Living organisms including plants and animals need tissues and other supporting systems to enable them carry out life processes such as movement, respiration etc. For example without the various bones and tissues vertebrate may not be able to stand, respire, move and carry out other life processes.
Skeleton is the bony frame work of the body which provides support, shape and protection to the soft tissues and organs in animals. Without skeleton animals may not be able to move or carry out other life process.
The cuticle is composed of a protein called chitin and a thin water proof layer of wax. Chitin is anon-living substance, hence animals with this type of skeletal material can grow by moulting or ecdysis.
Bone is a tissue and a major component of the vertebral skeleton. It consists of living bone cells (osteocytes) protein fibres (collagen) and minerals, mainly Calcium Phosphate and Calcium Carbonate.
Cartilage is a tissue found in the skeleton of complex vertebrates. It consists of living cells (Chondroblasts) Carbohydrates and protein fibres. It is a tough and flexible tissue that has great tensile strength.
TYPES OF SKELETON
i) HYDROSTATIC (FLUID) SKELETON
Hydrostatic skeleton is the type of skeleton possessed by soft bodied animals. They have fluid pressure to provide support.
Exoskeleton is the type of skeleton which is found outside or external part of the body of some animals. Most invertebrates do possess cuticle which is composed of chitin.
Endoskeleton is the type of skeleton which is found inside the body of animals. Endoskeleton exists in bony or cartilaginous skeleton of fishes, toad, lizards, birds and mammals
BONES OF AXIAL AND APPENDICULAR SKELETON
1. AXIAL SKELETON: The axial skeleton is made up of the skull, vertebral column or backbone, the ribs and sternum or breastbone.
2. APPENDICULAR SKELETON: The appendicular skeleton is made up of limb girdles (pectoral and pelvic girdles)and the limbs (fore limbs and hind limbs).
3. THE SKULL: The mammalian skull is made up of several flat bones which are joined together by means of joints called sutures.
SUPPORTING TISSUES IN PLANTS
1. HERBACEOUS PLANTS
i) Parenchyma cells by their turgidity
ii) Collenchyma cells by their turgidity and the thickening at the corner of their cell wall.
iii) Xylemtracheids by their thick liquefied cell walls.
iv) Pericycle fibres by their thick liquefied walls.
2. WOODY PLANT
i) Sclerenchyma in the cortex
ii) Xylem strengthened by deposits of liquid in their walls.
iii) Pericycle fibres
iv) Secondary growth/thickening provides extensive wood or secondary xylem and bark.
FUNCTIONS OF SUPPORTING TISSUES IN PLANTS
i) They help to maintain the shape of the plant.
ii) They give rigidity/firmness to the plants body.
iii) They provide mechanical support and strength.
iv) They confer resilience and flexibility to plants.
v) They prevent breakage of stem.
vi) Xylem conducts water and mineral salts.
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