LyfeLabz Biology Review Lab | Extension: Are Viruses Alive?

Background

First: What Even Is a Virus? 🤔

Before you can decide if a virus is alive, you need to know what it actually is. Viruses are unlike anything else you've studied so far.

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Genetic Material

Every virus contains either DNA or RNA — the same kind of genetic instructions found in living cells. This is the "blueprint" it uses to make copies of itself.

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Protein Coat (Capsid)

The genetic material is wrapped in a protective protein shell called a capsid. That's it — no cytoplasm, no organelles, no nucleus.

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Incredibly Tiny

Viruses are about 100× smaller than a typical bacterium. They are so small they cannot be seen with a regular light microscope — only an electron microscope can reveal them.

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Host-Dependent

A virus cannot do anything on its own. It must invade a living cell (called a host cell) and hijack that cell's machinery to replicate. Outside a host, it just sits there.

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Incredibly Common

Viruses infect every type of life on Earth — animals, plants, fungi, and even bacteria. You've already encountered viruses: the flu, the common cold, and COVID-19 are all caused by viruses.

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The Big Question

Scientists disagree about whether viruses are alive. They have some life-like features — but they also break almost every rule of life. That's what you're here to investigate.

Extension Task

Virus vs. The 6 Characteristics of Life ✅

Use the checklist below. For each characteristic, decide if a virus clearly meets it, clearly does not meet it, or only shows it in a limited way.

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1) Made of Cells

Viruses are not made of cells. They are genetic material inside a protein coat.

Does Not Meet

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2) Obtain and Use Energy

Viruses do not carry out metabolism. They do not make ATP on their own.

Does Not Meet

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3) Grow and Develop

Viruses do not grow by getting bigger. New viruses are assembled inside a host cell.

Does Not Meet

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4) Reproduce

Viruses can increase in number, but only inside a host cell using the host cell machinery.

Only With a Host

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5) Respond to Stimuli

Viruses can react to conditions (like attaching to specific receptors), but they do not sense and respond like cells.

Limited

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6) Maintain Homeostasis

Viruses do not regulate an internal environment because they are not cells.

Does Not Meet

So what is the verdict?

Many scientists describe viruses as being on the border between living and nonliving. For this class, you can defend either side, as long as you use evidence from the checklist and explain your reasoning.

Are Viruses Alive? 🦠

First: What Even Is a Virus? 🤔

Virus vs. The 6 Characteristics of Life ✅

So what is the verdict?

Virus Reasoning Quiz 🧠