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:
a.Many mitochondrial genes resemble proteobacteria genes, while the genes in the chloroplast resemble genes found in some photosynthetic bacteria.
c.Mitochondria and chloroplasts both have their own circular DNA and 70S ribosomes that are similar to those found in bacteria.
d.Mitochondria and chloroplasts replicate by a process similar to mitosis.
Explanation:
Endosymbiotic theory states that mitochondria and chloroplast which are organelles of eukaryotic cells were once independently living micro-organisms but with due course of time eukaryotic cells engulfed them and they become an integral part of these eukaryotic cells.
The resemblance between mitochondrial genes with those of proteobacteria and chloroplast genes with photosynthetic bacteria strongly support endosymbiotic theory. Apart from this, the presence of their own DNA that too circular just like prokaryotic microbes and 70 S ribosomes also support this theory. Also just like prokaryotic cells, before cell division mitochondria and chloroplasts undergo replication by means of a process known as binary fission.
Answer:
Most restriction enzymes recognize sequences of 20-25 bp in length
Explanation:
Sequences of DNA that are recognized by restriction enzymes are called recognition (or restriction) sites are usually are between 4 and 8 bases long. Many of them are palindromic, which means that they are the same when you read it backwards and forwards (mirror-like).
Restriction enzymes are endonucleases, which means they cut phosphodiiester bonds within DNA. These enzymes are from prokaryotic organisms (archea and bacteria) which use them as defending mechanism against viruses. Prokaryotes protect their own DNA via methylation, performed by methyltransferase.
Answer: false
the faster a river goes the more sediment it will carry cuz the current will be stronger there for lifting and carrying more sediment
