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B1 - Cell Biology - Coggle Diagram
B1 - Cell Biology
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L3 and L4 - Microscopy
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Light microscopes cannot be used to view mitochondria or ribosomes. Electron microscopes offer a much higher level of magnification and resolution than light microscopes. They are much more expensive however.
When using a light microscope, a low setting for the objective lens should be used so that it can be ensures that the specimen is within the microscope's field of view. As well as this, the specimen should be dyed to increase the visibility under the light microscope.
L7 - Chromosomes
Chromosomes are kept in the nucleus of cells, they are made of DNA molecules; each chromosomes carries a number of genes.
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The sex determination chromosomes is the 23rd pair; and XX pair indicates a female, an XY indicates a male.
L14 - Exchange Surfaces
Fish have certain adaptations that aid in gas exchange (their gills have a very large surface area, the capillaries in each gill filament have a large surface area, the capillaries are close to each gill filament).
Root hair cells: Large surface area, many mitochondria
Alveoli: Large number of capillaries provides concentration gradient required, walls are one cell thick
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L10 & L9 - Cloning
In therapeutic cloning, embryonic stem cells are often used on a patient with the same genes, this means that the stem cells are not rejected by the patient. There a risks to using stem cells on humans: there is a risk of viral disease transmission and there are ethical concerns about the use of these undifferentiated cells.
The cloning of plants has the potential to save plant species from extinction, as well as producing plants that are genetically engineered to be economically preferable and beneficial.
L11 - Diffusion
Diffusion is the net, passive movement of particles from an area of high concentration to an area of low concentration (in favour of the concentration gradient) through a semi-permeable membrane.
Diffusion can happen in gasses and in liquids; the particle move until they are evenly distributed on both sides of the membrane. In the body, diffusion occurs in the small intestine and in the alveoli.
L12 - Rate of Disffusion
Changing the difference in concentration can affect the rate of diffusion; as can changing the surface area or increasing the temperature of the system.
Factors that make an effective exchange surface include: a thin membrane, a large surface area, moist to prevent cells from drying.
L17 - Active Transport
Active transport is the movement of molecules against the concentration gradient (area of low to high concentration), this process requires energy so it is not passive.
Long protrusions found on root hair cells increase the surface area of the cells. The soil that surrounds these cells contain a smaller concentration of mineral ions than the concentration within the cell itself, this means that energy is required to transport these ions.
L2 - Prokaryotic Cells
Prokaryotic cells differ from eukaryotic cells, most prokaryotic cells have:
- Plasmid DNA
- Single DNA loops
- Ribosomes
- Cytoplasm
- Flagellum(for movement)
L5 - Specialised cells
Some cells are adapted to suit their purpose/function, such cells include sperm cells, nerve cells, muscle cells, root hair cells, xylem and phloem.
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L13 - SA to V Ratio
A single celled organism has a relatively large surface area to volume ratio. This allows for molecules to diffuse in and out of the organism with ease.
L15 - Osmosis
Osmosis is the diffusion (passive) of water from a dilute solution to a more concentrated solution through a partially permeable membrane.
L16 - Osmosis Req Prac
Method: Three identical objects will be obtained, it will be ensured that they are the same volume. One of these objects will be placed in a test tube with 10cm^3 of water containing a 0.5 mol sugar solution, the next will be 10cm^3 of a 0.25 solution and the next will be placed in 10cm^3 of distilled water.