Immune System - Free Printable

Let's solve this step-by-step.

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Matching the Descriptions with Correct Terms

We’ll go through each numbered description and match it with the correct term from the list (A–R).

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1. Occurs when the immune system attacks a body’s healthy cells
→ This is Autoimmune disease
✔ Answer: D

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2. The largest blood cells of the immune system living throughout the body
→ These are Macrophages, which are large white blood cells that engulf pathogens.
✔ Answer: M

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3. In charge of keeping the body safe from invading germs
→ This refers to the entire Immune system
✔ Answer: H

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4. The first defense against germs entering the body
→ The Skin acts as the first physical barrier.
✔ Answer: P

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5. Proteins produced by the body to fight germs
→ These are Antibodies
✔ Answer: B

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6. Moves in the blood seeking germs and bacteria that don’t belong
→ Lymphocytes (especially T-cells and B-cells) circulate in the blood and lymph to detect invaders.
✔ Answer: L

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7. Destroys infected cells
→ Killer T-cells (also called cytotoxic T-cells) destroy infected or abnormal cells.
✔ Answer: I

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8. Tells B-cells to start making antibodies and gives instructions to T-cells
→ Helper T-cells coordinate the immune response.
✔ Answer: G

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9. White blood cells that attack infections of the body
→ This is a general description of Lymphocytes, which include B and T cells.
✔ Answer: L

> Note: While "Macrophages" also do this, they're not strictly classified as *white blood cells* in the same way lymphocytes are. But lymphocytes are key white blood cells involved in adaptive immunity. However, Neutrophils (O) are also white blood cells that attack infections. But since “lymphocytes” are more specifically tied to adaptive immunity and the context includes B and T cells, L is best.

Wait — let’s double-check:
- Neutrophils (O): First responders, phagocytic, attack infections.
- Lymphocytes (L): Include B and T cells, involved in specific immunity.

But the phrase says “attack infections” — both do. But since neutrophils are the most abundant white blood cells that attack infections, O might be better?

However, the term "Lymphocytes" is broader and includes cells that produce antibodies and kill infected cells. But the description doesn't specify type.

Actually, Neutrophils are the primary white blood cells that attack infections via phagocytosis.

But let’s look at the options:
- O = Neutrophils
- L = Lymphocytes

Since the sentence says “white blood cells that attack infections,” and neutrophils are the most common ones doing so, O is likely correct.

But wait — earlier we used L for #6. Let’s reevaluate.

Wait — #6: “Moves in the blood seeking germs...” → That’s Lymphocytes (they circulate).
#9: “White blood cells that attack infections” → Could be Neutrophils, but also macrophages, lymphocytes, etc.

But Neutrophils are the main phagocytic white blood cells that attack infections quickly.

So #9 → O (Neutrophils)

But let’s check if M (Macrophages) could be better? Macrophages are larger and also attack infections.

But macrophages are not just in blood — they’re tissue-based. Neutrophils are the most common circulating white blood cells that attack infections.

So:

✔ #9 → O (Neutrophils)

Wait — but in many textbooks, lymphocytes are considered white blood cells that attack infections via specific immunity.

But “attack” can mean direct killing or antibody production.

But the word “attack” suggests active destruction.

So Neutrophils are best for #9.

But let’s keep going and come back.

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10. Another term for germs; the invaders of the body
→ Antigen – a substance that triggers an immune response, often a germ or part of one.
But “antigen” is not exactly “germ” — it's a molecule on the germ.

Better term? Pathogen isn’t listed.

But “antigen” is the closest, though not perfect.

Wait — actually, antigen is the molecule that the immune system recognizes, not the whole germ.

So maybe “pathogen” is the term, but it’s not listed.

But antigen is often used loosely.

Alternatively, perhaps “antigen” is acceptable.

But let’s see: Is there a better fit?

No. So C. Antigen is the best choice, even if imperfect.

But actually, antigen is not the germ itself — it’s a part of it.

So maybe this is a trick.

Wait — another possibility: “germ” is not a technical term, but the closest is antigen.

But no — antigen is what the body detects, not the invader.

The invader is the pathogen.

But “pathogen” is not listed.

So perhaps C. Antigen is intended here.

But let’s read again: “Another term for germs” — so synonym.

But antigen is not a synonym for germ.

Perhaps “microbe” or “pathogen” — but not listed.

Wait — “Antigen” is not a synonym for germ.

This might be a mistake.

Wait — “Antigen” is a molecule that causes an immune response, often from a germ.

But the term “germ” is informal.

Maybe the answer is C. Antigen — but it's not quite right.

Alternatively, “Pathogen” is missing.

But let’s look at other options.

Is there a better fit?

No.

But perhaps the question means: “What do we call the substances that germs produce that trigger immunity?” → antigen.

But it says “another term for germs.”

So perhaps the intended answer is C. Antigen, even if inaccurate.

But that’s wrong.

Wait — maybe it's “Microorganism” — not listed.

Alternatively, “invaders” — not listed.

Hmm.

Wait — perhaps “Antigen” is being used incorrectly.

But let’s skip and come back.

Wait — “Antigen” is the correct term for the substance that the immune system detects, but not the germ itself.

So maybe the question is poorly worded.

But looking at the list, C. Antigen is the only possible choice.

Alternatively, is “Virus” or something else?

No.

Wait — perhaps “Pathogen” is implied by “Antigen”?

No.

Wait — maybe the answer is C. Antigen, because antigens are found on germs.

But that’s not a synonym.

Alternatively, maybe “Germs” is meant to be “Antigens”?

But that’s not accurate.

Wait — perhaps the intended answer is C. Antigen, even if misleading.

But let’s move on.

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11. Remember the germs that previously attacked the body
→ This is Memory cells
✔ Answer: N

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12. Glands that collect and destroy bacteria/viruses before they travel through the body
→ Lymph nodes filter lymph and trap pathogens.
✔ Answer: J

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13. Controls the flow of blood throughout the body
→ This is the Circulatory system
✔ Answer: F

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14. Finds hidden germs or unhealthy cells and destroys them
→ This is Killer T-cells (cytotoxic T-cells)
✔ Answer: I

Wait — #7 was also “destroys infected cells” → also Killer T-cells.

Yes, so both 7 and 14 could be I.

But #7 is “destroys infected cells” → I
#14 is “finds hidden germs or unhealthy cells and destroys them” → also I

But can one term be used twice?

Yes, unless specified otherwise.

But let’s check — is there overlap?

Yes, Killer T-cells do both.

So both #7 and #14 → I

But wait — #7 is “destroys infected cells” → I
#14 is “finds hidden germs or unhealthy cells and destroys them” → I

So yes, both are I.

But let’s confirm.

Yes, Killer T-cells recognize and destroy infected or abnormal cells.

So both are I

But is that allowed? Yes, terms can be reused.

But let’s continue.

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15. Occurs when the immune system attacks too often, even against safe food products
→ This is Allergies — overreaction to harmless substances like food.
✔ Answer: A

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16. A weak virus that is injected into the body
→ This describes a Vaccine
✔ Answer: R

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17. Place where lymph fluid travels to different parts of the body
→ Lymph system transports lymph fluid.
✔ Answer: K

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18. Produces antibodies and are used for specific germs
→ B-cells produce antibodies.
✔ Answer: E

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Now go back to unresolved ones.

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#2: The largest blood cells of the immune system living throughout the body
→ Macrophages are large, but are they blood cells? They originate from monocytes (which are blood cells), but mature in tissues.

But macrophages are often described as large immune cells.

But are they the largest?

Neutrophils are smaller.

Monocytes are large, but macrophages are bigger.

But macrophages are not always in blood — they’re in tissues.

But the question says “living throughout the body” — so yes.

And M. Macrophages is an option.

So #2 → M

Earlier I said #2 → M — yes.

But #6: “Moves in the blood seeking germs…” → Lymphocytes, which are white blood cells that circulate.

So #6 → L

Now #9: “White blood cells that attack infections” — this could be Neutrophils (O), Macrophages (M), or Lymphocytes (L)

But Neutrophils are the most abundant and first to attack infections.

So #9 → O

But #2 is already M, so M is used.

So #9 → O (Neutrophils)

But Neutrophils are white blood cells that attack infections — yes.

Now #10: “Another term for germs; the invaders of the body”

→ Antigen? No — antigen is not a synonym.

Wait — Antigen is a molecule on the germ.

But perhaps the question means: “What do we call the substances that germs have that the body recognizes?”

Then C. Antigen is correct.

But it says “another term for germs” — so synonym.

But “antigen” is not a synonym.

Unless the question is misworded.

Wait — perhaps “Antigen” is intended.

But that’s incorrect.

Alternative: “Pathogen” — not listed.

But “Antigen” is the only possible choice.

So perhaps C. Antigen is expected.

But let’s think: Is there a better fit?

No.

So #10 → C. Antigen

Even if it’s not perfect.

Alternatively, maybe “Invader” — but not listed.

So C. Antigen

But that’s not a synonym.

Wait — perhaps the question means: “What do we call the foreign substances that germs carry?” → then antigen.

But it says “another term for germs”.

So probably a mistake.

But in some contexts, people say “antigen” for germ — but it’s wrong.

So perhaps C. Antigen is the intended answer.

Alternatively, maybe “Microbe” — not listed.

So we’ll go with C

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Now let’s compile all answers:

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✔ Final Answers:

1. D – Auto immune disease
2. M – Macrophages
3. H – Immune system
4. P – Skin
5. B – Antibodies
6. L – Lymphocytes
7. I – Killer T-cells
8. G – Helper T-cells
9. O – Neutrophils
10. C – Antigen
11. N – Memory cells
12. J – Lymph nodes
13. F – Circulatory system
14. I – Killer T-cells
15. A – Allergies
16. R – Vaccine
17. K – Lymph system
18. E – B-cells

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Now: Using your own words, describe how a vaccine works:

Answer:
A vaccine works by introducing a harmless version of a virus or bacteria (or parts of it) into the body. This could be a weakened virus, a dead virus, or just proteins from the germ. The immune system recognizes this as foreign and starts building a defense, producing antibodies and memory cells. If the person later encounters the real virus, their immune system remembers it and can quickly respond to fight it off before it causes illness.

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Final Answer Summary:

```
1. D
2. M
3. H
4. P
5. B
6. L
7. I
8. G
9. O
10. C
11. N
12. J
13. F
14. I
15. A
16. R
17. K
18. E
```

How a vaccine works:
A vaccine trains the immune system by exposing it to a safe form of a pathogen. This helps the body create antibodies and memory cells without getting sick. If the real pathogen enters later, the immune system can quickly destroy it.