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.