Coordination

Question 1

definition of stimulus

Answer 1

change in environment that is detected by a receptor causing a response

Question 2

definition of response

Answer 2

action resulting from perception of stimulus

Question 3

three types of neurones

Answer 3

sensory/relay/motor

Question 4

describe the structure of sensory neurone (6)

Answer 4

long myelinated axon
cell body in the middle
one side is myelin sheath
other side is dendrone
many mitochondria in cytoplasm of axon
many vesicles for neurotransmission

Question 5

describe purpose of sensory neurone

Answer 5

receptor to CNS

Question 6

describe purpose of relay neurone

Answer 6

intermediate neurone

pass action potentials

Question 7

describe structure of relay neurone (4)

Answer 7

long axon
pre synaptic terminal
cell body
dendrites

Question 8

describe structure of motor neurone (8)

Answer 8

dendrites lead to cell body
nucleus in cell body
many mitochondria
much RER
long axon
synaptic knobs
schwann cells
node of ranvier

Question 9

describe the myelin sheath (5)

Answer 9

Schwann cells wrap around axon
to form myelin sheath;
insulate axon;
depolarisation occur at nodes of ranvier;
long local circuits;
action potentials move by saltatory conduction;

Question 10

describe the reflex arc

Answer 10

Stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector

Question 11

describe the purpose of reflex arc (4)

Answer 11

fast for protection
automatic
same specific response
doesn’t pass CNS

Question 12

describe the transmission of action potentials (10)

Answer 12

Na+ channels open;
Na+ enters axon;
depolarisation;
Na+ channels close;
K+ channels open;
K+ move out of cell;
repolarisation;
local circuits;
one way transmission;
happens at nodes of ranvier;

Question 13

what is the resting potential of axon

Answer 13

-60mV

Question 14

how is the resting potential maintained (3)

Answer 14

active transport
sodium and potassium pump
sodium ions out and potassium ions in
against electrochemical gradient

Question 15

what gradient causes the flow of Na+/K+

Answer 15

electrochemical gradient

Question 16

how is the speed of conduction quick

Answer 16

jump from one node to the next (saltatory conduction)

faster in thin axons with less resistance

Question 17

describe action potential in taste buds (6)

Answer 17

Na+ diffuse through microvilli
membrane depolarised
stimulates voltage gated calcium ions to open
calcium ions flood in cytoplasm
stimulate vesicles of neurotransmitter to perform exocytosis
stimulation above threshold = action potential passed

Question 18

describe the synaptic transmission (7)

Answer 18

nerve impulse reach presynaptic membrane
voltage gated channels for calcium ions to diffuse in cytoplasm
calcium ions cause vesicles with acetylcholine to move to presynaptic membrane and fuse with membrane → exocytosis
acetylcholine released and diffused across synaptic cleft
acetylcholine molecules bind with receptors on post synaptic membrane, Na+ channels open
depolarisation

Question 19

describe recycling acetylcholine

Answer 19

acetylcholinesterase hydrolyses Ach → acetate + choline
choline reabsorbed into presynaptic neurone
Choline + Acetyl CoA → Acetylcholine
packed into vesicles to be released again

Question 20

what is the purpose of acetylcholinesterase (5)

Answer 20

breaks down acetylcholine;
acetylcholine leaves binding site;
depolarisation stops in post synaptic membrane;
stops continuous action potentials;
recycle Ach;

Question 21

purpose of synapses (4)

Answer 21

one way transmission
interconnection between pathways
depolarisation of membrane
memory and learning

Question 22

describe muscle fibres (12)

Answer 22

fibres are multinucleate;
cell surface membrane is sarcolemma;
sarcoplasm has many mitochondria;
sarcoplasmic resticulum membranes have protein pumps;
T system;
myofibrils;
myosin attached to M line;
actin attached to Z line;
sarcomere is distance between M line;
myosin is fibrous protein with globular head;
actin is chain of globular protein molecules;
tropomyosin attached to actin;

Question 23

what is present in sarcolemma

Answer 23

T tubules/deep infolds

Question 24

what is present in sarcoplasm

Answer 24

many mitochondria

Question 25

what is present in sarcoplasmic reticulum

Answer 25

many protein pumps

Question 26

describe the structure of myofibril

Answer 26

``` A band H band I band M line Z line ```

Question 27

events in neuromuscular junction

Answer 27

same as synaptic transmission but sarcolemma sarcoplasm

Question 28

process of muscle contraction (9)

Answer 28

in muscle fibres sarcolemma is depolarised; T tubules depolarised due to spread; calcium ions diffuse out of sarcoplasmic reticulum through channel proteins; calcium ions bind to troponin; troponin changes shape and tropomyosin moves; binding site of actin exposed; myosin heads tilt through sliding filament model; sarcomere shortens and muscle contracts; ATP hydrolysis releases myosin from actin to repeat;

Question 29

what happens when ATP is unavailable in muscle contraction (5)

Answer 29

``` no detachment of myosin head; no hydrolysis; no power stroke; no recovery stroke; no pumping of calcium ions in sarcoplasmic reticulum; ```

Question 30

definition of voltage gated channels | IONS

Answer 30

ion transport open/close when voltage changes specific protein

Question 31

describe threshold for action potential to occur

Answer 31

all-or-nothing law (as long as its above threshold); | action potential same size no matter how strong stimulus;

Question 32

where is FSH and LH secreted

Answer 32

anterior pituitary gland

Question 33

where is oestrogen and progesterone secreted

Answer 33

ovaries

Question 34

describe the menstrual cycle (14)

Answer 34

FSH secreted by anterior pituitary; stimulates growth of follicle; dominant follicle secretes oestrogen; oestrogen stimulates repar of endometrium; oestrogen inhibits further release of FSH; increase in oestrogen day 14; stimulates secretion of PH from anterior pituitary; LH stimulates ovulation; LH stimulates development of corpus luteum; corpus luteum secretes progesterone; progesterone maintains endometrium/buildup; progesterone inhibits LH/FSH; corpus luterum degenerature - conc. of progesterone falls; endometrium breaks down;

Question 35

describe birth control pills

Answer 35

synthetic long lasting hormone of progrestone/oestrogen

Question 36

purpose of birth control pills (4)

Answer 36

suppress secretion of FSH; thick mucus shielding sperm; no ovum matured; inhibit LH;

Question 37

describe electrical communication of venus fly trap (13)

Answer 37

``` Mechanical energy converted to electrical; Sensory hair cell; Cell membrane depolarises; Two hairs touched; Action potential occurs; Action potential spreads over leaf; H+ pumped out of cells; Cell wall cross linked broken; Ca2+ enters cells; Water enters by osmosis; Cells become turgid; Change from convex to concave; Trap shuts quickly in 0.3s; ```

Question 38

describe chemical communication in plants (auxin) (11)

Answer 38

``` Acid growth; Proton pumps; On cell surface membrane; H+ pump into cell wall By active transport pH of cell wall decreases; Activates expansins; To break bonds between cellulose microfibrils; Cell wall loosens; Turgor pressure increases; Cell expands; ```

Question 39

describe effect on cell wall with many hydrogen ions moving into cell wall (5)

Answer 39

``` cell wall becomes acidic activates expansins to loosen bonds between cellulose microfibrils allow cell wall to expand turgor pressure ```

Question 40

purpose of gibberellins

Answer 40

stem elongation - activates cell division and cell elongation in stem

Question 41

how does giberellins cause these effects

Answer 41

regulating genes involved in synthesis of amylase

Question 42

what is germination

Answer 42

development of plant from seed after dormancy

Question 43

what is dormancy

Answer 43

very little water | metabolically inactive

Question 44

how does germination take place (6)

Answer 44

``` water uptake initiates; embryo synthesises giberellins; aleurone layer synthesises amylase; amylase breaks down starch into maltose; maltose turned into glucose; endosperm tissue contains starch reserves ```