Cell Organisation
Unicellular – A single cell performs all the basic life process. Example: Amoeba sp., Paramecium sp., Chlamydomonas, Bacteria and Euglena.
Multicellular – An organism consists of more than one cell. Each group of cell specialized to carry our life processes. Example: Homo sapien (human), animals and plants. It has five levels of organisation
- Cells: basic units of structure and function.
Example: Red blood cells and xylem vessel cells. - Tissues: made up of cells with similar in structure and function.
Example: Epithelial tissues and vascular tissues. - Organs: made up of tissues that perform a specific function.
Example: Heart and flower. - System: two of more organs that perform a specific function.
Example: Digestive system and root system. - Organisms: whole living thing that carry out all the basic life processes.
Example: Human and durian tree.
1. Cell structure
- Amoeba sp.: plasma membrane, food vacuole, contractile vacuole, pseudopodium, nucleus, ectoplasma, endoplasm.
- Paramecium sp.: food vacuole, posterior contractile vacuole, cytostome, gullet, oral groove, cilia, macronucleus, micronucleus, anterior contractile vacuole.
- Amoeba sp.: Pseudopodium (false foot) helps it to move forward slowly and it is known as amoeboid movement.
- Paramecium sp.: Hair-like cilia to beat against water. It beats its cilia backwards diagonally (swim forward) and it rotates on its axis. It beats its cilia forward (swim backwards).
- Amoeba sp.: Omnivore. Eat bacteria, plant cells, algae and other microscopic organisms.
- Entrapment – extend pseudopodium.
- Engulfment – engulf tiny food (phagocytosis) with its pseudopodia.
- Digestion – food enclosed in food vacuole
- Absorption – enzyme digests the bacteria
- Egesting – expel indigestible material.
- Paramecium sp.: Eat bacteria, organic material and other microscopic organisms.
- Sweeping – movement of cilia. Food moves along the oral groove into the gullet and cytostome.
- Digestion – food vacuole circulates round the cell.
- Elimination – undigested food is eliminated at the anal pore.
4. Reproduction
- Amoeba sp.: two types of reproduction.
- Binary Fission – nucleus divides (favourable condition) and then follows by division of cytoplasm. Two daughter cells are formed (mitotic division).
- Spore Formation – spores form (bad condition) and germinate into new amoeba under favourable condition.
- Paramecium sp.: two types of reproduction.
- Binary Fission – micronucleus undergoes mitosis (favourable condition). Macronucleus begins to elongation and form two. Cell content divide and two daughter cells are formed.
- Conjugation (Sexual reproduction) – two same species parent paramecia exchange genetic material of their micronuclei. Each parent divides and forms four daughter cells.
- Amoeba sp.: water moves into the cell by osmosis and prevention of bursting, it has a contractile vacuole.
- Paramecium sp.: water moves into the cell by osmosis and prevention of bursting, it has two contractile vacuoles.
6. Respiration
- Amoeba sp. and Paramecium sp. (both): exchange gases throughout the whole cell membrane
- Amoeba sp. and Paramecium sp. (both): waste products are ammonia and carbon dioxide by diffusion. Solid waste in paramecium is expelled through its anal pore.
Cell Organisation (Multicellular) in Human
- Cells: Epithelial cells, muscle cells, white blood cells, red blood cells, sperm, nerve cells.
- Tissues: Epithelial tissue, smooth muscle tissue, connective tissue, skeletal tissue, nerve tissue.
- Organs: Stomach, heart, kidney, lung, liver.
- Systems: Circulatory system, respiratory system, digestive system, excretory system, muscular system, lymphatic system, integumentary system, skeletal system, nervous system, endocrine system, reproductive system.
- Organisms: Human.
- Cells: Parenchyma cells, collenchyma cells, sclerenchyma cells, epidermal cells.
- Tissues: Epidermal tissue, meristem tissue, vascular tissue.
- Organs: Leaf organ, flower organ, stem organ, root organ.
- Systems: Shoot system, root system.
- Organisms: Plant.
