increasing number of separate and confined food chains. 5. In food web there is increased stability due to the presence of the complex food chains. 6. The whole food chain gets affected even if one group of an organism is disturbed. 6. The food web does not get disturbed by the removal of one group of organisms. 7. Member of higher trophic level depends or feed upon the single type of organisms of the lower trophic level. 7. The members of higher trophic level depend or feed upon many different types of the organism of the lower trophic level. 8. Food chain consists of only 4-6 trophic levels of different species. 8. Food web contains numerous trophic levels and also of different populations of species. 9. Competition is seen in members of same trophic level. 9. Competition is seen in members of same as well as different trophic levels. 10. Food chains are of two types:1. Grazing food chain 2. Detritus food chain. 10. In food web there are no types Q. 4. Long answer questions. 1. Define ecological pyramids and describe with examples, pyramids of number and biomass. Answer. 1. Ecological Pyramids : Ecological Pyramids are the representation of relationships between different components of ecosystem at successive trophic levels. 2. Pyramid of numbers: 3. Pyramid of biomass:(1) Pyramid of biomass are constructed by taking into consideration the different biomass in every successive trophic level.(2) Pyramid of biomass in seas in inverted as the biomass of fishes is more than the biomass of phytoplankton. 2. What is primary productivity? Give brief description of factors that affect primary productivity. Answer. (1) Primary Productivity : The rate of generation of biomass in an ecosystem which is expressed in units of mass per unit surface (or volume) per unit time, for instance grams per square metre per day (g/m²/day) is called primary productivity. (2) Primary productivity is described as gross primary productivity (GPP) and net primary productivity (NPP). (3) The rate of production of organic matter during photosynthesis is called gross primary productivity of an ecosystem. Of this the amount of energy lost through respiration of plants is called respiratory losses. (4) Gross primary productivity minus respiratory losses gives the net primary productivity (NPP). (5) Net primary productivity is the available biomass for the consumption to heterotrophs (herbivores, carnivores and decomposers). (6) Factors affecting primary productivity: Gross primary productivity (GPP) depends on the following factors: 3. Define decomposition and describe the processes and products of decomposition. Answer. 4. Write important features of a sedimentary cycle in an ecosystem. Answer. 5. Discribe carbon cycle and add a note on the impact of human activities on carbon cycle. Answer. I. Carbon cycle:(1) The entire carbon cycle has following basic processes viz. Photosynthesis, Respiration, Decomposition, Sedimentation and Combustion. (2) Carbon is an important element as it forms 49% of the dry weight of all organisms. 71% of global