Explain why cells in multicellular organisms are organised into tissues, organs, and systems.

Cells in multicellular organisms are organized into tissues, organs, and systems to perform specific functions efficiently and effectively. Here's a step-by-step explanation:

1. Cell Specialization: In multicellular organisms, cells become specialized to perform specific functions. This process is known as cell differentiation. For example, muscle cells are specialized to contract and relax, nerve cells to transmit signals, and red blood cells to carry oxygen.

2. Formation of Tissues: Similar cells that perform the same function group together to form tissues. For example, muscle cells group together to form muscle tissue, nerve cells form nervous tissue, and so on. This allows for a higher level of organization and efficiency in carrying out specific functions.

3. Formation of Organs: Different tissues come together to form an organ. Each organ performs a specific function. For example, the heart, which is an organ, is made up of muscle tissue (to pump blood), nervous tissue (to regulate the heartbeat), and connective tissue (to provide structure).

4. Formation of Systems: Organs that work together to perform a broader function form a system. For example, the heart and blood vessels work together in the circulatory system to transport blood throughout the body.

5. Overall Coordination and Efficiency: This organization into tissues, organs, and systems allows for better coordination and efficiency. Each cell, tissue, organ, and system has a specific role, and all work together to ensure the survival and health of the organism. For example, the digestive system breaks down food into nutrients, which are then transported by the circulatory system to cells throughout the body.

In summary, the organization of cells into tissues, organs, and systems in multicellular organisms allows for specialization, increased efficiency, and overall coordination, all of which are crucial for the survival and functioning of the organism.