Answer:
except natural killer cells.
Explanation:
The Helper T cells produce cytotoxic T cells and help B cells, but not natural killer cells
The jet stream brings down colder air from the north into the southern regions of the United States so B . southeast I think.
Answer:
The correct answer would be - "bacterial populations evolve in response to the selection pressure imposed by antibiotics".
Explanation:
The given information provided in the question about the bacterial infection supports the hypothesis that the bacterial population shows the evolution in response to the selection pressure caused by the antibiotics due to the fact that bacteria increased resistance gradually with time. This resistance towards antibiotics increased the percentage of bacterially infected children in the late 1980s and early 1990s.
In this case, the population of bacteria having resistance genes is selected to evolved selected to increase their offsprings.
These viruses – known as phages – attach to the surface of bacterial cells, inject their genetic material, and use the cells' enzymes to multiply while destroying their hosts. To defend against a phage attack, bacteria have evolved a variety of immune systems
