exam Flashcards
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
state the differences between sperm and ovum
sperm: motile smaller no stored nutrients either x or y chr has tail acrosome present ovum: cant move larger stored nutrients only x chr no tail acrosome not present
