Stimuli and response and nervous coordination

Question 1

Why do organisms respond to changes in their environment

Answer 1

To increase survival chance

Question 2

Define Taxis response

Answer 2

A simple response directional response in which a whole organism moves towards or away from a stimulus

Question 3

Define Kinesis response

Answer 3

Random movement of a whole organism in response to a non directional stimuli eg temperature or humidity. this may be an increase/decrease in speed or turning frequency

Question 4

How do plants respond to stimuli

Answer 4

Using growth factors

Question 5

What is IAA

Answer 5

Auxin. It is a plant hormone. It allows plants to be photo and gravotrophic

Question 6

Where in a plant is IAA produced

Answer 6

The tips of roots and shoots

Question 7

How does IAA effect cells in shoots and roots

Answer 7

It promotes cell elongation in shoots and restricts it in roots

Question 8

Outline the pathway of a simple reflex arc

Answer 8

Stimulus - receptors - sensory neurone - CNS- relay neurone - motor neurone - Effectors- response

Question 9

What three neurones are involved in a simple reflex arc

Answer 9

Sensory neurone, replay neurone, motor neurone

Question 10

What purpose does a simple reflex arc serve

Answer 10

Protective response to increase survival chance

Question 11

What do the Pacinian corpuscles detect

Answer 11

Mechanical pressure

Question 12

What ion channels are present in the Pacinian corpuscles

Answer 12

Stretch mediated sodium ion channels

Question 13

What is established when a receptor is stimulated

Answer 13

A generator potential

Question 14

When is an action potential triggered

Answer 14

When a generator potential exceeds a threshold

Question 15

What is the connective tissue called that is wrapped around the sensory nerve ending in Pacinian corpuscles

Answer 15

Lamellae

Question 16

What two types of cells detect light in the eyes

Answer 16

Rod cells

cone cells

Question 17

Which type of cell has high visual acuity

Answer 17

cone cells

Question 18

Why do the two types of cells have different visual acuity

Answer 18

Several rod cells connect to one bipolar neurone. This means that they are sensitive but have low visual acuity as it isn’t possible to tell which exact rod cell(s) was stimulated

A cone cell is attached to a single bipolar neurone. This means that they have high visual acuity

Question 19

Which of the two types of cell is most sensitive to light

Answer 19

Rod cells

Question 20

Which type of cell is responsible for trichromatic vision

Answer 20

cone cells

Question 21

What is responsible for the blind spot of an eye

Answer 21

The location where the optic nerve leaves the eye is the blind spot

Question 22

What neurone connects photoreceptors to the optic nerve

Answer 22

bipolar neurone

Question 23

What is different about myogenic muscle tissue

Answer 23

It can contract and relax without receiving signals from nerves
Cardiac muscle fibres are Myogenic

Question 24

Outline the roles of the sinoatrial node (SAN)

Answer 24

Sends regular electrical impulses to the atrial walls to control heart rate. Causes right and left atria to contract simultaneously

Often referred to as pacemaker

Question 25

Outline the roles of the Atrioventricular node (AVN)

Answer 25

Passes the impulse to the bundles of His. Has a slight delay to ensure atria are empty

Question 26

Outline the roles of the Bundle of His

Answer 26

Through the atrioventricular septum to the base of the ventricles where the bundle branches into smaller fibres of purkyne tissue. The wave of excitation is released from the purkyne tissue causing the ventricles to contract quickly at the same time from the bottom of the heart upwards

Question 27

Outline the roles of the Purkyne tissue

Answer 27

This tissue is fibres from the bundle of His. It carries waves of electrical activity into the ventricle walls, causing simultaneous contraction from the bottom up

Question 28

What section of the brain subconsciously controls the rate at which the SAN fires

Answer 28

Medulla

Question 29

Where are the baroreceptors located and what are they stimulated by

Answer 29

Aorta and carotid arteries - pressure

Question 30

Where are the chemoreceptors located and what are they stimulated by

Answer 30

Aorta, carotid arteries and medulla. O2 levels, CO2 levels and Ph (which indicates O2 levels)

Question 31

What effectors are related to slow down heart rate

Answer 31

Acetylcholine, which binds to receptors on the SAN

Question 32

What effectors are related to speed up heart rate

Answer 32

Noradrenaline, which binds to receptors on the SAN

Question 33

When low 02, high CO2 or low blood pH is detected, how is heart rate changed to bring back normal levels

Answer 33

Heart rate is increased. This is done by releasing noradrenaline

Question 34

State the equation linking Cardiac Output (CO), Stroke Volume (V) and Heart Rate (R)

Answer 34

CO=VxR

Question 35

What is a myelin sheath

Answer 35

An electrical insulator

Question 36

What ells are myelin sheaths made from

Answer 36

Schwann cells

Question 37

What is the term for the bare patches of membrane between the cells

Answer 37

Nodes of Ranvier

Question 38

What are sodium ion changes concentrated at

Answer 38

Nodes of Ranvier

Question 39

In a myelinated neurone, where does depolarisation occur

Answer 39

Nodes of Ranvier

Question 40

How does myelination effect the speed of conduction

Answer 40

Increases it all less depolarisation has to occur

Question 41

Give two other features that would effect speed of conduction

Answer 41

Temperature | Axon Diameter

Question 42

When a resting potential is established how is the outside of a cell charged in comparison with the inside

Answer 42

It is positively charged

Question 43

What proteins create and maintain a resting potential

Answer 43

Potassium ion channels, Sodium potassium pumps

Question 44

Why are there more sodium ions outside the cell than on the inside

Answer 44

They are actively transported out and the cell membrane is not very permeable to them

Question 45

When a stimulus is detected, what channel proteins open

Answer 45

Na+ channels open

Question 46

What occurs when the threshold is reached

Answer 46

Lots more Na+ channels open

Question 47

When repolarisation occurs, how does the membrane permeability to sodium and potassium change

Answer 47

Impermeable to sodium, permeable to potassium

Question 48

What effect does the refractory period have on nervous impulses

Answer 48

Acts as a time delay so impulses don't overlap. Ensures impulses are discrete. Means there is a limit to how often impulses can fire

Question 49

As described thy the all-or-nothing principle, how would a bigger stimulus effect the size of an action potential

Answer 49

No change

Question 50

As described thy the all-or-nothing principle, how would a bigger stimulus effect the frequency at which an action potential fires

Answer 50

Faster frequency

Question 51

What is contained in the vesicles of the presynaptic knob

Answer 51

Neurotransmitters

Question 52

What is the gap between the cells at the synapse called

Answer 52

Synaptic cleft

Question 53

Why are synapses unidirectional

Answer 53

Only the post-synaptic neurone has receptors

Question 54

When an action potential arrives at a Cholinergic synapse, what three steps happen

Answer 54

Ca2+ ions move into presynaptic knob. Vesicles with Each fuse with membrane of synapse releasing neurotransmitter. This diffuses across the synaptic cleft and activates the receptors. The neurotransmitter is then broken down by AChE

Question 55

What is summation in relation to synapses

Answer 55

Where the effect of many neurones, or one stimulated multiple times, is added together

Question 56

State the names of both types of summation

Answer 56

Spatial summation | temporal summation

Question 57

How is ACh removed from he synaptic junction

Answer 57

AChE breaks it down and the products are reabsorbed by the presynaptic neuyrone

Question 58

What are stored in clefts at a neuromuscular junction

Answer 58

AChE

Question 59

suggest 2 advantages of simple reflexes

Answer 59

``` rapid protect against damage to the body do not have to be learnt help escape predators enable homeostatic control ```

Question 60

stimuli are detected by

Answer 60

receptors

Question 61

a response to a stimuli is controlled by a

Answer 61

coordinator (brain)

Question 62

a response to a stimuli (eg hormone secretion) is produced by

Answer 62

an effector

Question 63

Movement of a whole organism towards light is called, and give an example of such an organism

Answer 63

phototaxis (algae)

Question 64

Positive taxis is

Answer 64

movement towards a stimulus by a whole organism

Question 65

Negative taxis is

Answer 65

movement away from a stimulus by a whole organism

Question 66

define tropism

Answer 66

the growth of part of a plant in response to a directional stimulus eg light, gravity or water

Question 67

when plants grow towards light it is called

Answer 67

positive phototropism

Question 68

when plant shoots grow away from gravity it is called

Answer 68

negative gravitropism

Question 69

When plant roots grow away from light it is called

Answer 69

negative phototropism

Question 70

Why do woodlice increase their rate of turning if they exit favourable conditions

Answer 70

to increase the probability that they will reenter the favourable conditions

Question 71

why do woodlice decrease their rate of turning and move rapidly after spending a while in unfavourable conditions

Answer 71

to increase the chances that they will pas through the unfavourable conditions and enter more favourable ones

Question 72

When roots grow towards water it is called

Answer 72

positive hydrotropism

Question 73

give the location of the osmoreceptors in the body of a mammal

Answer 73

hypothalamus

Question 74

the pressure receptors in the skin are called

Answer 74

pacinian corpuscles

Question 75

what is a transducer

Answer 75

a receptor cell which converts one form of energy (eg light) into a form that can be understood by the body (eg an electrical impulse)

Question 76

What is a stretch mediated sodium channel

Answer 76

a sodium channel protein whose permeability to sodium ions increases they they are deformed

Question 77

In which part of the eye are light receptor cells found

Answer 77

the retina

Question 78

rod cells are responsible for _____ vision

Answer 78

black and white

Question 79

why can rod cell images only be seen in black and white

Answer 79

they can not distinguish between different wavelengths of light

Question 80

rod cells are sensitive to ____ intensity light

Answer 80

low

Question 81

cone cells are sensitive to _____ intensity light

Answer 81

high

Question 82

which pigment, that breaks down in low intensity light, is found inside rod cells

Answer 82

rhodopsin

Question 83

How many types of cone cell are there

Answer 83

3

Question 84

each of the 3 types of cone cell contain a specific group of pigments called

Answer 84

iodopsins

Question 85

does iodopsin break down in the presence of high or low intensity light

Answer 85

high

Question 86

where does the lens of the eye focus light

Answer 86

fovea

Question 87

where is the fovea

Answer 87

central point in the retina

Question 88

outer periphery of the retina contains ____ cells

Answer 88

rod

Question 89

the fovea contains ____

Answer 89

cone

Question 90

what are cholinergic synapses

Answer 90

synapses that use acetylcholine

Question 91

What is a synapse

Answer 91

the junction between a neurone and the next cell

Question 92

what ensures that impulses cross the synapse in one direction only

Answer 92

Neurotransmitter is released from the presynaptic knob. Receptor for the neurotransmitter is only found on the post synaptic membrane

Question 93

what happens to the neurotransmitter once they have attached to the receptors on the post synaptic membrane

Answer 93

They are broken down by enzymes and their products are taken back into the neurone

Question 94

What stimulates the synaptic vesicles to move towards the presynaptic membrane in a cholinergic synapse

Answer 94

Calcium ions diffuse into the synaptic knob causing the synaptic vesicles to move towards the presynaptic membrane

Question 95

What happens when the acetylcholine bind with the receptors on the post synaptic membrane

Answer 95

Sodium channels open and sodium floods in. If the threshold is reached an action potential is generated

Question 96

How is acetylcholine removed from the synaptic cleft

Answer 96

Acetylcholinesterase breaks acetylcholine and the products are reabsorbed to make more acetylcholine

Question 97

What is temporal summation

Answer 97

where there are two or more nerve impulses that arrive in quick succession from the same presynaptic membrane and action potential is more likely to occur

Question 98

What is spatial summation

Answer 98

When many neurones connect to one neurone. The small amount of neurotransmitter released from each of these neurones can be enough to reach the threshold value

Question 99

What are the nodes of Ranvier

Answer 99

Bare areas of neurones that are not insulated by myelin