processes

Question 1

phagocytosis

Answer 1

attracted to pathogen by chemoattractants
forms phagosome by engulfing
migration of lysosomes and lysozyme mechanism
pathogen hydrolysed, debris released by exocytosis
display of antigens on cell surface membrane

Question 2

phloem

mass transport of sugars

Answer 2

enters by A.T. by companion, loweing wp
water enters by osmosis creating a high hydrostatic pressure
more volume and pressure in leaves so mass flow of sugars to the sink/roots and unloaded

Question 3

cohesion tension theory

Answer 3

water lost by transpiration > stomata
wp of mesophyll cells decreases
water pulled up xylem creating tension
form hydrogen bonds via cohesion and adhere to xylem walls
lost water is replenished by osmosis in the roots

Question 4

formation
return
of tissure fluid

Answer 4

high hydrostatic pressure at arteriol end of capillary, created by pumping of the heart
water forced out
plasma proteins/ large molecules remain

at venous end low wp due to large molecules
water reenters by osmosis
OR excess tissue fluid drained by lymphatic system

Question 5

cell fractionisation

Answer 5

homogenisation in cold, isotonic, buffered solution releasing cell contents
filtered to remove debris
ultracentrifuge at low speed until pellet forms
spin supernatent at higher speed

heaviest organelle deposited first

Question 6

dna replication

Answer 6

dNA helicase - breaks hydrogen bonds between 2 strands
free floating nucleotides attracted to exposed based as complentary pairing occurs
dNA polymerase - forms phosphodiester bonds between adjacent nucleotides

Question 7

transcription

Answer 7

DNA helicase - breaks hydrogen bonds between nucleotides
one strand acts as a template
free floating nucleotides attracted to exposed based as complentary pairing occurs
RNA polymerase - joins nucleotides together foming a pre-mRNA molecule.
spliced, removal of introns

Question 8

translation

Answer 8

mRNA moves through cytoplasm
ribosome attaches to start codon of mRNA
tRNA with complentary anticodon moves to ribosome attached with corresponding aa
ribosome moves onto next codon until reaches stop codon
aa joined by peptide bond in condenstation reactions fueled by ATP

Question 9

effects of mutations

Answer 9

change in one base alters primary structure
affects secondary and tertiary structure/postion of bonds
active site no longer complementary/enzyme denatured
prevents E-S complex from forming
so non functional

Question 10

ventilation in lungs

Answer 10

EXPIRATION
contraction of internal intercostal muscles
diaphragm relax
decrease volume in thoriacic cavity and increase in pulmonary/lung pressure
air pushed out by pressure gradient