Chapter 2 Self-test questions

. What are the five distinct groups of pathogens?

Bacteria, viruses, fungi, parasites, and prions.

Bacteria, viruses, fungi, parasites, and microorganisms.

Bacteria, fungi, viruses, endotoxins, and exotoxins.

Viruses, fungi, bacteria, prions, and endotoxins.

. Which of these statements best explains why prokaryotic organisms are so successful?

They use plasmids to reproduce, and can exist in many different environments.

They reproduce asexually and rapidly, and can transfer DNA horizontally using plasmids.

They can transfer DNA horizontally using plasmids and reproduce sexually.

They reproduce rapidly and can use a host organism to transfer DNA.

. What is the estimated weight of bacteria on and within our bodies, making up the "human biome"?

1.0kg

1.5kg

2.0kg

2.5kg

. Infection with bacteria Helicobacter pylori can lead to which of the following conditions?

Colon cancer and duodenal ulcers.

Cervical cancer, gastritis, and cold sores.

Mouth ulcers and throat cancer.

Gastritis, stomach ulcers, and stomach cancer.

. Why did Gram-staining have little practical use when it was first developed in 1884?

Because not all bacteria had been identified at that time.

Because the stain was difficult to prepare and use.

Because bacterial infections could not be treated at that time.

Because it also stained viruses.

. What prevents many fungi from causing diseases in humans?

They are multicellular and too large to infiltrate the body.

Our relatively low body temperature makes it difficult for fungal cells to grow.

Our relatively high body temperature makes it difficult for fungal cells to grow.

Our skin is too tough for fungi to penetrate easily.

. What does the phrase "viruses are obligate parasites" mean?

Viruses can reproduce sexually or asexually.

Viruses can infect parasitic organisms.

Viral illnesses are caused by parasitic organisms.

Viruses can only reproduce using the organelles in host cells.

. Why were viruses not seen until the mid-20^th Century?

They only live in host cells, and so could not be seen using microscopes.

They are too small to be seen using light microscopes.

The correct staining procedures to visualise them had not been developed.

Scientists were not aware of their existence.

. What is the definition of a pandemic?

An outbreak of disease across a very large area.

An outbreak of disease outside its usual seasonal times.

An outbreak of disease that only affects young, fit people.

An outbreak of a viral illness.

. What does the term apoptosis mean?

A form of budding used in viral reproduction.

The replication of viruses involving transport across cell. membranes in a vesicle.

Programmed cell death, for example when the host cell of a virus ruptures to release more viral particles.

The use of macrophages in viral replication.

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