Q4. Fill in the blank: the major reservoir of carbon on earth is ______. (NCERT Exercise 1(e), page 215.)
Oceans. NCERT’s Summary names the atmosphere or hydrosphere as the reservoir of the gaseous carbon cycle (page 214), and of these two the oceans hold far more: beyond the NCERT text, the oceans hold about 38 000 gigatons of carbon, about 50 times as much as the atmosphere (NOAA National Centers for Environmental Information, public domain). Strictly, most of Earth’s carbon, about 65 500 gigatons (billion metric tons), is stored in rocks (NASA Earth Observatory, public domain), but it moves through the cycle only very slowly. The current chapter covers nutrient cycling only in its Summary, so this exercise goes a little beyond the text.
Q5. Name the two types of nutrient cycle, with the reservoir and one example of each.
Gaseous: the reservoir is the atmosphere or hydrosphere; example, carbon. Sedimentary: the reservoir is the Earth’s crust; example, phosphorus (NCERT Summary, page 214).
Q6. List the four aspects through which the components of an ecosystem function as a unit. Which of them does NCERT call the ecosystem’s input, and what makes up its output?
Productivity, decomposition, energy flow and nutrient cycling. The input is productivity; the output is degradation and energy loss, and the transfer of energy runs through food chains and webs and nutrient cycling (NCERT pages 205–206).
Q7. Name the producers, consumers and decomposers of a pond, and say where the decomposers are most abundant.
Producers: phytoplankton, some algae, and floating, submerged and marginal plants. Consumers: zooplankton and the free-swimming and bottom-dwelling forms. Decomposers: fungi, bacteria and flagellates, especially abundant at the bottom of the pond (NCERT page 206).
Q8. Which abiotic factors regulate the rate at which a whole pond functions?
The solar input, the cycle of temperature, day-length and other climatic conditions (NCERT page 206).
Q9. What are ecosystem services? Give NCERT’s example.
The products of ecosystem processes are called ecosystem services; for example, forests purify air and water (NCERT Summary, page 214).