paper threeeee

Question 1

how does water get out of the xylem?

Answer 1

water potential gradient due to evaporation

Question 2

for translocation

Answer 2

ringing experiments
respiratory poisons
stops moving up at night
sap 
companion sells have mitochondria

Question 3

against translocation

Answer 3

solutes move at different speeds
movement at the same rate down the whole plant
sieve plates weird

Question 4

what are sink cells

Answer 4

respiring cells

Question 5

why does the bohr effect happen

Answer 5

lower ph changes the shape of haemoglobin

Question 6

purpose of double circulatory system

Answer 6

allows pressure to be raised again after oxygenation so blood can get to organs

Question 7

name of outside heart blood vessels

Answer 7

coronary artery, cardiac vein

Question 8

diastole- valves

Answer 8

av open

sl closed

Question 9

atrial systole- valves

Answer 9

av open

sl closed

Question 10

ventricular systole- valves

Answer 10

av closed

sl open

Question 11

what is tissue fluid made of

Answer 11

blood plasma

Question 12

why do arterioles have thicker muscle layers

Answer 12

controls movement into capillaries

Question 13

other way for tissue fluid to return to the blood

Answer 13

lymph fluid

Question 14

what changing shape does to bonds of substrate

Answer 14

distorts

Question 15

light-dependent reaction (5)

Answer 15

• chlorophyll absorbs light- it is photoionised
• some energy from photoionisation is conserved in the production of atp and nadph
• some atp is also produced from chemiosmosis, using energy from the electron transfer chain
• h+ are pumped into the thylakoid and catalyse atp synthase by moving out
• photolysis of water produces protons, electrons (which enter the etc) and oxygen

Question 16

what are schwann cells?

Answer 16

myelin-containing cells that provide electrical insulation/general protection

Question 17

where is myelin?

Answer 17

in the cell membranes of schwann cells

Question 18

open at resting potential

Answer 18

k+ channels, net movement of na+ out of pump

overall negative inside positive outside (so it flips when action potentials arise)

Question 19

when do na+ channels close?

Answer 19

when +40mv potential has been established

Question 20

what causes hyper-polarisation?

Answer 20

outward transport of k+ through the channels that are able to close

Question 21

repolarisation

Answer 21

voltage-gated k+ channels shut, resting potential restored

Question 22

name for the node of ranvier thing

Answer 22

saltatory conduction

Question 23

greater axon diameter

Answer 23

increases speed of conductance due to less ion leakage

Question 24

types of summation

Answer 24

spatial- multiple neurones

temporal- high frequency of neurotransmitter release from one neurone

Question 25

3 purposes of the refractory period

Answer 25

one direction only
discrete impulses
limits number of action potentials

Question 26

action of an inhibitory synapse

Answer 26

• neurotransmitter causes chloride ion channels to open
• cl- move in, also triggers k+ channels to open, so they move out
• membrane potential drops
• this hyperpolarisation makes it less likely that an action potential will be triggered

Question 27

structures in the mitotic spindle

Answer 27

centrioles at the poles, fibres attach to centromeres of chromosomes

Question 28

when do spindle fibres develop?

Answer 28

prophase

Question 29

at what point do the chromatids become known as chromosomes again?

Answer 29

anaphase

Question 30

what happens during binary fission after dna replication?

Answer 30

cell wall splits

Question 31

root tip cells

Answer 31

totipotent stem cells in meristem

Question 32

what do you do to the root tips in rp2?

Answer 32

add to hot acid to denature the enzymes involved in mitosis so cells stop dividing

Question 33

how to focus a microscope

Answer 33

coarse then fine knob

Question 34

what is done to dna before it is fingerprinted?

Answer 34

cut into fragments using restriction endonucleases

Question 35

how are fragments seen in elecrophoresis?

Answer 35

attached to dna probes

Question 36

how are dna fragments produced from rna?

Answer 36

mrna from cells that produce a lot of the protein converted to cdna using reverse transcriptase

Question 37

how gene machines make dna fragments

Answer 37

small, overlapping sequences of nucleotides assembled and replicated using pcr

Question 38

pros of pcr

Answer 38

• fast

- doesn’t require living cell cultures

Question 39

pros of vectors

Answer 39

• low risk of contamination due to the specific restriction endonucleases used
• less mistakes- mutations are rarer than mistakes with pcr

Question 40

step in adding genes to a plasmid that allows it to be replicated

Answer 40

adding promoter and terminal regions to allow binding of rna polymerase

Question 41

what is required by the ribosomes during translation?

Answer 41

enzyme to catalyse the formation of the peptide bond, atp

Question 42

what are genome and proteome defined in terms of?

Answer 42

cells

Question 43

where is iaa produced?

Answer 43

tips of the root/shoot

Question 44

what does a kinesis change?

Answer 44

speed and direction of movement

Question 45

pathway for control of heart rate

Answer 45

receptor > medulla > nervous system > san

Question 46

word to describe heart muscle

Answer 46

myogenic

Question 47

movement of electrical impulse from avn

Answer 47

bundle of his > av septum > purkyne tissue bundles > impulse released

Question 48

benefits of reflexes

Answer 48

• free up the brain for more complex processes
• present from birth
• helps avoid harmful stimuli