Botany MCQs for NEET — Practice Questions with Answers

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.'

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.

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.

The text explicitly mentions: 'in some viruses, RNA is the genetic material (for example, Tobacco Mosaic viruses, QB bacteriophage, etc.).'

The text states: 'DNA acts as the genetic material in most of the organisms. RNA though it also acts as a genetic material in some viruses, mostly functions as a messenger. RNA has additional roles as well. It functions as adapter, structural, and in some cases as a catalytic molecule.' So, genetic material storage is primarily for DNA.

The context states: 'DNA contains a five carbon sugar molecule called 2-deoxyribose whereas RNA contains ribose.' Deoxyribose sugar lacks an oxygen atom at the 2' position compared to ribose sugar.

The text mentions: 'Both DNA and RNA contain adenine, guanine and cytosine. The fourth base is thymine in DNA and uracil in RNA.'

The context states: 'Therefore, among the two nucleic acids, the DNA is a better genetic material. ... but DNA being more stable is preferred for storage of genetic information. For the transmission of genetic information, RNA is better.'

The criteria listed are: '(i) It should be able to generate its replica (Replication). (ii) It should be stable chemically and structurally. (iii) It should provide the scope for slow changes (mutation) that are required for evolution. (iv) It should be able to express itself in the form of 'Mendelian Characters’.' Direct involvement in protein synthesis as part of its primary structure is not explicitly listed as a criterion for genetic material itself, although genetic material needs to express characters.

The text states: 'But, RNA being a catalyst was reactive and hence unstable. Therefore, DNA has evolved from RNA with chemical modifications that make it more stable. DNA being double stranded and having complementary strand further resists changes by evolving a process of repair.'