Third Grade Life Science
In the early grades, plants are one of the first forms of life that you are asked to observe or study. This could be because they are readily available and are relatively easy to study. Life science gives a good amount of attention towards plants because they are usually connected to the other topics covered in life science. A study of habitats involves the various plants found in different habitats, as well as the different plants that are edible to herbivores and omnivores. This is also linked to a study of the food web or food chain, which always begins with plants being eaten, and ends with the earth preparing itself for the growth of new plants. Needless to say, plants are important, and are a vital part of the earth.
Parts of a Plant
To understand plants better, it is important that we understand its different parts. A basic plant has four main parts. These are the root, the stem, the leaves, and the flowers. Each part plays a specific role in the plant's life and in its reproduction.
The roots of a plant grow downwards, into the ground. They do this because they are in search of water. As a plant grows, its root systems grow as well. When allowed, roots can grow to be really thick, almost like branches or trunks. The tall trees we see like the giant redwoods have root systems that go deep into the ground and can spread out into all directions as well. There are two types of root systems, taproots and fibrous roots.
Plant roots have two main uses. They anchor the plant to the ground, securing the plant well, making sure it doesn't fall over from the wind or get washed away by heavy rain. The second use is for water. Roots suck water from the earth and distribute it upwards towards the other parts of the plant, this is vital for the plant's growth and strength. Apart from these two uses, roots can also store carbohydrates or sugars that the plant can use as food when needed.
Apart from the roots, stems are parts of the plant that also offer support. Stems can stretch upward and outwards. They grow in ways which will optimize sunlight and food production for the plant. Stems mainly support the leaves, flowers, and fellow stems of each plant. The part of the plant that connects the leaves to the stems are called the nodes, between leaves a stem is called an internode.
There are two types of plant stems. They are the herbaceous type (bendable) and the woody type (not bendable, like a tree trunk.) Despite the difference, the main job of both types of plant stems is to distribute the water from the roots to the other parts of the plant. This water distribution is made possible by the xylem cells found in stems. Another type of cell found in stems are phloem cells. These cells are cells that distribute food (glucose and starch) from the plant leaves towards the other parts of
the plant.
The plant food distributed by the phloem cells are manufactured in the plant's leaves. This third plant part is extremely important to the survival and health of any plant. The leaves of a plant capture sunlight, and use this sunlight to produce food in a process called photosynthesis. Every leaf is connected to a petiole which in turn is connected to the stem of the plant. The petiole is what is responsible for bringing water up to the leaves and food down to the rest of the plant.
Page Two: Parts of a Plant (Third Grade Life Science continued)
