Plant viruses can’t penetrate intact plant cells because (a) ________; therefore, they enter cells by (b) ________. Plant viruses can be cultured in (c) ________.

Verified step by step guidance

1. Step 1: Understand why plant viruses cannot penetrate intact plant cells. Plant cells have a rigid cell wall made of cellulose, which acts as a physical barrier preventing direct viral entry. So, for part (a), the answer relates to the presence of this cell wall.
2. Step 2: Consider how plant viruses gain entry into plant cells despite the cell wall barrier. They typically enter through mechanical damage or via vectors such as insects that breach the cell wall, allowing the virus to access the cell interior. This explains part (b).
3. Step 3: Identify the common methods used to culture plant viruses. Unlike animal viruses, plant viruses cannot be cultured in standard cell cultures. Instead, they are often cultured in whole plants or plant tissue cultures, which provide the necessary living cells for viral replication. This addresses part (c).
4. Step 4: Summarize the answers by linking the concepts: (a) the cell wall prevents penetration, (b) viruses enter through wounds or vectors, and (c) viruses are cultured in living plants or plant tissue cultures.
5. Step 5: Review the biological reasoning behind each part to ensure a clear understanding of plant virus infection mechanisms and culture methods.

Key Concepts

Plant Cell Wall as a Barrier

Plant cells have a rigid cell wall made of cellulose that protects them and prevents direct entry of viruses. This physical barrier blocks viruses from penetrating intact cells, unlike animal cells which lack such a wall.

Mechanisms of Virus Entry into Plant Cells

Since plant viruses cannot penetrate the cell wall, they enter cells through mechanical damage or via vectors like insects that breach the cell wall. This indirect entry allows viruses to infect plant tissues.

Culturing Plant Viruses

Plant viruses cannot be cultured in standard cell cultures; instead, they are propagated in living plants or plant tissue cultures. This is because viruses require living host cells to replicate, and plant viruses need intact plant systems.