2Objectives 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.
3What Does a Plant Need? Plants need Air Water Energy from food A place to live
4What 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.
5What Does a Plant Need? Plants are made up of different parts. LeavesStemRootsA 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.
6Why are leaves important? Plants cannot live without leaves.Leaves make most of a plant’s food.
7What Do Leaves Do?VeinsThey 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.
8What 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.StomataOn the lower epidermis are tiny openings from which gases and water vapor pass in and out.
9What 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.
10Why is a stem important? Stem Carries food, water, and other materials to and from the roots and leaves.
11What Is a Stem’s Job? A plant’s stem grows above the ground. It holds the leaves up to the light.
12What 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.
13Two 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.
14Two Types of Stems Non-woody Stems Smaller plants have stems that are soft, green, and bendable.Plants with non- woody stems rely on the pressure of the watery sap in their stems for support.
15RootsRoots 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.
16Roots 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.
17Roots Without roots, a large plant might topple to the ground. 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
18Roots Some examples include carrots, radishes, and parsnips. 3. Some plants use their roots to store food.Some examples include carrots, radishes, and parsnips.Many people like to eat these roots.
21Two 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.
22Two 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.
23Root 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.
24How 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.
25PhotosynthesisDuring 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.
27PhotosynthesisVeins 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.
28Photosynthesis vs. Respiration They are opposites They both occur in green plants It stores energyIt uses carbon dioxide and gives off oxygenOccurs during bright light/daylight.The plant produces more food than it uses during respiration.RespirationReleases energyIt uses oxygen and gives off carbon dioxide.Occurs at night.The plant consumes food for growth and other processes.
29What 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.
30How 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.
31How 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.
32Cactus Its roots spread wide to take in water from a large area. Designed for a hot, dry environment (desert).Its stem is often large and fleshy so it can store water.
33CactusThis shape keeps the plant from losing too much water through transpiration.Their leaves are sharp spines.The sharp spines do not allow animals to eat the plant to get water stored in the stems.
34Evergreens They survive in cool, dry areas. Unlike the oak and maple trees, these trees and shrubs keep their leaves for 1 to 18 years.
35EvergreensOthers, 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.Some evergreens have broad, flat leaves.
36Why It Matters Other plants provide valuable medicines. 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.
37Medicinal 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.
38Medicinal Plants Echinacea Boosts the immune system and aids the body in fighting infection.HypericumEffective in treating mild to moderate depression.It is also effective for anxiety and insomnia.