How do Living Organisms Get Energy?

Every Breath You Take …

Every cell carries out several important functions to stay alive. (See: Parts of a Cell). These functions are possible because the cell obtains energy to do so. Energy is being continuously obtained through chemical reactions to keep the cell and the entire organism alive and healthy. These chemical reactions that take place in a cell are called the cell’s Metabolism. Where does it get the energy to do so? A cell requires food just as you and I do. How does it obtain this food and how does it convert food to energy? Through a process called Respiration.

Respiration

Respiration is the process by which all living organisms obtain and use oxygen. Almost all living organisms require oxygen to live. A plant or animal takes in oxygen from its environment and releases carbon dioxide. In animals, oxygen is then carried in the blood by the circulatory system to each and every cell of its body. Inside the cells, oxygen is used in chemical reactions to release energy and produce carbon dioxide and water as waste products. This is called cellular respiration. The carbon dioxide released is carried back to the lungs in the blood which is breathed out by the organism.

Let us look at cellular respiration in some more detail.

Plant Respiration

Respiration in plants occurs through the process of Photosynthesis – using energy from sunlight to combine carbon dioxide and water to make food. Plant leaves contain a pigment called Chlorophyllwhich is essential in the process of photosynthesis to produce vital sugars. These sugars are stored in the form of food in special organelles called Chloroplastsfound inside plant cells. These sugars, combined with other nutrients from the soil, such as nitrogen, sulfur, phosphorus, help plants make starch, fat, protein, vitamins, and other complex compounds essential for life. Photosynthesis provides the chemical energy needed to produce these compounds.

Check Point

1. A cell converts food to energy through a process called ______.
2. The part of respiration taking place inside a cell is known as ______.
3. Organelles named ______ in the cytoplasm of a cell are responsible for cellular respiration.
4. A pigment called ______ is essential in the process of photosynthesis to produce vital sugars.
5. Plant respiration occurs through the process of ______.

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