Transcription
The amazing process of photosynthesis! A look around in nature is an absolute treat to our senses. We all enjoy the colors and fragrance of plants, but seem to forget about their important contribution. Plants are an absolute necessity for life on Earth, because of the process of photosynthesis.
A closer look at a plant shows that it is firmly held in the soil by the help of roots. These roots absorb water from the soil and, through tiny tubes, transport it to the stem and then to the leaves. The stem holds the leaves in such a way that they absorb maximum energy from sunlight. A leaf is a very important part of the plant; photosynthesis, the ultimate provider of food and oxygen, occurs in the leaf. A leaf consists of a flat, thin lamina which is joined to the stem by a petiole. The flattened lamina provides a large surface area for trapping sunlight.
A cross-section of the leaf shows the upper and lower layers of cells, which are flat and irregular. Below the upper layer is a layer of tightly packed cells. These cells have specialized organelles called chloroplasts. Chloroplasts contain the pigment chlorophyll, which gives the green color to the leaf. The next layer has loosely arranged cells with large air spaces. The section also shows tubes specific for transporting the absorbed water into the leaves. The lower layer has many pores called stomata; each stoma is surrounded by two guard cells which regulate opening and closing of the stomata. A leaf absorbs carbon dioxide from the environment through these stomata, which, after passing through air spaces, enter into the chlorophyll-containing cells. Both water and carbon dioxide molecules are finally absorbed by the chloroplast.
These chloroplasts also have the capacity for trapping energy from sunlight. This energy is used to synthesize glucose and oxygen from carbon dioxide and water. These oxygen and glucose molecules diffuse out of the chloroplast. The glucose is transported through other specialized tubes to all parts of the plant, aiding in their growth. The oxygen present in these air spaces diffuses out through the stomata. So, during photosynthesis, oxygen is given as the life-sustaining gaseous component of the atmosphere, while glucose, or food, is transported to all parts of the plant and used for growth.
To summarize: green plants can make their own food by the process of photosynthesis. Plants are held in the soil with the help of roots. These roots absorb water and send it to the leaves through specialized tubes. The lower layer has many pores called stomata. A leaf absorbs carbon dioxide from the environment through these stomata. Both water and carbon dioxide molecules are finally absorbed by the chloroplast where, in the presence of chlorophyll and sunlight, they synthesize glucose and release oxygen. The oxygen diffuses out through the stomata. The glucose is transported through other specialized tubes to all parts of the plant, aiding in their growth.