This AS CIE Biology syllabus analysis offers a comprehensive, step-by-step explanation of each syllabus point, directly mapped to the official curriculum. Each topic is thoroughly explained, providing students with clear insights and helping them understand key concepts in a structured manner. This...
1. make temporary preparations of cellular material suitable for viewing with a light
microscope
• Place a drop of water or mounting medium on a slide.
• Collect a small sample of the material to be viewed.
• Transfer the sample to the drop on the slide.
• Gently lower a coverslip onto the sample.
• Place the slide on the microscope stage.
• Start with low magnification, then increase to observe cells.
• Record your observations.
• Clean the slide and coverslip after use.
2. draw cells from microscope slides and photomicrographs
• Observe cells, noting shapes and structures.
• Lightly sketch cell outlines with a pencil.
• Add details like organelles, using shading for contrast.
• Label structures if identifiable.
• Review and refine the drawing for accuracy.
• Finalize by darkening lines and erasing guidelines.
• Add annotations if necessary.
• Repeat for other cells or structures.
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,3. calculate magnifications of images and actual sizes of specimens from drawings,
photomicrographs and electron micrographs (scanning and transmission)
• Find the scale or magnification provided.
• Use the formula: Magnification = Image Size / Actual Size.
• If magnification is given, use Actual Size = Image Size / Magnification.
• Ensure units are consistent (e.g., micrometers).
• For electron micrographs, apply additional corrections if needed.
• Verify your calculations.
• Record and report your results.
4. use an eyepiece graticule and stage micrometer scale to make measurements anduse
the appropriate units, millimetre (mm), micrometre (μm) and nanometre (nm)
• Calibrate the Microscope: Place the stage micrometer on the stage and focus
on the scale using the lowest magnification. Note the number of eyepiece
graticule units that correspond to a known distance on the stage micrometer
(e.g., 1 mm = 100 eyepiece units).
• Measure the Object: Place the object on the stage and focus on it. Use the
eyepiece graticule to measure the size of the object in eyepiece units.
• Calculate the Size: Use the calibration factor to convert the eyepiece units to
the appropriate units (mm, μm, or nm). For example, if 1 mm on the stage
micrometer corresponds to 100 eyepiece units, and you measure 20 eyepiece
units, the size of the object would be 0.2 mm.
• Use Correct Units: Use the appropriate units based on the size of the object.
For larger objects, use millimeters (mm); for smaller objects, use micrometers
(μm); for very small objects, use nanometers (nm).
• Record and Report: Record your measurements and units accurately, andreport
, them in your findings or reports.
5. define resolution and magnification and explain the differences between these
terms, with reference to light microscopy and electron microscopy
• Resolution: Ability to distinguish two points as separate. Limited by
wavelength.
• Magnification: Enlargement ratio of image to actual size. Achieved with
lenses.
• Light Microscopy: Resolution limited by visible light wavelength (400-700
nm).
• Electron Microscopy: Higher resolution due to shorter electron wavelength
(0.005 nm).
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, 1.2 Cells as the basic units of living organisms
1. recognise organelles and other cell structures found in eukaryotic cells and outline
their structures and functions, limited to:
• cell surface membrane
• Structure: Phospholipid bilayer with embedded proteins and cholesterol molecules.
• Function: Regulates the movement of substances in and out of the cell; provides cell-
cell recognition and communication; maintains cell integrity and shape.
• nucleus, nuclear envelope and nucleolus
Nucleus:
• Structure: Surrounded by a double membrane called the nuclear envelope, which has
nuclear pores for transport.
• Function: Contains genetic material (DNA) and controls cell activities such as growth,
metabolism, and reproduction.
Nuclear Envelope:
• Structure: Double membrane with nuclear pores.
• Function: Regulates the movement of materials between the nucleus and cytoplasm.
Nucleolus:
• Structure: Dense region within the nucleus.
• Function: Site of ribosome assembly.
• rough endoplasmic reticulum
• Structure: Network of membrane-bound sacs and tubules with ribosomes attached to
its surface.
• Function: Involved in protein synthesis, folding, and transport; plays a role in the
synthesis of membrane proteins and proteins destined for secretion.
• smooth endoplasmic reticulum
• Structure: Network of membrane-bound tubules and vesicles lacking ribosomes on its
surface.
• Function: Synthesizes lipids, including steroids
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