Answer:
The shortcomings or drawbacks of cell theory are: Viruses are considered as acellular entities or organisms that do not have cell machinery, yet they are taken into account as organisms in this cell theory. Matthias Schleiden and Theodor Schwann did not know the mechanism of the cell.
Explanation:
Answer:
B) Nitrogen-fixing bacteria and lightning
Explanation:
Nitrogen cycle is the natural process in which atmospheric nitrogen is converted into nitrite and nitrate with the help of bacteria.
Nitrogen cycle is directly dependent on nitrogen-fixing bacteria and lightning.
As bacteria are responsible for most of the chemical conversion in the nitrogen cycle such as nitrogen fixation (first step) is done by soil bacteria (Cyanobacteria) that form ammonia, which is toxic to plants; nitrification in which ammonia is converted into nitrites and nitrates with the help of Nitrobacter and denitrification bacteria involve Pseudomonas, and Achromobacter which convert nitrite and nitrate into nitrogen.
The lightning breaks nitrogen molecules and allow it to combine with oxygen in atmosphere which further dissolve in rain and form nitrates.
Hence, the nitrogen cycle is most directly dependent upon nitrogen-fixing bacteria and lightning and the correct option is B.
Answer:
E. Variations in Earth's orbit occur gradually over 100,000 years.
The right answer is A.
Osmosis is a phenomenon that considers only the exchanges between two liquid solutions of different concentrations in liquid phases separated by a semi-permeable wall. Osmosis is a phenomenon of diffusion of matter, demonstrated when solvent molecules pass through a semi-permeable membrane separating two solutions whose solute concentrations are different; the overall transfer of solvent is then from the least concentrated solution (hypotonic medium) to the most concentrated solution (hypertonic medium) to equilibrium (isotonic media).
The diffusion of matter, or chemical diffusion, refers to the natural tendency of a system to render uniform the chemical potential of each of the chemical species it contains.
Chemical diffusion is an irreversible transport phenomenon that tends to homogenize the composition of the medium.
Photosynthesis puts oxygen in the atmosphere.
