3rd Grade ICSE

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Chapter: 05. Plants In The Surroundings

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Proper care is essential for healthy plants at home. Firstly, ensure your plants receive an adequate amount of sunlight, which varies depending on the plant species. Secondly, provide sufficient space between individual plants to prevent competition for resources like food and water. Regular watering is also crucial, but the frequency and amount depend on the specific plant’s needs. Additionally, enrich the soil every few months by adding compost, manure, or fertilizers to supply vital nutrients. Finally, keep plants clean by rinsing or spraying water to remove dust, and regularly remove unwanted weeds that compete for resources.

A dicot seed, like a kidney bean, has a specific structure designed for protection and early growth. Externally, it is covered by a tough, protective layer called the seed coat, which shields the internal parts from damage. Inside, the most prominent features are two large cotyledons, also known as seed leaves. These cotyledons serve as a vital food supply, storing all the nourishment the young embryo needs before it can produce its own food. Tucked between these two cotyledons is the tiny embryo, which is the miniature baby plant. The embryo contains a plumule, destined to grow upwards into the shoot system, and a radicle, which will develop downwards into the root system.

Germination is the remarkable biological process by which a seed sprouts and develops into a young plant, also known as a sapling. For this transformation to successfully take place, specific environmental conditions must be met. Primarily, the seed requires the right amount of warmth (temperature), as extreme cold or heat can prevent the necessary metabolic activities. Adequate water is crucial for activating enzymes, softening the seed coat, and allowing the embryo to absorb nutrients. Finally, sufficient air (oxygen) is needed for the seed to respire and generate energy for growth. Without these three essential conditions, a seed will remain dormant and not germinate.

Photosynthesis is the fundamental process by which green plants create their own food. It occurs primarily in the leaves, where the green pigment chlorophyll traps energy from sunlight. Using this trapped solar energy, along with carbon dioxide absorbed from the air and water absorbed by the roots from the soil, plants convert these raw materials into sugars (food) and oxygen. This process is crucial because it provides the plant with the energy needed for growth and survival. Furthermore, the oxygen released during photosynthesis is vital for the survival of almost all living organisms, including humans and animals, who breathe it to live.

Taproots have a single, prominent main root that grows directly downwards from the base of the stem, producing smaller lateral roots. This type of root system typically grows deep into the soil, providing strong anchorage. Examples include carrots, turnips, and mango trees. In contrast, fibrous roots consist of a cluster of many fine, thin, branching roots that arise from a common point at the base of the stem and spread widely, usually in the upper layers of the soil. They lack a dominant main root and are found in plants like rice, wheat, and grass.

The stem plays several vital roles in a plant’s life. Its primary function is to provide structural support, holding the branches, leaves, flowers, and fruits upright and allowing them to receive adequate sunlight. The stem also acts as a crucial transport system, carrying water and absorbed minerals from the roots upwards to all parts of the plant. Conversely, it distributes the food manufactured by the leaves during photosynthesis downwards to the roots and other non-photosynthesizing sections. Additionally, some specialized stems, such as those of ginger or potato, function as underground storage organs for food.

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