Living Processes of Multicellular Organisms

2.3 Living Processes of Multicellular Organisms
Specialised cells in animals and humans:

Epithelium cell

Structural adaptation: Thin cells; arranged closely



  • Provide protection
  • Aid in gaseous exchange
  • Helps in nutrients absorption, secretes mucus

Muscles cell

Structural adaptation:

  • Contains many fibres; aid in movement
  • Have many mitochondria; provide energy for muscle contraction

Function: Contracts to produce movement


Nerves cell

Structural adaptation:

  • Have long dendrites and axon
  • Axons covered with myelin sheath; faster transmission

Function: Transmits nerve impulse from one part to another part of the body


Red blood cell

Structural adaption:

  • Contains haemoglobin; transport oxygen
  • Elastic and flexible; allow the blood to squeeze through thin blood capillaries
  • Has a biconcave disc shape; increases the ratio of surface area per volume; increase the diffusion of respiratory gases

Function: Transports respiratory gases


White blood cell

Structural adaption: Can change shape; easily squeeze through the tiny blood vessels to the interstitial space to hunt the pathogens

Function: Protects the body from pathogens


Sperm cell

Structural adaption:

  • Has a long tail; helps the sperm to move
  • Contains mitochondrion; provide energy for the sperm to swim
  • Contains enzymes; helps the sperm to penetrate the ovum

Function: Fertilises the ovum

Specialised cells in plants:

Spongy palisade mesophyll cell

Structural adaptation: Packed loosely; efficient gaseous exchange

Function: Facilitate gas permeation



Structural adaptation:

  • Consists of porous long tubes; to transport substances efficiently
  • Strengthen by lignin; to prevent the xylem from collapse
Function: Transport water and mineral salts from the roots to a whole plant

Sieve tubes

Structural adaptation:

  • Matured sieve tubes have no nucleus; provide more space for transportation
  • Have sieve plates
  • No lignin
Function: Transport organic substances; sucrose, amino acids and hormones from the shoots to other parts of the plant

Root hair cell

Structural adaptation:

  • Have many mitochondria; provide energy to absorb more mineral salts through active transport
  • The root hairs increase the surface area; maximising the absorption
Function: Absorb water and dissolved mineral salts in the ground

Guard cell

Structural adaptation:

  • Have chloroplasts; produce glucose
  • Have a large vacuole; control the osmotic pressure of the cell; aid in controlling the opening and closing of the stoma
Function: Control the opening and closing of the stoma
Cell Organisation in animals:
Types Characteristics and functions

Consists of one or more layers of cells

Some epithelium tissues form glands (exocrine and endocrine glands)

Epithelial tissues carry out functions associated with protection, secretion and absorption


Musculoskeletal: involves involuntary movements; contracts and relaxes to move the bones

Smooth: contracts and relaxes that allows involuntary movements; peristalsis in intestines

Cardiac: found in the heart walls; contracts and relaxes that allows pumping the blood


Consists of neurons or nerve cells

Functions to transmit nerve impulses, control and coordinates the activities in the body

Connective Consists of several types of cells and fibres that are distributed across the body that has many functions
Connective Tissue:
Types Characteristics and functions
Loose connective tissues

Places between the organs

Functions to anchor the epithelium tissues to other tissues and places the organs in one place

Fibrous connective tissues

Consists of fibrous collagens that are arranged close to one another

Found in tendon and ligament


Strong and flexible

Supports the nose, ears and covers the end of the bones, which functions to absorb pressure and shock


Consists of cells in one matrix of mineral salts and fibrous collagen

Collagen matrix is hardened by the deposition of minerals such as calcium phosphate

Functions to protect the organs and provides support to the body

Blood tissues

Consists of blood cells; red blood cells, white blood cells and platelets

Blood functions to protect, transport and regulate

Adipose tissues

Functions to store fats, protects the organs and insulates heat

Found in the skin dermis and at the surroundings of the organs

Tissue organisation in plants:

Meristematic tissue

A group of undifferentiated cells; active in cell division

  • Two types; apical and lateral meristems


  • Apical meristem: primary growth; vertical growth
  • Lateral meristem: secondary growth; horizontal growth

Parenchyma tissue

Thin-walled cells; loosely arranged with spaces between them


  • Provides support and shapes
  • Stores food
  • Conducts photosynthesis

Collenchyma tissue

  • Elongated, polygonal cells with unevenly thickened cell walls
  • The cell walls are thickened by cellulose and pectin


Provides support to:

  • Herbaceous plants
  • Young stems
  • Leaf stalks
  • Petioles

Sclerenchyma tissue

  • The cells are rigid
  • Have cell walls; thickened by lignin
  • Most of the cells are dead at maturity

Function: Provide support and protection to the plant



  • The outermost layer that covers the whole plants
  • The wall of epidermal cells is normally covered by cuticle


The cuticle on the epidermal tissue helps to:

  • Prevent water loss
  • Protects the plants from mechanical injury
  • Prevent the invasion by disease-causing microorganisms

In roots, some of the epidermal cells have long projections called root hairs; increase the surface area for absorption of water and minerals

In leaves, the lower epidermis contains specialised cells, called guard cells; controls the opening and closing of stomata



  • Consists of tracheids and xylem vessels; long tubes joined together end to end
  • The cell walls of the xylem are thickened with lignin; provide support to plants
  • Xylem tissues die upon reaching maturity; form hollow tubes


  • Xylem carries water and minerals from the roots to the leaves
  • Xylem provides support and mechanical strength to the plant


  • Phloem tissue consists of parenchyma cells, sclereids, sieve tubes and companion cells
  • The sieve tubes have pores at both ends; called sieve plates
  • Sieve tubes obtain nutrients and energy from the adjacent companion cells

Function: Phloem transports carbohydrates, amino acids, hormones from the leaves to storage organs and to the growing parts of plants

The density of certain cell components and specialised cell functions:


  • Muscle cell; Provide energy for muscle contraction
  • Sperm cell; Provide energy for the tail of sperm during swimming to fertilise the ovum
  • Meristem cell; Provide energy for cell division and cell growth
  • Kidney cell; Provide energy for active transport to transport substances across the plasma membrane


  • Palisade mesophyll and spongy mesophyll; To conduct photosynthesis

Rough endoplasmic reticulum and Golgi apparatus

  • Goblet cell and pancreatic cell; Produces mucus, synthesises and secretes digestive enzymes

Smooth endoplasmic reticulum and Golgi apparatus

  • Liver cell; Conduct carbohydrate metabolism and detoxification drugs and poisons