Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

biology > 6. organisms respond to changes > Flashcards

6. organisms respond to changes Flashcards

1
Q

where is IAA produced?

A

tip of shoots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

describe resting potential

A

high conc of Na+ ions outside of membrane
high conc of K+ ions inside of membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how do ions move through ion channels?

A

simple diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how do ions move through K+/Na+ pump?

A

active transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

why do myelinated cells conduct faster?

A

depolarisation only occurs at nodes of ranvier
mylenation provides insulation
saltatory conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is myelination?

A

electrical insulation, Schwann cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is saltatory conduction?

A

when depolarisation only occurs at nodes of ranvier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

advtanges of simple reflex arc

A

rapid, dont have to be learnt, protects from damage to tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

give two things which makes action potential unidirectional

A

neurotransmitters only released from pre-synaptic knob
receptors only on post-synaptic knob

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how is resting potential maintained?

A

membrane only partially permeable to K+ ions, non permeable to Na+ ions
Na+/K+ pump moves Na+ out of membrane and K+ into membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how do cones/rods send signals to brain?

A

tips bleached, action potential, diffuses to bipolar cell, ganglion cell, optic nerve, brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

why does the end of an axon only experience resting potential or action potential, not generator potential?

A

all or nothing principle, threshold has to be reached, all action potentials have same voltage, none larger than the others

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

why do cones have higher visual acuity than rods?

A

all connected to their own bipolar cell, individual impulses to brain means they have higher acuity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe what happens during generator potential

A

pressure on pacinian corpuscle causes lamellea to deform and stretch mediated sodium ion to open
Na+ ions flow into membrane via f.d.
change in potential difference causes depolarisation/generator potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe difference between generator and action potential

A

if threshold is reached, action potential is triggered and wave of depolarisation is fired down neurone/axon membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

describe wave of depolarisation

A

interior of axon becomes more positive than exterior

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

describe hyperpolarisation

A

potassium ion channel may close too slowly so when resting potential is reached K+ ions may still need time to move out of membrane
potential difference is more negative than at resting potential (more positive charge outside membrane than usual)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

give five factors which effect speed of action potential

A

temperature
axon diameter
summation
inhibitory signals
myelination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how does axon diameter effect speed of action potential?

A

larger diameter = quicker action potential
more space for ions to move in/out quickly and send wave of depolarisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

name the two types of summation

A

temporal
spatial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is spatial summation?

A

more presynaptic membranes in one place means action potential more likely to be generated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is temporal summation?

A

multiple signals from presynaptic membranes in a short space of time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

how do inhibitory signals work?

A

hyperpolarise membrane by opening K+ ion channels so they diffuse out
or
causes K+ ions to move out of post synaptic membrane

more Na+ ions needed to generate action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

how does an action potential cross a synapse

A

action potential arrives at pre synaptic membrane and causes voltage gated Ca2+ channels to open so ions diffuse into knob
influx of ions causes vesicles of Ach to fuse with post synaptic membrane
released into synaptic cleft by exocytosis
diffuse across cleft and bind to post synaptic membrane on cholinergic membrane receptors
causes voltage gated Ca2+ ion channels to open and calcium ions to diffuse into post synaptic knob
depolarisation triggers action potential
Ach left in cleft broken down by acetyl cholinesterase and absorbed by pre synaptic membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
where do sensory neurones take signals
from receptors to CNS
26
where do motor neurones takes signals
from CNS to effectors
27
IAA effect on roots
inhibits growth/cell elongation
28
IAA effect on shoots
stimulates cell elongation
29
what effects IAA conc in roots
gravity pulls it downwards
30
order the reflex arc
stimulus - receptor - sensory neurone - relay neurone - motor neurone - effector
31
advantages of reflex arc
quicker not to be learnt/subconscious homeostatic control
32
CNS
central nervous system brain
33
peripheral nervous system
neurones between CNS and rest of body
34
somatic response
conscious
35
autonomic response
unconscious
36
parasympathetic response
calming down peace
37
sympathetic response
fight or flight stress
38
myogenic
no external stimulus e.g. heart rate
39
how does the heart beat?
wave of depolarisation/excitation from SAN causes atria to contract non conducting tissue stops signal going straight to ventricles depolarisation carried to AVN after slight delay AVN sends to purkyne fibres to BOH purkyne fibres split at BOH cause ventricles to contract from bottom
40
what detects blood pressure levels
barro receptors
41
response to high blood pressure
inhibitory system in medulla stimulates parasympathetic nerves releases acetyl choline
42
response to low blood pressure
excitatory system in medulla stimulates sympathetic nerves releases noradrenaline
43
what detected oxygen/carbon dioxide blood levels
chemoreceptors
44
response to high oxygen/low CO2
inhibitory system in medulla stimulates parasympathetic nerves releases acetyl choline to slow down heart rate
45
response to high CO2/low oxygen
excitatory system in medulla stimulates sympathetic nerves releases noradrenaline
46
name of two muscles which work in pairs
agonistic
47
cytoplasm in muscle cells
sarcoplasm
48
name of cell surface membrane in muscles
sarcolemma
49
thin protein filaments in myofibrils
actin
50
thick protein filament in myofibrils
myosin
51
H band
only thick myosin filaments
52
A band
only myosin + overlap
53
I band
only thin actin filaments
54
M line
down centre of myosin filaments
55
Z line
down centre of actin filaments
56
neuromuscular junctions
action potential at neuromuscular junction causes calcium ions to be released from sarcoplasmic reticulum Ca2+ ions bind to troponin causing them to change shape causes troponin and tropomyosin to move on actin filament meaning actin binding site is exposed myosin heads bind forming myosin-actin bridged
57
muscular contraction
myosin heads are bonded, bridges formed myosin head moves towards sarcomere dragging binding site and actin filament with it ATP binds to head causing myosin to unbind from actin and myosin head can bind to next binding site which is now at original myosin head position
58
what is ATP used for in muscle contraction
movement of myosin head to actin binding site hydrolysis of actin binding site when myosin is bonded
59
phosphocreatine equation and use
ADP + phosphocreatine -> ATP + creatine rapid production of ATP
60
fast muscle fibers
conduct rapidly lots of Ca2+ anaerobic respiration for ATP fewer capillaries light red
61
slow muscle fibers
conduct slowly aerobic respiration for ATP dark red lots of large mitochondria
62
taxis
directional movement towards/away from a stimuli
63
kinesis
random movement in response to a stimuli
64
name of a pair of muscles which work together
antagonistic
65
negative feedback loop
maintaining optimum levels if a change leads to a decrease of the variable system works to increase the variable, if a change leads to an increase in a variable, system works to decrease the variable magnitude of response needed to maintain optimum levels is monitored
66
positive feedback loop
MORE when MORE enhance initial stimulus work to increase the level of change repair of broken bones
67
response to high blood glucose levels
absorbed by beta calls in islets of langerhans secrete insulin via vesicles from beta cells stimulates uptake of glucose by muscle cells, fat cells and the liver activates ENZYMES for glycogenesis alpha cells stop secreting glycogen
68
mechanism of insulin
insulin binds to specific receptors on membranes of target cells stimulates the addition of more glucose channel proteins making membrane more permeable to glucose rate of f.d increases activates ENZYMES for glycogenesis
69
glycogenesis
converts glucose in the liver to glycogen maintains high concentration gradient between outside the liver and inside (rate of f.d. of glucose out of blood)
70
response to low blood glucose concentration levels
detected by alpha and beta cells in the pancreas alpha cells secrete glucagon beta cells stop secreting insulin
71
action of glucagon
binds to receptors on the liver activates ENZYMES for glycogenelysis (break down of glycogen to glucose) activates ENZYMES for gluconeogenesis (glucose from glycerol + fatty acids)
72
response to in-optimum glucose levels in blood
detected by chemoreceptors communicated to control centre via hormonal/nervous system effectors receive message
73
limits of mechanism of negative feedback
can't counteract change which is too extreme
74
hypothalamus
detects heat change in brain
75
hormone secreted by alpha cells
glucagon
76
hormone secreted by beta cells
insulin
77
mechanism of glucagon
binds to receptors on liver cells to allow for glycogenelysis (glycogen to glucose) gluconeogenesis - new glucose from glycerol and amino acids
77
mechanism of insulin
bind to hepatocytes and increases permeability in cell membrane of liver (more glucose channels), glucose moves into cells and out of blood activates enzyme for glycogenesis (glycogen from glucose)
78
response to increase of blood glucose
detected by beta cells in eyelets of langerhans insulin released higher glucose permeability in liver cells glycogenesis increase rate of resp blood glucose decreases
79
response to decrease of blood glucose
detected by alpha cells in eyelets of langerhans glucagon released decreases rate of respiration gluconeogenesis glycogenolysis increase in conc of glucose
80
adrenaline response to low glucose levels
binds to liver cell chemically similar to glucagon activates glycogenolysis inhibits glycogenesis
81
mechanism of binding of adrenaline
adrenaline binds to hormone receptor ATP converted to cAMP (secondary messenger) activates protein kinase A enzyme for cascade reaction of glycogenolysis
82
mechanism for type 1 diabetes
immune system attacks beta cells in islets of langerhans no response to high blood glucose hypoglaeceamia treated with insulin genetic or viral infection
83
mechanism for type 2 diabetes
beta cells dont release enough insulin receptors to insulin dont work
84
three layers separating glomerular capillary and bowmans capsule
capillary endothelium basement membrane capsule epithelium
85
layers of kidney
inner = medulla outer = cortea
86
mechanism of ADH
binds to cells in convoluted tubules and collecting duct more protein channels more water moves through by osmosis more water reabsorbed into blood
87
water potential too low
ADH released by pituitary gland so more water reabsorbed less urine
88
water potential too high
ADH not released water not reabsorbed more urine
89
how is water potential detected in blood
osmoreceptors, feel water moving in and out sends signal to hypothalamus hypothalamus triggers pituitary gland
90
movement of blood through kidney
afferent arteriole -> glomerulus -> efferent arteriole
91
process of ultrafiltration
movement of water, salts, glucose, amino acids and urea from glomerulus to Bowmans capsule
92
what is reabsorbed at proximal convoluted tubule
glucose f.d. and active transport
93
what is reabsorbed in descending loop of henle
water osmosis
94
what is reabsorbed in ascending loop of henle
salts f.d. and active transport
95
what is reabsorbed in distal convoluted tubule
excess water moves back in by osmosis
96
function of collecting duct
waste and excess water to bladder

biology (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions