Quick Notes

Quick Notes

Science Chapter 2: Cell As The Basic Unit of Life
2.1 Cell - Structure, Function and Organisation
 
2.1  Cell - Structure, Function and Organisation
 
Definition
Cel is the basic unit that compose living things
 
  • The function of cell: Carry out all life's functions (growth, respiration and excretion)
  • Cells undergo a division process to form new cells and replace damaged cells
 
Plant Cell
 

 

 
Animal cell
 
 
Comparison between animal cells and plant cells
 
Animal cell Plant cell
Nucleus
Cell membrane
Cytoplasm
Mitochondria
No cell wall Has cell wall
No chloroplast Has chloroplast
No vacuole Has vacuole
No fixed shape Has fixed shape

 

 
Unicellular and Multicellular Organisms
 

 

Unicellular
Consist of only one cell

Unicellular in the animal kingdom:

  • Amoeba
  • Paramecium
 

Unicellular in plant kingdom

  • Chlamydomonas
 

Unicellular that has both plant and animals:

  • Euglena
 

 

 

Multicellular
Consist of more than one cell

Examples of multicellular organisms:

  • Human
  • Animals
  • Plants
  • Mucor
  • Spirogyra

 

The types and functions of Animal Cells
Nerve cells
  • Contain long fibres that function to carry information in the form of impulse to all parts of the body.
Red blood cells
  • Have no nucleus.
  • Biconcave disc shaped to increase surface area
  • Contain haemoglobin that functions to transport oxygen to all parts of the body.
  • Transport carbon dioxide from cells in all parts of the body to the lungs.
White blood cells
  • Change their form to surround foreign particles and destroy them.
Reproductive cells
  • Sperms carry male genetic materials and an ovum carries female genetic materials.
Muscle cells
  • Contract and relax muscles to enable movement.
Epithelium cells
  • Form a layer that protects organs in the body. These cells also secrete mucus.

 

The types of cells in plants

Epidermal cells

  • Function to reduce water loss, allow gaseous exchange and absorption of water and nutrient

Palisade cells

  • Contain chlorophyll to absorb sunlight to carry out photosynthesis

Guard cells

  • Guard cells control the opening and closing of stoma. A stoma is a small pore between the guard cells. The stoma is usually open during the day to carry out photosynthesis. The stoma is closed at night or when the plant loses a lot of water on a hot day

Root hair cells

  • Root hair cells increase the surface area to absorb more water and nutrient from the soil

 

 
The order of cell organisation
Cell \(\rightarrow\) Tissue \(\rightarrow\) Organ \(\rightarrow\) System \(\rightarrow\) Organism
 
Cell organisation in animals and plants
 
Animals Plants
Epithelium cell Epidermal cell
Epithelium tissue Epidermal tissue
Stomach Leaf
Digestive system Transportation system
Organism Organism

 

 
Systems in the human body
 
Systems Explanation
Excretory system Removes excretory waste from the body.
Skeletal system Supports the body and protects the inner organs such as the lung and heart.
Lymphatic system Drains lymphatic fluid into blood vessels to protect the body from infections of bacteria, virus and others
Digestive system Breaks down complex food into simpler form so that it is more easily absorbed by the body
Muscular system Helps in the movements of the body and inner organs
Integumentary system Protects the body from dehydration and regulates body temperature
Nervous system Carries information from the brain to
the entire body in the form of impulse
Blood circulatoy system Transports necessary oxygen, nutrients and hormones to all parts of the body
Respiratory system Absorbs oxygen and releases carbon dioxide from the body.
Endocrine system Produces hormones required to coordinate reactions in the body
Reproductive system Produces sperms and ovum to produce offspring.