Cell specialization (also called cell differentiation) is the process by which generic unspecialized cells change into specific types of cells to complete tasks certain tasks within a multicellular organism. In unicellular organisms, there is only one general, unspecialized cell capable of carrying out all of the organism's processes itself. By comparison, multicellular organisms must have a variety of cells specialized to carry out basic tasks. One or multiple types of specialized cells come together to form tissues, which form organs, which come together to form organ systems that carry out processes essential to the organism, like digestion in humans or translocation in plants.
When cells become specialized, the organism overall is better able to execute their requisite processes. For example. as we discussed previously, red blood cells are anucleate (have no nucleus) and biconcave to facilitate squeezing through the thin area of the capillaries.
CSEC also requires that you know examples of some tissues from both plants and animals. In plants:
Vascular Tissue- Includes the phloem sieve tubes and xylem vessels, responsible for providing support, and transporting water, mineral salts and dissolved substances. These are found throughout the leaves, stems and roots.
Photosynthetic tissue- Includes the mesophyll cells in leaves containing chloroplasts. They produce glucose through photosynthesis.
Epidermal Tissue- Composed of epidermal cells around leaves, young stems and roots. Protects the surfaces of these organs from mechanical damage and drying out.
Packing Tissue- Includes parenchyma cells inside stems and roots. They fill spaces, store food and support non-woody stems (when they become turgid).
Muscle Tissue- Composed of muscle cells responsible for movement.
Nerve Tissue- Includes neurones which transport nerve impulses.
Epithelial Tissue- Sheets of cells which cover and protect the inner and outer surfaces of the body (such as the outer layers of the skin and the lining of the stomach).
Connective Tissue- This includes blood tissue (blood cells and plasma), adipose tissue (fat cells) and other tissues which help to transport materials around the body, insulate the body or act as a reserve of food materials.