<h2>Gram staining is a technique used to differentiate between Gram-positive and Gram-negative bacteria.</h2>
Explanation:
Gram stain color the bacteria either red or violet depending on whether they are Gram positive or Gram negative. Gram positive bacteria have thick cell wall containing peptidoglycan compared to Gram negative bacteria which have thin cell wall. Due to this Gram positive bacteria stains purple by crystal violet. So, slide containing <em>S. pyogenes</em> with purple violet indicates that it is a Gram positive bacteria.
<span>An increase in hours of television viewing leads to increases in the sales of snack foods. This is an example of a correlation hypothesis.</span>
