Final answer:
An approximate 90% of bacteria are harmless, playing vital non-pathogenic roles, particularly in the human gut, where Bacteroides are a prevalent genus. The correct option is d.
Step-by-step explanation:
The approximate percent of all bacteria that are harmless is believed to be quite high, with many sources estimating that 90% of bacterial species do not cause disease and can be considered non-pathogenic or even beneficial to humans and the environment.
While we don't address the exact statistics of specific bacterial shapes like bacilli (rod-like) or cocci (circular), or the specific statistics of the United States' disease rate in this answer, it's important to note that bacteria significantly outnumber human cells in our bodies.
They play essential roles in our gut microbiome, with species like Bacteroides comprising a significant proportion of our gut flora and are not typically pathogenic.
Regarding the concept of decimal reduction time, this term refers to the amount of time it takes to reduce a microbial population by 90% (Option C). This is a crucial concept in microbiology that helps in understanding the effectiveness of sterilization and disinfection processes.
For the relationship between adenine and thymine in a DNA molecule, if 30% of the bases are adenine, the percentage of thymine will also be 30% (Option C), due to the base pairing rule where adenine always pairs with thymine.
In the human gut, Bacteroides are one of the most prevalent bacteria, not cyanobacteria, staphylococci, or Borrelia, as they can comprise up to 30% of the gut microbiota.
Finally, Cytophaga, Fusobacterium, and Bacteroides are classified together as the CFB group due to their shared characteristics and their role in the complex ecosystem of the human microbiome. The correct option is d.