Plant Structure and Function PDF

# Plant Structure and Function ## 7-05-2024 ## Classification of plants - Plants can be classified into flowering and non-flowering plants. ### Flowering plants - The bright colourful flowers that you see on trees and plants help them to reproduce. - All flowering plants produce flowers, which l...

# Plant Structure and Function ## 7-05-2024 ## Classification of plants - Plants can be classified into flowering and non-flowering plants. ### Flowering plants - The bright colourful flowers that you see on trees and plants help them to reproduce. - All flowering plants produce flowers, which later turn into fruits with seeds inside them. ### Non-flowering plants - Not all plants bear flowers, so how do they reproduce? - **Conifers** produce seeds in cones, which are hard protective coverings around the seeds. - **Ferns and mosses** produce spores. ### Important parts of a plant - Like the body of an animal, the body of a plant also has different parts and systems. - Some parts of a plant grow above the ground, while some parts grow below. - **Parts of a plant:** - **Root** - **Stem** - **Leaf** - **Flower** - **Fruit** - **Seed** ## Vocabulary - **Conifers:** Plants that have seeds in cones - **Spores:** Tiny, dust-like particles that grow into new plants ## Chapter 2 ### Roots - Roots grow below the ground and form the root system. - They have fine hair-like structures on them called **root hair**. - **Root Systems:** - **Tap Root System** - **Fibrous Root System** - **Functions:** - They hold the plant firmly in the soil. - The root hair absorbs water and minerals from the soil and sends it to the stem. ### The stem - The stem is the main support of the plant and forms the shoot system. - Branches, leaves, flowers, and fruits grow from the stem. - Some stems are green and soft. - Some stems are hard and brown. - The hard brown stems of trees are called **trunks**. - **Functions:** - They hold the plants upright. - They carry the water and nutrients that the roots absorb to the leaves. - They transport food made by the leaves to other parts of the plant. ## Vocabulary - **Root hair:** Fine thread like structures seen on the roots that absorb water and nutrients from the soil. ## Think about it - The roots of some plants can be eaten. These are known as **root vegetables**. - Think carefully and make a list of root vegetables that you know. ## Activity - Work in groups. - Take a clear glass jar and add some water to it. - Add 3-4 drops of food colouring (blue) to the water, and stir it gently. - Cut 2-3 stalks of celery with a few leaves, about a quarter of an inch in length from the bottom. - Place the stalks in the coloured water. - After a day or two, observe the stalks and leaves. - What happened? - Why? - What is the function of the stem? ## The leaves - The flat, green structures on plants and trees are called leaves. - While most leaves are green, some can also be red, yellow, and purple. - Green leaves contain a substance called chlorophyll that helps them make their food in the presence of sunlight. ## Flowers - Flowers are the most beautiful part of a plant. - The brightly coloured parts of the flower are the **petals**. - Below the petals are green, petal-like structures called **sepals**. - Sepals protect flowers when they are buds. - The colours, nectar, and fragrance from plants like rose and jasmine help flowers attract bees, butterflies, and insects. - Fruits containing seeds develop from flowers. - In this way, they help plants reproduce. ## Vocabulary - **Chlorophyll:** A green colored substance in leaves that helps prepare food for the plant. - **Bud:** A small green growth that develops into a flower - **Nectar:** A sweet liquid produced by flowers - **Fragrance:** Pleasant scent, perfume ## Let's Explore - How many eyes does a bee have? Why do you think it has so many eyes? - **A bee has five eyes. Two are large, compound eyes. Three are small eyes.** ## Chapter 2 - **Petals:** Brightly coloured and scented leaf-like structures that attract insects towards the flower. - **Sepals:** The outermost part of a flower contains a set of green leaf-like structures called sepals. Generally, there are five or more sepals in a flower. Protect the flower in its bud stage. Can also prepare food for the plant. - **Stamens:** The male parts of a flower are called stamens. **Filament:** Each stamen consists of a green, long, and thin stalk called a filament. **Anther:** A bag-like structure called an anther is present at the tip of the stamen. Anthers produce dust-like particles called pollen grains. The stamen is the male reproductive part of a flower and helps in reproduction. Stamens of the flower are collectively called androecium. - **Carpels or pistils:** The female reproductive units of the flower are called carpels or pistils. There may be a single pistil or a group of pistils in the gynoecium. **Stigma:** The sticky, swollen tip of the pistil. It receives pollen grains. **Style:** A thin, long, tube-like structure that connects stigma with the ovary. **Ovary:** The swollen base of the pistil. It contains **ovules**. The ovules consist of eggs or the female gametes. The ovary forms the fruit of the plant, whereas the ovules form the seeds. ## Transportation of water in plants - Water is essential for all living things, including plants. - Plants need water in order to make their food by the process of photosynthesis in the leaves, but how does water reach the leaves? - **First:** Plants absorb water and nutrients from the soil through their roots. - **Second:** Water travels through the root cells until it reaches the stem, which contains large hollow cells adapted for carrying water. - **Third:** Water then reaches to the leaves through tubes in the leaf stalk. - The leaf stalk tubes join the major thick vein in the leaves, which branch into progressively smaller veins. ## Structure of a flower - Did you know that there are about 400,000 types of flowers in the world? - How many can you name? - The basic structure of most flowers is the same. - Learn more about the parts in detail: - **Stigma** - **Style** - **Carpel** - **Ovary** - **Ovules** - **Pedicel** - **Petal** - **Anther** - **Filament** - **Stamen** - **Sepal** - **Thalamus** ## Pollination - For new plants to be produced, the pollen grains must transfer from the anther to the stigma. - This transfer is called **pollination**. - It is pollination that leads to the formation of seeds and fruits. - From these seeds and fruits new plants can grow. - Pollen grains may be transferred within the same plant or from one plant to another. - After pollination, the ovary swells and changes into a fruit, whereas the ovules change into seeds. - Pollination usually occurs with the help of wind, water, birds, and insects. - These are called agents of pollination. - **Honey bees** have a pollen basket on their back. - When bees suck nectar from the flower, they carry pollen from one flower to the other in their pollen baskets, and thus help in pollination. ## Think about it - Do you think human beings also act as agents of pollination? ## It’s a fact - **Honey bees** have a yellow or orange pollen basket on their back. When they suck nectar from the flower, they carry pollen from one flower to the other in their pollen baskets, and thus help in pollination. ## Seed dispersal - Once the seeds are produced, they must be scattered or spread far from the parent plant and each other. - This prevents the seeds from being forced to compete with each other for resources, like food, light, and space which can be harmful for plant growth. - Plants have a variety of ways to spread their seeds, i.e., by wind, by water, by animals, and by explosion. ## Seed germination - The process during which a seed develops into young plant or seedling is called **germination**. - A seed germinates only when there is enough light, air, water, and warmth. - Water, along with light and air, plays an important role in seed germination. - It softens the seed coat and helps in seed rupture. - Seeds also require an appropriate temperature to germinate. - The seed coat ruptures and a small young plant emerges out of the seed which is called a seedling. - The seedling keeps growing and develops into a mature plant. ## Life cycle of a flowering plant - In flowering plants, reproduction takes place in a manner similar to a cycle. - Each and every flowering plant begins as a seed. - A seed begins to sprout when it receives appropriate amount of warmth, air, water, and sunlight. - **The life cycle of all flowering plants includes:** - **The process by which a plant grows from a seed is called germination.** Under the soil, roots grow. Above the ground, the stem, leaves, and flowers appear. - **A flower's pollen is transferred to another flower by insects or the wind.** - **When pollen enters another flower, it moves towards the ovary, where seeds are produced.** Seeds are dispersed by different methods and will develop into new plants. ## Role of plants in sustaining life on Earth - During the day, green plants take in carbon dioxide from the air to make their food and give out oxygen. - All living organisms need oxygen to survive. - The food prepared by plants is used by both plants and animals. - Insects like butterflies and bees **depend on** flowers for nectar. - Many animals, like birds and squirrels build their homes in trees. ## Professions associated with plants - There are many **occupations** associated with plants. - People who are engaged in these occupations pursue their careers in the field of plants and their parts like flowers and fruits. - **Gardener:** Work in gardens where they grow and take care of plants. They also work to prevent plants from diseases and to enhance growth of fruits and vegetables. They are hired for homes as well as for large organisations. - **Botanist:** Study structures and functions of different plants. Through their study they observe the impact of plants on the environment and their role in controlling environmental pollution. - **Farmer:** Work on farms. They manage different sizes of lands and grow variety of crops, grains, fruits, and vegetables. They also raise animals. - **Florist:** Cut, arrange, and sell flowers. They possess good knowledge of different species of flowers and know how to use them in decoration and floral arrangement. ## Vocabulary - **Depend on:** To rely on something - **Occupation:** A profession or a job ## Think about it - How do you think human beings can be involved in seed dispersal? ## It’s a fact - The largest flower on Earth is **Rafflesia**. - Unlike typical sweet-smelling flowers, the Rafflesia flower smells like rotten meat. ## Fertilisation - When the pollen grains from the anther, fall on the stigma of the flower they mix with the ovules present in the ovary. - This process called **fertilisation** which results in the formation of seeds. - After fertilisation, the ovary develops into fruits we eat, which hold the seeds. - Seeds and fruits are the products of fertilisation in flowering plants. ## Vocabulary - **Fertilisation:** The fusion of pollen grains with the ovules which results in the formation of seeds and fruits. - **Dispersal:** The action or process of distributing or spreading things over a wide area.