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  • Support is the ability of organisms to bear their weight and maintain their body forms. It involves holding body parts in their position and allow for movement.
  • Movement is the displacement of parts of the body of an organism e.g. growth movements in plants and limbs in animals.
  • Locomotion is movement of the whole organisms.

Support and Movement in Plants

  • This can be at cell level e.g. gametes in bryophytes and Pteridophytes or at organ level in tropic and nastic responses.

Importance of Movement in Plants

  1. Enable plants to obtain resources such as sunlight, water and nutrients due to tropic and nastic responses.
  2. Enhances fertilization in bryophytes and Pteridophytes
  3. Enhance fertilization in flowering plants by growth of pollen tube towards the embryo sac.
  4. Helps plants to escape harmful stimuli such as high temperature

Importance of Support in Plants

  1. Hold flowers in position for pollination to occur.
  2. Help plants to withstand forces of the environment such as gravity and air currents.
  3. Fruits are held in appropriate position for dispersal to occur.
  4. Increase the efficiency of photosynthesis as the leaves are firm and arranged in mosaic pattern for maximum absorption of light and carbon (iv) oxide.

Arrangement of Tissues in Plants


  • Parenchyma. The cells are spherical or elongated. They are unspecialized cells forming the packing tissues. When turgid, they help in providing support in herbaceous plants.
  • Collenchyma. It’s underneath the epidermis. They are similar in appearance to parenchyma and they contain living protoplasm. They have deposition of cellulose to provide mechanical support. They are mainly found in young leaves and stems.
  • Sclerenchyma. They appear as long fibres in stems. Cells are dead and they have lignin. Mainly found in stems and midrib of leaves. The walls are pitted to allow exchange of substances between cells.
  • Xylem vessels and Tracheids. Xylem vessels are long tube like structures with lignified walls used for transporting water and mineral salts and also give plant mechanical support. Tracheids are long cells with tapering ends whose walls are lignified to give the plant mechanical support. Both xylem vessels ant tracheids are made of dead cells manly present in woody stems.
  • Tendrils and Climbing stems. Some herbaceous plants support themselves by use of tendrils e.g. pumpkins, garden peas etc. Others obtain support by twinning round other hard objects such as stem of passion fruit, morning glory etc.
  • Spines and Thorns. Some plants use spines and thorns to attach to solid objects for support e.g. in rose.

Practical Activity 3

To Observe Wilting in Plants

Support and Movement in Animals

  • Animals have a firm and rigid framework for support called the skeleton.

Importance of Movement in Animals

  1. Enable searching of food, mate and shelter.
  2. Move to avoid predators.
  3. To colonize new areas
  4. Move from areas with unfavourable conditions such as fire, earthquakes, flood etc.

Types and Function of Skeletons

  1. Hydrostatic skeleton
  2. It is found in soft bodied animals such as the earthworm.
  3. Exoskeleton
  4. It is made of the external covering found in arthropods.
  5. It’s made of waterproof cuticle which contains the protein Chitin secreted by the epidermal cells.

Functions of the Exoskeleton

  1. Reduces water loss
  2. Protection against microbial infections and mechanical injury
  3. Support body tissues and organs.
  4. Provide point for attachment of muscles allowing locomotion to take place.
  5. Enhance flight in insects by means of wings which are the flattened parts of the exoskeleton.
  6. Enhance walking in insects using jointed appendages.

NB/.         1. Exoskeleton has a disadvantage as it limits growth. To overcome this limitation it is periodically shed through moulting (ecdysis).

        2. Insects that jump or hop have powerful hind limbs. The femur of the hind limb has powerful antagonistic muscles.


  • Endoskeleton.
  • It is found in all vertebrates.
  • Muscles are external to the hard framework.
  • It is made of living tissues either cartilage or bone which increase in size as the animal grows and therefore need not to be shed as in exoskeleton.

Functions of the Endoskeleton

  1. Supports the animal’s body
  2. Gives the body its shape
  3. Protects inner delicate organs such as the lungs, heart, liver etc from mechanical injury e.g. ribs.
  4. Provide surface for muscle attachment facilitating movement.
  5. Production of blood cells i.e. the long and short bones
  6. Acts as a reservoir of calcium and phosphate ions in the body

Locomotion in Finned Fish (Tilapia)


Practical Activity 5

Practical Activity 6

How a finned fish is adapted to locomotion in water

  1. Streamlined body/ tapered anteriorly and posteriorly; to minimize water resistance;
  2. Inflexible head; to maintain forward thrust;
  3. Overlapping scales facing posterior end; to bring about less resistance; Overlapping of scales also prevents wetting of the skin;
  4. Slimy/oily substance to moisten scales; hence reduce resistance between water and fish;
  5. Swim bladder; air filled cavity which controls/ brings buoyancy; and depth at which it swims;
  6. Flexible backbone /series of vertebrae with Myotomes/ muscles blocks; which contract and relax alternately bringing about thrust/force; which propels fish forwards;
  7. Pectoral and pelvic fins (paired fins); which bring about balancing effect; braking; and changing direction; they also control pitching i.e. control upward and downward movement;        
  8. Dorsal fin, caudal fin and anal fin (unpaired fins); to increase vertical surface area; and therefore prevent rolling from side to side; and yawing;
  9. Tail fins/caudal fins that are long and flexible; for steering/ more force/ thrust;
  10. Lateral line has sensory cells; which enables to perceive vibrations; hence can locate objects so that it escapes / changes direction;

Support and Movement in Mammals

Diagram of a human and rabbit skeleton

The skeleton is divided into:

  • Axial (skull, sternum, ribcage and vertebral column.)
  • Appendicular ( consists of girdles and the limbs attached to them)

Axial Skeleton

  1. Skull
  2. Made up of many bones fused together to form the cranium.
  3. The bones are joined together forming immovable joins called Sutures.
  4. Cranium encloses and protects the brain, olfactory organs, the eyes, middle and inner ear.
  5. Facial skeleton has a fixed upper jaw called maxilla and a movable lower jaw known as the mandible.
  6. At the posterior end, there are two smooth rounded projections called occipital condyles. These articulate with the first bone of the vertebral column (atlas) forming a hinge joint.
  7. This joint permits nodding of the head.
  8. Ribcage and sternum
  9. Ribcage encloses the thoracic cavity protecting delicate organs such as the lungs and heart.
  10. Cage is made up of ribs that articulate with vertebral column at the back and sternum to the front.
  11. In birds, the sternum is modified to form the keel which gives a large surface area for attachment of flight muscles.
  12. Ribcage and sternum help during breathing because they offer the surface for attachment of the intercostals muscles.
  13. Vertebral column
  14. Consists of bones called vertebrae that are separated from each other by cartilage called inter-vertebral discs.
  15. The discs absorb shock and reduce friction. It also makes the vertebral column flexible.
  16. There are five types of vertebrae in the vertebral column;
  17. Cervical vertebrae
  18. Thoracic vertebra
  19. Lumbar vertebrae
  20. Sacral vertebrae
  21. Caudal vertebrae

All the vertebrae have a common basic plan.

Structure of a Vertebra

Each vertebra is made up of the following parts.

  1. Centrum (body). It supports the weight of the vertebra and the weight of the entire vertebral column..
  2. Neural arch. It encloses the neural canal.
  3. Neural spine. Provides surface for muscle and ligament attachment.
  4. Neural canal. It protects the spinal cord which passes through it.
  5. Transverse processes. Provides surface for muscle and ligament attachment.
  6. Zygapophysis (facets). These are smooth patches for articulation with the other vertebrae. (The one in front and the other one behind). The front facets are called PreZygapophysis while the back pair facets are called Post-Zygapophysis


  1. Cervical vertebrae
  2. Atlas (First cervical vertebra)
  3. Distinctive features.
  4. No Centrum
  5. Broad and flat transverse processes.
  6. Has vertebraterial canal in each transverse process for vertebral arteries to pass through.
  7. Front facets are large and grooved to articulate with condyles of the skull to allow nodding on the head.
  8. Neural spine is very small.


  • Functions
  • Protect the spinal cord.
  • Provide surface for muscle attachment.
  • Allows head to nod.
  • Axis (second)
  • Distinctive features.
  • Centrum prolonged to from the odontoid process.
  • Has vertebraterial canal in each transverse process for vertebral arteries to pass.
  • Small wing like transverse processes.
  • Wide neural canal.
  • Functions
  • Protects the spinal cord.
  • Allows the head to rotate. Odontoid process forms a peg which fits into the neural canal of the atlas.
  • Provide surface for muscle attachment


  • The other cervical vertebrae.
  • Distinctive features
  • Short neural spine
  • Transverse process divided and broad.
  • Has vertebraterial canal in each transverse process for vertebral arteries to pass through.
  • Wide centrum


  • Functions
  • Provide surface for attachment of neck muscle.
  • Protect the spinal cord.
  • Supports the weight of the head.
  • Thoracic vertebrae
  • Distinctive features
  • Long neural spine pointing backwards.
  • Large centrum.
  • Short transverse processes.
  • Tubercular facets on each transverse for articulation with tuberculum of the rib.
  • Two pairs of capitular demi-facets for articulation with capitulum of the rib.


  • Functions
  • Helps to form the rib cage.
  • Provides articulation for one end of each rib.
  • Protects the spinal cord.
  • Provides surface for muscle attachment.
  • Lumbar vertebrae
  • Distinctive features
  • Large broad centrum to offer support.
  • Broad neural spine.
  • Broad and long transverse processes.
  • Have extra processes like metapophysis, anapophysis and hypapophysis.
  • Functions
  • Protects the spinal cord.
  • Provides surface for muscle attachment.
  • Protect and support the heavy organs in the abdominal cavity.
  • Supports the heavy weight of the upper part of the body.

4)   Sacral vertebrae

  • Distinctive features
  • All sacral vertebrae fused to form sacrum
  • Transverse processes of first sacral vertebra large and wing like for articulation with pelvic girdle
  • Pairs of holes on the lower surface for the spinal nerves to pass through.
  • Sacrum is broader on the front side and narrow towards the tail.


  1. Protects alimentary canal on dorsal side.
    1. Provides attachment to hip girdle
    1. Protects the spinal cord
    1. Provides attachment for the muscles


  • Caudal vertebrae
  • Distinctive features
  • Very small in size
  • No neural canal


  1. Provides attachment for tail muscles
  2. Helps in the movement of the tail
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