3. Describe the six levels of organization of the human body from simple to complex: chemical (molecular)level organism level (body as a whole)

1. **Chemical (Molecular) Level:** This is the most basic level, involving atoms and molecules. Atoms like carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur combine to form molecules such as water, proteins, carbohydrates, lipids, and nucleic acids (DNA and RNA). These molecules are the building blocks of all cells and carry out essential life functions.<br /><br />2. **Cellular Level:** Molecules combine to form cells, the smallest structural and functional units of life. Different types of cells, such as muscle cells, nerve cells, and blood cells, are specialized to perform specific functions.<br /><br />3. **Tissue Level:** Similar cells with a common function group together to form tissues. There are four primary tissue types: epithelial tissue (covers body surfaces and lines organs), connective tissue (supports and connects other tissues), muscle tissue (allows for movement), and nervous tissue (transmits nerve impulses).<br /><br />4. **Organ Level:** Different tissues work together to form organs. An organ is a structure with a specific shape and function, such as the heart, lungs, stomach, or brain. Each organ performs a complex task.<br /><br />5. **Organ System Level:** Multiple organs work together in an organ system to perform a larger function. For example, the circulatory system (heart, blood vessels, and blood) transports oxygen and nutrients throughout the body. Other organ systems include the respiratory, digestive, nervous, and skeletal systems.<br /><br />6. **Organism Level:** All the organ systems of the body work together to maintain life and form the complete organism – a human being. This is the highest level of organization.<br />