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Biology Revision (Non-communicable Diseases (Cancer (Cancer is a non…
Biology Revision
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Cells
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Some cells are specialised, meaning that they are adapted for a specific task. Examples of specialised cells include sperm cells and root hair cells.
Stem Cells
There are two types of stem cells: embryonic stem cells, and adult stem cells (which are harvested from bone marrow).
Embryonic stem cells are more advantageous; unlike adult stem cells, they can differentiate into any type of cell. However, there are many ethical issues surrounding harvesting stem cells from embryos, since it requires destroying an embryo - some see this as murder.
Adult stem cells can differentiate into many types of cells, but not every type of cell.
They are harvested from the bone marrow, and cannot specialise. They are simply stuck as what they were originally specialised to do, which is less of a benefit,
Microscopy
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Electron Microscope - Positives and Negatives
The energy source used in the electron microscope is a beam of electrons. Since the beam has an exceptionally short wavelength, it strikes most objects in its path and increases the resolution of the microscope significantly. Viruses and some large molecules can be seen with this instrument.
POSITIVE: Extremely high resolution and magnification, giving a good quality and reliable image
NEGATIVE: Also extremely high cost, which some companies may not be able to afford
Light Microscope - Positives and Negatives
A light microscope (LM) is an instrument that uses visible light and magnifying lenses to examine small objects not visible to the naked eye, or in finer detail than the naked eye allows.
POSITIVE: Relatively cheap and affordable
NEGATIVE: Quite low resolution and magnification, which gives an image which is limited in quality.
Parts of a Light Microscope
Stage
Light/Mirror
Stage Clips
Eyepiece
Objective Lens
Fine Focus Wheel
Coarse Focus Wheel
Condenser
Digestion and Enzymes
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Digestive System
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Stomach: Muscular organ containing hydrochloric acid and protease which breaks down the ingested food further.
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Circulation
The Heart
The Heart is a complex organ and muscle which is responsible for pumping blood around the body. Its main function is to pump blood and provide Oxygen to muscles and other vital organs
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Pulmonary Vein (takes deoxygenated blood into the heart to be pumped to the lungs for oxygenation via the pulmonary artery)
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Cell Transport
Diffusion, Osmosis and Active Transport
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