Practice free Botany NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
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.'
Secondary productivity is defined as the rate of formation of new organic matter by:
The NCERT defines secondary productivity as 'the rate of formation of new organic matter by consumers.' The summary further states, 'Secondary productivity is the rate of assimilation of food energy by the consumers.'
If an ecosystem's Gross Primary Productivity (GPP) is 1200 kcal $m^{-2}yr^{-1}$ and the respiration loss (R) by producers is 300 kcal $m^{-2}yr^{-1}$, what is the Net Primary Productivity (NPP)?
As per the formula provided in NCERT, NPP = GPP - R. Therefore, NPP = 1200 - 300 = 900 kcal $m^{-2}yr^{-1}$.
Which of the following units is commonly used to express productivity?
The NCERT states, 'It is expressed in terms of gm $^{-2}$ yr $^{-1}$ or (kcal $m^{-2}$) yr $^{-1}$ to compare the productivity of different ecosystems.' Options 1 and 2 represent standing crop or biomass, not the rate of production.
Productivity is one of the four important components of an ecosystem. The other three are:
The summary section of the NCERT chapter states, 'Productivity, decomposition, energy flow, and nutrient cycling are the four important components of an ecosystem.'
Which statement about Net Primary Productivity (NPP) is correct?
The NCERT explains, 'Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP). GPP – R = NPP.' Also, 'NPP is the remaining biomass or the energy left after utilisation of producers.'
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