This morning, I went to the school playground to clean. Because it is early autumn, the leaves of the buttonwood tree keep falling. I happened to find an interesting phenomenon, that is, most of the leaves of buttonwood trees that fell to the ground were upward? Why is this?

Make a guess

I picked up a fallen leaf from the ground and observed it carefully: I saw that the leaf surface was smooth, but the back was very rough. I guess: Could it be that the leaf surface density is high and the leaf back density is low? Because of the gravity of the earth, when a leaf falls to the ground, its dense side hits the ground first and its back is up. When I got home, I told my mother about this discovery. My mother said, "Your guess has some truth, but it must be verified by experiments." With the help of my mother, I began to take action.

Experimental process

Start with a haircut.

I first found some thick sketch paper to draw, then asked my mother for some thin colored paper, then cut it into the shape of leaves, and then coated glue on a thick paper leaf and a thin paper leaf respectively, overlapping them and sticking them together. In this way, a * * * made 20 double paper leaves.

Go upstairs and throw it away.

Holding these 20 paper leaves tightly, I climbed to the third floor of the school. My mother stood downstairs and shouted, "One, two, three, throw!" " "I immediately loosen the palm of your hand and scatter the paper leaves in my hand into the air. I saw paper leaves floating lightly to the earth like beautiful butterflies, colorful and beautiful, attracting a group of students who were watching.

Count carefully.

I ran downstairs and began to count carefully. I dropped 20 paper leaves, of which 18 was cut with thick sketch paper, with one side facing up. I am so excited! Mom said, "An experiment doesn't mean anything. Do the same experiment at least three times. " So, I picked up the paper leaves on the ground and ran to the third floor again to start the second and third rounds of experiments.

Make a note.

I recorded the results of three experiments:

The number of leaves in the paper decreased in the number of experiments, and the thick sketch paper had one side up.

First time 20 18

Second 20 19

Third 20 17

Think about it.

According to the statistical results of three times, every time 20 leaves are dropped, the average probability of thick sketch paper facing upwards is 18. Therefore, my guess is reasonable. The back of the fallen leaves must be lighter than the front.

Take another look.

Teacher Ma, who teaches our science class, is very interested in my little research. In order to verify my idea again, he offered to lend me a microscope and instructed me to further observe the tissue structure of fallen leaves. I observed through a microscope that the cells on the leaf surface were rectangular and arranged regularly; The cells on the back are huge and irregularly arranged.

Check online.

Take me online to check the information right away. The data says: "The cells on the surface of leaves are called palisade tissue; The cells on the back of leaves are called spongy tissue. The palisade tissue is closely arranged and contains a lot of chlorophyll. They are mainly used to receive light energy and produce a large number of high-density organic substances by using carbon dioxide in the air. The sea tissue is loosely arranged, with less chlorophyll, which is mainly used to store products and water in plants, and the density is low. Therefore, not only the color of the leaf surface is usually brighter than that of the back of the leaf, but also its weight is relatively large. "

come to a conclusion

Haha, now I finally understand: most of the fallen leaves of plants are with their backs up and their leaves down. This is not a trick played by autumn wind, but the special internal structure of leaves.

picture information

Sweeping the fallen leaves on campus early in the morning, I found a strange phenomenon.

Why do most fallen leaves face upwards?

I use thick sketch paper and colored tissue paper to make paper leaves.

Count, one * * * made 20 pieces.

I threw 20 leaves from the stairs.

Wow! Miracle happened, most of the paper leaves are thick sketch paper, with one side facing up.

Collect a fallen leaf as a specimen and want to observe the structure of the leaf carefully.

Haha, I finally see the different structures of leaf cells and back cells.