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Biology Mine > 3.6 ORganisms respond to cganges in their internal and exteranl enviroments > Flashcards

3.6 ORganisms respond to cganges in their internal and exteranl enviroments Flashcards

3.6 ORganisms respond to cganges in their internal and exteranl enviroments

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1
Q

what is the definition of stimulus

A

Stimulus – a detectable change in the internal or external environment of an organism that leads to a response in the organism.

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2
Q

what are the three things that an organisum needs inorder to respond to there inviroment

A

A Receptor. Detects stimuli. Receptors are specific to one type of stimulus.

Receptors detect information from inside the body and from the surroundings.

A co-ordinator. Formulates a suitable response to a stimulus This could be at the molecular level, the brain or spinal cord (CNS), or a simple collection of cells.

An effector. Produces a response. This could be a muscle or a gland.

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3
Q

what are the two diffrent means of communication in organisms

A

Hormones – relatively slow process, found in both plants and animals

Nervous system – more rapid means of communication found in animals

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4
Q

what is Taxes

A

A taxis is a simple response whose direction is determined by the direction of the stimulus

Directional response to stimulus ie – moves toward (positive taxis) or away (negative taxis) from the stimulus

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5
Q

what is positive taxis, also give an example

A

when an organisum moves directly towards a stimulus
single celled algea - show a positive photo taxis

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6
Q

what is negative taxis, also give an example

A

when an organisum moves directly away from a stimulus
earth worms - have a negative phototaxis

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7
Q

what is kineses

A

A response when an organism does not move towards or away from a stimulus. Instead it changes the speed at which it moves and the rate at which it changes direction.

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8
Q

kinesis is referd to as

A

non direction response to stimulus

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9
Q

why is dom so ulgly and dumb dunmb sna also really sweaty for some reason especially on his back idk why its really weird helpm e im so scared thankk you ;3

A

idk bro good luck tho

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10
Q

why is dom so mean

A

idk bro but good luck again

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11
Q

luisa why are you so ugly

A

shes not never say that EVER??????? agin

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12
Q

what happens if you inrease the light intensity

A

the more unfavourable the conditions innit bruv the more rapidly the organism moves innit fam

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13
Q

why is dom actually so rude and abusive to his mentally disabled girlfriend

A

because he hates disabled people

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14
Q

what happens when a organisum that uses kinesis is in unfavourable conditions

A

The more unfavourable the conditions the more rapidly the organism moves and changes direction more often.

This response enables the organism to return to favourable conditions more rapidly.

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15
Q

what are some organisums that use kinesis

A

woodlice

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16
Q

kinesis vs taxis

A

Taxes - enables a faster direct response to the stimulus but is only possible if the stimulus is directional

Kineses – A slower random response but allows a response to a stimulus that isn’t always directional eg temperature and humidity

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17
Q

list some tropisms in plants

A

Light - phototropic

Gravity - gravitropic

Water – hydrotropic

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18
Q

what is a plant growth factor and give an example and what it does

A

Exert their influence by affecting growth

Some plant growth factors affect the tissues that release them rather than acting on a distant target organ.

Indoleacetic acid (IAA) is a plant growth factor belonging to a group of sunstances called Auxins. IAA controls plant cell elongation.

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19
Q

where is IAA relesed

A

at the tip (of my penis by luisa )

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20
Q

what kills a werewolf

A

a silver bullet

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21
Q

describe the process in which IAA causes elongation

A

Cells in the tip of the shoot produce IAA, which is then transported down the shoot

The IAA is initially transported evenly throughout all regions as it begins to move down the shoot

Light causes the movement of IAA from the light side to the shaded side of the shoot

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22
Q

what does IAA do to a plant

A

As IAA causes elongation of shoot cells and there is a greater concentration of IAA on the shades side of the shoot, the cells on this side elongate more

The shaded side of the shoot elongates faster than the light side, causing the shoot to bend towards the light.

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23
Q

does gravity effect IAA

A

yes

Gravity leads to a change in the distribution of IAA carrier proteins that export IAA from cells

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24
Q

how is IAA used in roots

A

rember IAA is an INHIBITAR in the ROOT CELLS

As IAA inhibits the elongation of root cells and there is a greater concentration of IAA on the lower side, these cells elongate less than those on the upper side

This causes the root to bend downwards towards the force of gravity.

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25
Q

how is IAA used in shoots

A

The greater concentration of IAA on the lower side increases cell elongation so shoots grow upwards away from gravity

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26
Q

essay 25 marker information

A

IAA is produces in root and shoot tips. It is then transported in one direction away from the tip. IAA increases a plant cell’s plasticity (ability to stretch) of their cell walls. The response only occurs in young cell walls where cells are able to elongate. As the cells mature they develop greater rigidity so older parts of the root or shoot will not be able to respond.

The way in which IAA increases the plasticity of cells is called the acid growth hypothesis. Hydrogen ions are actively transported from the cytoplasm into the spaces in cell walls causing the cell walls to become more plastic allowing the cell to elongate by expansion.

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27
Q

what does afferent mean

A

means carrys things to a central pont

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28
Q

waht does efferent mean

A

carrys things away from a central point

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29
Q

what composes the central nervous system

A

Brain and the spine , these are the two things that impulses go to

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30
Q

what is the system called that is responsible for transporting signals from the central nervous system to body parts

A

peripheral nervous system

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31
Q

describe the centrel nervous system in the spine

A

A column of nervous tissue that runs along the back and lies inside the vertebral column for protection. Emerging at intervals along the spinal cord are pairs of nerves.

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32
Q

waht is the function of the spinal cord

A

To relay impulses in and out of any particular point along the cord, and to relay impulses up and down the body, including to and from the brain.

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33
Q

why are reflex arcs important

A

An involuntary response that is very rapid.

It is not under the control of the brain.

It is protective and prevents damage to the body.

basically the spinal bit

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34
Q

what does the automonic nervous system do

A

receives and processes sensory information , initiates responses , stores memory , generates thoughts and emotions.

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35
Q

what does the voluntary nervous system do

A

conducts signals to and from the brain , controlls the activitys of the muscle

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36
Q

make a flow chart of the nervous system

A

check biology folder

37
Q

what is the function of the central nervous system in the nervous system

A

recives and processes information , initiates action

38
Q

what is the function of the peripheral nervous system (PNS) in the nervous system

A

transmits a signal between the CNS and the rest of the body

39
Q

what is the function of the motor neurones in the nervous system

A

carry signals from the CNS that control the activitys of muscles and glands

40
Q

what is the function of the sensory neurones in the nervous system

A

carrys signals to the central nervous system

41
Q

what is the function of the somatic nervous system in the nervous system

A

controls the volentary movements by activating skeletal muscle

42
Q

what is the function of the automic nervous system
in the nervous system

A

controlls involentary response by infuencing organs , glands , and smooth muscle

43
Q

what is the function of the sympathetic division

A

prepares the body for stressful or energetic activity flight or flight

44
Q

what is the function of the parasympathetic division

A

dominates during times of rest and digest

45
Q

what is the function of thespinal cord in the nervous system

A

conducts signals to and from the brain (volentary) controlls reflex activits (involentary)

45
Q

what is the function of the brain in the nervous system

A

receives and processes sensory information , initiates responses stores memories generates thoughts and emotions

46
Q

name a couple of examples of reflex actions

A

light acting as stimuls which changes pupal size

heat as stimulus makes arm contract moving away from the heat object

47
Q

extran information card

A

Involuntary so don’t need the brain to make a decision so the brain is left to carry out more complex responses and not overloaded.

Some impulses are still sent to the brain via ascending and descending tracts in the spinal cord. The brain may store this information or it may relate the information with sense data from, say, the eyes. As a result of receiving this extra information impulses may be sent from the brain to modify the response. Sometimes the response is over-ridden by the brain along inhibitory nerve fibres. (You don’t just drop an expensive, hot plate!)

48
Q

what is the importance of reflex arcs

A

They protect the body from harm. They are effective from birth and do not need to be learnt

They are fast as neurone pathway is short with often one or two synapses (this is the slowest link in a neurone pathway)

As no decision making needed the action is rapid.

49
Q

what is a transducer

A

A transducer is a device that converts energy from one form to another.

49
Q

info card

A

AQA Specification

The Pacinian corpuscle should be used as an example of a receptor to illustrate that:
* receptors respond only to specific stimuli
* stimulation of a receptor leads to the establishment of a generator potential.

The basic structure of a Pacinian corpuscle.
Deformation of stretch-mediated sodium ion channels in a Pacinian corpuscle leads to the establishment of a generator potential.

The human retina in sufficient detail to show how differences in sensitivity to light, sensitivity to colour and visual acuity are explained by differences in the optical pigments of rods and cones and the connections rods and cones make in the optic nerve.

50
Q

what is a pacinian corpuscle

A

A Pacinian corpuscle is a receptor which responds to changes in mechanical pressure.

It is specific to a single type of stimulus

It produces a generator potential by acting as a transducer

51
Q

what is the pacinian corpuscle cell responsible for

A

This is the receptor responsible for our awareness off smooth vs rough surfaces, shallow vs intense tactile sensation, etc.

52
Q

where are pacinian corpuscle cells most commonly found

A

They are found deep in the skin and are most abundant on the fingers, the soles of the feet and the external genitalia. They also occur in joints, ligaments and tendons.

53
Q

what do pacinian corpuscle detterc

A

they detec mechanical stimuli such as pressure and vibrations

54
Q

draw and labble a pacinian corpscle cell

A

https://www.savemyexams.com/a-level/biology/aqa/17/revision-notes/6-organisms-respond-to-changes-in-their-environments-a-level-only/6-1-response-to-stimuli-a-level-only/6-1-7-the-pacinian-corpuscle/

A Pacinian corpuscle is a single sensory neurone in the centre of a layer of tissues, each separated by a gel.

Within the plasma membrane there are protein channels such as sodium channels.

The sodium channel is known as a stretch mediated sodium channel. It is named this way because it’s permeability changes as it’s shape changes

55
Q

describe how a pacinian corpuscle cell produces an action potential

A

Pressure on the skin changed the shape of the Pacinian corpuscle.

This changes the shape of the pressure sensitive sodium channels in the membrane, making them open.

Sodium ions diffuse in through the channels leading to depolarisation of the membrane and thereby producing a generator potential.

The greater the pressure the more sodium channels open and the larger the generator potential.

If a threshold value is reached, an action potential occurs and nerve impulses travel along the sensory neurone.

The frequency of the impulse is related to the intensity of the stimulus

56
Q

what are the two types of receptors in eyes

A

Rods are extremely sensitive in low light and can perceive as few as 6 photons,

while cones sense more abundant light and therefore can identify different colours.

57
Q

where are rods found more commonly

A

in the periphery of the retina while cones are found more near the fovea

58
Q

what is the pigment found in rods called , and how is it used

A

rhodopsin , When light shines on this pigment, it is broken down in a process called bleaching which creates a generator potential that then stimulates an action potential that is detected in the brain.

59
Q

why is there a 3:1 ratio of rods to bipolar neutones and what is it called when 3 recepters converge into one neurone

A

There is a 3:1 ratio of rod cells: bipolar neurone because a threshold value has to be exceeded before a generator potential is made in bipolar neurone. With a 3:1 ratio this is more likely. This is called retinal convergence.

60
Q

why are rods not very usefull in light conditions

A

However, the rhodopsin is very sensitive to light, and is therefore best in dim conditions; since in brighter conditions it is broken down faster than it is reformed. This is why, in dim conditions we will see mainly in black and white

61
Q

what are the effect of neurone summation for rods /retical convergance

A

Many rods usually connected to one bipolar cell so even if many rods detect light only a single impulse will be sent to the brain.

This means that the brain cannot distinguish between separate sources of light that stimulated the Rod cells, so Rod cells give poor visual acuity (i.e. rods are not good at resolving fine detail).

62
Q

what is the pigment called in cones

A

iodopsin

63
Q

info card about cones

A

This cell has a different pigment called iodopsin.
There are 3 different types of iodopsin: sensitive to either red, blue or green wavelengths.

Therefore we have red sensitive, green sensitive and blue sensitive cones. We see different colours by the stimulation of different combinations of iodopsins. E.g red and green cones being stimulated = orange light

Each cone has its own bipolar neurone so they do not create generator potential when stimulated en masse.

They only respond to high light intensity which breaks down iodopsin. It is only then a generator potential is produced.

64
Q

why do cones have a better acuity

A

because they have a 1:1 rato with the ganglio cell

65
Q

draw out a heart

A

https://my.clevelandclinic.org/health/body/21704-heart

66
Q

draw out an eye

A

https://harvardeye.com/uncategorized/diagram-of-the-eye/

67
Q

what are the receptors in the heart called

A

chemoreceptors

68
Q

what type of muscle is the heart made out of

A

cardiac

69
Q

what does myogenic mean

A

originating in muscle tissue (rather than from nerve impulses).

basically , this muscle has the ability to contract and relax without any stimulation and is therefore said to be myogenic

e.g the heart

70
Q

give a description of sinoatrial node SAN

A

It is essential that the sequence of muscle contraction and relaxation takes place in the right order

The sequence is controlled by a group of cardiac muscle cells called the sinoatrial node (SAN) near the top of the right atrium

Known as the natural pacemaker it sets the timing/rate/rhythm of all cardiac muscle cells

A wave of excitation is initiated at the SAN which passes over both of the atrial walls causing the atria to contract simultaneously

71
Q

give a description of the atrioventricular septum

A

The horizontal septum (atrioventricular septum) between the atria and the ventricles is non-conducting and so the wave of excitation cannot pass to the ventricles

The electrical impulse is received by the atrioventricular node (AVN).

This leads to a small delay so that the atria empty fully before the ventricles contract

72
Q

give a description of the Bundle of His

A

From the AVN specialised fibres called the Purkinje tissue (which make up a structure called the bundle of His) conduct electrical impulses rapidly down the vertical septum between the ventricles (like a bottleneck)

73
Q

give a description of the Purkinje Fibres

A

From the Bundle of His the wave of excitation travels back up the ventricles through the Purkinje network of fibres through the ventricular muscle

This causes the ventricles to contract from the apex up

The contraction of the ventricles is therefore delayed after the atria

74
Q

describe the process of heart contraction

A

The mammalian heart is made up of a special type of muscle called cardiac muscle.

This muscle has the ability to contract and relax without any stimulation and is therefore said to be myogenic .

The heart beat is initiated in an area of the right atrium called the sinoatrial node (SAN).
The wave of excitation passes across both atria until it reaches an area of tissue called the atrialventricular node .
This in turn passes the wave to a group of fibres called the bundle of his and then the purkinji fibers which transfer the wave to the tip of the ventricles.

This causes the ventricles to contract from the base upwards and forces blood to flow out of the heart through the aorta and the pulmonary arteiry .

75
Q

changes to the heart rate and force are controlled by a region of the brain called

A

medulla oblongata

76
Q

the parasympathetic nervous system is associated to which nerve

A

the vagus nerve

77
Q

the sympathetic nervous system is associated to which nerve

A

accelerator nerve

78
Q

When do you think the sympathetic nervous system is most dominant?

A

Stress and excitement

79
Q

When do you think the parasympathetic nervous system is most dominant?

A

rest and sleep

80
Q

what is the sympathetic nervous system

A

prepars the body for stressful / energetic activity ‘flight or flight’ -raising heart rate - blood vessiles contract - glucose relesed from liver.

81
Q

what is the parasympathetic nervous system

A

dominates during time of rest and peace mainly focuses on maintance activitys : digestion of food , expulsion of waste

82
Q

CO2 levels increase so pH of the blood is

A

decreases

83
Q

Chemoreceptors in wall of carotid arteries and the aorta detect the change and send an impulse to the

A

medulla oblongata

84
Q

where are chemoresptors found

A

carotid arteries and aorta

85
Q

what happens when blood pressure is high

A

Pressure receptors transmit more impulses to the centre in the medulla oblongata that decreases heart rate .
The centre sends impulses via the parasympathetic nervous system to the SAN which leads to a decrease in heart rate

86
Q

what happens when blood pressure is low:

A

Pressure receptors transmit more impulses to the centre in the medulla oblongata that increases heart rate .
The centre sends impulses via the sympathetic nervous system to the SAN which leads to a increase in heart rate

87
Q
A

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