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Biology unit 4 > unit 4 > Flashcards

unit 4 Flashcards

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1
Q

What is a tropism

A

A directional growth response in which the direction of the response is determined by the direction of the external stimulus

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2
Q

What are the 4 types of tropisms

A

Photo tropism
Geotropism
Chemotropism
Thigmotropism

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3
Q

What is phototropism

A

When shoots grow towards the light which enables them to photosynthesis. They’re positively phototrophic

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4
Q

What is Geotropism

A

Roots grow towards the pull of gravity
Anchors them in the soil and helps them to take up water need for support, for a raw material of photosynthesis and to help cool the plant.

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5
Q

What is Chemotropism

A

On a flower when pollen tubes grow down the style attracted by chemicals, towards the ovary where fertilisation can take place

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6
Q

What is Thigmotropism

A

Shoots of climbing plants such as ivy wind around other plants or solid structures and gain support

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7
Q

What are hormones

A

Coordinate plant responses yo environmental stimuli

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8
Q

What are plant hormones referred to and why

A

Plant growth hormones

Unlike animal hormones they are no produced in endocrine glands, but by cells in a variety of tissues in the plant

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9
Q

Some hormones can have different effects on different tissues

Term when they amplify each others effects. Term when they cancel out each others effects

A

Synergy

Antagonism

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10
Q

If a plant responds towards a stimulus it’s a positive tropic response

If it’s away it’s still a tropic (directional) response but negative

A

Just saying

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11
Q

What limits the cells ability to divide

Consequence

A

The cell wall around a plant cell

Growth only. Happens in particular places in the plant

Meristems

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12
Q

4 types of Meristems

A

Apical
Lateral bud
Lateral
Intercalary

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13
Q

Apical Meristems

A

Found at tips or spices (apex) of roots and shoot and are responsible for the roots and shoots getting longer

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14
Q

Lateral bud Meristems

A

Found in buds

Could give rise to side shoots

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15
Q

Lateral

A

Found in a cylinder near the outside of the roots and shoots and are responsible for the roots and shoots getting wider

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16
Q

Intercalary Meristems

A

Found between the nodes

Growth between the ndes is responsible for the shoot getting longer

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17
Q

Where does cell division happen

What about elongation

A

Closest to the apex

Just behind the apex

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18
Q

Where are auxin produced

A

Apex

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19
Q

How does auxin travel to the cells in the zone of elongation

A

Diffusion or active transport

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20
Q

What happens when auxin reach the cells I the zone of elongation

A

Cells elongate making the shoot grow

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21
Q

Role of auxin

A

Stimulate shoot growth by causing elongation

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22
Q

How do auxin increase the stretchiness of the cell wall

A

By promoting the active transport of hydrogen ions by an atpase enzyme on the plasma membrane into the cell wall
The resulting low pH provides optimum conditions for wall loosening enzymes (expansins) to work which break the hinds within the cellulose
Hydrogen ions also disrupt hydrogen bonds within the cellulose so the walls become less rigid and can expand as the cell takes in water.

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23
Q

Why does a shoot bend

A

Cz shaded side elongates faster than illuminated side

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24
Q

Evidence

A

Light shining on one side of the shoot causes the auxin to be transported to the shaded side, where they promote an increase in the rate of elongation making the shoot bend towards the light

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25
Q

How does the light cause redistribution

A

2 enzymes
Phototropin 1 and 2
Activity is promoted by blue light
So There’s a lot of Phototropin 1 activity on the light side, but less on dark

The gradient is the cause

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26
Q

Role of cytokinins

A

Stop the leaves of deciduous trees senescing by making sure leaf acts as a sink for phloem transport so it’s got a good supply of nutrients

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27
Q

What happens if cytokinins production drops

A

Supply of nutrients fall
Senescence begins
Followed by leaves being shed or abscission

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28
Q

Role if auxin in shedding leaves

A

Inhibit abscission by acting on cells in the abscission zone

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29
Q

What is the cerebrum

A

Largest and most recognisable part of the brain.

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30
Q

What is the cerebrum responsible for

A

The laments of the nervous system that are associated with being human including thought imaginations and reasoning and judgement

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31
Q

How many hemispheres is the cerebrum divided into

Whatvare they connected via

A

2

Corpus callosum

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32
Q

What are cerebral cortex made of

A

Outermost layer of the cerebrum folded into thin layer of Nerve cell bodies

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33
Q

What does the cerebral cortex control

3

A

Conscious thought and emotional responses

Ability to override some reflexes

Features associated with intelligence, judgement and reasoning

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34
Q

3 things cerebral cortex is subdivided into

A

Sensory areas
Association areas
Motor areas

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35
Q

Sensory areas

A

Receives impulses indirectly from the receptors

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36
Q

Association areas

A

Compare input with previous xps in order to interpret what the input means and judge an appropriate response

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37
Q

Motor areas

A

Send impulses to effectors

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38
Q

Motor area on right side of cerebral cortex control the muscular movements on the left side of the body and vice versa

A

Just saying

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39
Q

The fine control of muscular movements requires a significant level of non conscious operation

A

Just saying

40
Q

4 examples of non conscious operation

A

Muscular activities associated with responding to changes in body positions to remain. Balanced and upright

Sensory activities such as judging the positions of objects and limbs

Feedback info on muscle position tension and fine movements

Operation. Of antagonistic muscles to coordinate contraction and relaxation

41
Q

Neurones from the cerebellum carry impulses to the motor areas so that motor output to the effectors can be adjusted appropriately in relation to these requirements (level if non conscious operation)

A

Explains why we go into autopilot, they’re programmed into the cerebellum

42
Q

Role of cerebellum

A

Controls coordination of balance and fine motor movement

43
Q

Where does the cerebellum process it’s sensory info from to coordinate balance and fine movemen

A

The retina
Balance organs in the inner ear
Spindle fibres in muscles which give info about muscle tension
Joints

44
Q

What’s the hypothalamus

A

Controls the autonomic nervous system and the endocrine glands

45
Q

Medulla oblongata

A

Controls the action of smooth muscle in gut wall, and controls breathing movements and heart rate.

46
Q

Why do animals need to coordinate a vast set of responses

example

A

To stay alive
Coordinated voluntary muscle actions to rub away from predator
Fine control of balance posture and temperature regulation

47
Q

What do coordinated responses use

A

Nerves and hormones

48
Q

What does the nervous system do

A

Coordinates the actions of the body through electrical impulses

49
Q

What does it work in conjunction with

A

Endocrine system

50
Q

Whys the nervous system divided

A

Helps us describe nervous action and understand coordination processes

51
Q

What is the nervous system divided into

A

Cns

Peripheral nervous system

52
Q

What is the cns made up of

A

Grey matter non myelinated

White matter
Myelinated

53
Q

What is the peripheral nervous system made up of

A

Neurones that carry impulses into and out of the cns

54
Q

What are sensory neurones do

Motor

A

Carry impulses from the receptors to the cns

Carry impulses from cns to effector organs

55
Q

What is the motor system divided into

A

2
Somatic
Autonomic

56
Q

Somatic motor neurones

A

Carry impulses from the cns to skeletal muscles

Under voluntary or conscious control

57
Q

Autonomic motor neurones

A

Carry impulses from the cns to cardiac muscle to smooth muscle in the gut wall and to glands
Non under voluntary control

58
Q

What does autonomic mean

A

Self governing

59
Q

What’s the autonomic nervous system responsible for

A

Controlling the majority of homeostatic mechanisms

60
Q

Autonomic nervous system involved in responses associated with the stress response too

A

Just saying

61
Q

3 differences of autonomic nervous system to somatic

A

Most autonomic neurones are nonmyelinated

Autonomic connections to effectors always consist of atleast 2 neurones unlike somatic
2 neurones connect at ganglion

Autonomic motor neurones occur in 2 types. Sympathetic and parasympathetic

62
Q

Why are the sympathetic and parasympathetic nervous systems referred to as antagonistic

A

Cz when one works 5 he other opposes the action of the other

63
Q

Stimulation of the stress response EADS to ab altered balance of stimulation between the 2 systems which leads to an appropriate response.

A

Just saying

64
Q

What is the cns

A

Consists of the brain and spinal cord

65
Q

What is the peripheral nervous system

A

Consists of all of the sensory and motor neurones that are outside the central nervous system -connecting the receptor and effector to the cns

66
Q

Parasympathetic ans sympathetic stimulation occurs all the time it’s just balance of stimulation is altered

A

Just saying

67
Q

Coordinated movements require the action of the brain in sending impulses along motor neurones to voluntary muscles

A

Just saying

68
Q

What attached bones and voluntary muscles together

A

Tendons

69
Q

Whatvare tendons made of

A

Inelastic collagen which is continuous with the muscle and the periosteum

70
Q

Why does the movement of a bone at a joint require the coordinated action of atleast 2 muscles

A

Cz muscles are only capable of producing a force when they contract

71
Q

What are antagonistic muscles

A

Muscles that work in pairs opposite to each other

72
Q

What type of joint is the elbow joint

What does it need

A

Synovial

A large degree of movement

73
Q

What us synovial fluid

A

A lubricant that eases movement

74
Q

How do the biceps and triceps act

A

Antagonistically

75
Q

Nervous system controls muscle action s because motor neurones are connected to muscle cells at a neuromuscular junction

A

Just saying and check stages

76
Q

What controls the strength of contraction why

A

Brain

Cz many motor neurones stimulate a single muscle

77
Q

Wach motor neurone branches to neuromuscular junctions, causing the contractions of a cluster of muscle cells (motor unit)

The more motor units stimulated, the greater the force of contraction. This is known as gradation of response

A

What is a motor unit cluster of muscle cells

78
Q

What are muscles composed of

A

Cells that are elongated to form fibres

They contact and relax

79
Q

What do muscle cells contain

How does this produce a force on contraction

A

Actin and myosin

Basically filaments

80
Q

What are the types of muscle

A

Involuntary - smooth
Cardiac muscle
Voluntary - skeletal muscle

81
Q

Smooth muscle is innervated by neurones of the ans so contraction is non voluntary

A

Just saying

82
Q 
They don't appear streaked
Look spindle shaped
Single nucleus
Contraction slow
But muscle tires slowly
A

Just saying

83
Q

What are the 3 types of cardiac muscle

A

Ventricular
Atrial
Excitatory and conductive muscle fibre

84
Q

What do atrial and ventricular muscles contract similar to

How are they different

A

Skeletal muscles

Longer duration of contraction

85
Q

What do the excitatory and conductive fibres do

A

Contact feebly

Conduct electrical impulses and control the thymic heartbeat

86
Q

What is myogenic contraction

A

Fibres stimulating contraction without a nerve impulse

87
Q

Where do neurones of the autonomic system carry impulses to

A

Heart to regulate rate of contraction and smooth

88
Q

What does the action of voluntary muscles do

A

Leads to movement of the skeleton at the joints which miles the limbs

89
Q

How much nuclei do voluntary muscles have

A

Several

90
Q

What’s the cell surface membrane surrounding each fibre in voluntary muscles
Cytoplasm

A

Sarcolemma

Sarcoplasm

91
Q

What is a sarcomere

A

The smallest contractile unit of a muscle cell

92
Q

What organelles found in voluntary muscle cells

A

Mitochondria
Sarcoplasmic reticulum
Myofibrils - there are contractile elements which consist of of sarcomeres. Within length of protein myofillaments are actin and myosin

93
Q

Under microscope voluntary look like what?

How do they contract

A

Striped/streaked

Quickly and powerfully but fatigue quickly

94
Q

Span from one z line ti the next is known as the sarcomere

A

Just saying

95
Q

Z lines are close together during contraction
I band and h Zone are reduced

A band doesn’t change

A

Just saying

96
Q

How many protein filaments are involved in contraction

A

2

97
Q

What are the protein filaments involved in contraction

A

Thin filaments
2 strands
Made mainly of f actin
Each strand is composed of g actin subunits
Tropomyosin molecules coil around f actin to reinforce it
Troponin complex is attached to each tropomyosin
Troponin consists of 3 polypeptides
One binds to actin
One to tropomyosin
One to calcium ions

Biology unit 4 (2 decks)

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