The Immune System

Question 1

Liam received a flu vaccine a few weeks ago. When a real flu virus later reaches his body, which statement most accurately describes why his body can fight it faster?

Accepted Answer

The vaccine gave Liam a safe copy of the flu germ, so his body made special cells that remember it and can attack the real flu quickly.

Answer

The vaccine removed all germs from Liam’s body, leaving none for the flu virus to infect.

Answer

The vaccine made Liam’s skin thicker, so the flu virus cannot get inside his body.

Answer

The vaccine only works after Liam actually gets the flu, because his body needs a real infection to learn.

Question 2

When Maya gets a small cut on her hand while gardening, which statement best explains how her skin helps keep her from getting sick?

Accepted Answer

The skin acts like a shield that blocks most germs from entering her body.

Answer

White‑blood cells in the skin quickly destroy any germs that get in.

Answer

The cut releases a special medicine that stops germs from growing.

Answer

The skin produces antibodies that attack germs as soon as they touch it.

Question 3

A virus has just entered Sam’s bloodstream. Which of the following best explains what the white blood cells do next?

Accepted Answer

They recognize the virus as a foreign invader and release chemicals that kill it.

Answer

They change into skin cells to cover the blood vessels and block the virus.

Answer

They wait until Sam feels sick before moving to the infected area.

Answer

They only look for bacteria, so the virus is left alone.

Try three questions

Liam received a flu vaccine a few weeks ago. When a real flu virus later reaches his body, which statement most accurately describes why his body can fight it faster?

When Maya gets a small cut on her hand while gardening, which statement best explains how her skin helps keep her from getting sick?

A virus has just entered Sam’s bloodstream. Which of the following best explains what the white blood cells do next?

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