Final answer:
The correct way to combine the sentences is option B) 'Some bacteria are harmful, but some are helpful.' This reflects the dual nature of bacteria in relation to humans, where they can be either beneficial or detrimental.
Step-by-step explanation:
To combine the sentences 'Some bacteria are harmful.' and 'Some are helpful.' into one sentence, the correct option would be B) Some bacteria are harmful, but some are helpful. This option correctly acknowledges that there are different types of bacteria with varying effects on humans and ecosystems.
Bacteria and humans have complex interactions, with some bacteria playing beneficial roles such as aiding in digestion, producing vitamins, or decomposing organic material, which are examples of mutualistic or commensalistic relationships. On the opposite end, there are also bacteria that can cause diseases, and these participate in parasitic relationships, where they benefit at the expense of harming the human host.
While discussing such topics, it's important to recognize that the majority of bacteria are either benign or beneficial to humans, and only a minority are pathogenic.
When combining the sentences "Some bacteria are harmful" and "Some are helpful," we can use the conjunction "but" to show the contrast between the two statements. This creates a compound sentence that accurately conveys the information in both original sentences. The combined sentence would be: "Some bacteria are harmful, but some are helpful."