6 public questions tagged with this topic.
Cyanobacteria were the first organisms to release oxygen through photosynthesis, transforming Earth's atmosphere.
Ref: NCERT Class 12 Biology Chapter 6: Evolution Darwinism Lamarckism and Modern Synthetic Theory
Oxygen was absent in the primitive atmosphere. The early Earth had a reducing atmosphere with gases like methane, ammonia, and water vapor.
Ref: NCERT Class 12 Biology Chapter 6: Evolution Darwinism Lamarckism and Modern Synthetic Theory
The ozone layer protects life by blocking harmful UV radiation, which was crucial for the evolution of terrestrial life.
Ref: NCERT Class 12 Biology Chapter 6: Evolution Origin of Life - Theories Miller Urey Experiment
Photosynthesis reflects key principle in quiz on section b solved pyqs, where evolutionary mechanisms shape genetic variation and adaptation. In this context, Photosynthesis aligns with experimental and theoretical evidence from population genetics, behavioral ecology and molecular phylogeny. Textbooks like Campbell Biology, Futuyma Evolution and Hartl Principles illustrate supporting data. Understanding why Photosynthesis fits helps integrate natural selection, environment.
Ref: Futuyma, Evolution, Drift and Speciation PYQs.
Photosynthesis reflects key principle in quiz on section b pyqs- origin of life, where evolutionary mechanisms shape genetic variation and adaptation. In this context, Photosynthesis aligns with experimental and theoretical evidence from population genetics, behavioral ecology and molecular phylogeny. Textbooks like Campbell Biology, Futuyma Evolution and Hartl Principles illustrate supporting data. Understanding why Photosynthesis fits helps integrate natural selection, environment.
Ref: Miller & Lazcano, J Mol Evol, Prebiotic Chemistry and RNA World.
Dry air consists of about 78.08% nitrogen by volume, approximately 20.95% oxygen, 0.93% argon, and only about 0.04% carbon dioxide. Nitrogen therefore dominates the atmosphere quantitatively. Its abundance reflects the stability of molecular nitrogen, whose strong triple bond limits rapid biological or chemical removal, although nitrogen-fixing organisms make part of it biologically available. Atmospheric inversions can trap contaminants near the surface, while wind, turbulence, precipitation, and chemical transformation determine their eventual distribution and removal. At organismal level, respiratory surfaces are especially exposed because large volumes of air contact thin, moist epithelia designed for rapid gas exchange. Sound classification links the source, atmospheric fate, exposure route, and mechanism of toxicity rather than relying only on the pollutant's name. Effective management combines cleaner fuels, emission standards, monitoring, urban planning, and protection of populations with high exposure or physiological vulnerability. The distinction is ecologically important because emission control must target either the directly released precursor or the product formed after atmospheric transport and reaction.
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
