SPM Biology 2 Cell Biology & Organization Part 5 Levels of Organization in Multicellular Organisms

Multicellular organisms - Living things with multiple or many cells organized together (eg. animals, plants)

Cell specialization in multicellular organism

• Cell changes in structure or function in order to carry out a specific function
• Most of them rely on cooperation of other cells to survive.

Cell organization in multicellular organism

Cells organization

Levels of organization in multicellular organism 

Meristematic tissue in plants 

Meristematic tissue in plants 

Organs and systems in plants 

Shoot system - stems, leaves, buds, flower, fruits and etc.

Root system - all roots 

Systems in plants

Organs in plants

Notes for plants: 

• Parenchyma tissue - to store starch, protein and water.
• Collenchyma tissue - giving support to young, non-woody stems.
• Sclerenchyma tissue - giving support to mature parts of the plant.

• Vascular tissue / bundle = xylem tissue + phloem tissue
• Xylem tissue - transport water and mineral salts from the roots to other parts of the plant,
• Phloem tissue - transport organic matters (sucrose etc.) from the leaves to all parts of the plant.

SPM Biology 2 Cell Biology & Organization Part 4 - Living Processes in Multicellular Organisms

There are various types of cells in multicellular organisms which are different in:

• size
• shape
• arrangement

Each type of cell is specialized to carry out a specific function.

Specialized cells found in humans

White blood cell

1. White blood cell

• Various shape
• Function: Destroy pathogen

Red blood cell

2. Red blood cell

• X nucleus
• Shape: biconcave disc
• Function: Transport oxygen

Epithelial cell

 3. Epithelial cell

• Thin, flat
• Coats the surface of organs

Muscle cell

4. Muscle cell

• Arranged as multinuclear striated fibers
• Function: Generate movement

Nerve cell

5. Nerve cell

• Long, thin
• Function: Sending nerve impulses

Sperm cell

6. Sperm cell

• Has long tail 
• Head carries chromosomes from the male 

Specialized cells found in plants

Root hair cell

1. Root hair cell

• Long
• Function: Absorb water and mineral salts

Xylem vessel

2. Xylem vessel

• Long, continuous hollow tube
• Function: Transport water and mineral salts from roots to other parts of the plant

Sieve tube element

3. Sieve tube element

• Long cylindrical tubes
• Function: Transport organic materials from leaves to storage organs (fruits etc.)

Palisade mesophyll cell & Spongy mesophyll cell

4. Palisade mesophyll cell

• Long cylindrical cells 
• Function: Absorb sunlight for photosynthesis 

5. Spongy mesophyll cell 

• Cells arranged with lots of air space in between
• Function: Allow gases exchange from inside of the leave to palisade mesophyll cells

Guard cell

6. Guard cell

• Modified lower epidermal cells with thicker cell wall on inner side
• Function: Controls opening and closing of stoma (the opening that allows exchange of oxygen and carbon dioxide)