Transcript Plant Parts
Plant Parts Chapter 1, Lesson 6 Objectives Students will: Explore the role of leaves on plants. Describe the structures and functions of roots, stems, and leaves. Contrast photosynthesis and respiration. Compare how evergreen and cactus plants survive in dry climates. What Does a Plant Need? Plants need ◦ Air ◦ Water ◦ Energy from food ◦ A place to live What Does a Plant Need? Green plants make their own food. Plants need light, water, and carbon dioxide to make food. ◦ Carbon dioxide is a gas in the air. What Does a Plant Need? Plants are made up of different parts. ◦ Leaves ◦ Stem ◦ Roots A plant needs all three parts to live, grow, and stay alive. Each part plays a role in helping a plant get or make what it needs to survive. Why are leaves important? Leaves ◦ Plants cannot live without leaves. ◦ Leaves make most of a plant’s food. What Do Leaves Do? Veins ◦ They are bundles of tubes that carry food and water in stems and roots. ◦ The veins also carry water to the leaf. ◦ They also take food from the leaf to the stem and roots. What Do Leaves Do? Epidermis ◦ A thin layer on the leaf’s top and bottom. ◦ It helps keep the leaf from losing water and drying out. Stomata ◦ On the lower epidermis are tiny openings from which gases and water vapor pass in and out. What Do Leaves Do? Transpiration ◦ A plant uses its stomata to control how quickly it loses water. ◦ Any extra water exits through the stomata in a process called transpiration. Why is a stem important? Stem ◦ Carries food, water, and other materials to and from the roots and leaves. What Is a Stem’s Job? A plant’s stem grows above the ground. It holds the leaves up to the light. What Do Stems Do? Inside a stem there are several different types of tiny tubes. They act as a transportation system, moving things up and down the stem. Vascular Tissues - transport water and food through the plant. Phloem: straw-like tubes conducting food downward in a plant. Xylem: straw-like tubes conducting water and minerals upward in a plant. Two Types of Stems There are two kinds of stems. ◦ Woody stems Shrubs and trees have woody stems. They provide extra support to these larger plants. Two Types of Stems Non-woody Stems ◦ Smaller plants have stems that are soft, green, and bendable. ◦ Plants with nonwoody stems rely on the pressure of the watery sap in their stems for support. Roots Roots They take in some of the materials a plant needs to make food. Roots grow downward into the soil. You can’t see them. They help the plant stay alive. Roots Roots do three main tasks. 1. Roots absorb water from the soil. ◦ ◦ ◦ Just like living things, they need water to stay alive. As they take in water, they absorb minerals from the soil. The minerals provide the nutrients that a plant needs to live and grow. Roots 2. Roots hold a plant in place. Without roots, a large plant might topple to the ground. A smaller plant might blow away in the wind Roots 3. Some plants use their roots to store food. Some examples include carrots, radishes, and parsnips. Many people like to eat these roots. Two Kinds of Roots Two Kinds of Roots Two Kinds of Roots Taproot ◦ Plants such as dandelions, carrots, and grapevines have taproots. ◦ They send a single large root into the soil. ◦ A grapevine’s taproot may grow as long as 49 ½ feet. Two Kinds of Roots Fibrous Roots ◦ They spread out into the surrounding soil. ◦ No one root is larger or more important than the others. ◦ Most trees have fibrous roots. ◦ Grass also has a fibrous root. Root Hairs Root Hairs. ◦ Root hairs are threadlike cells on a root. ◦ They take in water and minerals from the soil. ◦ Most plants have root hairs. How Do Plants Make Food? Chances are that you have eaten several plant foods. Just like plants, we eat food to get energy. However, plants make their own food through a process called photosynthesis. Photosynthesis During daylight a green plant uses special leaf cells containing chlorophyll to trap sunlight. There little energy is used to combine waste and carbon dioxide from the air. The result is sugar and oxygen. Photosynthesis Photosynthesis Veins carry the sugars the plant makes to all parts of the plant. These sugars give the sweet taste to fruits such as strawberries and peaches. The oxygen the plant makes goes into the air. Photosynthesis vs. Respiration They are opposites They both occur in green plants Photosynthesis ◦ It stores energy ◦ It uses carbon dioxide and gives off oxygen ◦ Occurs during bright light/daylight. ◦ The plant produces more food than it uses during respiration. Respiration ◦ Releases energy ◦ It uses oxygen and gives off carbon dioxide. ◦ Occurs at night. ◦ The plant consumes food for growth and other processes. What is Respiration? The plant stores food until it is needed. Then its cells use oxygen to break apart sugars. When sugars break apart, they give off energy. This process is called respiration. How are a Cactus and an Evergreen Different? Each fall the leaves of trees such as oaks and maples turn bright colors. During the winter the trees stay alive but are dormant: they save their energy for growth when warm weather returns in the spring. These trees drop their leaves to save water during the winter. How are a cactus and an evergreen different? Plants such as the cactus and the evergreen have other ways to prevent water loss. They both can live in places that are too dry for other plants. Cactus Designed for a hot, dry environment (desert). Its stem is often large and fleshy so it can store water. Its roots spread wide to take in water from a large area. Cactus Their leaves are sharp spines. This shape keeps the plant from losing too much water through transpiration. The sharp spines do not allow animals to eat the plant to get water stored in the stems. Evergreens They survive in cool, dry areas. Unlike the oak and maple trees, these trees and shrubs keep their leaves for 1 to 18 years. Evergreens Some evergreens have broad, flat leaves. Others, such as spruces and firs, have needle shaped leaves. They both have a thick outer layer and a coating of wax which helps reduce water loss. Why It Matters Without plants to make oxygen, people would not survive. We also use the woody stems, or trunks, of trees to build houses and furniture. Other plants provide valuable medicines. Medicinal Plants Bloodroot It has been used historically to reduce tumors. Research focusing on its role in cancer reduction is underway. Also, the main plant extract has been incorporated into toothpaste and mouthwash for years due to its ability to reduce plaque and gingivitis. Medicinal Plants Echinacea Boosts the immune system and aids the body in fighting infection. Hypericum Effective in treating mild to moderate depression. It is also effective for anxiety and insomnia. The End