Lesson Worksheet: Pathogens and Disease Biology

In this worksheet, we will practice describing examples of communicable diseases in plants and animals, and outlining their impact on society.


True or False: Most bacteria are pathogenic.

  • AFalse
  • BTrue


True or False: Globally, most human deaths are caused by communicable diseases.

  • ATrue
  • BFalse


Which of the following statements about viruses is not true?

  • AViruses can only reproduce inside a living cell.
  • BAll naturally occurring viruses are pathogenic.
  • CViruses are smaller and less complex than bacteria.
  • DViruses mutate and evolve more slowly than bacteria.
  • EBacteriophages are viruses that infect bacteria.


Cells can be prokaryotic or eukaryotic.

Which of the following types of pathogens has a prokaryotic cell structure?

  • ABacteria
  • BFungi
  • CProtoctista
  • DViruses

Not all pathogens are considered to be organisms.

Which of the following types of pathogens could be considered to be nonliving?

  • AViruses
  • BFungi
  • CBacteria
  • DProtoctista


Some diseases can be passed from animals to humans.

Which term describes a disease that normally exists in animals but can mutate and infect humans?

  • AZoonosis
  • BDiagnosis
  • CPrognosis
  • DZoology

Which pathogen has moved from animals to infect humans and caused disease?

  • AHuman influenza A
  • BCholera
  • CCOVID-19
  • DMumps


The figure compares the global mortality rates of two viral infections, influenza (flu) and COVID-19.

Using the data provided, state whether the following conclusions are true or false.

Older people are more likely to die from COVID-19 than from the flu.

  • AFalse
  • BTrue

The overall death rate from COVID-19 is higher than the flu.

  • ATrue
  • BFalse

It is not possible to make specific age comparisons using the data provided.

  • AFalse
  • BTrue


Some communicable diseases involve vectors.

What is the role of a vector in a communicable disease?

  • AIt is contaminated clothing that may cause the spread of disease.
  • BIt is an injection that makes you immune to a disease.
  • CIt is an organism that causes disease.
  • DIt is an organism that carries pathogens from one organism to another.

Malaria is a disease that affects over 200 million people every year. Controlling its vector is the key to limiting its spread. What is the vector for this disease?

  • ALice
  • BMosquitoes
  • CSand flies
  • DFleas
  • ETicks


The figure shows data from the WHO on the prevalence of tuberculosis (TB), a bacterial disease caused by Mycobacterium tuberculosis, and HIV in African countries.

What is the relationship between these two diseases?

  • AThere is no correlation between the prevalence of the two diseases.
  • BThere is a negative correlation between the prevalence of the two diseases.
  • CThere is a positive correlation between the prevalence of the two diseases.

What is an explanation for the relationship shown in the figure?

  • AHIV also infects and damages the lungs.
  • BHIV suppresses the immune system.
  • CHIV infects M. tuberculosis, making it more infectious.
  • DHIV prevents the antibiotic treatment for TB from working.


The figure shows pathogenic bacteria of different shapes.

Which letter represents Vibrio cholerae, the bacterium that causes cholera?

  • AA
  • BD
  • CB
  • DC

Which letter represents Staphylococcus aureus, the bacterium that causes MRSA infection?

  • AC
  • BB
  • CD
  • DA

Which letter represents Bacillus anthracis, the bacterium that causes anthrax?

  • AD
  • BC
  • CA
  • DB


The figure shows the life cycle of Plasmodium, the Protoctista that causes malaria. A plasmodium alternates between a mosquito and a human host.

How does this Protoctista cause damage to the cells in both hosts? Use the figure to help you.

  • ABy digesting the contents of the cells and reproducing inside them
  • BBy taking over the cells’ metabolism using its own genetic material
  • CBy releasing enzymes that digest cells
  • DBy producing toxins that poison the host cells

This lesson includes 6 additional questions for subscribers.

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