Agriculture Science - Leaves PDF

**[Agriculture Science]** Look at this video before writing the notes. **[Leaves]** - All leaves have the same basic structure - a midrib, an edge, veins and a petiole. - Leaves are found on the stem of a plant. - Leaves are normally green in colour but not all leaves are green. S...

**[Agriculture Science]** Look at this video before writing the notes. **[Leaves]** - All leaves have the same basic structure - a midrib, an edge, veins and a petiole. - Leaves are found on the stem of a plant. - Leaves are normally green in colour but not all leaves are green. Some plants like croton have leaves with a mixture of colours like red, yellow, white and orange. - Leaves are also different shapes and sizes. - Tiny pores found on the underside of plant leaves called **stomata** help them to exchange gases (respiration) and release water (transpiration). **[Functions of Leaves]** **1. Photosynthesis** - The main function of a leaf is to carry out photosynthesis, which provides the plant with the food it needs to survive. **Photosynthesis** is the process whereby green plants manufacture food in the present of sunlight. - **Photosynthesis** is a vital process that occurs in the leaves of a plant. During photosynthesis, the leaves use light energy to convert **carbon dioxide** and **water** into **oxygen** and **glucose**. The glucose acts as a source of food for the plant. - The leaves contain **chloroplast**, which is filled with a green pigment called **chlorophyll**. Leaves use this green pigment to produce food by converting the energy in sunlight, water and carbon dioxide into chemical energy. **2. Transpiration** - Plants keep absorbing water from the soil all the time through the root. Plants use some of the water in the process of making food. The excess water evaporates from the surface of the leaves through **stomata**. This process of water removal is called **transpiration**. Transpiration usually occurs on hot days. **3. Respiration** **Respiration** is the process by which plants break down glucose (sugar) to release energy. It\'s similar to how humans breathe, but plants do it in a different way. **How Plants Breathe:** 1. **Take in Oxygen:** Plants absorb oxygen from the air through tiny pores called stomata on the underside of their leaves. 2. **Break Down Glucose:** Inside the plant cells, glucose is broken down with the help of oxygen. 3. **Release Energy:** This process releases energy that the plant can use to grow and carry out other functions. 4. **Release Carbon Dioxide:** As a byproduct of respiration, plants release carbon dioxide back into the air. [Diagram of a leaf] Leaves \| Boundless Biology [Leaves have several features that play an important role in photosynthesis:] - A **large surface area** helps the leaf to absorb as much sunlight as possible. - Leaves are **thin**, minimizing the distance for carbon dioxide to travel into leaf cells. - A **midrib** provides strength throughout the leaf, keeping it upright and sturdy in the wind. - **Chlorophyll** is the green pigment that absorbs sunlight. - **Veins** transport water and glucose around the plant. - The **petiole** attaches the leaf to the plant's stem. - **Stomata** are tiny openings or pores, which allow carbon dioxide to enter and oxygen to exit the leaf. **[Types of Leaves]** - Leaves can be classified into two main types: simple and compound. **Simple Leaves:** - A single, undivided blade attached to a petiole (leaf stalk). - Can have various shapes, such as oval, heart-shaped, or lobed. - Examples: cashew, mango, cherry, orange. **Compound Leaves:** - A blade divided into multiple **leaflets**, each attached to a central petiole. - Examples: tamarind, golden apple, plum, damsel. - Other types of leaves include: - **Serrated**: Leaves with a saw-toothed edge. Examples include hibiscus and rose. - **Lobed**: Leaves with deep indentations or lobes. Examples include breadfruit, breadnut, bois cano. - **Fleshy**: Leaves that are thick and succulent, often adapted to store water. Examples include cactus and succulent leaves. - **Floral leaves**: Modified leaves that form the petals, sepals, stamens, and pistils of a flower. - **Cotyledonous leaves**: The first leaves to emerge from a seed, often providing nutrients to the seedling. They are also known as cotyledons. - **Scale leaves**: Small, thin leaves that protect buds or underground stems. They are often found on woody plants.  Lobed Leaf  Scale Leaf