"evolution of populations over time" is <span>represented by the base root of a phylogenetic tree</span>
Answer:
The correct answer is option C. "2+".
Explanation:
A common procedure to test for the presence of antigens is to perform an agglutination reaction by performing an antibody screen. In an agglutination reaction that is graded 2+ the red blood cells start to be broken and medium-sized agglutinates are formed. In this reaction no red blood cells are free, only agglutinates are seen at the bottom of the microtubes. The characteristics of the reaction herein described concur with an agglutination reaction that is graded 2+.
It's called chemical reaction.
(I'm not real sure)
Answer:
No harm upon ecosystems or the environment, prevention of any harmful contributions to air, water and land pollution.
Answer:
The colonies are carrying the resistance genes from plasmids
Explanation:
Bacteria can acquire beneficial characteristics that they didn’t have. One way for these is through plasmids, which ones are little fragments of DNA that usually contains resistance genes (for antibiotics, disinfectants, heavy metals, etc.) or other capacities, like the ability to use some substances (for example sugars).
In this specific situation, we already know that the plasmid carrying genes for tetracycline resistance and the <em>lacZ</em> gene.
A little explanation:
Tetracycline is an antibiotic that inhibits bacterial growth and kills the bacteria. The bacteria can “fight” to this antibiotic if it has a resistant gene, the result is that the antibiotic can’t affect the bacteria and survive. An analogy is like a Police Officer (bacteria) that have a bulletproof vest (tetracycline-resistant gene) so the bullets (tetracycline) didn’t affect the police.
In the case of X-gal, is a compound consisting primarily in one sugar called galactose. Not all bacteria can eat galactose, they need an enzyme called β- galactosidase (comes from <em>lacZ</em> gene) that helps the bacteria “eat” the sugar (cuts the sugar in little pieces so the bacteria can eat).
Then, as the bacterial colonies can grow in the medium with tetracycline and X-gal, we know that those bacteria are carrying the resistance genes for tetracycline (does not affect the bacteria) and the <em>lacZ</em> gene (bacteria produce β- galactosidase that cuts galactose). These genes are coming from the plasmids because we already know that the plasmid carries these genes and not from the exogenous DNA.
