Final answer:
Lambda phages enter the prophage state and engage in the lysogenic cycle; T4 phages infect and lyse the host cell through the lytic cycle. Hence, the correct answer is (a) Lambda, T4.
Step-by-step explanation:
Lambda phages enter the prophage state, while T4 phages burst the host cell. The correct answer to the student's question is option (a) Lambda, T4. In the lysogenic cycle, a lambda (λ) phage's DNA is integrated into the bacterial host genome, where it remains dormant and can replicate along with the host for generations. On the other hand, T4 phages act through the lytic cycle, where after the phage infects a bacterial cell, it hijacks the host cell's machinery to replicate and assemble new virus particles, which ultimately leads to the lysis or bursting of the cell to release new phages into the environment.
A good example of a phage that can employ both the lytic and lysogenic cycle is the lambda (λ) phage. Once the lambda phage's DNA integrates into the host genome and becomes a prophage, it can stay inactive within the lysogen, the host bacterium housing the prophage. However, environmental stressors such as starvation or exposure to toxic substances may trigger the prophage to excise itself from the host genome and switch to the lytic cycle, resulting in the production of new virions and the eventual lysis of the host cell.