Chapter 14Organization of Multicellular

Organisms

Organization of Multicellular Organisms

• All organisms are systems, with parts that work together to help them live, grow, and reproduce.

• The parts of a multicellular organism can be examined at different levels.

Cells and Tissues• The basic unit of life is the cell.• Cells are tiny structures composed of organelles and membranes that carry out life processes.

Cells and Tissues• In multicellular organisms, different cells perform different functions.

• Examples:• Red Blood Cells: deliver oxygen• Nerve Cells: send electrical impulses

Cells and Tissues

• Cells form tissues – a group of similar cells that share structure and function.

• For example: heart cells make up heart tissues.

Organs• Within a multicellular organism, different types of tissues can form an organ.• Example: stomach• Function: digest or breaks down food• Tissues:• Muscle – Mix food• Epithelial – Secrete gastric juices• Nervous – Communicates to rest of

body• Circulatory – brings oxygen and carries

away waste• Connective – hold other tissues

together.

Organs Systems• Organs for organ systems.

• Organ systems – group of related organs that work together to do a particular function.

• In complex, multicellular organisms, organ systems function to meet the needs of cells throughout the body.

Structure and Function in Plants

• The structures of plant cells, tissues, and organs help them to carry out their specific functions.

• Plant vascular tissues are made of differentiated cells that stack together to form tube-like structures.

Structure and Function in Plants

• Vascular tissues allows plants to transport food, water, and minerals through out the plant body.

•Without vascular systems to transport material, plants would grow no taller than mosses.

Structure and Function in Plants

• In a plant leaf, the inner mesophyll cells carry out photosynthesis.

• Photosynthesis is the process of using the energy from sunlight to convert water and carbon dioxide to glucose and oxygen.

Structure and Function in Plants

• The upper layer of the leaf is transparent, so light can pass through them to the cells beneath.

• The wax cuticle keeps water in the leaf.

Structure and Function in Plants

• The underside of a leaf contains stomata, openings that allow water vapor and other gases in and out of the plant.

• Guard cells on either side of the stomata regulate the size of the opening.

Guard Cells