Escherichia coli (E. coli) bacteria normally live in the intestines of people and animals. Most E. coli are harmless and actually are an important part of a healthy human intestinal tract.
Answer:
directional selection
Explanation:
The directional selection is a type of Darwinian selection where a particular phenotype is favored in the population, thereby modifying the allelic frequencies to increase the proportion of the favored phenotype. <em>Biston betularia</em>, also known as peppered moth, is a species that was influenced by directional selection in its recent past. Before the industrial revolution, the frequency of light-colored moths was predominant compared to the darker-colored phenotypes, because this color has higher adaptive fitness in a clean, no pollution environment, thereby light-colored moths were able to avoid predatory birds. However, during the industrial revolution, the frequency of dark-colored moths increased in response to pollution (i.e. darker environment), thereby conferring a higher adaptive fitness to darker phenotypes.
Compounds microscope is an optical instrument for forming magnifying images of small objects having an objective Len with a very short focal length. While electron microscope is a high power of microscope uses beam of electron focused by magnetic lenses instead of rays of light.
Answer:
B. Oncogene
Explanation:
A gene that makes the body cells to divide in an uncontrolled manner is called an oncogene. An oncogene is responsible for the development of tumors due to disturbed regulation of cell division. The gene src makes the cells to enter the process of cell division in response to the growth factors.
However, the mutant src gene does not require the presence of growth factors and signals the cells to enter the process of cell division even in the absence of the growth factors. Since the mutant src gene causes uncontrolled cell division, it represents an oncogene.
