Which fact is the reason a virus is not counted as a living cell?

A student examines a bacterium and a bacteriophage at high magnification. Which structure is present in the bacterium but absent from the phage?

Why is it wrong to describe a virus as 'a very small bacterium'?

Which process can a bacterium carry out that a virus particle cannot?

A lab technician grows bacteria on a plate of nutrient agar, but the same plate will not grow influenza virus. What is the biological reason?

Which list puts an animal cell, a bacterium and an influenza virus in order from largest to smallest?

Which feature does a virus particle share with a living cell?

Most viruses are too small to be seen with an ordinary light microscope in a school lab.

Which part of a virus determines which host cells it is able to enter?

What does the capsid of a virus do?

Which statement about the genetic material of viruses is accurate?

Influenza and HIV are wrapped in a lipid envelope taken from the membrane of the last cell they left. What does that envelope explain?

A bacteriophage has a head, a tail sheath and tail fibers. Which part makes the first contact with the surface of the bacterium?

Which structure would you never find inside a virus particle?

The diagram shows the lysogenic cycle with one step replaced by a question mark. Which event belongs there?

In the diagram, one arrow leaves the question mark and another arrow returns to the same place from it. What happens at the question mark?

The question mark in the diagram sits on the path that leads to the cell bursting. Which event belongs at the question mark?

One box in the lytic cycle diagram has been left blank. Which stage belongs in it?

The last box of the lytic cycle diagram is blank. What happens at that stage?

A blank box sits between the injection of the viral nucleic acid and the assembly of new particles. What is happening in it?

Which statement correctly compares the lytic and lysogenic cycles?

In the lysogenic cycle, which event comes immediately after the viral DNA joins the bacterial chromosome?

Which sequence gives the stages of the lytic cycle in the correct order?

The first box of the diagram is blank. Which event must go there?

According to the diagram, what happens between attachment and the copying of viral parts?

In the diagram, which event fills the question mark that follows attachment?

The final step of the diagram is marked with a question mark. What happens there?

A patient's cold sore virus produces no symptoms for months and then flares up again. Which explanation fits what is known about viral cycles?

HIV infects human helper T cells but not human skin cells, even though both carry the same DNA. What accounts for the difference?

Tobacco mosaic virus destroys the leaves of tobacco and tomato plants, but a farmer working in the field does not catch it. Why not?

A bacteriophage added to a mixed culture destroys one species of bacterium and leaves the others untouched. What is the best explanation?

Every virus is wrapped in a lipid envelope taken from a host cell's membrane.

A doctor will not prescribe an antibiotic for a patient with influenza. What is the biological reason?

The influenza vaccine is reformulated almost every year, while the measles vaccine is not. What explains the difference?

How does a vaccine protect a person from a viral disease?

Public health advice during a flu outbreak is to cover coughs and wash hands often. Which route of transmission is that advice aimed at?

A person can pass influenza to someone else on the day before their own symptoms appear.

In one town, 240 people caught measles in a month, against a usual total of 2 a year. Which term describes what happened?

An antiviral drug can slow a viral infection, while an antibiotic cannot. What do antiviral drugs actually interfere with?

In a school where almost every student is vaccinated against measles, one unvaccinated student who catches it infects no one else. Why does the outbreak stop?