The light area on the left side of this photo is the Milky Way. What is the Milky Way?

1. A constellation.

   No. The Milky Way contains many more stars than a constellation.

2. A solar system.

   No. A solar system only has one star, not a huge number of stars.

3. A galaxy.

   Yes! Our solar system is part of the Milky Way galaxy. When we lived in the city, the lights made it difficult to see the Milky Way. Now that we live far from city lights, it is amazingly easy to see.

4. A universe.

   No. The Milky Way is only a small part of the entire universe.

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The "strings" in a stalk of celery are made up of xylem and phloem. Which part of your body comes closest to serving the same function?

1. Skeleton

   No. Your skeleton provides support and protection. In plants, the cell wall provides support and protection.

2. Intestines

   No. Your intestines allow you to absorb nutrients from your food. Plants make their own food, so they do not need a digestive system.

3. Nerves

   No. Your nerves carry signals to let the parts of your body communicate. They carry messages for your senses, to move your muscles, etc. Instead of having nerves, plants release chemicals that signal other parts of the plant.

4. Blood Vessels

   Yes! Your blood vessels carry water and nutrients to different parts of your body. In plants, the xylem is made up of tubes that carry water and some nutrients from the roots upwards to other parts of the plant. The phloem is made up of tubes that carry the sugar produce by photosynthesis to other parts of the plant. While they work in very different ways, your blood vessels serve basically the same function (carrying water and nutrients) as the xylem and phloem in plants.

Click to see which state standards this question tests, and which of my videos, experiments, and other resources support that topic.