Sect 12.1

6th Grade Science

Chapter 12 Plant

Processes

Notes Section

12.1

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• What raw materials do leaves take in?• Leaves take in carbon dioxide that is used in

photosynthesis.• What are the waste products of photosynthesis

and respiration?• Oxygen is the waste product of photosynthesis.

Carbon dioxide is the waste product of respiration.

Key Questions 1

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• Where is most of the plant’s food made?• Most of the plant’s food is made in the palisade

layer.• Why are chloroplasts green?• Chloroplasts are green because they contain the

green pigment chlorophyll.

Key Questions 2

The Tadpole Galaxy

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In fall, the chlorophyll in some leaves breaks down and the leaves change color as other pigments become visible.

• What is a pigment?• A pigment is a substance that reflects a particular

part of the visible spectrum. Green leaves absorb all the colors of the rainbow except green.

• Where is the plant’s excess sugar stored?• Excess sugar produced in the leaves of a carrot

are stored in the orange root.

Key Questions 3

The Sombrero Galaxy

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• Photosynthesis occurs only in a carrot plant’s lacy green leaves.

• Excess sugar produced in the leaves is stored in the familiar orange root that you and many animals eat.

• Besides light, plants also need the raw materials carbon dioxide and water for photosynthesis.

• The overall chemical equation for photosynthesis is shown.

• Reactions that don’t need light are called the light-independent reactions of photosynthesis.

• The light energy trapped during the light-dependent reactions is used to combine carbon dioxide and hydrogen to make sugars.

• One important sugar that is made is glucose. The chemical bonds that hold glucose and other sugars together are stored energy.

Light-Independent Reactions

• During light-dependent reactions, chlorophyll and other pigments trap light energy that eventually will be stored in sugar molecules.

• Light energy causes water molecules, which were taken up by the roots, to split into oxygen and hydrogen.

• The oxygen leaves the plant through the stomata.

• Hydrogen produced when water is split is used in photosynthesis reactions that occur when there is no light.

Light-Dependent Reactions

• What is the main form of food for plant cells?• Glucose is the main form of food for plant cells

and the basis of a plant’s structure.• What is respiration?• Respiration is a series of chemical reactions that

breaks down food molecules and releases energy.

Key Questions 4

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1. Describe how gasses enter and exit a leaf.2. Explain why photosynthesis and respiration are

important.3. Identify what must happen to glucose molecules before

respiration begins.4. Compare and contrast the number of organisms that

respire and the number that photosynthesize5. Humidity is water vapor in the air. Infer how plants

contribute to humidity.

Questions Section 12.1

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