Samacheer Class 6 Science - The Living World of Plants

The correct order of plant parts from bottom to top is root, stem, leaf, and flower. The root is the underground part that absorbs water and minerals. The stem grows upward and supports the leaves and flowers. Leaves are attached to the stem and carry out photosynthesis. Flowers are the reproductive organs that develop at the top of the plant. This hierarchical arrangement shows how different plant organs are organized in a typical flowering plant.

The correct sequence of these plant processes in order is fixation, absorption, conduction, and transpiration. Fixation refers to the process where plants fix carbon dioxide during photosynthesis. Absorption is when roots take in water and mineral nutrients from the soil. Conduction is the transport of water, minerals, and food through the vascular tissues of the plant. Transpiration is the loss of water vapor from the leaves and other aerial parts of the plant into the atmosphere. This sequence represents the flow of materials and energy through a plant.

Plants can be classified into two main categories based on their habitat. Terrestrial plants are those that live on land and include trees, shrubs, and herbs found in forests, grasslands, and deserts. These plants have roots adapted to absorb water from soil and leaves adapted to reduce water loss. Aquatic plants are those that live in water environments such as ponds, lakes, and rivers. These plants have special adaptations like floating leaves, air-filled tissues, and roots that absorb nutrients directly from water. Both types of plants are well-suited to their respective environments.

Habitat is the natural dwelling place or environment where an organism lives and reproduces. It is the specific location that provides all the necessary conditions for the survival of an organism, including food, water, shelter, and suitable climate. Every organism requires a habitat to meet its basic needs and to carry out its life processes. Different organisms have different habitats depending on their adaptations and requirements. For example, aquatic habitats like ponds and rivers are home to fish and water plants, while terrestrial habitats like forests are home to trees, animals, and other land organisms. The habitat provides the organism with everything it needs to survive and grow.

Leaves and photosynthesis are closely related because leaves are the primary organs where photosynthesis occurs in plants. Leaves are typically green in color because they contain a pigment called chlorophyll, which is essential for photosynthesis. Chlorophyll absorbs light energy from the sun, which is used to convert carbon dioxide and water into glucose and oxygen. The glucose produced serves as food for the plant, while oxygen is released as a byproduct. The broad, flat structure of leaves provides a large surface area to capture maximum sunlight. Therefore, leaves are specifically adapted structures that enable plants to perform photosynthesis and produce their own food.

Jasmine plants are called twiners because they have weak stems that cannot support their own weight or stand upright independently. These plants have developed the ability to climb by twining or spiraling their stems around any available support structure such as a pole, fence, or another plant. This climbing mechanism allows the jasmine plant to reach sunlight and grow upward without expending energy on developing a strong, rigid stem. By using a support, the plant can survive in its habitat and compete with other plants for light. The twining growth habit is an adaptation that helps weak-stemmed plants like jasmine to thrive in their environment.

Terrestrial habitats occur on land and have soil, air and varying temperatures, so organisms are adapted to support and conserve water, whereas aquatic habitats occur in water (fresh or marine) and provide buoyancy and dissolved gases, so organisms are adapted to living and breathing in water with adaptations like gills or streamlined bodies.

Examples of plants commonly found in school gardens include mango tree, which is a large fruit-bearing tree, neem tree, which has medicinal properties, water lily, which is an aquatic plant with floating leaves, clitoria, which is a flowering plant, and hibiscus, which is an ornamental flowering plant with colorful blooms. These plants represent different types of vegetation found in typical school gardens.

The correct order of these stem structures from top to bottom is terminal bud, axillary bud, node, and internode. The terminal bud is located at the tip of the stem and contains the growing point. Axillary buds are located in the angles between the stem and leaf petioles. Nodes are the points on the stem where leaves and buds are attached. Internodes are the segments of the stem between two consecutive nodes. Understanding these structures helps in identifying different parts of the stem.

Monocotyledonous plants are those that have a single cotyledon or seed leaf, and examples include grass, paddy, and maize. These plants typically have parallel leaf venation, fibrous root systems, and flower parts in multiples of three. Dicotyledonous plants are those that have two cotyledons or seed leaves, and examples include bean, mango, and neem. These plants typically have reticulate or net-like leaf venation, taproot systems, and flower parts in multiples of four or five. These two groups represent the two major classes of flowering plants.