Final answer:
Bacteriophage lambda is known as a temperate phage because it can undergo both the lytic and lysogenic life cycles, giving it a strategic advantage in survival and proliferation.
Step-by-step explanation:
Bacteriophage lambda is a temperate phage, meaning that it can go through either a lytic or lysogenic life cycle. In the lytic cycle, the phage replicates and lyses the host cell. In contrast, during the lysogenic cycle, the phage DNA gets integrated into the host genome and can be passed on to successive bacterial generations as a prophage.
This dual nature offers an evolutionary advantage, allowing the phage to either multiply by killing the host or remain dormant and protect itself under unfavorable conditions, which could, for instance, enhance bacterial virulence through lysogenic conversion.