OS9 Looking at Sprout Roots

Up to now I think the Investigations are pretty complete including the pictures. Starting with this Investigation there are some pictures missing because I split much larger Investigations into two different ones and made some other changes.

When you complete an Investigation, please let me know if something isn’t clear or doesn’t seem to work with the procedure I have given. This will help me fix those problems.

One thing you learn as a writer is how easy it is to see what you think you wrote instead of what you actually wrote. This is why a writer sends a book to an editor. For these Investigations, you are my editors.

Outside Project 9

Looking at Sprout Roots

No matter which way a seed points, the root still grows down into the soil as you saw in Investigation 4. A plant needs lots of water to grow and make sugar. The air is too dry so this water must come from the soil. Since the root is in the soil, it must get the water and send it to the rest of the plant. First let’s find out about how water moves through a sprout root. Then go on to Investigation 10 to see how water moves through a stem.

 

Question: How does water move through the roots of a sprout?

sprouts for Investigation

Materials:

2 Pumpkin sprouts with their first true leaves

Jar

Water

Food coloring (red or blue)

Knife

Paper towel

Magnifying glass

 

Procedure:

Preparation: You will need 2 pumpkin sprouts for this Investigation. You can use the same ones for the next Investigation if you do them the same day. You can start the seeds in a cup of dirt or you can start them in a glass jar like you did for Investigation 4. Using the glass jar lets you see how the roots grow and you don’t have to clean the dirt off.

Step 1: Open your Science Journal and write “Investigation 9” and the date.

Step 2: Put water in the jar so it is half full and add food coloring to make it dark.

sprout in colored water

When a sprout root absorbs water full of food coloring, the color goes with the water and shows where the water goes inside the root.

Step 3: Take the two sprouts out of the cup. Wash the dirt off the roots.

Step 4: Prop one sprout in the cup so the roots are in the colored water and the cotyledons and leaves are out of the water. Set it aside until color appears in a leaf. This can take up to a day.

Step 5: Set the other sprout on a moist paper towel. Examine it with the magnifying glass.

Step 6: Carefully spread the roots out and examine the roots carefully from the tip to the cotyledons. Draw and describe the roots.

sprout root

A pumpkin sprout has a main root that quickly branches off into many smaller roots.

Step 7: Cut about 1cm of the main root tip off with your fingernails or the knife. Put the rest of the sprout in a cup of water so the roots are in and the top is out of the water.

Step 8: Place the root tip on the table.

Step 9: Examine the root tip using the magnifying glass.

Step 10: Carefully split the root tip piece lengthwise and examine the cut sides with the magnifying glass.

Step 11: Take the second sprout out of the jar, rinse it, place it on a moist paper towel, carefully spread the roots and examine them with the magnifying glass.

 

colored sprout roots

Food coloring makes a sprout’s roots easier to see.

Step 12: Cut about 1cm off the main root tip. Put the rest of the sprout back in the jar with the food coloring.

Step 13: Place the cut root tip on the table.

Step 14: Examine this piece using the magnifying glass.

Step 15: Carefully split this piece lengthwise and examine the cut sides with the magnifying glass.

 

Observations:

Describe the roots on the sprout without coloring:

 

piece of sprout root

A sprout root piece shows the root has a main piece with small rootlets going off of it.

Describe the roots on the sprout from the colored water:

 

colored root piece

Food coloring starts in the small rootlets and moves into the bigger root.

Describe the tip of the roots, plain and colored:

 

Describe the tops of the roots where they join the stem, plain and colored:

 

split open sprout root

Splitting the sprout root open where it joins the stem shows the root is solid and the stem is hollow.

Conclusions:

Was it easier to see the different parts of the root with or without the coloring in the sprout? Explain.

 

What does the tip of the root do in the soil as the root grows? Why would cells here have to be different than in other parts of the radicle?

 

Why does the very tip of the root not absorb water?

 

Where are the cells that take water up the root to the plant located? Why are they located here?

 

split stem with coloring

Blue food coloring goes up through the outside parts of a sprout root so water must go up this way too.

How does the outside of the root change above where water is absorbed?

 

Why would this make it hard for this part of the root to absorb water?