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test for starch
starch is placed on spotting tile a drop of yellow brow iodine is added will change blue black in presence of starch
test for glucose
glucose and distilled water benedicts’ sol added(few drops) water bath and boil blue will change to brick red
test for protein
biurets solution protein and distilled water pale purple
test for lipid
pipette used to add one drop of oil ethanol water white layer forms
describe how energy content of food can be measured
mass of food sample is found measured vol of 20cm3 water is placed in a boiling tube tube is supported by stand and clamp temperature of water is recorded food is speared on end of mounted needle and held on to a bunsen burner flame until it catches fire needle is used to hold burning food under boiling tube of water this is continued,relighting if the flame goes out until the food can no longer burn thermometer is used to stir gently so heat is evenly distributed and final temp is recorded energy in joules per gram= (final temp-initial temp)x20gx4.2/mass of food(g) errors:(heat lost in test tube and water distance between food and water not equal)
describe the process of transcription
happens in the nucleus in a chromosome part of the DNA helix unwinds and unzips so the 2 strands separate exposing the bases along the template strand DNA forms framework and mRNA is formed building blocks of mRNA are RNA nucleotides they line up according to the complementary base pair rule mRNA leaves nucleus and moves in to cytoplasm through the pores of the nuclear membrane DNA helix then zips up again
describe the process of translation
takes place at ribosome first tRNA binds to bind at mRNA does so at start codon another tRNA brings an anticodon which binds with next codon on mRNA bonds form between first and second amino acid process is ongoing forming a polypeptide at end of chain is stop codon
what are the differences between DNA and RNA
DNA is a double helix RNA is a single strand DNA contains the sugar deoxyribose RNA contains ribose RNA contains the base uracil instead of thymine
where does protein synthesis take place
cytoplasm of cell
tough outer coat of eye, visible white coat
sclera
transparent window which allows light to enter eye
cornea
coloured ring of tissue
iris
hole which lets light through
pupil
dark layer underneath sclera which contains many pigment cells and blood vessels
choroid
place where light energy is converted to nerve impulses at back of the eye
retina
nerve which carries impulses to brain
optic nerve
place where cones are concentrated
fovea
what are the adv of having 2 eyes
cancelling blind spot wider field of vision stereoscopic vision better sense of distances
what are the changes that occur that allow distant objects to be seen
ciliary ms relax suspensory ligaments are pulled tight lens flat
state cause, result and method of correction for long sight
cause: lens not convex enough or eyeball too short result: light focused beyond retina method of correction: convex lens to converge light before it enters the eye
state cause, result and method of correction for short sight
cause: lens too convex or eye ball too long result: light focused short of retina method of correction: concave lens to converge lens before it enters the eye
discuss the differences between regular and irregular astigmatism
regular: occurs when surface of cornea or lens is not perfectly spherical but rounder in one direction than the other person’s eye will be in focus in one direction but not the other corrected by glasses or lenses irregular: curvature of cornea or lens is in more than one direction corrected by lenses only
what is a cataract and how is it treated
a condition in which the lens becomes cloudy and opaque so person is unable to see can only be treated by surgery lens is replaced by artifical lens
roles of vitamins+deficiency
A:making chemical in retina and protects eye surface deficiency: night blindness B1: helps with cell respiration def: beri beri B2:helps with cell respiration def: poor growth and dry skin B3:helps with cell respiration def: pellagra(dry red skin, poor growth, and digestive disorders) C:sticks together lining surfaces such as the mouth def: scurvy D: helps bone absorb calcium and phosphate