(Book) Plant
| Site: | Learnbps |
| Class: | Grade 4 Life Science Commons |
| Book: | (Book) Plant |
| Printed by: | Guest user |
| Date: | Sunday, December 22, 2024, 9:04 PM |
Description
Introduction to Plants
It's your grandmother's birthday today. Tonight your parents are having a party for her. Everyone is helping out, even you. The table needs to be set with dinnerware. Mom is making your grandmother's favorite meal. You are helping by picking up your things and putting them away. You are almost finished when the doorbell rings. You run to the door to answer and there stands friends of your grandmother. They are here for the party.
You notice one person holding cut flowers. Another person is holding a plant. Flowers and plants are a common gift in our society.You are thinking that you would rather have a video game. Why are flowers and plants so important to us? Sure, they look nice. Might there be some other reasons? Perhaps!
Lesson Objectives
- Describe plants, their needs, and their importance.
- Describe the structure and function of roots, stems, and leaves.
Lesson Vocabulary
- leaf
- plant
- root
- stem
What Are Plants?
Plants are not like animals. Plants cannot move to find food. Instead, they must have the ability to survive where they are. They also must have the ability to make their own food. They also cannot move around to find a mate, so they have evolved unique ways to reproduce.
Needs of Plants
Plants are somewhat limited by temperature in terms of where they can grow. They need temperatures above freezing. The can survive temperatures below freezing, but cannot grow during this period of time. They also need light, carbon dioxide, and water. These are the ingredients they need to make their own food. Like most other living things, plants need oxygen. Oxygen is required for cellular respiration. In addition, plants need minerals. The minerals are required to make proteins and other organic molecules.
Importance of Plants
Life as we know it would not be possible without plants. Why are plants so important?
- Plants supply food to nearly all land organisms, including people. We mainly eat either plants or other living things that eat plants.
- Plants produce oxygen. Oxygen is needed by almost all the Earth's organisms.
- Plants absorb carbon dioxide from the air. This helps control the greenhouse effect and global warming.
- Plants recycle matter in ecosystems. For example, they are an important part of the water cycle. They take up liquid water from the soil through their roots. They release water vapor to the air from their leaves.
- Plants provide many products for human use. They include timber, medicines, dyes, oils, and rubber.
- Plants provide homes for many other living things. For example, a single tree may provide food and shelter to many species of animals.
Plant Structures
Most modern plants have several structures that help them survive and reproduce. Major structures of most plants include roots, stems, and leaves.
Roots
Roots are important organs in most modern plants. There are two types of roots. First, there are the primary roots, which grow downward. Secondly, there are the secondary roots. These roots branch out to the sides. Together, all the roots of a plant make up the plant's root system. Figure below shows two different types of plant root systems. A taproot system has a very long primary root, called a taproot. A fibrous root system has many smaller roots and no large, primary root.
The roots of plants have three major jobs.
- They must absorb water and minerals, anchor and support the plant, and store food. Roots have special features that are well suited to absorb water and dissolved minerals from the soil.
- Root systems help anchor plants to the ground. They allow plants to grow tall without falling over.
- In many plants, roots store food produced by the leaves. This process is called photosynthesis.
Two types of root systems
Stems
Stems are organs that hold plants upright. They allow plants to get the sunlight and air they need. Stems also bear leaves, flowers, cones, and smaller stems. These structures grow at points called nodes. The stem between nodes is called an internode. (See Figure.) Nodes and internodes of a stem Nodes and internode of a stem
Stems are needed for transport and storage. They carry water and minerals from roots to leaves. It carries dissolved sugar from the leaves to the rest of the plant. The stem is like an elevator for the plant. The stem allows movement from the top of the plant to the bottom and vice versa. Without this connection between roots and leaves, plants could not survive. In many plants, stems also stores food or water during cold or dry seasons.
Leaves
Leaves are the keys not only to plant life but to virtually all life on land. The primary role of leaves is to collect sunlight. This sunlight is needed for the plant to make food. Leaves vary in size, shape, and how they are arranged on stems. You can see examples of different types of leaves in Figure.
Plant leaves come in a variety of shapes and sizes
Variation in plant leaves
Each type of leaf is well suited for the plant's environment. It maximizes light exposure while conserving water. They are also reduces wind resistance. Leaves also benefit the plant in some other way in its particular habitat. For example, some leaves are divided into many smaller leaflets. This reduces wind resistance and water loss.
Leaves are basically factories for photosynthesis.
- A factory has specialized machines to produce a product. In a leaf, the "machines" are the chloroplasts.
- A factory is connected to a transportation system that supplies it with raw materials and carries away the finished product. In a leaf, transport is carried out by veins containing vascular tissue. Veins carry water and minerals to the cells of leaves. They carry away dissolved sugar.
- A factory has bricks, siding, or other external protection. A leaf is covered with dermal cells. They secrete waxy cuticle to prevent evaporation of water from the leaf.
- A factory has doors and windows to let some materials enter and leave. The surface of the leaf has tiny pores called stomata (stoma, singular). They can open and close to control the movement of gases between the leaves and the air.
What is Photosynthesis?
If a plant gets hungry, it cannot walk to a local restaurant and buy a slice of pizza. So, how does a plant get the "food" it needs to survive? Plants are producers, which means they are able to make, or produce, their own "food." They also produce the "food" for other organisms. Plants collect the energy from the sun and turn it into special chemicals. Using the energy from the sun, they produce the special chemicals using air, water and nutrients from the soil. So once again, how does a plant get the food it needs to survive? The plants is able to make its own "food" from the sun's energy, carbon dioxide from the air, and water.
Actually, almost all organisms obtain their energy from plants. For example, if a bird eats a caterpillar, then the bird gets the energy that the caterpillar. The caterpillar gets its energy from the plants it eats. So the bird indirectly gets energy from the plant. Therefore, the process of photosynthesis is central to sustaining life on Earth.
Review
Lesson Summary
- Plants feed most other organisms. They also perform many other services.
- Three organs (structures) commonly found in modern plants are roots, stems, and leaves.
Lesson Review Questions
- What are plants? What do plants need?
- How do plants grow?
- Outline the general life cycle of a plant.
Apply Concepts - Choose one of the three main organs of plants: roots, stems, or leaves. State the primary function of the organ, and then explain how the organ's structure suits it for its function.
Think Critically - Why would life as we know it be impossible without plants?