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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.'
David Tilman's long-term ecosystem experiments using outdoor plots suggested that:
From the 'BIODIVERSITY AND CONSERVATION' chapter, it's mentioned that 'Tilman found that plots with more species showed less year-to-year variation in total biomass. He also showed that in his experiments, increased diversity contributed to higher productivity.'
Primary productivity varies in different types of ecosystems due to various factors. Which of the following is NOT specified as a key factor influencing it?
The NCERT states, '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.' Consumption by secondary consumers affects energy flow and biomass at higher trophic levels, not directly primary productivity.
Which of the following is NOT a characteristic of RNA that makes it less stable compared to DNA?
The context states: 'Further, 2'-OH group present at every nucleotide in RNA is a reactive group and makes RNA labile and easily degradable. RNA is also now known to be catalytic, hence reactive. Therefore, DNA chemically is less reactive and structurally more stable when compared to RNA.' Also, single-stranded molecules are generally less stable than double-stranded ones. However, the presence of uracil instead of thymine does not make it less stable; rather, the presence of thymine confers additional stability to DNA itself, indirectly suggesting uracil's presence in RNA doesn't inherently make it unstable compared to its other characteristics.
In certain viruses, RNA functions as the genetic material. An example given in the text is:
The text explicitly mentions: 'in some viruses, RNA is the genetic material (for example, Tobacco Mosaic viruses, QB bacteriophage, etc.).'
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