Which of the following best describes the process by which a virus introduces its genetic material into a host cell?

• A. Fusion of the viral envelope with the host cell nucleus
• B. Injection of viral nucleic acid through the host cell membrane
• C. Direct uptake of the entire virus by endocytosis
• D. Release of viral proteins into the extracellular environment

Answer: (B)

Verified step by step guidance

1. Understand that viruses must deliver their genetic material into a host cell to initiate infection.
2. Recognize that the viral genetic material can be introduced by different mechanisms depending on the virus type, but the key process involves crossing the host cell membrane.
3. Evaluate each option: Fusion with the host cell nucleus is incorrect because fusion typically occurs at the plasma membrane or endosomal membrane, not directly with the nucleus.
4. Injection of viral nucleic acid through the host cell membrane is a process used by some viruses (like bacteriophages) where the viral genome is directly injected into the host cell, bypassing the cytoplasm.
5. Direct uptake of the entire virus by endocytosis is another mechanism some viruses use, but it involves internalization of the whole virus particle, not just injection of nucleic acid.