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441 Cards in this Set
- Front
- Back
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Why is water's boiling point relatively high? |
Hydrogen bonds between molecules make it difficult for it to change state |
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How is water used inside of the body? |
- As a (major) component of tissues - As a reaction medium - As a transport medium |
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Why is ice less dense than water? |
Hydrogen bonding allows water to form gaps between molecules when it is frozen, making the structure less dense |
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What is useful about ice being less dense than water? |
- stable environments are created in the water under the ice in winter - aquatic animals are insulated against extreme cold in ponds and rivers |
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Why is water a good transport medium? |
Water is a good solvent; it is polar. |
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What benefit is it to cells that over 70% of the cytoplasm is water? |
Water is a polar solvent that will allow molecules and ions to move around and react together efficiently |
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What causes cohesion and surface tension in water? |
Hydrogen bonding |
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Give 2 things that cohesion and surface tension allow to happen in nature |
- insects (e.g. pond skaters) can walk on water - columns of water in vascular plants can be pulled up the xylem tissue from the roots |
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What is the importance of water's relatively high specific heat capacity? |
- this allows prokaryotes and eukaryotes to have a stable temperature for enzyme controlled reactions to occur - Aquatic organisms in general need a stable environment |
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What is the significance of latent heat of evaporation with regards to water? |
It's high in water, meaning water can cool organisms (take heat away) by evaporating off them |
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In which reactions in an organism is water a reactant? |
- Photosynthesis - Hydrolysis (e.g. digestion of starch) |
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What does the term hydrated carbon mean? |
For every carbon atom in a compound, there are 2 hydrogen atoms and an oxygen atom |
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What do carbohydrates function as in an organism? |
- sources of energy - stores of energy - structural units |
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Give 2 properties of monosaccharides |
- sweet-tasting - soluble in water [insoluble in non-polar solvents] |
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Are pentoses and hexoses more likely to be found in straight chains or in cyclic form? |
Cyclic |
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What are the common isomers of cyclic glucose? |
Beta glucose and alpha glucose |
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Give 2 common disaccharides |
-Lactose -Maltose |
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Which two monosaccharides are made by the hydrolysis of lactose? |
Galactose and alpha glucose |
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In the condensation reaction of a monomer of galactose and a monomer of alpha glucose, which disaccharide would be produced? |
Lactose |
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Which monomers are produced by the hydrolysis of maltose? |
2 alpha glucose molecules |
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In the condensation reaction of 2 alpha glucose molecules, which disaccharide would be produced? |
Maltose |
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Which two monosaccharides are produced by the hydrolysis of sucrose? |
Fructose and alpha glucose |
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In the condensation reaction of a monomer of fructose and a monomer of alpha glucose, which disaccharide would be produced? |
Sucrose |
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What is the definition of a monomer? |
A molecule that can bond to other molecules to form a polymer |
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What is the definition of a polymer? |
A substance made up of several monomers bonded together |
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What is the definition of the word 'hydrolysis'? |
The chemical break-down of a substance due to reaction with water |
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What is meant by the term 'condensation reaction'? |
A reaction in which two smaller molecules bond to become a larger molecule; a small molecule such as water is released. |
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What is the definition of a polysaccharide? |
A carbohydrate consisting of several monosaccharides bonded together |
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What type of bond forms between 2 monosaccharides when they combine to become disaccharides or polysaccharides? |
Glycosidic bond |
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What is the difference between alpha and beta glucose? |
Alpha glucose has an alcohol group below the plane on carbon 1 while beta has it above the plane. |
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What kind of bond would form between two amino acids? |
A peptide bond |
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Give two examples of secondary structure |
Beta pleated sheets and alpha helices. |
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What is the prosthetic group found in haemoglobin? |
The haem group |
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When drawing a table of results, where is the independent variable placed? |
In the first column on the left |
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What is random error? |
Error made due to judgement error made by the experimenter |
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What is systematic error? |
Error inherent in the equipment, e.g. zero error |
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How can random errors be reduced? |
Repeat the procedure |
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How can systematic errors be reduced? |
These cannot be technically reduced, though a calculation can be done to determine the margin of error |
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What is accuracy? |
How close data values obtained are to the actual value |
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What is preciseness? |
How exact the values are; how close a value is to the mean value |
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What is validity? |
The extent to which a measurement, test or study measures what it purports to measure |
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What is magnification? |
How much bigger an image appears compared with the original object |
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What is resolution? |
The ability of an optical instrument to see or produce an image that shows fine detail; the clarity of an image or the ability to distinguish two points from each other |
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What are the benefits of optical microscopes? |
- Cheap - Easy to use - Portable! - Can study living organisms |
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What are the disadvantages of optical microscopes? |
- limited magnification - No depth selectivity |
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Where are laser scanning microscopes used in daily life? |
In the medical profession and in biological research |
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What is a disadvantage of a TEM microscope? |
You have to dehydrate and stain samples, which must be dead. |
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What is an advantage of a confocal (laser scanning) microscope? |
Depth selectivity and high resolution |
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What is an advantage of a TEM? |
Very high magnification |
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What is an advantage of SEM? |
Colour can be added |
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What is a disadvantage of electron microscopes? |
They are large and expensive |
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What is one micrometer in metres? |
0.0000001 |
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What does acetic orcein bind to? |
DNA; stains chromosomes red |
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What does eosin stain? |
Cytoplasm |
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What does Sudan red stain? |
Lipids |
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What does iodine stain? |
Cellulose yellow and starch granules blue/black |
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What is the nucleolus? |
Where ribosome units are made |
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What is the job of nuclear pores? |
Allows RNA to pass out of the nucleus |
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What is the RER? |
Rough endoplasmic reticulum; system of membranes continuous with the nuclear membrane coated with ribosomes and so used in protein synthesis |
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What is the SER? |
Smooth endoplasmic reticulum; system of membranes continuous with nuclear membrane, containing enzymes that catalyse reactions involved in lipid metabolism |
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What is the golgi apparatus? |
Site of protein modification and transport |
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Describe the structure of a mitochondrion? |
Double membranes organelle with folds called cristae forming a matrix for respiration to occur on |
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What is the vacuole surrounded by? |
The tonoplast |
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What is a lysosome? |
A small bag filled with powerful hydrolytic enzymes |
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What do cilia do? |
'Waft' the cell along |
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What do undulipodia contain to keep structure? |
Microtubules |
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What are ribosomes |
Non-membrane organelle that translates mRNA to synthesis polypeptides |
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What are centrioles? |
Organelles used to form spindle apparatus during nuclear division |
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What is the cytoskeleton made of? |
Microfilaments made of subunits of actin |
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What is the plant cell wall made out of? |
Bundles of cellulose fibres |
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How are prokaryotic cells different to eukaryotic cells? |
The have no membrane bound nucleus or organelles They are much smaller They have no centrioles Cell wall is peptidoglycan |
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What is the plasmid? |
A small loop of DNA in a prokaryotic cell |
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What are the hair like structures on the surface of bacteria called? |
Pili |
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How do prokaryotic cells divide? |
Binary Fission |
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Why are polysaccharides good energy stores? |
Most are compact, hold glucose in chains that can be 'snipped off', insoluble so don't affect water potential |
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What is amylose? |
Long chain of alpha glucose molecules, glycosidic bonds between C1 and C4 [plants]. Form of starch. |
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What is amylopectin? |
Chain of glucose molecules with glycosidic bonds between C1 and C4, C1 and C6 [plants]. Most abundant of the two forms of starch. |
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What is glycogen? |
Chain of glucose molecules with glycosidic bonds between C1, and C4 and C1 and C6, more compact than amylopectin. [animals] |
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Why is cellulose a good material for cell walls? |
The macrofibrils it is found in have very high tensile strength; there is a 'criss-cross' structure of fibrils. |
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What are exoskeletons made out of? |
Chitin |
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What are lipids? |
a group of alcohol-soluble substances including triclycerides, phospholipids, glycolipids and cholesterol |
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What are triglycerides made of? |
Glycerol and fatty acids |
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What are triglycerides used as? |
Energy sources Energy stores Insulation Boyancy Protection |
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Which part of a phospholipid is hydrophobic? |
The fatty acid tail |
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What does cholesterol do? |
It regulates fluidity of the phospholipid membrane |
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What is the quaternary structure of a protein? |
The structure made by multiple chains of polypeptide to form one functioning protein |
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Which monomers can act as buffers? |
Amino acids |
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What is the primary structure of a protein? |
The sequence of amino acids |
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What is the secondary structure of an protein? |
The curvature or pleat of chains held by hydrogen bonds, e.g. alpha helices and beta sheets |
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What is the tertiary structure of a protein? |
The folded result of the protein, held by a variety of bonds including sulfide bridges, covalent and ionic bonds, hydrogen bonds, and hydrophobic/hydrophillic interactions. |
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What is a globular protein? |
One that appears spherical and has metabolic purposes; soluble in water |
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Give an example of a globular protein |
Haemoglobin |
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What is a fibrous protein? |
One that has a regular, repetitive sequence of amino acids and is insoluble; structural uses. |
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Give an example of a conjugated protein |
Haemoglobin |
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What is Ca 2+ used for in the body? |
Bone rigidity, blood clotting, enzyme activator, cell membrane permeability regulator. |
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What is Na + used for in the body? |
Regulation of osmotic pressure, control of water levels, contributor to nervous transmission |
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What is K + used for in the body? |
Control of water levels in body fluid, pH control, active transport, contributor to nervous transmission |
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What is H+ used for? |
Involved in photosynthesis, respiration, transport of oxygen and carbon dioxide, involved in regulation of blood pH |
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What is NH4 + use for? |
Compomnent of amino acids and chlorophyll, some hormones and nucleic acids |
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What is NO3 - used for? |
Component of amino acids, chlorophyll and vitamins an some hormones |
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What is HCO3 - used for? |
Regulation of blood pH and transport of CO2 in and out of blood |
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What is Cl - used for? |
Production of urine in kidney, transport of carbon dioxide, production of HCl (aq) |
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What is PO4 3- used for? |
Bone rigidity, phospholipids, regulation of blood pH |
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What colour is a positive test for reducing sugars? |
Brick red |
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What reagent is used in a test for reducing sugars? |
Benedict's solution (heated) |
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What must be added to the sample before Benedict's solution in a test for non-reducing sugar? |
Hydrochloric acid (heat with), then sodium hydrogencarbonate to neutralise |
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What is formed at the end of a positive lipid emulsion test? |
A cloudy white emulsion atop the organic layer |
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What reagent is used to test for peptide bonds? |
Biuret reagent |
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What colour is a positive test for proteins? |
Lilac |
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How can you use a qualitative test result to get quantified data about the results? |
Use a colorimeter to measure absorption through solutions/products formed. |
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What is the stationary phase in chromatography? |
The chromatography paper or the TLC plate |
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What is the mobile phase in chromatography? |
The solvent used |
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How can you observe invisible samples in chromatography? |
Use ultraviolet light in TLC , ninhydrin to see amino acids, or iodine |
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What does TLC stand for? |
Thin layer chromatography |
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What is the plate in TLC made of and lined with? |
Usually glass lined with silica gel |
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What is a nucleotide? |
The monomer of nucleic acids containing a pentose sugar, a base and a phosphate group |
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Which type of base do Adenine and Guanine belong to? |
Purine |
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Which type of base do Thymine, Cytosine and Uracil belong to? |
Pyramidine |
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How many bonds do bases A and T bond with? |
2 |
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How many bases do G and C bond with? |
3 |
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In which orientation does the complementary strand of DNA run in? |
antiparallel |
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What is the backbone in a DNA molecule? |
It is a sugar-phosphate backbone |
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How do you extract DNA from a kiwi fruit? |
Macerate the tissue, add a strong detergent and add ethanol so the DNA precipitates. Remove. |
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What is all the DNA in a cell referred to as? |
The genome |
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What is DNA polymerase? |
An enzyme that catalyses the formation of DNA |
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What is helicase? |
An enzyme that catalysis the breaking of the hydrogen bonds between bases ('unzips' helix) |
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What is semi-conservative replication? |
Where DNA is replicated so each new molecule (there are 2) contains one 'old' (conserved) strand and one new one. |
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What are the major difference between RNA and DNA? |
RNA contains Uracil instead of Thymine as a base, and contains Ribose instead of deoxyribose as its pentose sugar |
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What is meant by the genetic code being universal? |
In nearly all organisms, a DNA triplet will always code for a specific amino acid |
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What is meant by the genetic code being degenerate? |
For most amino acids, there is more than one base triplet able to code for it |
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What is meant by the genetic code being non-overlapping? |
The code is read a triplet at a time from a fixed order and any additions or deletions will change the entire sequence and how it's read |
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What does RNA polymerase do? |
It catalyses the formation of temporary hydrogen bonds between RNA nucleotides and their complementary DNA bases. |
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In translation, what is the DNA strand called? |
The template strand |
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What shape is a tRNA molecule? |
Clover shaped, with one end attached to an amino acid and the other hosting an anticodon. |
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How does the tRNA molecule bind to the mRNA molecule at the ribosome during translation? |
Temporary hydrogen bonds form between codon and anticodon |
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What does methyl green stain? |
DNA |
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What does pyronin stain? |
RNA |
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What is a catalyst? |
A protein molecule that speeds up the rate of a reaction but is not used up in it |
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What is an anabolic enzyme? |
One that forms one product from two reactants |
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What is a catabolic enzyme? |
One that forms two products from one reactant |
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What is formed when a substrate and enzyme combine? |
An enzyme-substrate complex |
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What is a prosthetic group? |
An inorganic part of the quaternary structure of a protein; in the case of enzymes, a permanently bound cofactor |
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What are cofactors? |
Substances that have to be present to ensure an enzyme-catalysed reaction takes place |
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What is a coenzyme? |
A small, organic non-protein molecule that binds temporarily to the active site of an enzyme molecule to ensure a reaction occurs |
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What is the induced fit hypothesis? |
The concept that a protein's active site changes slightly around the substrate to allow an enzyme-substrate complex to form |
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What do enzymes do that speed up a reaction? |
Provide alternative routes for a reaction with lower activation energies. |
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What is the temperature at which an enzyme-catalysed reactions reaches its maximum rate called? |
Its optimum temperature |
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Why does increasing temperature initially increase rate of an enzyme-controlled reaction? |
Substrates gain more kinetic energy with which to collide with enzymes with |
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When a protein/enzyme is seen to have unravelled, what is it referred to as being? |
Denatured |
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What is the temperature coefficient Q10? |
(Rate of reaction at T+10 deg) / (rate of reaction at T deg) |
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What are buffers? |
Compounds or molecules that can both accept or donate H+ ions in order to resist changes in pH |
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Why does changing the pH of a system affect an enzyme's activity? |
Excess protons (H+ ions) interfere with the hydrogen bonds in the protein's secondary structure |
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What is a limiting factor? |
One which prevents a reaction from obtaining a maximum rate (one not in excess) |
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What is an inhibitor? |
A substance that reduces or stops a reaction |
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What is competitive inhibition? |
Where inhibitors have a similar shape to the substrate molecule, attaching to the enzyme and blocking up the active site |
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What is non-competitive inhibition? |
Where inhibitors attach to the enzyme (not its active site) and change the shape of the enzyme and the active site completely |
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To what place does a non-competitive inhibitor attach to on an enzyme? |
The allosteric site |
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What is end-product inhibition? |
A method of regulating enzyme-controlled reactions, where product molecules may stay lightly bonded to the enzyme to avoid excess product being formed |
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What is the inactive precursor form of an enzyme? |
The form taken by an inactive enzyme that is only activated under certain conditions (some amino acids have to be removed in order for the enzyme to function) |
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How are metabolic pathways controlled when they involve enzymes? |
The products of various enzymes become the substrates to other enzymes, until the final product inhibits the first enzyme |
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What is meant by the 'fluid mosaic model'? |
The theory of cell membrane structure that dictates the membrane has a mosaic structure but is fluid due to lipids within |
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What do membranes do? |
Contain hydrolytic enzymes, provide surfaces for reactions to occur on, act as partially permeable barriers, and have antigens so the body recognises it as its own (cells) |
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What is a mesosome? |
A series of folds in the membrane of a prokaryotic cell which allow greater surface area for reactions etc. |
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What is a channel protein? |
An integral protein that allows charged particles to travel down an electrical gradient into the cell |
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What is an extrinsic protein? |
One that does not fully lie within the membrane of the cell |
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What role does cholesterol have in the cell membrane? |
It gives mechanical stability and flexibility |
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What is the layer atop the phospholipid membrane containing glycolipids and glycoproteins called? |
The glycocalyx |
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What is the myelin sheath in a neuron made of? |
Flattened Scwann cells |
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Define diffusion
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The net movement of particles from an area of high concentration to an area of low concentration |
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What affects diffusion rate? |
Surface area, Temperature, Diffusion distance, Size of molecule Concentration gradient |
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What is facilitated diffusion? |
Where diffusion happens by charged or large particles across an electrochemical gradient, or concentration gradient through channel proteins |
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What is osmosis? |
The diffusion of water molecules; the passage of water molecules down their water potential gradient across a partially permeable membrane |
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What is water potential? |
The tendency of water molecules to diffuse from one region to another |
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What is plant tissue with plasmolysed cells described as? |
Flaccid |
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When a plant cell has a very high water potential, what is it described as? |
Turgid |
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When an animal cell 'bursts' due to lots of water entering the cell, what is it referred to? |
Cytolysis |
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When a lot of water has moved out of an animal cell, was does the cell become? |
Crenated |
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When a lot of water has moved out of a plant cell, what has the cell become? |
Plasmolysed. |
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In which direction does active transport occur? |
Against the concentration gradient |
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What is endocytosis? |
Bulk transport of molecules too large to pass through a membrane into the cell |
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What is exocytosis? |
Bulk transport of molecules too large to pass through a cell membrane out of the cell |
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What proteins are used in active transport? |
Carrier proteins |
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What is cell drinking referred to as? |
Pinocytosis |
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What is cell eating referred to as? |
Phagocytosis |
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What will permanently damage cell membranes by creating gaps? |
Organic solvents, High temperatures |
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What affect will increasing temperature have on the permeability of a membrane? |
Permeability increases |
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What is cytokinesis? |
Cytoplasmic division following nuclear division |
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What does the cell cycle consist of? |
Interphase (G1, S, G2), 'M' phase (mitosis or meiosis), cytokinesis |
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What checkpoint happens during mitosis? |
At metaphase where it is checked that it is okay to go ahead with mitosis |
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What happens in G1? |
Growth, a checkpoint to ensure the cell is ready for DNA synthesis, biosynthesis |
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What happens in S phase? |
DNA replication |
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What happens at G2? |
Spindle forms, cell prepares for mitosis |
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What happens in prophase of mitosis? |
Chromosomes condense, spindle forms and nuclear envelope breaks down. |
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What happens in metaphase in mitosis? |
Chromosomes line up at the equator of the cell, attached to the spindle by their centromeres |
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What happens in anaphase in mitosis? |
The chromatids begin to be pulled to polar ends of the cell |
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What happens in telophase in mitosis? |
A nuclear membrane reforms around each set of chromosomes, the cytoplasm begins to pinch |
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How does cytokinesis occur in plant cells? |
And end plate forms where the equator of the spindle was, and new plasma membrane and cellulose wall material are laid down on either side along it. |
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Define 'haploid' |
As having only one set of chromosomes |
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What are homologous chromosomes? |
Chromosomes that 'match'; they contain the same genes at the same loci |
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Define diploid |
As having two sets of chromosomes |
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When does a reduction division occur in meiosis? |
At the first division; i.e. telophase I |
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What type of cell is formed just at the point of fertilisation? |
A diploid zygote |
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What happens in prophase I in meiosis? |
The chromatin condenses into chromosomes and the nuclear envelope breaks down. The spindle forms. Chromosomes come together in their homologous pairs |
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When does crossing over occur in meiosis? |
Prophase I |
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What happens in metaphase I in meoisis? |
Homologous pairs line up at the equator at random, with each member of each pair attached to a spindle fibre |
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When does independent assortment occur in meiosis? |
In metaphase I & II |
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What happens during anaphase I in meiosis? |
Homologous chromosomes are pulled to opposite poles. |
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What happens during telophase I in meoisis? |
New nuclear envelopes form around each set of chromosomes and the cell divides, followed by a brief interphase stage in animal cells. |
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What happens in prophase II in meoisis? |
Centrioles replicate and a new spindle axis is formed. The nuclear membranes break down again. |
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What happens in metaphase II in meiosis? |
Chromosomes attach by their centromere to the equator of the spindle in a random order. |
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What happens in anaphase II in meiosis? |
The centromeres divide and chromatids move to opposite ends of the cell |
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What happens in telophase II in meiosis? |
Nuclear envelopes reform around each new nucleus and in animal cells, the cell divides. |
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Define differentiate |
The process to become specialised |
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Where are guard cells found? |
Around the stomata on the underside of leaves |
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How are erythrocytes specific to their function? |
They have no nucleus and are a biconcave disc shape; this gives them a large surface area on which to carry oxygen. They are also flexible. |
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How are spermatazoa specific to their function? |
They are haploid cells with many mitochondira and an undulipodium for movement. They contain an acrosome to digest the outer coating of an ovum |
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How are palisade cells adapted for photosynthesis? |
They pack closely and have many chloroplasts |
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How are root hair cells adapted for their function? |
They have a large surface area and have carrier proteins in the plasma membrane to allow active transport of mineral ions (to lower water potential) |
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Define 'tissue' |
A group of cells working together to perform a specific function |
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What types of tissue are common in the body? |
Epithelial tissue, connective tissues, muscle tissue and nervous tissue |
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Describe squamous epithelium |
Continuous sheets of one-cell thickness that line alveoli etc. |
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Which type of muscle tissue cause bones to move? |
Skeletal muscles |
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Which type of muscle makes up the walls of the heart? |
Cardiac muscle |
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Which type of muscle propels substances along tracts in the body such as the intestine, blood vessels etc. ? |
Smooth muscle |
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What is the meristem? |
An area of unspecialised cells within a plant that can divide and differentiate into other cell types |
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What is an organ? |
A group of tissues working together to perform a specific function |
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What tissues are commonly found in plants? |
Vascular tissue, Epidermal tissue and meristematic tissue |
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What is the section of stem cells between vascular tissues called? |
Cambium |
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What organs are present in a plant? |
Leaves, stem, root |
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Define pluripotent |
Attribute belonging to stem cells; capable of becoming any cell |
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Suggest a disease that using stem cells could ease or treat |
Alzheimer's or Parkinson's |
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Where can stem cells be found in mammals? |
In an embryo In umbilical cords Multipotent cells in adult tissue |
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What is the process of growing new tissues and organs from stem cells called? |
Regenerative medicine |
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What is a blastocyst? |
A ball of cells, the outer layer (trophoblast) of which contain cells that will become the placenta. All cells within develop into embryonic tissues |
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Why do larger active mammals need a specific exchange system? |
Their surface area to volume ratio is too low to allow sufficient exchange by simple diffusion |
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What are the three features of a good exchange surface? |
Large surface area Thin barrier (short diffusion distance) Maintenance of a concentration gradient (e.g. good blood supply) |
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What is ventilation? |
The act of 'breathing' in humans; intake and removal of substance for respiration |
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How is a thin barrier maintained in the human gaseous exchange system? |
Both capillaries and alveoli are one cell thick and both are in close contact |
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How is a good blood supply maintained in the human gaseous exchange system? |
There is a capillary network over the alveoli |
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What do the external intercostal muscles do? |
Contract and relax to raise/let fall the ribs |
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What is the trachea lined with? |
Smooth muscle, ciliated epithelium and C-shaped cartilage |
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How is air inhaled in humans? |
Diaphragm contracts, moves down and flattens, external intercostal muscles contract to raise ribs. Volume of cavity increases, pressure decreases and air is drawn in |
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What do internal intercostal muscles do?
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Contract to push air out forcefully (during forced expiration only) |
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What tissues are present in the lungs? |
Elastic fibres, blood capillaries and squamous epithelium |
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What do goblet cells and ciliated epithelium cells do? |
Goblet cells produce mucus which traps pathogens and is moved at the top of the airway by the cilia of the epithelium cells |
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What is breathing rate? |
The number of breaths per minute |
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What is oxygen uptake? |
The volume of oxygen absorbed by the lungs in one minute |
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What equipment can be used to measure lung volume? |
A spirometer |
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What is tidal volume? |
The volume or air inhaled or exhaled in one breath |
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What is vital capacity? |
The greatest volume of air that can be expelled from the lungs after taking the deepest breath possible |
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What precautions must be taken when using a spirometer? |
The subject should be healthy, the soda lime should be fresh, the mouthpiece must be sterilised, and the water chamber must not be overfilled |
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What does the soda lime do in a spirometer? |
Absorb carbon dioxide |
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What is residual volume? |
The volume of air remaining in the lungs even after forced expiration |
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What is the bony structure protecting the opening of the gills in a fish called? |
The operculum |
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What are lamellae? |
Thin gill filaments used to create a large surface area for exhange |
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What is meant by countercurrent flow? |
Blood in fish flows opposite to the flow of water in the gills |
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What is the buccal cavity in fish? |
The mouth |
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How does air enter the body of an insect? |
Through spiracles, or from air sacs. Ventilation can occur due to specific movements of the wings too |
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What is the purpose of tracheal fluid in insects? |
Lactic acid created by anaerobic respiration in times of high activity draws in tracheal fluid to increase surface area for exchange |
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Where does gas exchange occur in insects? |
At the ends of the tracheoles |
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What is an open circulatory system? |
Where blood is not always held within vessels and instead bathes the organs to provide nutrients |
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What is a disadvantage of open circulatory systems? |
Circulation may be affected by body movements and blood pressure is low |
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Describe the structure of an artery |
Layer of endothelium (tunica interna) covered by elastic fibres (tunica media), then covered by smooth muscle, then covered by collagen fibres (tunica adventitia) |
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What structure does a vein have that arteries and arterioles don't? |
Valves to prevent backflow |
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What type of vessel precedes a vein but is attached to a capilary? |
A venule |
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What is hydrostatic pressure? |
That which a fluid exerts when pushing on the sides of a vessel |
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What is oncotic pressure? |
That created by the osmotic effects of the solutes in a fluid |
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What is lymph? |
Fluid held in the lymphatic system (a system that returns tissue fluid to the blood) |
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What are the atrioventricular valves called? |
The tricuspid and bicuspid valves |
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What do tendinous chords do in the heart? |
Prevent the valves from turning inside out |
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What is the septum? |
Tissue separating the ventricles of the heart |
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Why is the left ventricle of the heart thicker than the right? |
The left side pumps to the whole body, the right to the lungs only |
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Which arteries supply cardiac tissue itself? |
Coronary arteries |
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What are the three stages of the cardiac cycle? |
Diastole, atrial systole, ventricular systole |
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Where is the SAN (sino atrial node) found? |
At the top of the right atrium |
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Where is the AVN (atrio ventricular node)? |
At the top of the septum |
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What is the name of the conductive tissue running down the septum? |
Bundle of His, made of purkyne fibres |
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What letters denote the peaks and troughs of an electrocardiogram (ECG)? |
PQRST |
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In an ECG, what does the P wave indicate? |
Excitation of the atria |
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in an ECG, what does the QRS complex indicate? |
Excitation of the ventricles |
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What is bradycardia? |
Slow heart rate |
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What is tachycardia? |
Fast heart rate |
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What is atrial fibrilation? |
Atria beating more frequently than the ventricles; lack of clear p wave |
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What is an ectopic heartbeat? |
One that lies outside of the normal rhythm |
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What is haemoglobin referred to as when it has associated with oxygen? |
Oxyhaemoglobin |
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What is the release of oxygen from haemoglobin called? |
Dissociation |
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Does foetal haemoglobin have a higher or lower affinity for oxygen than adult haemoglobin? |
Higher to allow it to associate with oxygen more readily |
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How is most carbon dioxide carried in the blood? |
In the form of hydrogencarbonate ions |
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What is the Bohr effect? |
The effect that extra carbon dioxide has on haemoglobin, explaining the release of more oxygen |
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What is formed when haemoglobin combines with excess hydrogen ions donated by carbonic acid? |
Haemoglobic acid |
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What enzyme is used to catalyse the reaction of water and carbon dioxide? |
Carbonic anhydrase |
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What is the chloride shift? |
The movement of chloride ions into an erythrocyte to compensate for the movement of hydrogencarbonate ions out of the cell |
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What comprises the vascular tissue in plants? |
Phloem and xylem tissues (and sclerenchyma or collenchyma for support) |
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What are xylem vessels impregnated with? |
Lignin, either in annular rings, reticulate blocks or spirals |
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What allows lateral movement of water in the xylem? |
Bordered pits |
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In which direction does water in the xylem flow? |
Up towards the leaves |
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What is the continuous movement of water from root to leaf called? |
The transpiration stream |
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What does the phloem comprise of? |
Sieve tube elements and companion cells |
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What is the apoplast pathway of water movement through plants? |
Movement through cell walls until the casparian strip is reached |
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What is the symplast pathway of water movement through plants? |
Movement through all cell cytoplasms and membranes into the xylem tissue |
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What is the vacuolar pathway of water movement through plants? |
Movement through both the cytoplasm and the vacuoles in cells into the xylem tissue |
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Why does water move from root to xylem? |
There is a water potential gradient it follows |
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What is transpiration physically limited by? |
Closed or lack of stomata and increased waxy cuticle |
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What factors affect transpiration? |
Light intensity, temperature, humidity, air movement, and water availability |
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What equipment can be used to measure rate of transpiration? |
A Potometer |
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What is a xerophyte? |
A plant adapted to living in arid conditions |
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How are xerophytes adapted to their environment? |
Some are succulents and store water, have a thick cuticle, have few leaves or stomata in general to avoid water loss, or have rolled leaves to collect water drained off. |
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What is a hydrophyte? |
A plant that lives in water |
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What adaptations does a water lily have? |
Many large air sacs for buoyancy, underdeveloped xylem system, stomata on upper epidermis |
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Give an example of a xerophyte |
Marram grass |
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In which direction do assimilates in the phloem travel? |
From source to sink, in all directions |
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What is cotransport in translocation? |
Hydrogen ions are actively transported out, then diffuse back in with sucrose by cotransporters in the membrane |
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What pressure gradient moves phloem assimilates? |
Hydrostatic pressure |
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What is a pathogen? |
An organism that causes disease |
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How do fungi cause disease? |
Its hyphae form a mycelium under the skin's surface, then reproductive hyphae grow to the surface of the skin and release spores, causing irritation |
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What type pathogen causes black sigatoka? |
A fungus |
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What type of pathogen causes malaria? |
Protoctistan |
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What type of pathogen causes ringworm |
Fungus |
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What type of pathogen causes tomato blight? |
Protoctistan |
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What type of pathogen causes ring rot? |
Bacterium |
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What is direct transmission? |
The act of directly transmitting a pathogen from host to a new host |
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What is indirect transmission? |
Passing a pathogen from one host to another by a vector |
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What is a vector? |
An organism that carries a foreign DNA (in the case of disease, a pathogen) from one host to another |
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What does callose do in plants? |
It is deposited in the sieve tubes to block the flow of assimilates, preventing the spread of disease |
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What do phenols do in plants? |
Act as chemical defence in bark |
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Name some non-specific primary defences in humans |
Expulsive forces such as coughing, the skin layer, blood clotting and mucous membranes |
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What releases clotting factors at the start of the blood clotting process? |
Exposes collagen fibres in a blood vessel's wall |
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What binds to exposed collagen fibres at the sight of injury? |
Platelets |
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What is inactive thrombokinase (factor X) converted to in the blood clotting process? |
Active thrombokinase |
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What clotting factor and enzyme are needed to convert prothrombin to active thrombin? |
Ca 2+ and Active thrombokinase |
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What catalyses the conversion of soluble fibrinogen to insoluble fibrin in the blood clotting process? |
Thrombin |
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What does fibrin form in the blood clotting process? |
A mesh in which platelets are trapped to form a clot. |
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Name a secondary non-specific defence in humans |
The use of opsonins, or phagocytosis |
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Describe the structure of a neutrophil |
White blood cell with a lobed nucleus |
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What is an opsonin? |
A type of antibody that attaches on the surface of a pathogen to enhance phagocytosis |
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What is a macrophage? |
A large cell manufactured in the bone marrow that travels in the blood as a monocyte before settling in the body tissues |
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What do macrophages do? |
Act as APCs (antigen presenting cells) |
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What is the activation of specific B and T cells called? |
Clonal selection |
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What do T helper cells do? |
Release cell-signalling chemicals called cytokines, e.g. interleukins |
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What do T killer cells do? |
Release cytotoxins like perforin |
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What do T memory cells do? |
Provide long term immunity in case of second infection |
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What do T regulator cells do? |
Suppress the immune response after removal of a pathogen |
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What do plasma cells do? |
Manufacture and release antibodies |
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What do B memory cells do? |
Remain in the body to provide immunological memory |
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After clonal selection, how are plasma cells made? |
Clonal expansion (B lymphocytes divide and differentiate) |
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What is the structure of an antibody? |
Y shaped molecule with 4 polypeptide chains, with a constant region and a variable region. |
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What is the hinge region of an antibody? |
The region holding the two light chains to the heavy chain by disulfide bridges; this allows flexibility of the variable region |
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What does the constant region of an antibody do? |
Attach to phagocytic cells |
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What are the three types of antibody? |
Opsonin, Agglutinin and Antitoxin |
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What do agglutinins do? |
Bind multiple antibodies/attached pathogens together |
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What is vaccination? |
A method of immunity for specific diseases. Dead or weakened strains of pathogens are introduced to the immune system |
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What is herd vaccination? |
Vaccinations provided to all or almost all of a population at risk to protect those without vaccinations by preventing transmission |
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What is ring vaccination? |
Vaccination of all the people in immediate vicinity of a new case of a disease |
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What is an epidemic? |
A rapid spread of disease through a high proportion of a population |
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What is a pandemic? |
A world-wide epidemic |
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What is passive immunity? |
Antibodies directly introduced to the system |
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What is active immunity? |
Stimulation of the immune response for the body to produce its own antibodies; long term |
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What is artificial immunity? |
That provided by artificial means , e.g. by injection |
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What is natural immunity? |
That provided by natural means, e.g. from mother to child |
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What is personalised medicine? |
The development of person-specific drugs |
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Define Biodiversity |
A measure of the variation across species and habitats |
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Define habitat |
The place where an organism lives |
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Define habitat diversity |
The range of habitats in which a species lives |
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What is a species? |
A collection of organisms with similar physical and behavioural attributes that can successfully interbreed to produce fertile offspring |
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What is species biodiversity? |
The range of organisms in a habitat, denoted by species richness or species evenness |
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What is genetic biodiversity? |
The variation between individuals belonging to the same species |
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What is the benefit of random sampling? |
There is no bias; representation is more likely to be accurate |
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What is opportunistic sampling? |
A form of non-random sampling where the researcher makes decisions based on prior knowledge |
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What is stratified sampling? |
Where a habitat is divided into areas which appear different |
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What is systematic sampling? |
Where samples are taken at fixed intervals |
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How would you catch an invertebrate? |
Using a pooter, a pitfall trap, a tullgren funnel or a sweep net |
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How can you capture small animals? |
Using a Longworth trap |
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What is capture-mark-recapture? |
A sample of animals are caught and marked, then released. A second sample is obtained later; the estimated total population is the (first sample*total second sample)/(marked in second sample) |
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What mathematical test can be done to calculate biodiversity? |
Simpson's index |
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How do you calculate genetic diversity? |
By calculating the number of loci in one individual that are heterozygous, or by measuring percentage of loci in a population that have more than one allele |
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What are loci that have more than two alleles called? |
Polymorphic gene loci |
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What factors affect biodiversity? |
Human population growth, agriculture, extinction and climate change |
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What type of agriculture reduces genetic diversity? |
Monoculture and selective breeding |
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Give some ecological reasons to maintain biodiversity |
Organisms are interdependent, genetic resource is important |
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Give an economic reasons to maintain biodiversity |
Resources can be used in medicine/material synthesis |
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Give an aesthetic reason to maintain biodiversity |
People enjoy seeing diverse areas |
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What does Simpson's index of biodiversity measure? |
The relative abundance of each species in a habitat, as well as the number of individuals in that habitat |
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Where are T-cells made in and where do they mature? |
Made in the bone marrow, mature in the thymus |
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What is 'in-situ' conservation? |
Active management in maintaining biodiversity in a natural environment (habitat) |
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What is ex-situ conservation? |
Conservation outside of an organism's natural habitat |
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Give examples of ex situ conservation |
- Zoos - Botanic gardens - Seed banks |
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What is CITES? |
The Convention on International Trade in Endangered Species (trade agreement which regulates trade in plants and animal products) |
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What is the Countryside Stewardship Scheme? |
A scheme encouraging farmers and landowners to manage their land in a way promoting conservations |
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What is the binomial naming system? |
A universal naming system for organisms using genus and species names |
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What are the three domains? |
- Archaea - Eubacteria - Eukaryotae |
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List the modern classification heirachy |
[Domain] Kingdom Phylum Class Order Family Genus Species |
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List the 5 kingdoms |
Prokaryotae Protoctista Fungi Plantae Animalia |
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Define convergent evolution |
Evolution of very similar features in unrelated species |
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How can biological molecules be used to classify organisms? |
- Samples of cytochrome c can be sequenced - DNA sequencing |
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Are Archaea more closely related to Eukaryotae or Bacteria? |
Eukaryotae |
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Define phylogeny |
The study of evolutionary relationships between organisms through identifying ancestry |
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What evidence is there for evolution? |
- Fossils show visible similarities between extinct and current organisms - Analysis of biological molecules indicates varying degree of similarities in modern-day organisms |
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What is continuous variation? |
Variation with two extremes and a full range of values in between |
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Define discontinuous variation |
Variation measured in distinct categories with no scalar measurements |
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What is interspecific variation? |
Variation between species |
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Define intraspecific variation |
Variation within a species |
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What does standard deviation measure? |
The spread of data points around the mean |
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What is the purpose of a Student's t-test? |
A t-test compares two means, and is used to establish whether the difference between the means is significant or not. |
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What does Spearman's rank correlation coefficient establish? |
It determines the level of agreement between two variables, i.e. indicates whether two data sets are correlated or not |
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Define adaptation (noun) |
A characteristic that enhances the survival in a habitat |
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What are the three main types of adaptation? |
Anatomical, behavioural, physiological |
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How does natural selection work? |
1) mutation creates alternative alleles, creating variation 2) the environment selects for certain alleles by a selection pressure 3) organisms with advantageous characteristics survive and reproduce 4) the advantageous alleles are passed on and exist in a high proportion |
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What is ab initio protein modelling? |
Modelling based on physical and electrical properties of the atoms in each amino acid in a sequence |
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Define adhesion |
the attraction between water molecules and the walls of a xylem vessel |
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What is meant by the term amphiphillic? |
As containing both hydrophobic and hydrophillic components |
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What is angina pectoris? |
A condition marked by severe pain in the chest, resulting from inadequate blood supply to the heart, causing coronary artery spasm |
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What is apoptosis? |
Programmed cell death as part of a normal organism's growth and development |
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What is artificial classification? |
Classification based on just one or a few characteristics |
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What are assimilates? |
Substances that have become a part of the plant; substances travelling through the phloem in translocation |
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When is carbaminohaemoglobin formed? |
When CO2 reacts directly with haemoglobin in the blood. |
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What is the Casparian strip? |
an impermeable, waterproof layer of suberin in the walls of endodermal cells in roots |
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What is comparative protein modelling? |
Several approaches using known databases of amino acid sequences, e.g. protein threading |
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What are myosins, kinesins and dyneins examples of? |
Cytoskeletal motor proteins |
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What are dicotyledonous plants? |
Plants with two seed leaves and a branching pattern of veins in the leaf |
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What is endemicity? |
The degree of how endemic a condition is |
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What is meant by the term 'extant'? |
As being still in existence |
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What does an eyepiece graticule do? |
Integrated into the eyepiece, it provides a 'ruler' to measure the size of things seen through a microscope |
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What is genetic erosion? |
Where a limited gene pool diminishes because even those with favourable genetics do not have the opportunity to breed |
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What is heterotrophic ossification? |
overgrowth of bone, often in the wrong place |
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What compound do Mast cells release in response to injury or in allergic reactions? |
histamine |
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What are hydathodes? |
Structures in plants capable of releasing water droplets to evaporate from a leaf's surface |
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What is hypertension? |
Long term high blood pressure |
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What is the integumentary system? |
The organ system dedicated to protecting the internal environment from external pressures, i.e. the skin and its appendages |
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What are intercalated discs? |
Gap junctions between muscle cells in heart muscle |
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What is a leucocyte? |
A white blood cell |
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What is the karyotype of a cell? |
A photomicrograph of the chromosomes in a cell |
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What is a keystone species? |
A species that asserts a disproportionately large effect on its environment (relative to its abundance) |
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What is connective tissue referred to as?
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Mesenchyme |
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What is necrosis? |
Cell death caused by disease or injury |
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What is the concentration of oxygen usually measured in? |
Partial pressures |
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What is parenchyma? |
A packing tissue which fills spaces between tissues. |
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|
Define peristalsis |
The involuntary contraction and relaxation of the muscles layers of the intestine or other canals to create wave like movements which move the canal's contents. |
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Where would pepsin be found? |
The stomach |
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Where would trypsin be found? |
The small intestine |
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|
Describe the pericycle |
A thin layer of meristem tissue between the endodermis and phloem in a plant root |
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What is tylose? |
Tylose is an outgrowth from parenchyma cells in xylem vessels to block the vessel |
