Foundations in Biology
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- Created by: Beth_JaneCampbell
- Created on: 21-11-17 18:11
Outline the basic concepts of cell theory.
Both plant and animal tissue is composed of cells (1); cells are the basic unit of all life (1); cells only develop from existing cells (1)
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Explain why staining is used in microscopy.
Staining provides contrast (1) / different structures/organelles absorb stain differently allowing identification (1).
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Explain the benefit of having two lenses in a microscope.
Objective lens and eyepiece lens (1); objective lens magnifies the specimen (1); eyepiece lens magnifies image (from objective lens) (1); higher magnification (produced than with just one lens) (1)
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Calculate the low and high power magnifications of a microscope with an eyepiece lens x10.
0 × 10 = 100
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Calculate the low and high power magnifications of a microscope with objective lenses x10 and x40.
10 × 40 = 400 (1)
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The diameter of the lens is 2mm, the avg. diameter of the cells is 60um. Calculate the maximum number of cells that can be seen.
diameter of field of view = 2000 μm (1) / 2000 / 60 (1) / number of whole cells = 33 (1)
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Suggest why you should put all measurements into the same units before carrying out calculations.
simplifies calculation (1) / reduces errors (1)
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Calculate how many nanometres are present in 3846 centimetres.
3846 × 10 × 1000 × 1000 (1) / = 3.846 × 1010 (1)
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Explain the difference between contrast and resolution.
Contrast is difference in colour/shade between two objects (1) Resolution is the smallest distance between two objects that can still be seen as separate (1)
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Explain how diffraction limits resolution.
diffraction happens when light passes through structures (1) / light waves spread out (1) /(light waves) overlap (1) / individual objects do not appear separate (1) / causes blurring (1)
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Explain why eyepiece graticules do not have units.
(eyepiece graticule is) arbitrary scale / calibrated for each lens (1) / using stage micrometer (1)
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Explain why you would see more detail with an electron microscope than with a light microscope.
Electron microscopes use electrons instead of light and electrons have a shorter wavelength than light (1) which produces images with a higher resolution (1).
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Define the term artefact with reference to microscopy.
An artefact is a visible object (1) or distorted cell structure (1) present in an electron micrograph (or other micrograph) due to the sample preparation process (1).
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Explain why artefacts are more likely to be produced when preparing samples for electron microscopy.
more sample preparation (in electron microscopy) (1) / (leads to) more damage to specimen (1) / damage results in artefacts (1)
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Explain the meaning of the term fluorescence.
a emission of light (1); (that has been) absorbed (1)
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State why lasers are used to produce illumination in confocal microscopy.
increase intensity (of light) (1)
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Explain the purpose of the pinhole aperture.
scattered light / light from outside the focal plane (1); is eliminated (1); reduces blurring / increases resolution (1)
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One limitation of confocal microscopy is that it can't be used for deep tissue imaging, suggest why.
idea of light penetration (of sample) is limited (1)
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What is a lysosome and why is the membrane that surrounds it so important?
Lysosomes are specialised vesicles (1) that contain hydrolytic enzymes (1) for breaking down waste material. The membrane that forms lysosomes has an important role in compartmentalising these enzymes away from cell structures that could be damaged
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Explain why cells need to be compartmentalised, and describe three examples within an animal cell.
Incompatible reactions / catabolic and anabolic reactions require different conditions / damage due to hydrolytic enzymes (3) three named examples (e.g. nucleus, vesicle, lysosome, mitochondrion, Golgi body, endoplasmic reticulum, chloroplast) (1).
20 of 29
Compare the structure and function of the rough and smooth endoplasmic reticulum.
Rough ER has ribosomes attached and smooth ER does not have ribosomes attached (1); rough ER protein synthesis (and modification) (1); smooth ER lipid synthesis (1).
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Describe the structure and function of the cytoskeleton.
The cytoskeleton has three components: microfilaments (1) are contractile fibres made of actin that bring about cell contraction during cytokinesis (1); microtubules (1) are formed from the cylindrical protein tubulin and form scaffold like structure
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Discuss how microfilaments and microtubules are involved in movement based off their structure.
microfilaments composed of actin (1) / (actin is) contractile (1) / microtubules composed of tubulin (1) / (tubulin) polymerises (1) / (contraction and polymerisation lead to) change in length of filaments (1) / change in length (of filaments) resul
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Many different organisms have cell walls including fungi and bacteria, what is unique about plant cell walls?
plant cell walls contain cellulose (1)
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Give three functions of plant cell walls.
prevent cells bursting (1) / allows turgidity (1) / idea that keep plants upright (1).
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Describe the similarities and differences between a human cell and a plant root cell.
both have three named organelles (e.g. nucleus, cell surface membrane, mitochondria, ribosomes, Golgi body, endoplasmic reticulum) (1) / only plants have two named organelles (e.g. chloroplasts, cell wall, large (central) vacuoles) (1) / centrioles
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List three structural differences between prokaryotic and eukaryotic cells.
prokaryotic cells: no nucleus / no membrane bound organelles, e.g. mitochondria / smaller / 70s ribosomes / plasmid / extra chromosomal DNA / peptidoglycan / murein cell wall. (Any 3). Accept reverse arguments for eukaryotic cells.
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Suggest why the lack of membrane bound organelles doesn't stop prokaryotic cells making proteins>
Prokaryotic cells have ribosomes (1), which are needed for protein synthesis (1). Ribosomes are not membrane bound (1).
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Explain why anitbiotics kill bacteria and why they have no effect on eukaryotic cells.
Eukaryotic cells do not have peptidoglycan (1) cell walls (1) and these antibiotics do not damage any other cell components (1) named example (e.g., nucleus, ribosomes, mitochondria) (1)
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Other cards in this set
Card 2
Front
Explain why staining is used in microscopy.
Back
Staining provides contrast (1) / different structures/organelles absorb stain differently allowing identification (1).
Card 3
Front
Explain the benefit of having two lenses in a microscope.
Back
Card 4
Front
Calculate the low and high power magnifications of a microscope with an eyepiece lens x10.
Back
Card 5
Front
Calculate the low and high power magnifications of a microscope with objective lenses x10 and x40.
Back
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