A free printable microbiology worksheet for Grade 11 biology.
Students label a bacterial cell and a bacteriophage, compare viruses and bacteria feature by feature, identify bacterial shapes and arrangements, order the steps of the lytic cycle, explain the lysogenic cycle, and apply their knowledge to antibiotics and antibiotic resistance. Includes 30 questions (27 marks), word banks and a full answer key.
This free viruses and bacteria worksheet helps Grade 11 students see why a bacterium and a virus are completely different things, even though both can make us sick. Students label a drawn bacterial cell and a bacteriophage, then compare the two feature by feature.
The sheet goes on to bacterial shapes, the lytic and lysogenic cycles, antibiotics and antibiotic resistance, and two common misconceptions. The answer key gives every label, a completed comparison table and model answers for the written questions.
It supports the Ontario Grade 11 biology curriculum expectations on microorganisms in the Diversity of Living Things unit. Word banks are included for both labelling tasks.
Viruses vs Bacteria: The Key Differences
Feature
Bacteria
Viruses
Is it a cell?
Yes, a single prokaryotic cell
No, not made of cells
Approximate size
1–10 µm (seen with a light microscope)
20–300 nm (needs an electron microscope)
Genetic material
Circular DNA (nucleoid) plus plasmids
DNA or RNA, never both, inside a capsid
Ribosomes and metabolism
Has ribosomes; carries out its own metabolism
No ribosomes; uses the host cell’s machinery
How it reproduces
On its own, by binary fission
Only inside a host cell (lytic or lysogenic cycle)
Treated with antibiotics?
Yes, often
No; prevented with vaccines, some treated with antivirals
This is the completed version of the Part C table on the viruses and bacteria worksheet. The single biggest idea is that bacteria are cells and viruses are not. Almost every other difference follows from that. For a deeper look at viral structure, see Virus on Wikipedia.
Structure of a Bacterium and a Virus
A bacterium is a prokaryotic cell: it has no nucleus, so its circular chromosome sits in a region called the nucleoid. Outside the cell membrane is a cell wall, often wrapped in a sticky capsule. Many bacteria also have small DNA loops called plasmids, hair-like pili for attaching, and a whip-like flagellum for moving.
A bacteriophage is a virus that infects bacteria. Its genetic material sits inside a protein capsid. The tail sheath contracts to inject the DNA, and tail fibres grip the host cell's surface.
Bacteria are also identified by shape: cocci are spheres, bacilli are rods and spirilla are spirals. The prefix strepto- means chains and staphylo- means clusters. To practise sorting organisms into groups, try the dichotomous key worksheet.
The Lytic and Lysogenic Cycles
In the lytic cycle, a virus attaches to a host cell, injects its DNA, takes over the cell to copy itself, assembles new viruses and bursts the cell open. In the lysogenic cycle, the viral DNA joins the host chromosome as a prophage and is copied every time the cell divides, without harming it, until a trigger switches it into the lytic cycle.
That is why some viral infections, such as cold sores, keep coming back. Part E of the viruses and bacteria worksheet asks students to put the lytic steps in order and apply the idea to cold sores.
Viruses and Bacteria Worksheet Practice Questions
These questions match the viruses and bacteria worksheet PDF, which has the full-size diagrams, word banks and ruled answer space.
Parts A and B – Labelling
Questions 1–12: label the eight parts of the bacterial cell and the four parts of the bacteriophage shown above.
Part C – Compare Bacteria and Viruses
Questions 13–18: for each feature in the table above, describe bacteria and viruses.
Part D – Identify the Bacterial Shape
Questions 19–22: name each sample using its shape and arrangement.
Sample ASample BSample CSample D
Part E – The Lytic and Lysogenic Cycles
P – Assembly: new capsids and DNA are put together into new viruses
Q – Attachment: the virus binds to receptors on the host cell
R – Lysis: the cell bursts and releases the new viruses
S – Replication: the host cell copies viral DNA and makes viral proteins
T – Entry: the virus injects its DNA into the host cell
Put the steps of the lytic cycle in order using the letters.
How is the lysogenic cycle different from the lytic cycle?
Cold sores often return during stress or illness. Explain why, using what you know about viral cycles.
Part F – Antibiotics and Helpful Bacteria
Why do antibiotics work on bacteria but not on viruses?
Explain how a population of bacteria becomes resistant to an antibiotic. (2 marks)
Give two ways bacteria are helpful to humans or ecosystems. (2 marks)
Part G – Spot the Mistake
A student writes: “Viruses are the smallest living cells.” Explain the error and correct it.
A student says: “I have the flu, so my doctor should give me antibiotics.” Explain the error and correct it.
Viruses and Bacteria Worksheet Answer Key
Open each part of the viruses and bacteria worksheet answers to check your work. The printable key is at the end of the PDF.
Part A answers (Q1–8)
Capsule
Pilus
Cell wall
Cell membrane
Ribosome
Nucleoid (circular DNA)
Plasmid
Flagellum
Part B answers (Q9–12)
Capsid (protein coat)
Nucleic acid (DNA)
Tail sheath
Tail fibres
Part C answers (Q13–18)
Is it a cell?: bacteria – Yes, a single prokaryotic cell; viruses – No, not made of cells
Approximate size: bacteria – 1–10 µm (seen with a light microscope); viruses – 20–300 nm (needs an electron microscope)
Genetic material: bacteria – Circular DNA (nucleoid) plus plasmids; viruses – DNA or RNA, never both, inside a capsid
Ribosomes and metabolism: bacteria – Has ribosomes; carries out its own metabolism; viruses – No ribosomes; uses the host cell’s machinery
How it reproduces: bacteria – On its own, by binary fission; viruses – Only inside a host cell (lytic or lysogenic cycle)
Treated with antibiotics?: bacteria – Yes, often; viruses – No; prevented with vaccines, some treated with antivirals
Part D answers (Q19–22)
Streptococcus (cocci in chains)
Staphylococcus (cocci in clusters)
Bacillus (rod-shaped)
Spirillum (spiral)
Part E answers (Q23–25)
Q → T → S → P → R (attachment, entry, replication, assembly, lysis)
Viral DNA joins the host chromosome as a prophage and is copied each time the cell divides. No new viruses are made and the cell is not killed until a trigger switches it to the lytic cycle.
The herpes simplex virus stays dormant in nerve cells, similar to the lysogenic cycle. Stress or illness triggers it to enter the lytic cycle, making new viruses and a new cold sore.
Part F answers (Q26–28)
Antibiotics target structures and processes only bacteria have, such as cell walls and bacterial ribosomes. Viruses have no cell wall, ribosomes or metabolism of their own, so there is nothing to attack.
Random mutations give a few bacteria resistance. The antibiotic kills the non-resistant bacteria, and the resistant survivors reproduce by binary fission (and can share resistance genes on plasmids), so the population becomes mostly resistant. Overuse and unfinished courses speed this up.
Any two: digest food and make vitamin K in the gut; decompose dead matter and recycle nutrients; fix nitrogen in root nodules; make foods such as yogurt and cheese; produce insulin through genetic engineering.
Part G answers (Q29–30)
Viruses are not cells and are not usually considered living. They cannot reproduce or carry out metabolism outside a host cell.
The flu is caused by a virus, and antibiotics only work on bacteria. Rest and fluids help; the flu vaccine prevents it and antivirals can shorten it.
4 Common Misconceptions About Viruses and Bacteria
Part G of the viruses and bacteria worksheet targets the first two.
"Viruses are tiny bacteria." They are not cells at all, and they are roughly 10 to 100 times smaller.
"Antibiotics cure colds and flu." Both are viral. Antibiotics only work on bacteria, and overusing them drives resistance.
"All bacteria are harmful." Most are harmless or helpful: gut bacteria, decomposers and nitrogen-fixers keep us and ecosystems running.
"Resistant bacteria are created by the antibiotic." The resistance comes from random mutations that already exist; the antibiotic just removes the competition.
How to Use This Viruses and Bacteria Worksheet in Class
Lesson 1: Parts A–D of the viruses and bacteria worksheet, after introducing prokaryotic cells and virus structure.
Lesson 2: Parts E–G with the viral cycles and antibiotic resistance.
Discussion: Question 27 on antibiotic resistance makes a strong link to natural selection.
Yes. The worksheet and its answer key are free to download and print as a PDF, with no account needed.
What is the main difference between viruses and bacteria?
Bacteria are living single cells that reproduce on their own by binary fission. Viruses are not cells; they are DNA or RNA inside a protein coat and can only reproduce inside a host cell.
Why don't antibiotics work on viruses?
Antibiotics attack bacterial structures such as cell walls and bacterial ribosomes. Viruses have neither, so antibiotics have nothing to target. Viral diseases are prevented with vaccines and some are treated with antiviral drugs.
What is the difference between the lytic and lysogenic cycles?
In the lytic cycle a virus takes over the cell, makes new viruses and bursts the cell. In the lysogenic cycle the viral DNA joins the host chromosome as a prophage and is copied quietly until it switches to the lytic cycle.
What grade is this viruses and bacteria worksheet for?
It is written for Grade 11 biology (the Diversity of Living Things unit) and also suits Grade 9–10 science extension.
Ready to start? Download the free viruses and bacteria worksheet PDF (use the Download button above), print it double-sided, and keep the answer key pages for marking.