2.4 - Levels of Organisation in Multicellular Organisms

Different tissues combine and work together to form organs. For example, our lungs are made up of smooth muscle tissues, epithelial tissues, connective tissues and nerve tissues that will enable it to function as a whole. A biological system is formed when many organs work together to perform one or more functions. In humans, there are 11 main organ systems namely:

• Respiratory system
• Digestive system
• Blood circulatory system
• Lymphatic system
• Reproductive system
• Urinary system
• Endocrine system
• Integumentary system
• Muscular system,
• Nervous system
• Skeletal system.

In plants, it can be divided mainly into shoot and root systems. The shoot system consists of the leaves, flowers, stems, fruits and shoots. On the other hand, the root system is made up of the roots.

Figure 22 - Just like in human, the plant system works to support the life of a plant. The shoot system is above the ground while the root system anchors the plant and helps with water and minerals absorption. Plant leaves store starch. The stem keeps the plant upright to get maximum amount of sunlight for photosynthesis. Flowers help in pollination.