Nota Terkini

Tuesday, March 24, 2009

[Biology Form 4] Single Cell

A single cell can carry out many function.

A single cell with its numerous components and organelles can be so complete that it is able to function as a complete organism!

Examples of such unicellular organisms (or organisms that are made up of ONE cell only) are protozoa, bacteria, viruses, and certain types of algae and fungi.

In fact, most microorganisms are usually unicellular in nature.

The following table, show how and where the living process are carried out in each of the unicellular organisms;

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Living process Paramecium Amoeba
a) Respiration Diffusion through its cell membrane Diffusion through its cell membrane
b) Excretion of excess water Contractile vacuole Contractile vacuole
c) Reproduction Mitosis (cell division of nucleus) - binary fission Mitosis (cell division of nucleus) - binary fission
d) Growth Synthesis of new cytoplasm and organelle Synthesis of new cytoplasm and organelle
e) Response to environment Taxis - whole cell moves toward favourable stimuli and away from unfavourable stimuli Taxis - whole cell moves toward favourable stimuli and away from unfavourable stimuli
f) Locomotion Pseudopodia Cilia
g) Nutrition (eating) Phagocytosis, digestion in food vacuoles and lysozymes Ingestion through oral groove, digestion in food vacuoles and egestion through its anal pore

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