Why Leaves Change Color - Super Teacher Worksheets

[Pages:7]Name: ____________________________________________

Why Leaves Change Color

By Lydia Lukidis

Every fall, you know the drill. The leaves on the trees change color from green to red, orange, and yellow. The trees become explosions of vibrant color. Eventually, the leaves turn brown and fall off the trees. Of course you know that leaves change color before winter. But do you know why?

Let's start with the basics. Trees need to eat and drink, just like us. But they don't eat food like we do. Instead, the leaves on trees use sunlight to produce food. This process is called photosynthesis. That's quite a mouthful to say! Let's take a closer look at how photosynthesis works.

Basically, the tree breathes in carbon dioxide, which is in the air around us. The tree takes in carbon dioxide through pores on its leaves. The tree also absorbs water through its roots. Every time it rains, the tree is happy!

The leaves are made up of very small cells, and inside those cells are tiny formations called chloroplasts. Each chloroplast has a green chemical that gives it its color. That green chemical is called chlorophyll. The chlorophyll is very important because it allows the photosynthesis to take place.

When the light from the sun enters the leaf, the chlorophyll absorbs the light energy. Then, oxygen is released from the leaves. That oxygen goes into the air and helps us breathe. Also, the light energy is turned into sugar that the trees use for food. That sugar is called glucose. Here's an easy way to remember this:

CARBON DIOXIDE +

WATER

SUNLIGHT

GLUCOSE +

OXYGEN

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Now let's get back to why leaves change color. During the spring and summer, there's a lot of sunlight. But once fall and winter roll around, it doesn't stay light outside as long. So, the leaves don't get as much sunlight as they used to. The chlorophyll in the leaves starts to decrease. And remember, chlorophyll gives leaves their green color. So if there is less chlorophyll, the leaves lose their green color.

So where do the other colors come from? Even though leaves look solid green, they actually have small amounts of other colors in them too. The chlorophyll is the main color and it's green. There is also "carotenoid," which makes yellow, orange, and brown. And there is "anthocyanin," which makes red and purple. When the green starts to fade, you can start to see the other colors coming out. Once the leaf runs out of food, it turns brown, dies, and eventually falls off.

Every tree is different, so the leaves change color at their own pace. And the colors depend on the temperature, the clouds, and the rain. It is different every fall. But, it is always magical.

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Name: ____________________________________________

Why Leaves Change Color

By Lydia Lukidis

1. According to the information in the article, which of the following does a plant require for photosynthesis?

a. sunlight, oxygen, and water b. carbon dioxide, water, and glucose c. water, oxygen, and carbon dioxide d. carbon dioxide, sunlight, and water

2. Identify two outputs of photosynthesis. (Hint: One of them benefits humans, and the other is a sugar.) _____________________________ and _____________________________

3. What is chlorophyll? ________________________________________________________________________________ ________________________________________________________________________________

4. Why does the amount of chlorophyll in leaves begin to decrease in the fall? ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________

5. Where do the red, orange, yellow, brown, and purple colors come from when the leaves begin to change in the fall? ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________

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Name: ____________________________________________

Why Leaves Change Color

By Lydia Lukidis

The following terms are vocabulary words from the article. Match the vocabulary word with its correct definition by writing the corresponding letter on the line.

1. ______ vibrant

a. lessen in amount or intensity

2. ______ photosynthesis 3. ______ chloroplast 4. ______ decrease 5. ______ chlorophyll 6. ______ carbon dioxide 7. ______ pores 8. ______ absorbs

b. small openings in a surface

c. a natural gas in the air that plants use for photosynthesis

d. vivid, bright

e. the smallest basic units of living organisms

f. takes in or soaks up energy, liquid, or another substance

g. gradually; not happening right away

h. a process by which green plants use sunlight to obtain food from carbon dioxide and water

9. ______ cells

i. a green pigment inside plants that helps them absorb sunlight for photosynthesis

10. ______ eventually

j. a formation inside a cell that contains chlorophyll; where photosynthesis takes place

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Name: ____________________________________________

Why Leaves Change Color

By Lydia Lukidis

In the article, "Why Leaves Change Color," you learned that the decrease of sunlight in the fall leads to the beautiful red, orange, yellow, purple, and brown colors we see on the trees all around us. On the lines below, describe what you like about autumn where you live. Does your hometown experience a visible change of seasons where you can see the leaves change color? What other things do you enjoy about autumn?

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_____________________________________________________________________________________

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_____________________________________________________________________________________

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_____________________________________________________________________________________

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ANSWER KEY

Why Leaves Change Color

By Lydia Lukidis

1. According to the information in the article, which of the following does a plant require for photosynthesis?

a. sunlight, oxygen, and water b. carbon dioxide, water, and glucose c. water, oxygen, and carbon dioxide d. carbon dioxide, sunlight, and water

2. Identify two outputs of photosynthesis. (Hint: One of them benefits humans, and the other is a sugar.)

__________o__x_y__g__e_n___________ and __________g__lu__c__o_s_e___________

3. What is chlorophyll?

___C__h_l_o__ro__p__h_y__ll__is__a__c__h_e__m__i_c__a_l__in__s_i_d_e___p_l_a__n_t_s__t_h_a__t_g__i_v_e_s__t_h__e_m___t_h__e_i_r_____ ___g_r_e__e_n___c_o__l_o_r__a_n__d__a__l_lo__w__s__p_h__o_t_o__s_y_n__t_h_e__s_i_s_t_o___o_c__c_u__r_. ___________________

4. Why does the amount of chlorophyll in leaves begin to decrease in the fall?

___T_h_e___d_a__y_s__b__e__c_o__m__e__s__h_o__r_te__r__in__t_h__e__f_a_l_l_,_a__n_d___t_h_e__d__e__c_r_e__a_s_e___in__________ ___s_u_n__l_ig__h_t__c_a__u__s_e_s__t_h_e___le__v_e__l_s_o__f_c__h__lo__r_o_p__h_y__l_l _i_n__t_h_e__l_e__a_v__e_s__t_o___________ ___le__s_s_e__n__a__s__w__e_l_l._____________________________________________________________

5. Where do the red, orange, yellow, brown, and purple colors come from when the leaves begin to change in the fall?

___T_h_e___o_t_h__e_r__c_o__l_o_r_s__a__p_p__e__a_r__w__h_e__n__t_h_e___c_h__l_o_r_o__p_h__y_l_l_l_e_v__e_l________________ ___d_e__c__re__a__s_e_s__. _T_h__e_y__c__o_m___e__f_r_o_m___c__h_e__m___ic__a_l_s__c_a__l_le__d__c__a__ro__t_e_n__o__id__s_______ ___a_n__d__a__n__th__o_c__y_a__n__in___th__a__t _h__a_v__e__b__e_e__n__i_n__t_h_e___p_l_a__n_t_a__l_l_a__lo__n__g_.___________

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ANSWER KEY

Why Leaves Change Color

By Lydia Lukidis

The following terms are vocabulary words from the article. Match the vocabulary word with its correct definition by writing the corresponding letter on the line.

1. ___d___ vibrant

a. lessen in amount or intensity

2. ___h___ photosynthesis 3. ___j___ chloroplast 4. ___a___ decrease 5. ___i___ chlorophyll 6. ___c___ carbon dioxide 7. ___b___ pores 8. ___f___ absorbs

b. small openings in a surface

c. a natural gas in the air that plants use for photosynthesis

d. vivid, bright

e. the smallest basic units of living organisms

f. takes in or soaks up energy, liquid, or another substance

g. gradually; not happening right away

h. a process by which green plants use sunlight to obtain food from carbon dioxide and water

9. ___e___ cells

i. a green pigment inside plants that helps them absorb sunlight for photosynthesis

10. ___g___ eventually

j. a formation inside a cell that contains chlorophyll; where photosynthesis takes place

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