In this chapter, students will explore the captivating world of gardens and the diverse range of plants that inhabit them. They will discover various types of plants, including grasses, bushes, flowering plants, and majestic coconut trees.
The focus of this chapter is to learn how to classify these plants based on their characteristics. Furthermore, students will delve into the study of different plant parts such as leaves, stems, roots, and flowers, gaining a comprehensive understanding of their structures and functions.
CBSE Class 6 Science Notes Chapter 7 Getting to Know Plants
The different topics covered in CBSE Class 6 Science Chapter 7 are tabulated below:
|7.1||Herbs, Shrubs and Trees|
Plants are living organisms that thrive on land or in water, adapting to various environments ranging from snowy mountain slopes to arid deserts.
Plants can be categorized into two main groups:
(i). Flowering Plants
Examples: sunflowers, orchids
(ii). Non-flowering Plants
Examples: mosses and ferns
All plants possess the remarkable ability to produce their own food through the process of photosynthesis, utilizing energy from sunlight. Unlike animals, plants are stationary and typically anchored to the ground by roots.
Ex : 7.1 – Herbs, shrubs and trees :
Plants are commonly classified into three categories: herbs, shrubs, and trees, based on their height, stem structure, and branching pattern:
Herbs: Plants with soft, green stems are referred to as herbs. They are typically short in height and may not have extensive branching.
Shrubs: Certain plants exhibit branches that emerge from the base of the stem. These plants have relatively harder stems, though not excessively thick. They are known as shrubs.
Trees: Some plants possess considerable height and feature robust, thick stems. They exhibit branching from the upper portion of the stem. Such plants are classified as trees.
Creepers and climbers:
Some plants have thin and weak stems that cannot stand upright on their own. Depending on their growth habit, they are classified as creepers or climbers:
Creepers: These plants have fragile and elongated stems that crawl along the ground. They lack the ability to stand erect or support their own weight. Examples of creepers include watermelon, strawberry, pumpkin, and sweet potatoes.
Climbers: In contrast, climbers possess thin, long, and weak stems that require external support to grow vertically. They utilize special structures called tendrils to climb and cling onto their support. Climber plant varieties include the pea plant, grapevine, sweet gourd, money plant, jasmine, runner beans, green peas, and more.
It is worth noting that climbers are more advanced in their climbing abilities compared to creepers. While both types rely on their unique stem structures, climbers have evolved mechanisms to effectively utilize external support and grow vertically.
Ex : 7.2 – Stem :
- The stem of a plant performs various functions such as bearing leaves, buds, flowers, and fruits.
- One of the important functions of the stem is to conduct water from the roots to the leaves and other parts of the plant. It also transports food from the leaves to the roots and other plant parts.
- Certain plants, such as potatoes, yams, ginger, onion, and others, may appear to be underground in the soil, but they are actually modified stems. These stems store food within them, serving as a storage organ for the plants.
- In summary, the stem of a plant plays a vital role in supporting the plant’s structure and functions. It serves as a pathway for water and nutrients, and in some cases, acts as a storage organ for food reserves.
Ex : 7.3 – Leaf :
The leaf is indeed a crucial part of the plant and plays a significant role in its overall functioning. Most leaves are green in color due to the presence of chlorophyll, a pigment that helps in the process of photosynthesis.
Leaves come in various shapes and sizes, which vary across different plant species. Some leaves are broad and flat, while others may be narrow and needle-like. The shape and size of leaves are adapted to suit the specific needs of the plant, such as capturing sunlight efficiently or reducing water loss through transpiration.
The diversity in leaf shapes and sizes is fascinating and reflects the incredible adaptation of plants to their environments. It is through the leaves that plants exchange gases with the atmosphere, absorb sunlight for photosynthesis, and regulate the loss of water.
Different parts of a Leaf :
The leaf consists of various distinct parts, each serving a specific function:
Midrib: The midrib is the central vein running through the middle of the leaf, providing support and structure.
Types of venation: Leaves exhibit two main types of venation patterns:
- Reticulate: If the veins form a net-like pattern on both sides of the midrib, it is referred to as reticulate venation. An example of a plant with reticulate venation is the peepal tree.
- Parallel: In grass leaves, the veins and veinlets run parallel to each other. This type of venation is known as parallel venation.
Node: Nodes are the points where leaves and branches are attached to the stem. They play a crucial role in plant growth and development.
Internodes: The segments of the stem between two adjacent nodes are called internodes. They contribute to the overall lengthening of the stem.
Functions of Leaves:
Transpiration: Transpiration is the process of water loss in the form of vapor through the stomata present on the surface of leaves. It aids in the regulation of plant temperature and the movement of water and nutrients.
Photosynthesis: Leaves play a vital role in photosynthesis, a process in which green plants use sunlight, carbon dioxide, and water to produce food (glucose) and release oxygen. This process is essential for the plant’s growth and survival.
In summary, the leaf is a complex structure with distinct parts like the midrib, different types of venation, nodes, and internodes. Leaves contribute to vital plant functions such as transpiration and photosynthesis, enabling plants to regulate water balance and produce their own food.
Ex : 7.4 – Root :
Roots are primarily found underground and serve several important functions in plants.
Absorption of water and minerals: Roots have specialized structures called root hairs that absorb water and minerals from the soil. This process is crucial for the plant’s growth and survival.
Anchorage: Roots anchor the plant in the soil, providing stability and preventing it from being uprooted. They help keep the plant upright, even in adverse weather conditions.
Storage: Some roots have the ability to store food and become swollen or plump. These storage roots serve as a reservoir of nutrients for the plant during periods of scarcity.
There are two main types of roots:
- Taproot: Taproots are observed in large trees and shrubs. They consist of a primary main root that grows vertically into the ground, with smaller lateral roots branching off from it. Taproots provide strong anchorage and enable the plant to access deep water and nutrients.
- Fibrous root: Fibrous roots are common in herbaceous plants (herbs). They form a dense network of thin, thread-like roots that spread out horizontally in the upper layers of the soil. Fibrous roots do not have a dominant primary root like taproots but rather consist of numerous similar-sized roots. They help plants effectively absorb water and nutrients from the topsoil.
Ex : 7.5 – Flower :
A flower is a reproductive structure of a plant that plays a crucial role in the formation of new seeds. It consists of several parts, including petals and other reproductive organs.
Reproduction in flowering plants:
Flowering plants have the remarkable ability to produce new seeds within their flowers through the interaction of male and female reproductive parts. It is interesting to note that certain plants, like holly trees, exhibit separate male and female flowers. In such cases, the male flowers are incapable of producing berries, which are exclusively formed on trees with female flowers.
This means that for berry production to occur, the tree must possess female flowers. This unique characteristic underscores the importance of cross-pollination between male and female flowers, as it enables the fertilization process necessary for the development of seeds and the subsequent production of berries.
Flowers, Fruits, and Seeds :
A flower serves as the reproductive organ of a plant, playing a crucial role in the process of plant reproduction. It contains the male and female reproductive structures necessary for fertilization and seed production. The seeds, on the other hand, are the encapsulated dormant embryos of plants. They are typically found within fruits and serve as a means of dispersing and propagating the plant species. When seeds are sown under favorable conditions, they germinate and give rise to new plants, continuing the life cycle of the plant species.
- The root system of a plant is composed of the parts that remain beneath the ground, primarily the roots themselves.
- The shoot system, on the other hand, encompasses the parts of the plant that extend above the ground, including the stem, leaves, flowers, and fruits.
- Roots can be classified into two main types: tap root system and fibrous root system.
- Roots have the ability to undergo modifications for various purposes such as providing support, storing food, facilitating propagation, and more.
- Stems can also undergo modifications to serve functions like support, protection, photosynthesis, food storage, and reproduction.
- Leaves acquire their green color due to the presence of a pigment called chlorophyll. This pigment enables green leaves to produce food through the process of photosynthesis, utilizing carbon dioxide, water, and light.
- Flowers, serving as the reproductive organs of plants, typically consist of petals, sepals, stamens, and carpels.
- For pollination to occur, pollen grains must be transferred from the anther of a flower to its stigma.
- Seeds contain an embryo that develops into a new plant under suitable conditions.
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