Living processes in unicellular organisms • Eg. Of living processes: Feed , respire, excrete, move, respond to stimuli, reproduce and grow.
Living processes in unicellular organisms
• Eg. Of living processes:
Feed , respire, excrete, move, respond to stimuli, reproduce and grow.
Unicellular organisms?
• Simple organisms – consisting of only one cell.
• Each cell is a complete unit of life.
• Able to carry out all living processes in order to survive.
Examples of unicellular microorganisms.
• Amoeba sp .
• Paramecium sp.
• They’re called protozoa.
Amoeba sp.
Pseudopodium
(False feet)
Contractile vacuole
Food vacuole
Nucleus
General features
Contractile vacuole
• Water continually enters the Amoeba sp. By osmosis. This is collected by contractile vacoule which swells up. When full, its expels the water from the cell- OSMOREGULATION.
• It enables Amoeba sp. To survive in its habitat.
Membrane
• Respiration - gaseous exchange by simple diffusion.
• Being so small, the oxygen that they need diffuse into the cell through the membrane.
• Similarly, carbon dioxide and any dissolved waste diffuses out of the cell into the water.
Cytoplasm
• Clear on the outside(Ectoplasm)
• Grainy on the inside (Endoplasm)
Movement
• An extension of cytoplasm - called pseudopodium (false foot).
• The rest of cytoplasm slowly flows into extension, hence moving the organisms along.
• Pseudopodia can be extended out into any direction.
Reproduction of Amoeba sp.
Fully grown Amoeba sp.
Two daughter cellTwo daughter cell
Fully grown Amoeba sp
(parent)
Reproduction
• Grown to a certain size
• Its nucleus divides to form two daughter nuclei
• The cytoplasm then divides and two daughter Amoeba sp. are formed
• This is called Binary fission
• During drought – can divide by spore formation
Feeding of Amoeba sp.
Feeding of Amoeba sp.
• By process of PHAGOSITOSIS.
• It simply moves round a food particle and take into cytoplasm.
• Then it form food vacuole.
• Enzyme digest the food
• Nutrient diffuse through cytoplasm
• Any waste left behind as it moves away
Cell specialisation in multicellular organisms