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UNIT 2: Cells as the Basis of Life - Coggle Diagram
UNIT 2: Cells as the Basis of Life
Nature of biology
Processes of life in unicellular organisms.
Metabolism: Chemical reactions that take place within the cell(s) of an organism.
Response to stimuli: Reacting to changes in the external environment.
Homeostasis: The maintenance of constant internal conditions, despite changes in their external environment.
Example in Paramecium and Chlamydomonas: A constant internal environment by collecting excess water in the contractile vacuoles and then expelling it through the plasma membrane.- Osmoregulation to maintain water balance.
Movement: Living things have some control over their place and position.
Examples: The wave action of the beating cilia helps to propel Paramecium in response to changes in the environment.
The flagella rotates, moving Chlamydomonas towards more favorable conditions.
Growth: Cells can increase in size over a period of time. In multicellular organisms, growth also refers to an increase in the number of cells that make up an organism.
Examples: As the Paramecium consumes food, it enlarges. Once it reaches a certain size it will divide into two daughter cells. In Chlamydomonas, Production of organic molecules during photosynthesis and absorption of minerals causes the organism to increase in size and after it reaches a certain size it divides into two daughter cells.
Reproduction: The production of offspring. Sexual or asexual.
Excretion: The removal of metabolic waste products.
Nutrition: The intake or production of nutrients.
Into to Cells and Microscopy
Light microscope
Benefits: Ease of use, less expensive to buy, can observe dead of living cells in color, cell movement can be studied, quick specimen preparation, and no need for high voltage electricity.
Limitations: Maximum magnification of about 1500X, and low resolving power (0.25 to 0.3 micrometres)
Electron microscope
Limitations: Expensive to use, requires cells to be killed and chemically, no movement can be seen, without stain or dye no color can be seen, high voltage electric current is required, specimen preparation usually takes fey days
Benefits: Magnification of 100,000X to 300,000X, and high resolving power (0.001 micrometer)