Practice free Ecosystem (Botany) NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
Decomposition is largely an oxygen-requiring process. This implies that:
The NCERT states, 'Decomposition is largely an oxygen -requiring process...low temperature and anaerobiosis inhibit decomposition resulting in build up of organic materials.' This means that without oxygen, organic materials accumulate because decomposition is slowed down.
In a pond ecosystem, which organisms are primarily responsible for decomposition?
The NCERT mentions, 'The decomposers are the fungi, bacteria and flagellates especially abundant in the bottom of the pond.'
All the steps in decomposition (fragmentation, leaching, catabolism, humification, and mineralisation) operate simultaneously on the detritus. This highlights the concept of decomposition as a:
The NCERT states, 'It is important to note that all the above steps in decomposition operate simultaneously on the detritus'. This indicates a complex and integrated process rather than a strictly sequential or independent one.
What is the primary role of detritivores, such as earthworms, in the decomposition process?
The NCERT explains, 'Detritivores (e.g., earthworm) break down detritus into smaller particles. This process is called fragmentation.'
Humification and mineralisation are two crucial processes occurring during decomposition in the soil. Which order accurately represents their typical occurrence relative to the initial stages of decomposition?
The NCERT states, 'Humification leads to accumulation of a dark coloured amorphous substance called humus...The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as mineralisation.' This clearly establishes humification occurring before mineralisation of the humus.
Which of the following describes the rate of biomass production by plants during photosynthesis?
As per the NCERT text, 'Gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis.' This directly refers to the total biomass produced.
The biomass available for consumption by heterotrophs (herbivores and decomposers) is represented by:
The NCERT states, 'Net primary productivity is the available biomass for the consumption to heterotrophs (herbivores and decomposers).' It is also defined as GPP minus respiration losses (GPP - R = NPP).
The annual net primary productivity of the entire biosphere is approximately:
According to the NCERT, 'The annual net primary productivity of the whole biosphere is approximately 170 billion tons (dry weight) of organic matter.'
Despite occupying about 70 percent of the surface, the productivity of oceans is only 55 billion tons. This indicates:
The NCERT states that 'Of this, despite occupying about 70 per cent of the surface, the productivity of the oceans are only 55 billion tons. Rest of course, is on land.' Since land occupies only 30% of the surface but accounts for $170 - 55 = 115$ billion tons, its productivity per unit area is higher.
Which of the following factors plays a crucial role in determining primary productivity?
The NCERT text mentions, 'Primary productivity depends on the plant species inhabiting a particular area. It also depends on a variety of environmental factors, availability of nutrients and photosynthetic capacity of plants.'
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