|
Hint
|
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Answer
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the similar biochemical basis for life for all living things evidences ____
|
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evolution
|
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small units from which larger molecules are made
|
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monomers
|
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made from many monomers joined together
|
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polymers
|
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two molecules react to form a chemical bond and eliminate a water molecule
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condensation
|
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a chemical bond between two molecules is broken by addition of a water molecule
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hydrolysis
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commonly used by cells as respiratory substrates, form structural components in plasma membranes and cell walls
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carbohydrates
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the monomers from which larger carbohydrates are made
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monosaccharides
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formed by the condensation of two monosaccharides
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disaccharides
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glucose + glucose
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maltose
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glucose + fructose
|
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sucrose
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glucose + galactose
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lactose
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glucose has two ____ called alpha and beta glucose
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isomers
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alpha glucose has a ____ group above the ring on carbon 5 whereas beta glucose has a ____ group below the ring
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hydroxyl
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test for ____: two drops of iodine + two drops of food sample, blue black coloration
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starch
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test for ____: heat in a water bath at 75C for 5 minutes, brick red precipitate
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reducing sugars
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test for ____: heat in a water bath with dilute HCl, neutralise with sodiumhydrogencarbonate, test for reducing sugars
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non reducing sugars
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polysaccharide of alpha glucose used for storage in plants
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starch
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(1) found in seeds and ____ organs like tubers
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storage
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(2) chains may be ____ or un____
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branched
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(3) the unbranched chain is ____ and wound into a tight coil to compact the molecule
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helical
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(4) large and ____ so does not affect cell water potential or diffuse out of cells
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insoluble
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(5) the branched form has many ends for ____ enzymes to act on
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hydrolytic
|
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polysaccharide of alpha glucose used for storage in animals
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glycogen
|
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more highly branched due to the higher ____ needs of animals
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respiratory
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made up of monomers of beta glucose to form straight, unbranched chains
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cellulose
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(1) ____ bonds form cross links between individual chains
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hydrogen
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(2) molecules are groups into ____ which are further grouped into fibres
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microfibrils
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(3) major component of the ____ that provides rigidity to the plant cell
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cell wall
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(4) exerts an inward pressure that prevents osmotic lysis so allows cells to be ____
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turgid
|
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turgidity is important to maximise ____ for photosynthesis
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surface area
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the primary constituents of the plasma membrane bilayer, used in hormones and as respiratory substrates
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lipids
|
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formed by condensation of one molecule of glycerol with 3 fatty acids
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triglycerides
|
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glycerol and fatty acids are bonded by an ____ bond
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ester
|
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the R group of a fatty acid may be ____ or un____
|
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saturated
|
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(1) high ratio of energy storing C-H ____ so are a good source of energy
|
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bonds
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(2) low ____ to energy ratio
|
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mass
|
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(3) large and ____ so don't affect water potential
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non polar
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(4) release ____ when oxidised
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water
|
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in ____ one fatty acid of a triglyceride is substituted by a phosphate group
|
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phospholipids
|
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comprise of a ____philic phosphate head and a ____phobic fatty acid tail
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hydro
|
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(1) form a ____ in an aqueous environment
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bilayer
|
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(2) form ____ by combining with carbohydrates within the cell surface membrane
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glycolipids
|
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test for ____: shake with ethanol then add water and gently shake, milky white emulsion
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lipids
|
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form many cell structures and are important as enzymes, chemical messengers, components of the blood
|
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proteins
|
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____ are the monomers of protein
|
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amino acids
|
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chiral ____ around which R, COOH, H and NH2 are found
|
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carbon
|
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condensation between 2 amino acids forms a ____ bond
|
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peptide
|
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formed by condensation of two amino acids
|
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dipeptide
|
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formed by condensation of many amino acids (a functional protein may contain one or more)
|
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polypeptide
|
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the sequence of amino acids joined by peptide bonds
|
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primary strucutre
|
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initial folding by formation of hydrogen bonds into alpha helices or beta pleated sheets
|
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secondary structure
|
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further folding into the complex specific 3D structure maintained by disulfide, ionic, hydrogen bonds and van der Waal's forces
|
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tertiary structure
|
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the combination of a number of polypeptide chains and sometimes a non-protein
|
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quarternary structure
|
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a non-protein group associated with a protein
|
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prosthetic group
|
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test for ____: Biuret test. add equal volumes of sample and sodium hydroxide, add very dilute copper sulfate, purple coloration
|
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proteins
|
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biological catalysts
|
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enzymes
|
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the active site forms as the enzyme and substrate interact and conformational change in the active site weakens bonds in the substrate
|
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induced fit model
|
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prior model of enzyme action
|
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lock and key
|
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enzymes are specific because they have different shaped ____
|
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active sites
|
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increasing temperature increases rate of reaction up until the optimum is passed, where the enzyme ____
|
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denatures
|
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changing pH alters the ____ on the enzyme's amino acids so changing it from the optimum decreases rate
|
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charges
|
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increasing enzyme or substrate concentration increase rate until the other factor becomes ____
|
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limiting
|
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occupy the enzyme's active site in competition with the substrate
|
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competitive inhibitor
|
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occupy the enzyme's allosteric site and deform the active site
|
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non competitive inhibitor
|
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DNA holds genetic information and RNA transfers that from DNA to the ____
|
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ribosome
|
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pentose sugar + nitrogeneous base + phosphate group
|
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nucleotide
|
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a condensation between two nucleotides forms a ____ bond
|
|
phosphodiester
|
|
nitrogenous bases: adenine, guanine, cytosine and then thymine/____ for DNA/RNA
|
|
uracil
|
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DNA is a ____ helix with hydrogen bonds between complementary base pairs
|
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double
|
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____ is a short polynucleotide chain
|
|
RNA
|
|
____ replication of DNA ensures genetic continuity between generations of cells
|
|
semi conservative
|
|
(1) the ____ bonds between bases in the double helix are broken
|
|
hydrogen
|
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(2) ____ catalyses this
|
|
DNA helicase
|
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(3) free DNA nucleotides pair to the strands by ____ base pairing
|
|
complementary
|
|
(4) ____ catalyses formation of phosphodiester bonds between adjacent nucleotides
|
|
DNA polymerase
|
|
this model was proved by ____ and Stahn
|
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Meselston
|
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(1) grew bacteria in a broth containing a heavy ____ of nitrogen
|
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isotope
|
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(2) bacteria with DNA containing only heavy ____ replicated in a broth containing light ____
|
|
nitrogen
|
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(3) DNA was extracted and ____
|
|
centrifuged
|
|
____ replication would predict two distinct bands
|
|
conservative
|
|
the actual result was one band somewhere in the middle indicating ____ replication
|
|
semi conservative
|
|
ribose + adenine + 3 phosphate groups
|
|
adenosine triphosphate/ATP
|
|
hydrolysis of ATP to ADP and an inorganic phosphate is catalysed by ____
|
|
ATP hydrolase
|
|
the inorganic phosphate released can ____ other compounds and make them more reactive
|
|
phosphorylate
|
|
ATP is resynthesised by ____ during photosynthesis or respiration
|
|
ATP synthase
|
|
water is a ____ in many reactions such as hydrolysis
|
|
metabolite
|
|
water is a ____ in which metabolic reactions occur
|
|
solvent
|
|
water has a high specific ____ buffering changes in temperature
|
|
specific heat capacity
|
|
water has a high ____ heat of vaporisation, providing a cooling effect through evaporation
|
|
latent
|
|
water is ____ which supports columns of water in plants and produces surface tension on the surface of water supporting small organisms
|
|
cohesive
|
|
____ ions determine pH (more hydrogen ions means lower pH)
|
|
hydrogen
|
|
____ ions are used in haemoglobin to bind to oxygen
|
|
iron
|
|
____ ions are used in cotransport of glucose and amino acids
|
|
sodium
|
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____ ions are components of DNA and ATP
|
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phosphate
|
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all life on Earth exists as ____ which have basic features in common
|
|
cells
|
|
all cells arise from other ____
|
|
cells
|
|
all cells have a ____
|
|
cell surface membrane
|
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phospholipid bilayer, controls movement of substances into and out of cells, selectively permeable, cell signalling
|
|
cell surface membrane
|
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contains genetic information in the form of chromosomes
|
|
nucleus
|
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transcribes ribosomal RNA
|
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nucleolus
|
|
site of aerobic respiration
|
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mitochondria
|
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site of photosynthesis
|
|
chloroplast
|
|
series of cisternae and vesicles - process, package and transport lipids and proteins, synthesises lysosomes
|
|
Golgi apparatus
|
|
contains hydrolytic enzymes used to break down waste material
|
|
lysosome
|
|
site of protein synthesis
|
|
ribosome
|
|
network of cisternae covered in ribosomes involved in the synthesis and transport of proteins
|
|
rough endoplasmic reticulum
|
|
network of cisternae that synthesises, stores and transports lipids and carbohydrates
|
|
smooth endoplasmic reticulum
|
|
supports the cell, prevents it from bursting, made up of polysaccharides
|
|
cell wall
|
|
large and central, contains cell sap, surrounded by the tonoplast (membrane), maintains pressure within the cell
|
|
permanent vacuole
|
|
____ are specialised by having no nucleus and a large amount of haemoglobin
|
|
erythrocytes
|
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____ have a lobed nucleus to fit through small gaps in capillary walls and have large quantities of RER to produce lytic enzymes
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phagocytes
|
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____ cells have many mitochondria to give energy for swimming
|
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sperm
|
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____ cells have many chloroplasts to absorb light for photosynthesis
|
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palisade
|
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prokaryotic cells do not have ____
|
|
membrane bound organelles
|
|
instead of a nucleus they have a ____ DNA molecule
|
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circular
|
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their cell wall contains ____
|
|
murein
|
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many also have plasmids, flagella, pilli, and/or a ____ capsule
|
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slime
|
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viruses are ____ and non-living. they comprise of genetic material, capside and attachment proteins
|
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acellular
|
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image size / actual size
|
|
magnification
|
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minimum distance apart two objects can be and still appear as separate items
|
|
resolution
|
|
resolution of a light microscope is about ____ micrometres
|
|
0.2
|
|
light microscopes have poor resolution due to the long ____ of visible light
|
|
wavelength
|
|
____ microscopes have a higher resolution because ____s have a short wavelength
|
|
electron
|
|
in light microscopes the beam is focussed by glass ____
|
|
lenses
|
|
in electron microscopes the beam is focussed by ____
|
|
electromagnets
|
|
resolution of electron microscopes is about ____ nanometres
|
|
0.1
|
|
an electron microscope requires a ____ to prevent electrons being absorbed or deflected by molecules in the air
|
|
vacuum
|
|
____ electron microscope: the beam passes though a thin section of the specimen
|
|
transmission
|
|
parts of the specimen ____ electrons and appear dark, others transmit them and appear bright
|
|
absorb
|
|
the image can be photographed to give a 2D ____
|
|
photomicrograph
|
|
cannot observe ____ specimens because the system is in a vacuum
|
|
living
|
|
requires a complex preparation and even then the image is not in ____
|
|
colour
|
|
the specimen must be very ____
|
|
thin
|
|
the image may contain ____
|
|
artefacts
|
|
things that result from the way the specimen is prepared
|
|
artefacts
|
|
____ electron microscope: passes the beam back and forth across a portion of the specimen
|
|
scanning
|
|
the electrons are ____ according to the specimen's surface contours so we can build up a 3D image based on the scattering pattern
|
|
scattered
|
|
its resolving power is ____ than a TEM but specimens need not be so thin
|
|
lower/less
|
|
we measure the size of objects on a light microscope using an ____
|
|
eyepiece graticule
|
|
we calibrate this using the ____
|
|
stage micrometer
|
|
process where cells are broken up and the different organelles they contain are separated out
|
|
cell fractionation
|
|
(1) the tissue is placed in a ____ solution to reduce enzyme activity
|
|
cold
|
|
the solution is ____ to prevent organelles bursting or shrinking
|
|
isotonic
|
|
the solution is ____ to prevent the structure of organelles or enzymes changing
|
|
buffered
|
|
(2) cells are broken up by a ____
|
|
homogeniser
|
|
(3) the ____ is filtered to remove debris
|
|
homogenate
|
|
(4) ____ separates the fragments by density
|
|
ultracentrifugation
|
|
spin on a low speed, and the densest organelles will form the ____
|
|
pellet
|
|
spin the ____ on a slightly higher speed and the next densest organelles will be separated out
|
|
supernatant
|
|
eukaryotic cells that retain the ability to divide have a ____
|
|
cell cycle
|
|
the part of the cell cycle where DNA replication occurs
|
|
interphase
|
|
a eukaryotic cell divides to produce 2 daughter cells, genetically identical to each other and the parent
|
|
mitosis
|
|
the chromosomes condense and become visible, spindle apparatus starts to form at the centrioles, nucleolus disappears, nuclear envelope breaks down
|
|
prophase
|
|
chromosomes arrange themselves at the equator and the spindle fibres attach at the centromere, mitochondria gather around spindle fibres
|
|
metaphase
|
|
centromere divides and the spindle fibres contract to pull the individual chromatids to opposite poles
|
|
anaphase
|
|
chromosomes uncondense into chromatin, spindle fibres disintegrate, nuclear envelope and nucleolus reform
|
|
telophase
|
|
the cytoplasm divides
|
|
cytokinesis
|
|
prokaryotic cells divide by ____
|
|
binary fission
|
|
the circular DNA and plasmids replicate and the cytoplasm divides to produce two daughter cells with a single copy of the circular DNA and a ____ number of plasmids
|
|
variable
|
|
phospholipids in the cell surface membrane: (1) allow ____ substances to enter/leave the cell
|
|
lipid soluble
|
|
(2) prevent ____ soluble substances entering and leaving the cell
|
|
water
|
|
(3) make the membrane flexible and self ____
|
|
sealing
|
|
proteins that occur in in the surface of the bilayer, give mechanical support or act with glycolipids as cell receptors e.g. for hormoes
|
|
extrinsic
|
|
span the bilayer, carrier or channel proteins
|
|
intrinsic
|
|
restricts the movement of molecules making up the membrane
|
|
cholesterol
|
|
carbohydrate covalently bonded to a lipid, extend outside of the cell, act as recognition sites and help cells attach and form tissues
|
|
glycolipid
|
|
carbohydrate attached to extrinsic protein, help cells attach, help cells recognise one another
|
|
glycoprotein
|
|
the cell membrane is ____ to control what enters and leaves
|
|
selectively permeable
|
|
the cell membrane is modelled as the ____ model
|
|
fluid mosaic
|
|
____ because the individual phospholipids move relative to each other
|
|
fluid
|
|
____ because the proteins embedded vary in size and shape
|
|
mosaic
|
|
net movement of molecules or ions from a region of higher concentration to a region of lower concentration directly across the bilayer
|
|
simple diffusion
|
|
diffusion using channel or carrier protein
|
|
facilitated diffusion
|
|
the net movement of water from a region of higher water potential to a region of lower water potential
|
|
osmosis
|
|
the movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using ATP and carrier proteins
|
|
active transport
|
|
(1) substance binds to receptor sites on the inside of the ____
|
|
carrier protein
|
|
(2) ATP ____ the protein and changes its shape
|
|
phosphorylates
|
|
(3) the carrier opens to the opposite side of the ____ and releases the substance
|
|
membrane/bilayer
|
|
(4) the ____ is released and the protein reverts to its original shape
|
|
phosphate
|
|
the movement of one molecule down its concentration gradient drives the transport of a second molecule against its gradient
|
|
cotransport
|
|
occurs notably in the ____
|
|
ileum
|
|
(1) ____ ions are actively transported out of epithelial cells into the blood
|
|
sodium
|
|
(2) sodium ions diffuse into the epithelial cells from the ____ down a concentration gradient
|
|
lumen
|
|
(3) they diffuse in through a ____ protein and carry glucose or amino acids with them
|
|
cotransport
|
|
cells specialised for membrane transport may have: (1) folded membranes to increase ____
|
|
surface area
|
|
(2) large numbers of ____ proteins
|
|
intrinsic
|
|
(3) many mitochondria to produce ATP for ____
|
|
active transport
|
|
a molecule present on the surface of a cell which triggers an immune response
|
|
antigen
|
|
____ limits effectiveness of vaccines because antibodies are no longer complementary
|
|
antigen variability
|
|
process of phagocytosis: part of the ____ immune response
|
|
non specific
|
|
(1) chemical products of pathogens act as attractants and the ____ move towards the pathogen
|
|
phagocytes
|
|
(2) they engulf the pathogen to form a ____
|
|
phagosome
|
|
(3) lysosomes fuse with the vesicle to form a ____
|
|
phagolysosome
|
|
(4) hydrolytic enzymes destroy ingested bacteria by ____ their cell walls
|
|
hydrolysing
|
|
(5) the soluble products are absorbed into the cytoplasm and the ____ are presented on the cell surface membrane
|
|
antigens
|
|
cells that display foreign antigens on their surface
|
|
antigen presenting cells
|
|
T-lymphocytes are responsible for ____ immunity
|
|
cell mediated
|
|
the receptors on each T-cell respond to a specific ____ and a specific T-cell binds to the ____s on an APC
|
|
antigen
|
|
this activates ____ of the specific T-lymphocyte
|
|
clonal expansion
|
|
these cloned T-cells can do one of four things: (1) develop into ____ cells that enable a rapid response to future infections by the same pathogen
|
|
T-memory
|
|
(2) stimulate phagocytes to engulf pathogens by ____
|
|
phagocytosis
|
|
(3) stimulate B-lymphocytes to divide and secrete their ____
|
|
antibody
|
|
(4) activate ____ T-cells which produce perforin and kill abnormal cells by making their membranes freely permeable
|
|
cytotoxic
|
|
B-lymphocyte are responsible for ____ immunity
|
|
humoral
|
|
(1) the surface ____ of an invading pathogen are taken up, processed and presented by a B-cell
|
|
antigens
|
|
(2) the T-____ cells attach to the antigens and activate clonal expansion of the B-cell
|
|
helper
|
|
(3) the B-cell clones to give ____ cells that produce and secrete the specific antibody
|
|
plasma
|
|
some B-cells will differentiate into ____ cells to respond to future infections
|
|
B-memory
|
|
where a lymphocyte is chosen and activated to respond to a specific antigen
|
|
clonal selection
|
|
a protein produced by the immune system in response to foreign substances with specific binding sites
|
|
antibody
|
|
antibodies are made up of ____ polypeptide chains: 2 heavy and 2 light
|
|
four
|
|
the two binding sites that fit the antigen precisely to form an antigen-antibody complex
|
|
variable region
|
|
the part of the antibody that is not specific to an antigen
|
|
constant region
|
|
antibodies cause ____ of bacterial cells to group them together and make it easier for the phagocytes to locate them
|
|
agglutination
|
|
production of antibodies and memory cells
|
|
primary immune response
|
|
memory cells differentiate into plasma cells to produce antibodies, faster and to an increased quantity
|
|
secondary immune response
|
|
produced by the introduction of antibodies into individuals from an outside source
|
|
passive immunity
|
|
produced by stimulating the production of antibodies by the individual’s own immune system
|
|
active immunity
|
|
the introduction of antigens into the body in order to stimulate an immune response
|
|
vaccination
|
|
when a large proportion has been vaccinated so it's difficult for a pathogen to spread
|
|
herd immunity
|
|
HIV structure: capsid, RNA, enzymes including ____, lipid envelope, attachment proteins, capsid
|
|
reverse transcriptase
|
|
HIV is a retrovirus because its RNA is converted to DNA by ____
|
|
reverse transcriptase
|
|
process of HIV replication: (1) a protein on the HIV attaches to a CD4 ____ cell
|
|
T helper
|
|
(2) the ____ fuses with the cell surface membrane and the RNA and enzymes enter the cell
|
|
capsid
|
|
(3) the RNA is transcribed to DNA by ____
|
|
reverse transcriptase
|
|
(4) the viral DNA is moved into the nucleus and inserted into the ____
|
|
genome
|
|
(5) the viral ____ and polypeptides are produced by the cell and assembled into new virus particles
|
|
mRNA
|
|
(6) the particles break away from the T-cell, taking with them a piece of the cell surface membrane to form the ____
|
|
lipid envelope
|
|
HIV causes the symptoms of ____ by interfering with helper T-cell function
|
|
AIDS
|
|
without enough T-helper cells the immune system can't stimulate B cells or ____ T cells so the immune response is weakened
|
|
cytotoxic
|
|
viruses are not susceptible to ____ because they do not have their own cell wall/metabolic pathway for them to target
|
|
antibiotics
|
|
a ____ is formed by fusion of a B-plasma cell and a tumour cell from mice
|
|
hybridoma
|
|
these are then cloned and can produce ____
|
|
monoclonal antibodies
|
|
you can produce monoclonal antibodies specific to ____ cells, attach a therapeutic drug, allowing for a localised approach to killing a tumour
|
|
cancer
|
|
monoclonal antibodies ethics: (1) involves deliberately inducing ____ in mice
|
|
cancer
|
|
(2) saved lives but also deaths associated with their use in treating ____ sclerosis
|
|
multiple
|
|
(3) human ____ for safety of new drugs are dangerous
|
|
trials
|
|
vaccines ethics: (1) ____ often used for production and testing, harming them
|
|
animals
|
|
(2) can have ____ effects that cause long term harm
|
|
side
|
|
(3) hard to make fully effective without making them ____ which can be seen as unethical
|
|
compulsory/mandatory
|
|
ELISA test
|
|
enzyme linked immunosorbent assay
|
|
(1) apply the sample to a surface to which all the ____ in the sample will attach
|
|
antigens
|
|
(2) ____ to remove unattached antigens
|
|
wash
|
|
(3) add ____ specific to the antigen we are trying to detect and leave to bind
|
|
antibody
|
|
(4) ____ to remove excess antibody
|
|
wash
|
|
(5) add a second antibody that binds to the first one with an attached ____
|
|
enzyme
|
|
(6) ____ to remove any unattached antibody
|
|
wash
|
|
(7) add the colourless ____ of the enzyme - colour change will occur if enzyme is present
|
|
substrate
|
|
(8) amount of ____ present is relative to the intensity of the colour
|
|
antigen
|
|
used in tests for HIV, tuberculosis, hepatitis, drug tests (because the ____ nature of the test is important)
|
|
quantitative
|
|
as organisms become larger, their surface area decreases compared to their ____
|
|
volume
|
|
large organisms thus need specialised ____ associated with mass transport systems to increase their SA:V ratio
|
|
exchange surfaces
|
|
features of these: (1) large ____ to increase rate of exchange
|
|
surface area
|
|
(2) very thin for a short ____
|
|
diffusion distance
|
|
(3) movement of the ____ to maintain a diffusion gradient
|
|
environmental medium
|
|
(4) a transport system to ensure the movement of the ____ also to maintain a diffusion gradient
|
|
internal medium
|
|
in single-celled organisms, gases are transported across the ____
|
|
cell surface membrane
|
|
insects have an internal network of ____ supported by strengthened rings
|
|
tracheae
|
|
the tracheae divide into smaller dead-end ____
|
|
tracheoles
|
|
these extend through all the insect's body tissues, allowing atmospheric air to be brought directly to all the ____ tissues
|
|
respiring
|
|
respiratory gases move in and out of the ____ system in 3 ways:
|
|
tracheal
|
|
(1) when cells respire, oxygen is used up, so its concentration falls in the tracheoles, so oxygen diffuses in (opposite direction for ____)
|
|
carbon dioxide
|
|
(2) the contraction of muscles in insects can squeeze the trachea allowing ____ movement of air in and out
|
|
mass
|
|
(3) the ends of the tracheoles are filled with ____
|
|
water
|
|
during ____, lactate is produced which lowers water potential of muscle cells
|
|
lactate
|
|
therefore water moves into the cells by osmosis and the ____ of water in the ends of the tracheoles decreases so air is drawn in
|
|
volume
|
|
gases enter and leave the trachea through ____
|
|
spiracles
|
|
in fish, the gills are made up of stacks of ____
|
|
gill filaments
|
|
gill ____ are perpendicular to the filaments and increase surface area
|
|
lamellae
|
|
water is taken in through the ____ and forced over the gills
|
|
mouth
|
|
____ flow of water and blood maintains a diffusion gradient across the whole length of the gill
|
|
counter current
|
|
leaves have many small pores called ____
|
|
stomata
|
|
there are numerous air spaces in the ____ so gases readily come in contact with ____ cells (which have a large surface area)
|
|
mesophyll
|
|
stomata are surrounded by a pair of ____ cells which open and close dependening on water potential
|
|
guard
|
|
water loss is limited in insects by: (1) waterproof ____ on body surface
|
|
cuticle
|
|
(2) ____ can be closed to reduce water loss (largely done when organism is at rest)
|
|
spiracles
|
|
(3) small SA:V ratio to minimise ____ over which water is lost
|
|
area
|
|
plants limit water loss by: (1) stomata close when ____ is low to conserve water when necessary
|
|
water potential
|
|
(2) waterproof waxy ____ on parts of the leaf
|
|
cuticle
|
|
plants that live in areas with low supplies of water
|
|
xerophytes
|
|
xerophyte adaptations: (1) thicker ____
|
|
cuticle
|
|
(2) leaves roll up to trap ____ and reduce the water potential gradient between the internal and external environment
|
|
vapour
|
|
(3) the leaves have ____ to trap moist air next to the leaf surface
|
|
hair
|
|
(4) ____ in pits or grooves trap air and reduce the water potential gradient
|
|
stomata
|
|
(5) reduced surface area of the leaves (but must be balanced with sufficient area for ____)
|
|
photosynthesis
|
|
in humans: (1) flexible airway supported by cartilage
|
|
trachea
|
|
(2) two divisions of the trachea are the ____ which branch into the ____oles
|
|
bronchi
|
|
(3) air sacs at the end of the bronchioles
|
|
alveoli
|
|
inspiration: (1) ____ intercostal muscles contract
|
|
external
|
|
(2) ribs are pulled up and out to increase volume of the ____
|
|
thorax
|
|
(3) reduces ____ to below atmospheric and forces air into the lungs
|
|
pressure
|
|
expiration: (1) ____ intercostal muscles contract
|
|
internal
|
|
(2) ribs move downwards and inwards, ____ volume, increasing pressure, forcing air out
|
|
decreasing
|
|
gas exchange is very rapid between the alveoli and blood because: (1) red blood cells are slowed as they pass through ____ capillaries allowing more time for diffusion
|
|
pulmonary
|
|
(2) the distance between alveolar air and red blood cells is reduced as the red blood cells are flattened against the ____ walls
|
|
capillary
|
|
(3) capillary and alveoli walls are both very thin to reduce ____
|
|
diffusion distance
|
|
(4) alveoli and pulmonary capillaries have a very large ____
|
|
surface area
|
|
(5) breathing movement ventilates the lungs and the action of the heart circulates blood to ensure a steep ____
|
|
concentration gradient
|
|
large biological molecules are hydrolysed to smaller molecules that can be absorbed across cell membranes
|
|
digestion
|
|
carbohydrates are initially digested by ____ which denatures in the low pH of the stomach
|
|
salivary amylase
|
|
the pancreas releases enzymes into the ____ including carbohydrases
|
|
duodenum
|
|
muscles in the intestinal wall push food along the ____
|
|
ileum
|
|
membrane-bound ____ hydrolyse maltose to glucose for example
|
|
disaccharidases
|
|
lipids are hydrolysed by pancreatic ____ into fatty acids and monoglycerides
|
|
lipases
|
|
a glycerol molecule with a single fatty acid attached
|
|
monoglyceride
|
|
lipids being split up into smaller droplets by bile salts to increase surface area
|
|
emulsification
|
|
in absorption, monoglycerides and fatty acids remain associated with bile salts to form ____
|
|
micelles
|
|
bile salts make lipids water soluble because they are ____
|
|
polar
|
|
(1) the micelles come into contact with the ____ cells lining the villi of the ileum
|
|
epithelial
|
|
(2) they break down and release the non-polar monoglycerides and fatty acids which enter the epithelial cells by ____
|
|
simple diffusion
|
|
(3) once inside the epithelial cells, the monoglycerides and fatty acids are transported to the ____ and recombined
|
|
endoplasmic reticulum
|
|
(4) they are packaged into ____ in the ER and Golgi by associating with cholesterol and lipoproteins
|
|
chylomicrons
|
|
(5) these move out of the epithelial cells by ____
|
|
exocytosis
|
|
they enter capillaries by ____ that are found at the centre of each villus
|
|
lacteals
|
|
proteins are digested by: (1) ____ which hydrolyse peptide bonds in the centre of polypeptides
|
|
endopeptidases
|
|
(2) ____ which hydrolyse peptide bonds at the end of polypeptides
|
|
exopeptidases
|
|
(3) ____ which hydrolyse the peptide bonds between two amino acids of a dipeptide
|
|
membrane bound dipeptidases
|
|
amino acids and monosaccharides are both absorbed from the ileum by ____
|
|
cotransport
|
|
haemoglobin structure: four polypeptide chains each with an associated ____ group
|
|
haem
|
|
the process by which haemoglobin binds with oxygen. takes place in the lungs
|
|
association
|
|
the process by which oxygen is released. takes place in the tissues
|
|
dissociaton
|
|
haemoglobin has a greater affinity for oxygen where ____ of oxygen is higher
|
|
partial pressure
|
|
oxygen binds ____ because the first oxygen binding changes the shape of the haemoglobin and makes it easier for the next to bind
|
|
cooperatively
|
|
the ____ effect: a greater carbon dioxide concentration decreases pH of the blood and changes the shape of the haemoglobin to one that more readily unloads oxygen
|
|
Bohr
|
|
____ circulatory system: blood is confined to vessels
|
|
closed
|
|
____ circulatory system: blood passes twice through the heart for each complete circuit of the body
|
|
double
|
|
the double system is useful because blood ____ is reduced in the lungs and it needs to be high enough to reach all the tissues
|
|
pressure
|
|
thin walled, elastic chamber, stretches as it collects blood
|
|
atrium
|
|
thicker, muscular wall, contracts strongly to pump blood
|
|
ventricle
|
|
connected to left ventricle and carries oxygenated blood to all parts of the body except the lungs
|
|
aorta
|
|
connected to the right atrium and brings deoxygenated blood back from the tissues of the body (except the lungs)
|
|
vena cava
|
|
connected to the right ventricle and carries deoxygenated blood to the lungs, where oxygen is replenished and carbon dioxide is removed
|
|
pulmonary artery
|
|
connected to the left atrium and brings oxygenated blood back from the lungs
|
|
pulmonary vein
|
|
____ artery ____ renal vein: carry blood to and from the kidneys
|
|
renal
|
|
semilunar valves closed, atrioventricular valves open, blood moves into atria and ventricles
|
|
diastole
|
|
atria contact and force blood into ventricles. semilunar valves closed, atrioventricular valves open
|
|
atrial systole
|
|
atria relax, ventricles contract, push blood away from heart. atrioventricular valves closed, semilunar valves open
|
|
ventricular systole
|
|
use of ____ valve: prevent backflow of blood when contraction of ventricles makes ventricular pressure exceed atrial pressure
|
|
atrioventricular
|
|
use of ____ valve: prevent backflow of blood into the ventricles when pressure in the vessels increases when elastic walls recoil
|
|
semilunar
|
|
use of ____ valve: ensure that when veins are squeezed when skeletal muscles contract, blood does not flow backwards
|
|
pocket
|
|
carry blood away from the heart and into arterioles
|
|
arteries
|
|
smaller arteries that control blood flow from arteries to capillaries
|
|
arterioles
|
|
tiny vessels that link arterioles to veins
|
|
capillaries
|
|
carry blood from capillaries back to the heart
|
|
veins
|
|
arteries, arterioles and veins have the same layers. from the ____ layer:
|
|
outer
|
|
(1) tough, fibrous layer that resists ____ changes
|
|
pressure
|
|
(2) ____ layer that can contract to control the flow of blood
|
|
muscle
|
|
(3) ____ layer that helps maintain blood pressure by stretching and recoiling
|
|
elastic
|
|
(4) ____ to reduce friction that is thin to allow diffusion
|
|
smooth endothelium
|
|
(5) the central cavity through which blood flows
|
|
lumen
|
|
____ have a thicker muscle layer than veins so they can constrict and dilate to control volume within them
|
|
arteries
|
|
they also have a thick elastic layer to keep pressure ____
|
|
high
|
|
____ have a thinner elastic layer and thicker muscle layer due to lower blood pressure and a need to restrict flow into capillaries respectively
|
|
arterioles
|
|
____ are numerous and highly branched to increase surface area for exchange
|
|
capillaries
|
|
they have a narrow diameter to permeate tissues and ensure no cell is far from a capillary (short ____)
|
|
diffusion distance
|
|
their ____ is narrow so red blood cells are flat against the side to reduce diffusion distance
|
|
lumen
|
|
there are spaces between the endothelial cells that make them up to allow ____ blood cells to deal with infections in tissues
|
|
white
|
|
networks of capillaries that connect veins and arterioles
|
|
capillary beds
|
|
watery fluid containing glucose, amino acids, ions, bathes all the cells of the body
|
|
tissue fluid
|
|
relatively constant environment for the cells it surrounds because it is formed from ____ whose composition is controlled by homeostasis
|
|
blood plasma
|
|
formed when ____ pressure at the arterial end of the capillary is great and fluid moves into the tissues
|
|
hydrostatic
|
|
____ occurs because cells and proteins remain in the blood
|
|
ultrafiltration
|
|
tissue fluid exchanges ____ materials with the cells it bathes and then returns to the circulatory system
|
|
metabolic
|
|
it can do this because hydrostatic pressure is lower at the venuous end (and ____ also occurs)
|
|
osmosis
|
|
some tissue fluid is carried back via the ____ system which drains its contents into the bloodstream via two ducts that join veins close to the heart
|
|
lymphatic
|
|
the contents of this system are moved by hydrostatic pressure of tissue fluid and by ____ of body muscles that squeeze the lymph vessels
|
|
contraction
|
|
____ inside the vessels ensure unidirectional flow
|
|
valves
|
|
mass transport of water in plants: ____ theory
|
|
cohesion tension
|
|
water ____ out of the mesophyll cells and stomata
|
|
evaporates
|
|
more molecules are drawn up behind due to ____
|
|
cohesion
|
|
a column of water is pulled up the xylem due to transpiration: ____
|
|
transpiration pull
|
|
this puts the xylem under ____ - there is negative pressure within the xylem
|
|
tension
|
|
mass flow theory of ____ in the phloem:
|
|
sucrose
|
|
(1) sucrose moves into ____ down a concentration gradient from photosynthesising cells
|
|
companion cells
|
|
via facilitated ____
|
|
diffusion
|
|
(2) sucrose is contransported with ____ ions into the sieve tube elements
|
|
hydrogen
|
|
(3) this reduces water potential so water moves in from the xylem by ____
|
|
osmosis
|
|
(4) this creates a ____ pressure gradient from source to sink so sucrose moves in that direction
|
|
hydrostatic
|
|
(5) sucrose moves into companion cells at the sink by facilitated diffusion and is ____ into storage and respiring cells
|
|
actively transported
|
|
ringing experiment: remove a section of the outer layers around the circumference of a woody stem and the region above will ____
|
|
swell
|
|
non-____ tissues below the ring will die but those above will grow
|
|
photosynthetic
|
|
this suggests the ____ accumulate above the ring and disrupt flow to regions below
|
|
sugars
|
|
tracer experiment: make radioactively labeled ____ using carbon-14 and grow a plant in an environment with that
|
|
carbon dioxide
|
|
this isotope will be incorporated into sugars which can be traced as they move within the plant using ____
|
|
autoradiography
|
|
this means removing a thin cross section and placing it on ____ film
|
|
X ray
|
|
the blackened regions only occur where the phloem tissue is suggesting only the phloem is responsible for ____
|
|
translocation
|
|
a base sequence of DNA that codes for a particular protein at a locus
|
|
gene
|
|
the DNA code is ____ (same for all living things)
|
|
universal
|
|
the DNA code is ____ (some amino acids are coded for by more than one codon)
|
|
degenerate
|
|
the DNA code is ____ (each base is read exactly one)
|
|
non overlapping
|
|
a DNA molecule plus its associated histone proteins in a eukaryotic cell
|
|
chromosome
|
|
sequences of DNA that code for a polypeptide
|
|
exon
|
|
sequences of DNA that do not code for a polypeptide
|
|
intron
|
|
complete set of genes in a cell
|
|
genome
|
|
full range of proteins a cell is able to produce
|
|
proteome
|
|
transcription: (1) the ____ bonds between the strands are broken
|
|
hydrogen
|
|
(2) free RNA nucleotides pair with the exposed bases on the ____ strand
|
|
template
|
|
(3) ____ joins nucleotides to form a pre mRNA molecule
|
|
RNA polymerase
|
|
(4) the DNA strands rejoin behind the enzyme which detaches when it reaches a ____ sequence
|
|
terminator
|
|
(5) in eukaryotic cells the introns are removed by ____ (prokaryotic cells do not have introns)
|
|
splicing
|
|
(6) the mRNA leaves the nucleus through a ____
|
|
nuclear pore
|
|
translation: (1) a ribosome attaches to the ____ codon on the mRNA
|
|
start
|
|
(2) the tRNA molecule with the complementary ____ moves to the ribosome and pairs to the complementary mRNA codon
|
|
anticodon
|
|
(3) the ____ moves along the mRNA, bringing together two tRNA molecules at any one time
|
|
ribosome
|
|
(4) the amino acids are joined by a ____ bond using ATP and when this happens the tRNA is released
|
|
peptide
|
|
(5) this continues until the ribosome reaches a ____ codon at which point the polypeptide is released
|
|
stop
|
|
spontaneous changes to the base sequence of DNA
|
|
mutations
|
|
____ agents increase rate of gene mutation
|
|
mutagenic
|
|
mutations in the number of chromosomes arise spontaneously by chromosome ____ in meiosis
|
|
non disjunction
|
|
meiosis: two nuclear divisions result in the formation of four ____ daughter cells from one diploid parent cell
|
|
haploid
|
|
genetically different daughter cells arise due to ____ of homologous chromosomes when they line up at random during metaphase 1
|
|
independent segregation
|
|
where homologous chromosomes exchange genes at their loci
|
|
crossing over
|
|
number of different alleles in a population
|
|
genetic diversity
|
|
natural selection (1) mutation gives rise to a new ____
|
|
allele
|
|
(2) the allele may benefit its possessor and increase chance of survival and ____
|
|
reproduction
|
|
(3) the advantageous allele is more likely to be inherited and increases in ____ over many generations
|
|
frequency
|
|
the population moves towards an extreme
|
|
directional selection
|
|
the population moves towards the median
|
|
stabilising selection
|
|
____ results in species better adapted to their environment in a way that is anatomical, physiological or behavioural
|
|
natural selection
|
|
organisms that can breed to produce living fertile offspring
|
|
species
|
|
____ behaviour allows individuals to identify a species-specific partner to mate with
|
|
courtship
|
|
a ____ classification system arranges species into groups based on their evolutionary relationships
|
|
phylogenetic
|
|
Linnaeus taxa
|
|
domain kingdom phylum class order family genus species
|
|
the number of different species in a community
|
|
species richness
|
|
the relationship between the number of species in a community and the number of individuals of each species
|
|
index of diversity
|
|
farming techniques reduce ____ because it reduces variation in habitat and food sources
|
|
biodiversity
|
|
you need to balance ____ with farming
|
|
conservation
|
|
e.g. maintain and plant hedgerows at field boundaries, reduce pesticide use, crop rotation that includes a nitrogen fixing crop to increase soil fertility, ____ to control weeds and pests, maintain existing ponds instead of draining for farmland
|
|
intercropping
|
|
you can find information about genetic diversity by comparing: (1) ____ of measurable or observable characteristics
|
|
frequency
|
|
(2) ____ sequence of DNA or mRNA
|
|
base
|
|
(3) ____ sequence of the proteins encoded by DNA and mRNA
|
|
amino acid
|
|
gene ____ has changed methods of investigating genetic diversity by favouring direct investigation of DNA sequences over investigating observable and measurable characteristics
|
|
technology
|
